Oil and Natural Gas Industrial Standard

of the People’s Republic of China

UP SY / T 4091 – 95U

Technical Specification of Anticorrosion for Petroleum

Engineering in Beach-Sallow Sea Issued on 18P

thP, December 1995 Effective from 1 P

stP, June. 1996

Published by: China National Petroleum Corporation

Oil and Natural Gas Industrial Standard of the People’s Republic of China

Technical Specification of Anticorrosion for Petroleum

Engineering in Beach-Sallow Sea

SY / T 4091 – 95 Compiled by: Liaohe Petroleum Exploration Bureau - Exploration and Designing Research

Institute (辽河石油勘探局勘察设计研究院) Approved by: China National Petroleum Corporation (中国石油天然气总公司)

Petroleum Industry Press

1995, Beijing

China National Petroleum Corporation Document U (95) Zhong You Ji Jian Zi Di No. 731

Notice about the approval of issuing 26 oil/natural gas Industrial standards including “Corrosion and Protection Investigation Methods and

Standards for Steel Pipeline and Tank”. For the units it may concern: The 26 oil/natural gas industrial standards (drafts) including “Corrosion and Protection Investigation Methods and Standards for Steel Pipeline and Tank” have passed the examination, and now they are approved to be the oil/natural gas industrial standards and formally published. The standard serial numbers and titles for each of them are as below: 1. SY /T 0087 – 95 Corrosion and Protection Investigation Methods and Standards for Steel

Pipeline and Tank 2. SY /T 0545 – 1995 Thermal Property Parameter Measurement for the Crude Oil’s Wax

Precipitation, Differential Scanning Calorimetry 3. SY /T 4013 – 95 Polythene Corrosion Coating Technical Standard for Underground Steel

Pipeline (Replacing SYJ 4013 – 87) 4. SY /T 4041 – 95 The installation and Acceptance Standard for Moisture Steam Generator

Specially used at Oil field (Replacing SYJ 4041 – 89) 5. SY /T 4084– 95 Beach- Shallow Sea Environment Conditions and Load Technical

Specification 6. SY /T 4085 – 95 Beach- Shallow Sea Field Oil/Gas Gathering Transmission Technical

Specification 7. SY /T 4086 – 95 The Design and Construction Technical Specification for the Pipe

Network Built on the Beach- Shallow Sea Fabrics 8. SY /T 4087 – 95 Ventilation and Air-conditioning Technical Specification for Beach-

Shallow Sea Oil Projects 9. SY /T 4088 – 95 Water Supply and Drainage Technical Specification for Beach- Shallow

Sea Oil Projects 10. SY /T 4089 – 95 Electrical Technical Specification for Beach- Shallow Sea Oil Projects 11. SY /T 4090 – 95 Power Generation Equipment Technical Specification for Beach-

Shallow Sea Oil Projects 12. SY /T 4091 – 95 Anticorrosive Technical Specification for Beach- Shallow Sea Oil

Projects 13. SY /T 4092 – 95 Insulation Technical Specification for Beach- Shallow Sea Oil Projects 14. SY /T 4093 – 95 Crane Selection and Installation Technical Specification for Beach-

Shallow Sea Oil Projects 15. SY /T 4094 – 95 Structure Design and Construction Technical Specification for Shallow

Sea Steel Fixed Platform 16. SY /T 4091 – 95 Structure Design and Construction Technical Specification for Shallow

Sea Steel Mobile Platform 17. SY /T 4096 – 95 Well Mouth Protection Device Technical Specification for Beach-

Shallow Sea Oil Field 18. SY /T 4097– 95 Structure Design and Construction Technical Specification for Beach-

Shallow Sea Sloping Aggregate Artificial Island 19. SY /T 4098– 95 Structure Design and Construction Technical Specification for Beach-

Shallow Sea Rampart Steel Mould-Concrete Artificial Island 20. SY /T 4099– 95 Design and Construction Technical Specification for Beach- Shallow

Sea Seawall 21. SY /T 4100– 95 Measurement Technical Specification for Beach- Shallow Sea Projects 22. SY /T 4101– 95 Survey Technical Specification for Beach- Shallow Sea Geotechnical

Engineering 23. SY /T 4102– 95 Valve Inspection and Installation Technical Specification 24. SY /T 4103– 95 Steel Pipeline Welding and Acceptance 25. SY /T 4104– 95 Oil Construction Project Quality Inspection and Evaluation Standard Pipeline Crossing/Spanning Project 26. SY /T 0088– 95 Cathode Protection Technical Standard for the Outer Wall of Steel Tank

Bottom The above standards are put into force from June 1, 1996 China National Petroleum Corporation December 18, 1995

Index

1. General Rules

2. General requirements

3. Surface preparation

3.1 General requirements

3.2 Surface preparation

3.3 Protection after Surface preparation

4. Overburden protection

4.1 General requirements

4.2 Protection of paint coating

4.3 Protection of spray metal

4.4 Protection of plating

4.5 Cover protection (Protection of cladding)

5. Cathode Protection

5.1 General requirements

5.2 Sacrificial anode Protection

5.3 Impressed current protection

Appendix A: Assessment criterion for anticorrosion of film coating

Appendix B: Material properties of common auxiliary anode and the geometrical shape of anode

Appendix C: Description for the wording in this specification

Additional explanation

Attachment:

Technical Specification of Petroleum Engineering in Beach-Sallow Sea Terminology

explanation

1. General Rules .0.1 The specification is defined to standardize the corrosion protection designing and installation for beach-sallow petroleum engineering steel structure, pipeline, oil and gas production plant in beach-sallow sea, and to ensure the safety and reliability, advanced technology, cost effectiveness and environment protection. 1.0.2 The specification is applicable to the designing, construction and acceptance of external surface corrosion protection for oil engineering steel structure, pipeline, oil and gas production plant in beach-sallow sea. 1.0.3 The design and construction of internal surface anticorrosion for beach-sallow sea oil engineering steel structure, pipeline, oil and gas production plant in beach-sallow sea can be according to “Recommended Practices for The Control of Internal Corrosion in Oil and Gas Transmission and Distribution Steel Pipeline” and “The construction and acceptance specification for Corrosion of Steel Vessel and the Heat Preservation Project”. The design, constructions for oil engineering reinforced concrete construction in beach-sallow sea can be carried out according to “The Corrosion specification for Reinforced Concrete Construction in seaport”. 1.04 Reference standards:

GB 1740 - 79 Measurement for the Humidity and Warm-proof of Painting Film GB 1764 - 79 Measurement for the Thickness of Paint Film GB /T 1766 - 95 Color Varnish and Varnish - Assessment Method for the Aging of Coating GB 1767 - 79 Measurement for the Weather resistance of Paint Film GB /T 1771 - 91 Color Varnish and Varnish – Measurement for the Character of

Resistance of Neutral Salt-spray GB 1865 - 80 Measurement for the Aging (artificially speedup) of Paint Film GB /T 4948 – 85 Sacrificial Anode of Aluminum-Zinc-Indium Series Alloy Sacrificial

Anode GB /T 4949 – 85 Chemically Analysis Method for the Sacrificial Anode of Aluminum

–Zinc -Indium Series Alloy Sacrificial Anode GB /T 4950 – 85 Sacrificial Anode of Zinc–Aluminum - Cadmium Series Alloy Sacrificial

Anode GB /T 4951 – 85 Chemically Analysis Method for Sacrificial Anode of Zinc–Aluminum -

Cadmium Series Alloy Sacrificial Anode GB /T 7387 – 87 Technical Condition for the Marine Type Reference Electrode

GB /T 7788 – 87 General Specification for Anodic Shield Coating of Ship and Ocean Engineering

GB /T 8923 – 88 The Corrosion Grade on Steel Surface before Paint Coating and the Derusting Grade

GB 9793 – 88 Coating of Thermal Spraying Zinc and Zinc Alloy GB 9794 – 88 Experiment Method for Coating of Thermal Spraying Zinc and Zinc

Alloy

GB 9795 – 88 Coating of Thermal Spraying Aluminum and Aluminum Alloy GB 9796 – 88 Experiment Method for Coating of Thermal Spraying Aluminum and

Aluminum Alloy GB 11373 - 89 General Rule for Surface Preparation of Thermal Spraying Metalwork GB 11375 - 89 Operational Safety of Thermal Spraying SYJ 7 - 84 Design Specification for Anticorrosion Project of Steel Pipeline and

Storage Tank SYJ 19 – 86 Application Technical Specification for Magnesium Alloy Sacrificial

Anode SYJ 20 – 86 Application Technical Specification for Zinc Alloy Sacrificial Anode SYJ 36 – 89 Design Code on Cathodic Protection with Impressed Current Way for

Buried Steel Pipeline SYJ 43 – 89 Color Paint Regulation for Pipeline and Equipment of Oil and Gas Field SY 0063 – 92 Standard Test Methods for Holiday Detection in Pipelines Coatings SY /T 0078– 93 Recommended Practices for The Control of Internal Corrosion in Oil and

Gas Transmission and Distribution Steel Pipelines SY /T 0079– 93 Standard of Coal Tar Enamel External Protective Coating for Buried

Steel Pipeline (SY/T 0379-98) SYJ 4007 – 86 Specification for Steel Surface Preparing Before Paint Coating SYJ 4047 – 90 Construction and Acceptance Code for Epoxy Coal Bitumen

Anticorrosion of Buried Steel Pipeline SY /T 4059 – 93 The Construction and Acceptance Specification for Corrosion of Steel

Vessel and the Heat Preservation Project SY /T 4806 – 92 Recommended Practices for Planning, Design and Construction for

Marine Fixed Platform Helipad JTJ 228 – 87 Specification for Construction Anticorrosion of Seaport Reinforce

Concrete 1.0.5 As far as the design, construction and acceptance of beach- shallow sea petroleum engineering anticorrosion is concerned, in addition to this specifications, it is required to comply with the applicable national standards (specifications).

2. General requirements 2.0.1 Anticorrosion design

2.0.1.1 Anticorrosion design of petroleum engineering in beach-shadow sea must be carried out by the qualified anticorrosion design unit, and shall observe the applicable regulations and standards of Chinese government.

2.0.1.2 Designing of anticorrosion for the external surface of steel structure, pipeline, oil and gas production plant for atmospheric zone, splash zone, continuous immersion zone and beach zone shall be performed respectively. The adopted anticorrosion measure shall satisfy the requirement of application, and should match the other measures such as heat preservation, etc.

2.0.1.3 Anticorrosion of atmospheric zone shall adopt coating protection or metal spraying protection; if the structure is complicate, plating protection is recommended.

2.0.1.4 Anticorrosion of splash zone shall adopt coating protection, metal spraying protection or plating protection, when necessary, reinforced corrosion protection by organic coating, resin slurry, concrete or alloy anticorrosion measures could be adopted.

2.0.1.5 Anticorrosion for continuous immersion zone shall adopt the combined Cathode Protection and coating, or adopt cathode protection only. When cathode protection is used, anticorrosion measure during construction phase shall be considered.

2.0.1.6 Anticorrosion of beach zone shall adopt the combined Cathode Protection and coating. 2.0.2 Anticorrosion construction

2.0.2.1 Anticorrosion construction for all kinds of steel structure, pipeline, oil and gas production plant for petroleum engineering in beach-shadow sea, shall be performed by qualified anticorrosion construction unit. 2.0.2.2 facilities and materials for anticorrosion engineering must have the proven industry application or have related demonstration testing, and have quality certification or ex factory quality inspection report, re-examination of quality is required when necessary. 2.0.2.3 The quality inspection of anticorrosion construction should be carried out by the inspectors who are familiar with concerned standards (specifications). 2.0.2.4 Corrosion protection construction shall have safety protection measures. 2.0.3 Acceptance of corrosion protection construction 2.0.3.1 Corrosion protection construction cannot be put into use without hand over acceptance. 2.0.3.2 the hand over documentation of corrosion protection construction shall accurate and complete. 2.0.3.3 In case of any non-conformance with design and the requirements of this specification, rework is required to meet the said requirements before acceptance. Rework records should be kept together with the hand over acceptance documentation. 2.0.4 The anticorrosion requirements for structure design

2.0.4.1 shall reduce the steel surface area that needs coating in atmospheric zone, structure design should be easy for anticorrosion installation.

2.0.4.2 shall reduce the steel surface area in splash zone, cross connections such as “T” type,

“K” type and “Y” type are not suitable for splash zone, and welded joints shall be avoided. 2.0.4.3 Structure design in continuous immersion zone shall be convenient for implementing

anticorrosion measure. 2.0.4.4 continuous welding is required to assembly metal components.

3. Surface preparation 3.1 General requirements

3.1.1 Prior to coating application on steel structures, pipeline, oil and gas production plant, it is required to conduct surface preparation. Coating application can only be carried out after surface preparations meets the specific requirements. 3.1.2 Derusting quality of steel surface jetting or impeller blasting (Sa), manual and power tool derusting (St), flame derusting (FI) shall meet the specifications of “The Corrosion Grade on Steel Surface before Paint Coating and the Derusting Grade”. Quality requirements of chemical derusting (Be) is: no visible grease and oil sludge on steel surface, oxide skin after acid cleaning, rusty and individual remaining mark of painting can be removed by manual or mechanical method, but the final surface shall be the original metal, without repeated corrosion.

3.1.3 surface roughness, which has met the quality grade of jetting or impeller blasting, shall meet design requirement.

3.1.4 Chemical treatment such as conversion type, stable type and penetration type is not suitable for surface preparation for main steel structure, oil and gas production plant of important engineering projects. 3.1.5 Surface preparation for steel structure, pipeline, oil and gas production plant, which are critical and vulnerable for strong corrosion, but with difficult access for maintenance, should be applied with a higher level according to actual conditions. Minimum grade for different paint surface preparation shall comply with table 3.1.5.

Minimum grade for different paint surface preparation Table 3.1.5 Minimum grade for Surface preparation

Paint type Spray or impeller

blasting

Manual or power tool

derusting

Inorganic zinc rich paint Not permitted

Bakelite lacquer, Epoxy asphalt paint St3

Alkyd resin paint St2

Non

-unc

tuou

s

pain

t

Other types paint

Sa2

Not permitted

Unctuous paint Sa2 St2

3.1.6 The minimum grade for spray metal surface preparation is , surface roughness shall not

be less than 60 µm. 3.1.7 Surface preparation process shall be equipped with safety protection measures, and environment protection should be considered.

3.2 Surface preparation

3.2.1 Surface cleaning 3.2.1.1 prior to the derusting, it is required to clean the steel surface with proper cleaning method

based on the character of pollutants, degree of pollution and the shape and dimension of derusting material. 3.2.1.2 prior to surface cleaning, it is required to clean and remove the welding residues, burrs and welding splashes on steel surface 3.2.1.3 Surface cleaning shall remove all visible oil, grease, dusty, lubricant and others dissoluble feculences on steel surface. 3.2.1.4 Surface cleaning method and requirement shall comply with “Specification for Steel Surface Preparing Before Paint Coating”. Application range for different cleaning method is as table 3.2.1.

Application range for different cleaning method Table 3.2.1

Cleaning method Application range Remarks

Solvent cleaning (such as industrial

gasoline, solvent gasoline,

chloroacetylene, trichloroethylene ，

etc)

Remove oil, grease, dissoluble

feculence and dissoluble

coating

Use nondestructive solvent for the

coating if want to remain the

original coating, regularly replace

the solvent and the rag

Alkaline cleaner cleaning Remove saponifiable coating,

oil, grease, feculence

Fully wash after cleaning, and do

passivation

Emulsion cleaning Remove oil, grease and other

feculence

Fully wash the residual from steel

surface after cleaning

Steam deoiling, can add solvent when

necessary, such as trichloroethylene,

methylene chloride, etc

Remove oil, grease and other

feculence. Also can remove

coating when have enough

pressure and temperature

Original coating can be corroded or

damaged during cleaning, fully

wash out the residual from surface

after cleaning

Note: special attention to clean the gaps and rivet areas completely during cleaning. 3.2.2 Surface derusting 3.2.2.1 Derusting by tooling, jetting (impeller blasting), and acid cleaning shall comply with

“Specification for Steel Surface Preparing Before Paint Coating”. 3.2.2.2 Surface derusting should use dry jetting (impeller blasting) derusting. Compressed air

for dry spray facility shall be dry and clean, free from moisture and oil feculence. Inspection method for the cleanness of compressed air is: put a piece of white cloth or white paint plate to compressed air flow for one minute, by visual inspection, the surface should be clean, without oil, water, and other pollution.

Spray derusting is not permitted when temperature on surface drops to 3 above dew point or relative humidity is larger than 85%.

3.2.2.3 Every process of chemical treatment shall be carried out continually without stop. Metal surface after passivation treatment shall be dried immediately.

3.3 Protection after surface preparation 3.3.1 a primer shall be painted on the treated steel surface in time (no more than 6 hours). 3.3.2 Temperature on steel surface shall be higher than dew point by 3, otherwise, proper measure is necessary. 3.3.2.1 When the treated steel surface is polluted again, new treatment is required.

4. Overburden (coating) protection 4.1 General requirements

4.1.1 Overburden could be paint coating, cover coating, spray metal and plating. 4.1.2 The overburden type, related steel surface preparation grade and construction method shall be determined according to comprehensive study on the steel structure, design life cycle of pipeline, oil and gas plant, environment medium, construction condition, working period and economic factors and so on. 4.1.3 The overburden material shall have advantages of adhesive force, anticorrosion, impact resistance and temperature resistance. Material’s property should pass the inspection, and have inspection report issued by certified inspection organization. Supplier shall provide product instruction, ex factory certification and other technical data.

4.2 Protection of paint coating 4.2.1 Selection of paint

4.2.1.1 Paint selection shall be based on the environment condition, paint performance, life cycle, the possibility of construction and maintenance, technical & economic assessment, and other factors. Long-term anticorrosion paint, priming, intermediate coat and surface paint should match each other. 4.2.1.2 Paint used in atmospheric zone shall have advantage of weather resistance. The overall

evaluation grade of weather resistance test (according to “Measurement for the Weather resistance of Paint Film”) for paint more than one year shall be over grade “1” (according to “Color Varnish and Varnish - Assessment Method for the Aging of Coating”).

4.2.1.3 as for the paint coating used for splash zone, weight corrosion protection coating system shall be applied when design life cycle is more than 10a; in general, solvent-free thick paste paint and high solid paint are used, also the compound layer of paint and glass fiber shall be considered, the selected paint shall meet below requirements:

(1) Resistance of salt-spray 4000h (test according to “Color Varnish and Varnish – Measurement for the Character of Resistance of Neutral Salt-spray ”);

(2) Aging resistance 2000h (test according to “Measurement for the Aging (artificially speedup) of Paint Film”);

(3) Humidity and heat-resistance 4000h (test according to “Measurement for the Humidity and Warm-proof of Painting Film”).

After salt-spray, aging, and humidity and hear proof test, anticorrosion grade of paint shall achieve grade 1 or grade 2 of the Appendix A: “Assessment criterion for anticorrosion of film coating” of this specification. At the same time, paint should have good impact resistance and good wear resistance, and can be suitable for the changes of dry and wet conditions.

4.2.1.4 Paint used for continuous immersion zone and beach zone shall match with cathode protection, have good ability to resist cathodic peeling and alkali resistance. Cathode protection characteristics of paint shall meet the following requirements: When paint sample corresponding to Cu/CuSoB4B , electrical potential of reference electrode

should not be negative to –1.10V, the paint coating shall be free from air bubble and peeling. 4.2.1.5 anti pollution paint coating shall be applied for continuous immersion zone. 4.2.1.6 When special concerns are required, paint should suit for related application condition.

4.2.2 Paint coating protection design 4.2.2.1 Coating system for atmospheric zone can be selected according to table 4.2.2-1. 4.2.2.2 Coating system for splash zone can be selected according to table 4.2.2-2. 4.2.2.3 Coating system for continuous immersion zone can be selected according to table 4.2.2-3. 4.2.2.4 Coating systems for submarine pipeline and riser can be selected according to table

4.2.2-4. Pipeline coating for beach zone can be determined by referring to the continuous immersion zone coating of table 4.2.2-4, and can be selected according to “Standard of Coal Tar Enamel External Protective Coating for Buried Steel Pipeline” and “Design Specification for Anticorrosion Engineering of Steel Pipeline and Storage Tank”.

4.2.2.5 high temperature resistance coating shall be applied for facilities and steel pipelines with service temperature above 90; other covers such as spray plating, enamel or ceramic paint can be considered also. 4.2.2.6 Color of surface paint of steel structure can be selected by referring to table 4.2.2-5; Color of surface paint of pipeline, equipment and oil and gas production plant on platform could be selected according to “Standard for Painting Color of Pipelines and Equipments in Oil-gas Field”.

Paint coating system for atmospheric zone Table

4.2.2-1 Paint depth

(µm) Design life

cycle (a) Matching paint

(1) (2)

Priming Zinc rich paint (Inorganic or organic zinc rich paint) 40 75

10~20

Surface

I

II

III

Ⅳ

Chlorinated rubber paint

Polyurethane paint

Acrylic resin paint

Vinyl resin paint

280 250

Priming Zinc rich paint (Inorganic or organic zinc rich paint) 40

Surface

I

II

III

Chlorinated rubber paint

Polyurethane paint

Vinyl resin paint

100

Type 1

I

II

III

Rubber resin paint (Chlorinated rubber paint or

Chlorosulphonated polyethylene paint)

Vinyl resin paint

Acrylic resin paint

180~220

Type 2

I

II

III

Ⅳ

Oil paint

Bakelite lacquer

Alkyd resin paint

Epoxy resin paint

190~230

Type 3 Polyurethane paint 220~240

5~10

Same type m

atched primer and surface

Type 4 Epoxy resin paint 240~260

Same type m

atched

primer and surface

I

II

III

Ⅳ

Oil paint

Bakelite lacquer

Alkyd resin paint

Epoxy resin paint

170~190 <5

Others 200

Paint coating system for splash zone Table 4.2.2-2

Paint depth

(µm)

Design

life cycle

(a)

Matching paint

(1) (2)

Priming Zinc rich paint (Inorganic or organic zinc rich paint) 40 75

Intermediate I

II

Epoxy resin paint

Polyurethane paint 310 270

Type

1

Surface

I

II

III

Chlorinated rubber paint

Vinyl resin paint

Acrylic resin paint

130 130

Priming I

II

Epoxy resin paint

Polyurethane paint 375

Type

2 Surface

I

II

III

Chlorinated rubber paint

Vinyl resin paint

Acrylic resin paint

65

10~20

Type

3

Same type

matched

primer and

surface

I

II

Epoxy coal tar asphalt paint

Polyurethane coal tar asphalt paint 450

Priming Zinc rich paint (Inorganic or organic zinc rich paint) 40 75

Intermediate

I

II

III

Epoxy resin paint

Polyurethane paint

Chlorinated rubber paint

180 135 Type

1

Surface

I

II

III

Chlorinated rubber paint

Vinyl resin paint

Acrylic resin paint

65 65

Priming

I

II

III

Epoxy resin paint

Polyurethane paint

Chlorinated rubber paint

230

Type

2

Surface

I

II

III

Chlorinated rubber paint

Vinyl resin paint

Epoxy resin paint

115

5~10

Type

3

Same type

matched primer

and surface

I

II

III

Ⅳ

Chlorinated rubber paint

Vinyl resin paint

Epoxy coal tar asphalt paint

Polyurethane coal tar asphalt paint

300

350

Priming I

II

Epoxy resin paint

Polyurethane paint 165 <5

Type

1 Surface

I

II

III

Chlorinated rubber paint

Chlorosulphonated polyethylene paint

Vinyl resin paint

70

Type

2

Same type

matched

primer &

surface

I

II

Epoxy resin paint

Polyurethane paint 240

Note: column I, II…in table for matching paint and paint depth (1), (2) can choice either one.

Paint coating system for continuous immersion zone Table 4.2.2-3 Paint depth

(µm) Design

life cycle

(a)

Matching paint (1) (2)

Priming Zinc rich paint (Inorganic or organic zinc rich paint) 40 75

Intermediate I

II

Epoxy resin paint

Polyurethane paint 310 270

Type 1

Surface

I

II

III

Chlorinated rubber paint

Vinyl resin paint

Epoxy resin paint

120 130 10~20

Type 2

Same type

matched

primer and

surface

I

II

Epoxy coal tar asphalt paint

Polyurethane coal tar asphalt paint 450

Priming Zinc rich paint (Inorganic or organic zinc rich paint) 40 75

Intermediate

I

II

III

Epoxy resin paint

Polyurethane paint

Chlorinated rubber paint

175 185

Type 1

Surface

I

II

III

Chlorinated rubber paint

Vinyl resin paint

Epoxy resin paint

60 65 5~10

Type 2

Same type

matched

primer and

surface

I

II

III

Ⅳ

Chlorinated rubber paint

Vinyl resin paint

Epoxy coal tar asphalt paint

Polyurethane coal tar asphalt paint

300

300

350

350

<5 Same type matched

primer and surface

I

II

III

Ⅳ

Chlorinated rubber paint

Vinyl resin paint

Epoxy coal tar asphalt paint

Polyurethane coal tar asphalt paint

220

220

230

250

Note: column I, II…in table for matching paint and paint depth (1), (2) can choice either one.

Paint coating system for submarine pipeline and riser Table 4.2.2-4

Environment zone Paint type Paint depth (µm)

Splash zone Vulcanizate

Nickel copper alloy covering

10~25

3~5

Atmospheric zone Chlorinated rubber, Epoxy resin and Vinyl resin paint system used

on zinc rich paint, see table 4.2.2-1 0.3~0.5

Continuous

immersion zone

Coal tar bituminous enamel *

Bituminous enamel *

Asphalt enamel *

Epoxy resin

Epoxy coal tar asphalt

4~5

5~6

15~20

0.3~0.5

0.5

Note: Paint with * is usually used together with concrete weight-coating to prevent mechanical wearing.

Painting Color for marine platform framework Table 4.2.2-5 Structural components name Color Structural components, pole, board, truss，ventilation structure, deck, floor

Orange, gray or black, etc

Bridge Silvery white Bracket of pavement and stair Yellow Bluster Zinc plating, gray Grating Zinc plating, gray Inner wall of blocking Offwhite Outside of blocking ceiling Aqua Fire extinguisher and safety facility Red Dangerous barrier Yellow and black alternate stripe Jib crane frame, beam with single rail, pulley Dark gray or dark green, middle ring is yellow Communication tower Orange yellow at top and bottom, Orange

yellow and white alternate stripe at middle, width of stripe is 1/7 of tower’s height

Helipad Should comply with “Recommended Practices for Planning, Design and Construction for Marine Fixed Platform Helipad”

4.2.3 Painting

4.2.3.1 Surface preparation shall be performed prior to painting; Surface preparation grade and quality requirement shall comply with chapter 3 of this specification.

4.2.3.2 the painting method shall be selected according to the physical characteristics of the paint, construction condition, painting requirement and surface conditions to be painted; painting methods include brush painting, roll painting and spray painting; also it is recommended to follow the instructions of manufacturer(s).

4.2.3.3 painting condition shall be controlled strictly; painting is not allowed under following conditions:

(1) Steel surface having been treated with surface preparation is corroded or polluted again; (2) Temperature on steel surface is lower than dew point by more than 3 of ambient

temperature or air relative humidity is more than 85%; (3) Steel surface is wet by moisture or wet by splash; (4) When applying epoxy paint, environment temperature for painting is lower than stated

temperature on paint technical instruction. (5) The required painting operation conditions cannot be fully assured.

4.2.4 Quality inspection 4.2.4.1 Shall conduct the quality inspection on the surface preparation before the painting,

painting can only be started after conformance. 4.2.4.2 prior to painting, it is important to ensure painting equipments, environment and paint

type, etc shall comply with painting technical conditions. 4.2.4.3 When painting, the number of painting pass and painting thickness shall comply with

designed requirements, and need to measure the painting thickness in time (can measure with

wet film thickness meters such as tooth type, disk type or plank type). 4.2.4.4 in case of defects during painting such as missed painting, sag, wrinkle, pores, crack and

so on, remedial action shall be taken immediately. Shall check the previous painting pass before next painting pass is applied; interval time of painting shall meet with design requirements.

4.2.4.5 When reinforced materials are required for the target structure, the connection performance between reinforced materials and paint film shall satisfy design requirements.

4.2.4.6 the coating characteristics shall be inspected after painting, the contents of inspection shall include:

(1) Visual inspection: coating thickness shall be even, the surface shall be free from missing painting, pores, air bubble, peeling and pollution.

(2) Thickness inspection: measure the dry film thickness with magnetic nondestructive thickness meter according to “Measurement for the Thickness of Paint Film”, dry film thickness that is larger than or equal to design thickness should account for more than 90% of total inspection quantity, the dry film thickness of the other inspected points also shall not be less than 90% of design thickness. The number of inspection point should meet with design requirements.

(3) Missing points inspection: conduct inspection according to “Standard Test Methods for Holiday Detection in Pipelines Coatings”, the quality standard is no missing dots. Inspection point quantity shall meet with design requirements.

(4) Adhesive force inspection: when there is a doubt, it is necessary to inspect adhesive force according to Appendix 1 inspection method of “Construction and Acceptance Code for Epoxy Coal Bitumen Anticorrosion of Buried Steel Pipeline” .

(5) Coating application inspection: Coating application inspection can be conducted along with adhesive force inspection according to “Standard of Coal Tar Enamel External Protective Coating for Buried Steel Pipeline”. Coating application shall meet with design requirements.

4.2.4.7 if coating quality fails to meet the following standards or design requirements, rework is required according to actual situations. Coating damage caused by inspections shall be corrected immediately.

4.2.5 Acceptance inspection 4.2.5.1 Acceptance inspection shall be performed after stated coating curing period 4.2.5.2 during acceptance inspection, the following documents are required:

(1) ex factory certificates of raw materials, technical documentation for alternative materials and other quality inspection documentations;

(2) Original design documents and design change notes; (3) Surface preparation and painting engineering records; (4) Repair and rework records.

4.3 Protection of spray metal

4.3.1 Selection of material 4.3.1.1 Spray metal layer shall be applied together with confined painting usually. 4.3.1.2 Generally, materials used for spray metal are zinc, aluminum and the alloy. Performance

of the materials shall comply with “Coating of Thermal Spraying Zinc and Zinc Alloy” and

“Coating of Thermal Spraying Aluminum and Aluminum Alloy”. 4.3.1.3 The type selection of spraying metal layer shall consider performance of spray layer’s

anticorrosion, environment, construction condition, technical & economic assessment, and other factors. Anticorrosion performance and impact resistance shall be verified by related testing.

4.3.2 Design of protection for spray metal layer 4.3.2.1 Spray metal layer of atmospheric zone could be selected according to table 4.3.2-1. 4.3.2.2 Spray metal layer of splash zone, continuous immersion zone could be selected

according to table 4.3.2-2. 4.3.2.3 Seal and high temperature treatment for spray metal layer shall satisfy “Coating of

Thermal Spraying Zinc and Zinc Alloy” and “Coating of Thermal Spraying Aluminum and Aluminum Alloy”.

Spray metal layer of atmospheric zone Table 4.3.2-1

Design life cycle T (a) Depth of spray metal layer (µm) Depth of seal spray layer (µm)

Zinc 250 T>20

Aluminum 200 30~60

Zinc 150 10<T<20

Aluminum 100 30~60

Note: Can select either of spray zinc or spray aluminum in this table.

Spray metal layer of splash zone, continuous immersion zone Table 4.3.2-2 Design life cycle T (a) Depth of spray metal layer (µm) Depth of seal spray layer (µm)

Zinc 300 T>20

Aluminum 250 60~100

Zinc 150 10<T<20

Aluminum 150 60~100

Note: Can select either of spray zinc or spray aluminum in this table.

4.3.3 Spraying 4.3.3.1 Prior to spraying, it is required to conduct the surface preparation, grade of surface

preparation and quality shall comply with chapter 3 of this specification and “General Rule for Surface Preparation of Thermal Spraying Metalwork”.

4.3.3.2 Spraying method could use air spraying or electric spraying. Spray operation shall comply with “Coating of Thermal Spraying Zinc and Zinc Alloy”, “Coating of Thermal Spraying Aluminum and Aluminum Alloy” and “Operation safety of Thermal Spraying”.

4.3.3.3 Spraying operation for seal paint layer shall be done as soon as possible after spray metal when necessary.

4.3.4 Quality inspection 4.3.4.1 Shall inspect the quality of the surface preparation before the spraying, spraying only

can be started after conformance. 4.3.4.2 Prior to spraying, it is necessary to check if spraying equipment, environment and

spraying type and so on comply with spraying technical conditions. 4.3.4.3 Shall inspect the spraying characteristics after spraying, contents include:

(1) Visual inspection: according to “Experiment Method of Thermal Spraying Zinc and Zinc Alloy”. Spraying layer shall be even, and free from air bubble，bubble，big droplet，cracks, falling pieces and other defects that may affect the application performance.

(2) Thickness inspection: inspect the thickness of spray layer according to “Experiment Method of Thermal Spraying Zinc and Zinc Alloy”. Measured thickness value shall not be less than 75% of design thickness. When it is required to inspect the thickness of diffusion layer, conduct the inspection according to “Experiment Method of Thermal Spraying Aluminum and Aluminum Alloy”, inspection result shall meet with the requirement of the specification.

(3) Porosity inspection: inspect with test paper that is soaked in the solution of 10g/L potassium ferricyanide and 20g/L sodium chloride. Put the test paper on inspected surface for about 5 minutes to 10 minutes, if the blue spots shown in test paper are less than 3 points/cmP

2P, the result is satisfactory. Inspected areas shall not be less than 5% of total

areas. (4) Connection performance: inspection method and performance requirement shall comply

with “Coating of Thermal Spraying Aluminum and Aluminum Alloy”. 4.3.4.4 as for quality inspection of seal coating layer, please refer to paragraph 4.2.4.6 of this

specification. 4.3.4.5 if the quality of spraying layer cannot meet design requirements, it is required to

perform the remedial spray or redo spraying. If the quality of seal coating layer cannot meet design requirements, second treatment is necessary. Shall repair the damaged part caused by inspection.

4.3.5 Hand over acceptance inspection As for the hand over acceptance inspection of spraying metal layer, please refer to item 4.2.5 of

this specification.

4.4 Protection of plating 4.4.1 Plating layer could be cathodic plating layer or anodic plating layer. Plating layer can be

used together with cover layer. Plating and overburden on the surface of structure or equipment could adopt electric plating, hot dip coating, chemical plating, etc.

4.4.2 Surface preparation before plating, treatment during and after plating shall comply with concerned national standard (specification).

4.4.3 quality inspection for plating layer shall be implemented according to applicable national standards (specification). Inspection items shall include visual inspection, thickness, connection performance, porosity, etc.

4.5 Cover protection (Protection of cladding) 4.5.1 Cladding could be steel abrasive wear resistance plate, nickel-copper alloy or copper-nickel

alloy, vulcanizing polychloroprene rubber, thick film organic coating, resin mortar, concrete, etc.

4.5.2 Surface preparation of cladding, quality requirement of cladding and maintenance measure shall comply with applicable national standards (specification).

4.5.3 quality inspection of cladding layer shall be implemented according to applicable national standards (specification). Inspection items shall include visual inspection, thickness, mechanical strength, etc.

5. Cathode Protection

5.1 General requirements

5.1.1 Cathode protection could adopt sacrifice anode, impressed current, or combination of both. 5.1.1.1 When impressed current is adopted, it is recommended to avoid over protection and bad

impact to adjacent facilities; protection system shall have sufficient mechanical strength. 5.1.1.2 insulation flange shall be installed when submarine pipeline is connected to platform

and enters the station. 5.1.1.3 As for cathode protection design for beach zone, please refer to “Design Code on

Cathodic Protection with Impressed Current Way for Buried Steel Pipeline” and “Application Technical Specification for Magnesium Alloy Sacrificial Anode”.

5.1.2 When evaluating the cathode protection effect, it is required to comply with below rules: 5.1.2.1 Protection potential rule:

(1) In general condition, protection potential of structural components and pipeline shall meet the requirements of table 5.1.2.

(2) When protection current is applied, the minimum variant occurred at cathode potential shall not be less than 300mV.

Protection potential of steel Table 5.1.2

Reference electrode Cu/ CuSOB4 B Ag/ AgCl Zn Steel

Protection potential (V) Minimum -0.85 -0.80 +0.25

Steel in aerobic environment Maximum -1.10 -1.05 +0.00 Minimum -0.95 -0.90 +0.15

Steel in anaerobic environment Maximum -1.10 -1.05 +0.00 Minimum -0.85 -0.80 +0.25 Very high strength steel

δ s> 700MPa Maximum -1.00 -0.95 +0.10 5.1.2.2 Visual inspection rule: All results obtained by all kinds of visual inspection methods (such as diver inspection or

touch, physical measurement, pictures or television scanning, etc) shall indicate the corrosion status do not surpass allowed limit of life cycle.

5.1.2.3 Test block rule:

Corrosion type and corrosion rate result from every test block shall be limited to allowable range.

5.1.3 Protection current density shall be determined according to the environment, surface conditions of object to be protected. The choice of protection current density shall be the values under similar conditions or shall be based on the testing results.

Protection current density of steel with coating iBc Bcould also be calculated according to formula 5.1.3:

iBc B= iBb B * CBb B (5.1.3) Where, iBc B ----- Protection current density of steel with coating, mA/mP

2P,

i BbB----- Protection current density of bare steel, mA/mP

2P,

C BbB----- Coating damage coefficient, see table 5.1.3.

Coating damage coefficient C Bb B/ % (forecast life cycle 25a) Table 5.1.3 Coating type Initial value Intermediate value Final value

Thick film pipeline paint 1 10 20 Vinyl system 2 20 50

Epoxy coal tar bitumen 2 20 50 Epoxy resin (thick film) 2 20 50

5.1.4 Shall collect the following environment data when designing cathode protection system:

(1) Soil temperature of beach-shallow sea zone, depth of frozen earth, water content, resistivity, PH value, etc.

(2) Temperature, oxygen level, resistivity, PH value and others of continuous immersion zone seawater and submarine soil;

(3) Seawater ice/freeze status; (4) Seawater flow rate, mud, sand and suspended substance in seawater; (5) bacteria growth and vegetation; (6) Environment pollution status; (7) The conditions of adjacent facilities and structural components; (8) Disturbance current; (9) Electric insulation and electrical connection.

5.2 Sacrificial anode protection

5.2.1 Anode material 5.2.1.1 Anode material can be zincic, aluminous and magnesian alloy. Magnesian alloy is only

used in the place of higher driving voltage, and with easy access to replace anode. 5.2.1.2 Selected anode materials shall be subject to electrochemistry performance test under

similar environment, and with certification of ex factory and inspection certificate (inspection certification, product instruction, result of anode electrochemistry performance test, and result of anode destructive test, etc).

5.2.1.3 Shall choose anode material according to the environment, application condition, protection requirement. When working temperature of anode does not surpass 50, could adopt zinc anode and aluminum anode; when working temperature of anode is more than 50, shall use aluminum anode.

5.2.1.4 Chemical compositions and electrochemistry performance of sacrificial anode and its test method shall comply with “Sacrificial Anode of Aluminum-Zinc-Indium Series Alloy Sacrificial Anode”, “Chemically Analysis Method for the Sacrificial Anode of Aluminum –Zinc -Indium Series Alloy Sacrificial Anode”, “Sacrificial Anode of Zinc–Aluminum - Cadmium Series Alloy Sacrificial Anode” and “Chemically Analysis Method for Sacrificial Anode of Zinc–Aluminum - Cadmium Series Alloy Sacrificial Anode”.

5.2.1.5 Appearance quality, quality deviation, dimensional tolerance of sacrificial anode shall meet with the design requirements. 5.2.2 Design calculation

5.2.2.1 Protection current: Total protection current I shall not be less than the calculated value according to formula

5.2.5-1: I=ΣSBpBi BpB + nc (5.2.5-1) Where, SBp B ----Area of every protection construction, mP

2P;

iBpB ----Protection current density, A/mP

2P;

n ----Number of oil well; c----Additional current for each oil well in order to protect oil well casing under

mud level, A (usually is 1.5A ~ 5.0A for each oil well). Protection area shall include the area of steel structure and pipeline of continuous immersion

zone, beach zone, water string area, and the area of steel structure under water and in mud that is electrically connected to protected construction. Protection area for different protection current density shall be calculated separately.

Selection of protection current density shall meet with paragraph 5.1.3 of this specification. 5.2.2.2 Output current of anode: Anode output current IBaB (A) shall be calculated as formula 5.2.2-2: (5.2.2-2) Where, ∆v ----Drive voltage, V; RBaB ----Circuit resistance (usually is resistance between anode and medium), Ω.

Resistance between anode and medium R BaB is confirmed by resistivity of surrounding environment medium and anode geometric shape, could be calculated according to formula 5.2.2-3, 5.2.2-4 and 5.2.2-5: Long and thin anode: (5.2.2-3)

Where, ρ ---- Resistivity of medium, Ω.cm; l ----Length of anode, cm; r ----Equivalent radius of anode, cm; a ----Section area of anode, cmP

2P.

Distance between anode and steel structure surface is lager than 30cm.

Plate shape anode: (5.2.2-4)

Where, s ---- Average length of anode dimension, cm, ; b ----Length of anode, cm; c ----Width of anode, cm.

Other shape anode: (5.2.2-5)

Where, A----Surface area of exposed anode, cmP

2P.

5.2.2.3 Usage of anode:

Usage of anode could be calculated according to formula 5.2.2-6: (5.2.2-6)

Where, W ----Net weight of anode, kg; T ----Effective life of anode, a; EBx B ----Consumption rate of anode, kg/(A.a); IBmB ----Average output current of every anode within its life, A; µ ---- Usage coefficient, shall be confirmed by consumption quantity of anode

material when remaining anode material cannot generate the required current. Could use the following usage coefficient value: Long and thin anode: 0.90 ~ 0.95; Bracelet anode: 0.75 ~ 0.80; Other shape anode: 0.75 ~ 0.85.

5.2.3 Distribution mode of anode Distribution mode of anode shall be favorable to the distribution of current; the distribution mode shall be even in horizontal and vertical direction based on the construction shape and required value of protection current. 5.2.4 Installation of anode

5.2.4.1 Shall inspect anode materials, facilities for construction and material before installation of anode, and check if they satisfy the design requirements.

5.2.4.2 Anode must be firmly fixed on protected body, and shall be connected in short circuit to protected body; the recommended connection method shall be the welding method to large extent.

5.2.4.3 When installing sacrificial anode by submarine electric welding, the welding shall be operated by qualified submarine welder.

5.2.4.4 Shall inspect anode according to the following requirements after installation: (1) Visual inspection: Installation mode and position of anode shall meet with the

specifications of design documentation. Painting and pollution on surface of anode are forbidden.

(2) Electrical connection performance: shall have reliable electrical connection between anode and protected body.

(3) Mechanical strength: anode, anode core and anode rack shall have sufficient strength. (4) Welding quality: all welding seams shall meet with the requirements of structure welding,

and shall be free from burr, sharp edge; the connection with base material shall be smooth and solid (no missed weld).

5.2.5 Protection system of sacrificial anode Protection system of sacrificial anode shall be subject to acceptance inspection. The acceptance inspection data shall include anode installation as built drawing, anode certification of ex factory, anode material inspection result report, original design documentation and design change notes, anode installation record, test report of protection performance. 5.2.6 Testing of protection performance Testing of protection performance for sacrificial anode system shall be carried out within one year when the system is put into use; this shall be implemented according to the requirements stated in paragraph 5.1.2 of this specification. Measured result shall satisfy the design requirements.

5.3 Impressed current protection

5.3.1 Power supply facility 5.3.1.1 Selected facilities shall have certification of ex factory and inspection report (inspection

certification, product instruction, facility performance inspection report, circuit diagram, facility spare part list, etc).

5.3.1.2 Selected power supply facilities shall have the following performance: (1) High reliability; (2) Easy for maintenance; (3) Long life cycle; (4) Adaptable to environment; (5) Adjustable for output current, voltage; (6) Equipped with the protection devices for over load protection, lightning-proof, failure.

5.3.2 Auxiliary anode materials 5.3.2.1 Auxiliary anode materials shall choose the materials with low consumption power, large application range of surface working current density, good polarization performance, large adaptability to environment, rich source, easy to manufacture, and shall be cost effective and reasonable.

5.3.2.2 Selected auxiliary anode materials shall pass electrochemistry performance test under similar environment, and with certification of ex factory and inspection data (inspection certification, product instruction, report of anode performance inspection and test, etc). 5.3.2.3 Auxiliary anode could use plumbum-silver alloy anode, high silicon iron, platinum anode along with various base material, graphite anode and so on. Electrochemistry performance of auxiliary anode shall satisfy the application requirements. Performance of common auxiliary anode shall meet the requirements of Appendix B in this specification. 5.3.3 Insulation shield materials 5.3.3.1 Selection of insulation shield materials shall consider anode output current, seawater resistivity, geometrical shape of component, relative position of other anodes and destructive function of environment factors and so on, and shall consider the life cycle and aging of shield material. Performance index of insulation shield materials shall meet the requirements in “General Specification for Anodic Shield Coating of Ship and Ocean Engineering”.

5.3.3.2 Selected shield materials shall pass test under similar environment, and with certification of ex factory and inspection data (inspection certification, product instruction, report of anode performance inspection and test, etc).

5.3.3.3 Shield material could use epoxy resin, polyester resin with reinforced fiberglass, polythene plastic, etc.

5.3.4 Design of protection system

5.3.4.1 Calculation of design: (1) Protection current I shall be calculated according to formula 5.3.4-1: I=k ΣSBpPB

. Pi Bp B + nc (5.3.4-1)

Where, k -----Shield coefficient, depend on the component’s shape of metalwork in medium

and the distribution of anode, usually select 1.10 ~ 1.25. (2) Voltage of direct current power supply V shall be calculated according to formula 5.3.4-2

and 5.3.4-3:

V = IRBt B (5.3.4-2) R BtB = RBLB + RBc B + RBwB + RBpmB (5.3.4-3)

Where, V -----Voltage of direct current power supply required for protection system, V; I -----Protection current of protection system, A; RBt B -----Total resistance of cathode protection system,Ω; RBLB -----Conductor wire’s resistance of protection system,Ω; RBc B -----Grounding/ water contact resistance of anode (calculation refer to formula

5.2.2-3, 5.2.2-4 and 5.2.2-5),Ω; RBwB -----Medium resistance,Ω; RBpmB -----Cathode resistance of protection component,Ω. (3) Power of direct current power supply P shall be calculated according to formula 5.3.4-4:

(5.3.4-4)

Where, P -----Power of power supply, W; η -----Current efficiency, usually is 0.8.

(4) Required amount of auxiliary anode W shall be calculated according to formula 5.3.4-5: W = K P

.P E P

.P TP

.P IBmB (5.3.4-5)

Where, W ----- Reserve coefficient, usually select 1.1 ~ 1.3. (5) Radius of disk shape shield layer (plate) anode with disk-shape r’ shall be calculated

according to formula 5.3.4-6: (5.3.4-6) Where, r’ ----- Radius of shield layer (plate), cm; r ----- Radius of anode, cm; IBaB ----- Output current of anode, A; EBo B -----Average protection voltage, V; E ----- Maximum negative voltage permitted by paint, V. (6) Length of rectangular shield layer (plate) of strip anode l’ and width b’ shall be calculated

according to formula 5.3.4-7 and 5.3.4-8: (5.3.4-7) (5.3.4-8)

Where, l’ ----- Length of shield layer (plate), cm;

b’ -----Width of shield layer (plate), cm; l ----- Length of anode, cm; r ----- Equivalent radius of anode, cm;

C ----- Section perimeter length of anode, cm.

5.3.4.2 Auxiliary anode design (1) Selection of auxiliary anode material shall be based on application condition,

performance of anode material and technical & economic evaluation, and other factors, Reference can be made to Appendix B of this specification.

(2) geometrical shape of auxiliary anode shall be designed according to the designed life cycle, material performance, environment medium, structure type of protected body, etc. As for geometrical shape of commonly used auxiliary anode, please refer to Appendix B of this specification.

(3) The joint between auxiliary anode and cable shall have waterproof seal and insulation, insulation resistance of joint in water shall not be less than 100 MΩ, and its service life shall be consistent with its designed life cycle.

(4) Layout of auxiliary anode shall ensure the protection potential of all places of protected structure shall follow the requirements of table 5.1.2 in this specification, and shall be distributed evenly as much as possible. When near-anode layout is applied, it is necessary to provide shield layer or shield cylinder; when long distance anode layout is applied, the distance between an anode and protected body shall not be more than 100 m.

5.3.4.3 Setting of confluence point shall be favorable to the distribution of protection current, all protection potentials of protected body shall comply with table 5.1.2 of this specification.

5.3.4.4 Setting of reference electrode shall near to protected body as possible, and in favor of the measurement of potential. Reference electrode shall have the characteristics such as low polarization, good reliability, wear resistance and long life cycle, and shall be adaptable to environment medium; as for the type of reference electrode and main technical performance, reference can be made to “Technical Condition of Reference Electrode of Ship” and table 5.3.4. Cable of reference electrode cannot be laid close to power cable, and its shielding wire (layer) shall be grounded at one terminal.

Main technical performance and applicable environment medium of general reference electrode

Table 5.3.4

Name Electrode

construction

Potential (V) (related to standard Hydrogen

electrode)

Applicable environment medium

Saturated calomel electrode

Hg / HgB2BCl B2B

Saturated KCl +0.242 Fresh water, seawater

Saturated copper sulfate electrode

Cu/ Saturated CuSOB4B +0.316 Seawater, fresh water,

soil Seawater silver chloride

electrode Ag / AgCl Seawater +0.250 Seawater

Zinc alloy electrode Zn alloy -0.784 Seawater, fresh water,

soil 5.3.4.5 Cathode cable and anode cable could use multi-strand copper core cable, cable jacket

(armouring) shall have good insulation and aging resistance, and the submerged part should have seawater corrosion protection. Reference electrode cable for control function shall choose the shielding cable with seawater corrosion protection and aging resistance; power supply

cable jacket (armouring) shall have seawater corrosion protection and aging resistance; connections of cables shall have sufficient strength, good insulation and corrosion protection.

5.3.4.6 Protection system shall have safety protection measures.

5.3.5 Installation of protection system 5.3.5.1 Shall inspect all equipment and material prior to installation, and ensure the

conformance with design requirements. 5.3.5.2 Connection method of protection system could use direct welding, weld reinforced steel

or cable connection. Area of connection point shall be larger than the section area of steel bar for connection or that of cable core; connection resistance shall not be larger than 0.01Ω, connection point shall be airproof.

5.3.5.3 installation of auxiliary anode and its shield plate (cylinder) shall meet design requirements. Metal short circuit between auxiliary anode and protected body is not allowed. Cable length of auxiliary anode in submerged area shall have sufficient allowance.

5.3.5.4 Reference electrode shall be constructed according to design drawing after inspection. Cable length of reference electrode in submerged area shall have sufficient allowance. Grounding point of reference electrode cannot share with cathode confluence point or next to it.

5.3.5.5 Direct power supply shall be located in place with good ventilation and easy for cleaning. When direct power supply is installed outdoors dispersedly, it shall be equipped with metal shell with good ventilation and drop-proof. Metal shell of direct power supply shall be grounded, the grounding resistance shall be less than 4Ω. Reversed connection of positive, negative pole of power supply with corresponding anode and cathode cables is strongly prohibited.

5.3.5.6 Cable shall be equipped with steel pipe, polyvinyl chloride tube, cable dyke (rack) with cover, cable shall not be exposed to direct sunlight and corroded by strong corrosive substance. When cable is connected by subsection, the joint of cable shall have good seal, and should not be exposed outside; junction box is required when necessary; the joint cannot contact shell of metal junction box. No damage to cable jacket when laying cable; if it is partly damaged, repair the cable; if cable is seriously damaged, replacement shall be provided.

5.3.5.7 Construction inspection of protection system shall include the following items: (1) Inspection of electrical connection: Electrical connection shall have no missing

connection area; welding shall meet with design requirements; cable connection should be firm; all joints should have good seal.

(2) Inspection of cathode and anode circuit: installation of circuit shall be correct; joint cannot be exposed, reverse connection is forbidden; joint shall be firm.

(3) Inspection of auxiliary anode installation: installation shall be firm, position shall meet with design requirements; metal short circuit between auxiliary anode and protected body is forbidden.

(4) Inspection of reference anode installation: installation shall be firm, position shall meet with design requirements; measured values of electrode shall meet with design requirements.

(5) Inspection of cable layout: cable laying shall meet with design requirements, cable jacket shall be in good condition, and have good insulation, reference electrode cable cannot be close to power supply cable; shielding wire of reference cable shall be grounded at one terminal; power supply cable shall be exclusive.

(6) Inspection of direct current power supply: instrument shell shall have good grounding; cathode confluence point cannot share with grounding point of reference electrode; connection sequence for power supply cable and instrument shall be correct.

(7) Inspection of safety measure: safety measures shall meet with design requirements; shall be equipped with explosion proof devices when explosive and flammable air exists.

5.3.6 Acceptance inspection of impressed current protection system Impressed current protection system shall pass acceptance inspection; acceptance inspection data shall include protection system as built drawing, ex factory certificate and inspection report for facilities and materials; test report of protection performance, original design documentation and design change notes, construction records and so on. 5.3.7 Testing of protection performance Testing of protection performance for impressed current protection system shall be carried out within one month after the system is put in use, this shall be conducted according to the requirements of item 5.1.2 in this specification. Measured result shall satisfy the design requirements.

Appendix A: Assessment criterion for anticorrosion of film coating

Assessment criterion for anticorrosion of film coating Table A

Grade Corrosion status

Grade 1

(Good)

Slight loss of gloss 5% ~ 20%;

Slight discoloration;

No obvious change on surface of paint, no air bubble;

No rusty and paint drop out

Grade 2 (Conformance)

Obvious loss of gloss 21% ~ 50%;

Obvious discoloration;

Slight air bubble on surface of coating, area less than 50%, area of local small air

bubble less than 40%, area of middle air bubble less than 1%;

The diameter of rusty spot less than 0.5 mm;

No paint peeling

Grade 3

(Nonconformance)

Serious loss of gloss;

Serious discoloration;

Obvious air bubble on surface of coating, slight air bubble on whole plate, area of

small air bubble more than 5%, area of middle air bubble larger than 2%, large air

bubble occurs;

Area of rusty spot above 2%;

paint peeling occurs.

Note: (1) Calculation of air bubble area: one small air bubble found in 1% of the area is regarded

as 1%. Grade of air bubble: slight air bubble is visible under 4 times magnifier; small air bubble

refers to the bubble with diameter less than 0.5mm; middle air bubble with diameter 0.6 ~ 1.0 mm;

large air bubble with diameter larger than 1.1 mm.

(2) Any damage within 5mm range around plate edges and the plate hole, and caused by

foreign factors will be discounted.

(3) Visual inspection will be conducted with 4 times magnifier.

Appendix B: Material characteristics of common auxiliary anode and the geometrical shape of anode

Material characteristics of common auxiliary anode and the geometrical shape of anode Table B

Type of anode

Anode material

Density (g/cmP

3P)

Applicable current density (A/mP

2P)

Consumption rate

[kg/(AP

.Pa)]

Maximum usage ratio

(%)

Anode geometrical

shape

Maximum application voltage (V)

Application environment Remarks

Solubility Carbon

steel, cast iron

7.8 10 ~ 100 8 ~ 10 50 -- No limit Seawater,

fresh water, soil

Could adopt steel strip and waste steel rail

Graphite About 1.8 10 ~ 100 0.2 ~ 0.9 66 Rod, block No limit

Seawater, fresh water,

soil Fragile

High silicon

cast iron 7.0 50 ~ 300 0.2 ~ 0.5 50 Cylinder,

rod No limit Seawater,

fresh water, soil

Fragile

Magnetic ferric oxide

-- 40 ~ 400 0.1 40 -- No limit Seawater,

fresh water, soil

Fragile

Micro solubility

Plumbum silver alloy

11.3 50 ~ 250 0.03 ~ 0.2 67 Cylinder, semicircle No limit Seawater Cannot use in water

deeper than 30m

Plumbum silver

alloy with little

platinum

11.3 50 ~ 1000 0.002~ 0.006 67 Cylinder No limit Seawater Cannot use in water deeper than 30m

Titanium plated

platinum 5 250 ~ 750 6 x 10P

-6 P~

10 x 10P

-6P

85 Column 8.75 Seawater Shall adopt cautiously, expensive

Tantalum plated

platinum 16.8 500 ~2000 6 x 10P

-6P 85 Flat, meshy

flat 200 Seawater,

fresh water, soil

Shall adopt cautiously, expensive

Insoluble

Niobium plated

platinum 8.8 500 ~2000 6 x 10P

-6P 85 Column 50 Seawater Shall adopt cautiously,

expensive

Appendix C: Description for the wording in this specification C. 0.1 Following wordings in this specification shall have different degrees of strictness: C. 0.1.1 The word to express very strict, no other selections but to do so:

Positive word is “must”; Negative word is “must not”.

C.0.1.2 The word to express strict, have to do so under normal situations: Positive word is “shall” or “can”;

Negative word is “shall not” or “can not”. C.0.1.3 The word to express a slight degree of optional, to do like this first of all if condition allows:

Positive word is “should” or “could”; Negative word is “should not” or “could not”.

Additional explanation

The main compiling unit and main drafters for this specification: Main compiling unit: Liaohe Petroleum Exploration Bureau - Exploration and Designing Research

Institute (辽河石油勘探局勘察设计研究院) Attendance unit: China National Petroleum Corporation Engineering Technical Academe (中国石

油天然气总公司工程技术研究院) Maim drafters: 孟凡顶，Meng Fan Ling, Hou Guang Yu, Wang Li Chun

Appendix C

Technical Specification of Anticorrosion for Petroleum Engineering in Beach-Sallow Sea

Terminology explanation C.0.1 When this specification is implemented, the terminology for strict requirement is as following: C.0.1.1 “shall” indicates requirements strictly to be followed in order to conform to this standard and from which no deviation is permitted. the following words are used: “shall” (positive way) “forbid/prohibit” (negative way) C.0.1.2 “Should” Indicates that among several possibilities, one is recommended as particularly suitable, without mentioning or excluding others, or that a certain course of action is preferred but not necessarily required. Other possibilities may be applied subject to agreement. “should” (positive way) “should not” “not allowed” (negative way) C.0.1.3 “may” verbal form used to indicate a course of action permissible within the limits of the standard, the following words are used “may” “can” (positive way) “may not” “not suitable” (negative way)

Additional notes The name list of the work units and people who are involved in drafting this specification: Work unit in charge: Liaohe Petroleum Exploration Bureau - Exploration and Designing Research Institute Participating work units: CNPC Engineering Technology Research Institute Drafted by: Meng Fanling, Hou Guangyu Wang Lichun

Attachment Technical Specification of Anticorrosion for Petroleum Engineering

in Beach-Sallow Sea

Clause Explanations

Compilation explanation According to the requirement of the document- (94)Zhong You Ji Jian Zi Di No. 79 issued by China National Petroleum Corporation, the document SY/T 4091- 95 “Technical Specification of Anticorrosion for Petroleum Engineering in Beach-Sallow Sea” compiled by Liaohe Petroleum Exploration Bureau - Exploration and Designing Research Institute, has been approved and issued by the China National Petroleum Corporation on Deceber 18, 1995, with the approval document -(95) Zhong You Ji Jiang Zi Di No. 731. During the course of compiling, the compilers abided by the state’s relevant principles and regulations, had carried out lots of research and investigation, concluded the works and experience of anticorrosion for petroleum engineering in beach-sallow sea, widely asked for other units opinions and suggestions, and repeatedly discussed and corrected for the document, finally the document had been examined and accepted by the Infrastructure Construction Engineering Bureau of China National Petroleum Corporation together with other relevant authorities. This specification is divided into 5 chapters, the main content includes: General rules, General requirements, Surface preparation, Overburden protection, Cathode protection. For the purpose of that this specification would be correctly understood and carried out by the units and personnel which are involved in infrastructure construction, design, construction, scientific research, and universities and institutes, this “Terminology explanation” is compiled according to state’s consolidated requirements on the compiling standards and specifications of this field, and following the sequence of original context’s chapter, section and paragraph. This specification will be served as a reference for people in this industry. Whereas this specification is firstly compiled, we hope that all units and personnel concerned shall learn and sum up their experiences during work, and record relevant data; for any corrective suggestions and supplementary opinions, please send your materials to: Liaohe Petroleum Exploration Bureau - Exploration and Designing Research Institute, Pan Jin City, Liao Ning Province (Post code: 124010), and the Standard Office of the Petroleum Engineering Technology Institute, No. 40 Jin Tang Highway, Tang Gu District, Tian Jin City (Post code: 300451), for the reference of further revision.

Liaohe Petroleum Exploration Bureau - Exploration and Designing Research Institute June, 1995

Index

1. General Rules

2. General requirements

3. Surface preparation

3.1 General requirements

3.2 Surface preparation

3.3 Protection after surface preparation

4. Overburden protection

4.1 General requirements

4.2 Protection of paint coating

4.3 Protection of spray metal

4.4 Protection of plating

4.5 Cover protection (Protection of cladding)

5. Cathode Protection

5.1 General requirements

5.2 Sacrificial anode protection

5.3 Impressed current protection

Appendix A: Assessment criterion for anticorrosion of film coating Appendix B: Material characteristics of common auxiliary anode and the geometrical shape of anode

1. General rules 1.0.1 Due to the fact that the environment in beach-sallow sea is different from onshore environment, as well as different from deep-water offshore environment, therefore the design and construction of corrosion protection for steel structure, pipeline, oil and gas production plant in beach-sallow sea can not fully use the standards (specifications) for deep-water offshore environment, nor copy the standards (specifications) of onshore environment. In order to meet the operational requirement of beach-sallow sea, this specification is compiled for the purpose to standardize the designing and construction in corrosion protection in beach-sallow sea, and to ensure the safety and reliability, advanced technology, cost effectiveness and environment protection. 1.0.2 This clause is the applicable range of this specification. 1.0.3 since the design and construction for internal surface anticorrosion for steel structure, pipeline, oil and gas production plant in beach-sallow sea is similar to that of onshore anticorrosion, so this specification will not repeat it. As for the design and construction of corrosion protection for reinforced concrete construction, reference can be made to the engineering technical specification in seaport “The Corrosion Specification for Reinforced Concrete Construction in Seaport”, which has described the requirements for materials’ quality and construction quality for reinforced concrete; but as for compiling the application of coating and cathode protection as corrosion protection method for reinforced concrete structure, at present, the conditions are not ready yet, it still needs further research.

1.0.5 Corrosion protection engineering of petroleum engineering construction in beach-sallow sea is closely connected with main structure engineering, covering a wide range. Therefore, it is required that the designing and construction of corrosion protection should observe the specifications stated in this specification, as well as the national standards (specifications) .

2. General requirements 2.0.1 This clause is the general requirements for anticorrosion design.

2.0.1.1 To ensure the quality of anticorrosion design of petroleum engineering in beach-shadow sea, this paragraph clearly defines the qualification of design unit.

2.0.1.2 Corrosion environment of petroleum engineering in beach-shadow sea is complicate, so the design of anticorrosion shall be conducted separately for steel structure, pipeline, and oil and gas production plant according to different environment and application conditions. When designing anticorrosion measure, it is recommended to consider heat preservation (insulation) and other methods.

2.0.1.3 Atmospheric zone refers to the structural part above splash zone, which is exposed to sunlight, wind, salt spray and raining water. Structure corrosion in atmospheric zone is light; Corrosion can be restrained by the means of coating protection or metal spraying protection. Plating is expensive and process is complex, so plating protection is only applied to complex structure shape in which coating protection or metal spraying protection fails.

2.0.1.4 Splash zone is an external surface of a structure or pipeline that are periodically in and out of the water by the influence of waves and tides. The range of splash zone is 2/3 above wave height from design high tide level (average wave height of 50a return period) to 1/3 below design low tide level. Since the external surface of a structure in splash zone is subject to impact force and floating ice in winter, therefore corrosion protection measures include coating protection, metal spraying protection or plating protection, and reinforced cladding protection when necessary.

2.0.1.5 Continuous immersion zone (or submerged zone) refers to the part of the structure or in-stallation below the splash zone, including buried parts). Metal facility in continuous immersion zone is lie in the electrolyte, electrochemistry corrosion is easy to occur, so the cathode protection can be effective in inhibiting the corrosion. Since the required protection current density on the surface of bare metal is large, the consumption of material and electric power is big, usually the Cathode Protection and coating protection are both used. When it is difficult to use coating protection, only cathode protection can be used.

2.0.1.6 Beach zone are coastal soil areas (include marsh) that are periodically in and out of the water by the influence of tides. The corrosion of metal facility in beach zone is electrochemistry corrosion; anticorrosion of beach zone usually adopts the combined Cathode Protection and coating protection. 2.0.2 This clause defines the requirement for anticorrosion construction. The construction quality of anticorrosion engineering will directly affect the anticorrosion performance of anticorrosion engineering, so it states the requirements to ensure the quality in terms of corrosion protection construction contractors, facilities and materials used for construction and inspection of construction. 2.0.3 This clause defines the requirements for acceptance inspection of anticorrosion engineering. The inspection quality of anticorrosion engineering will directly affect the operation, maintenance of anticorrosion engineering, engineering acceptance inspection is absolutely necessary, and data shall be complete to enable the normal operation, maintenance and management of anticorrosion

system. 2.0.4 This clause is the general requirements of anticorrosion for structural design. The purpose is to simplify the anticorrosion measures of petroleum engineering in beach-shallow sea. The content of this paragraph is the epitome of chapter 3 “Structure design of corrosion control” of industry standard Q/HS 7017-93 “Recommended Practice Corrosion Control of Steel Fixed Offshore Platforms Associated with Petroleum Production” issued by China National Offshore Oil Corporation (this standard is equivalent to NACE RP-01-76 “Recommended Practice Corrosion Control of Steel Fixed Offshore Platforms Associated with Petroleum Production”). As for the detailed requirements for structure design in anticorrosion engineering in beach-shallow, refer to the concerned paragraphs of this specification.

3. Surface preparation 3.1 General requirements

3.1.1 The quality of surface preparation will directly affect the quality of coating and life cycle of protected object, so surface preparations must be carried out before applying coating protection, the construction of coating will not start unless surface preparation meets the required objective. 3.1.2 This clause is the requirements of derusting quality grading of steel surface. Since in the corrosion protection engineering in beach-shallow sea, chemical derusting is suitable for many structural components. Therefore the chemical derusting grade requirements are added in the specification. The quality requirement of chemical derusting is quoted from Chemical Industrial Ministry engineering construction standard HGJ 34 “Specification of Corrosion Protection Design for Chemical Facility and External Surface of Pipeline”, chapter 2 “Surface preparation anticorrosion outside of equipment, pipeline and steel structure”.

3.1.3 Surface roughness will affect adhesive performance of coating; In designing, it is important to specify the required surface roughness for quality grade of jetting (impeller blasting) derusting. Value of surface roughness shall be determined according to different quality requirements, coating type, painting process, usually can use 30 ~ 80 µm.

3.1.4 After chemical solution treatment, residual liquid of chemical solution may remain on the treated steel surface, and will affect the surface structural conditions, so this paragraph states that chemical treatment such as conversion type, stable type and penetration type is not suitable for surface preparation for main steel structure, oil and gas production plant of important engineering projects. This is quoted from Ministry of Communications standard JTJ 230-89 “Technical Specification for Engineering Steel structure Anticorrosion of Seaport” chapter 4 section 3 “Surface preparation and coating”. 3.1.5 Surface preparation grade for steel structure, pipeline, oil and gas production plant is not only related to paint and primer used, but also related to their own important grades and corrosion environments. This clause is minimum surface preparation grade for different paints. Table 3.1.5 is quoted from Ministry of Communications standard JTJ 230-89 “Technical Specification for Engineering Steel structure Anticorrosion of Seaport” chapter 4 section 3. 3.1.6 Spray metal surfaces have strict requirements for surface preparation, not only requiring the cleanness of surface must meet the design objective, but also the roughness of surface must meet the design objective. This is quoted from “Technical Specification for Engineering Steel structure Anticorrosion of Seaport” chapter 5 section 4 “Construction of spraying metal”.

3.2 Surface preparation 3.2.1 This clause is a general requirement of surface cleaning. Surface cleaning is an important part of surface preparation; the quality of surface cleaning will affect the quality of surface

preparation. This clause is mainly based on related items of chapter 3 “cleaning” of “Specification for Steel Surface Preparation Before Paint Coating”, and based on related items of chapter 3 “Surface preparation of Corrosion Protection Base Material” of “Applied Corrosion Protection Technology” issued by China National Chemical Equipment Corporation, etc. Table 3.2.1 is quoted from chapter 3 “cleaning” of “Specification for Steel Surface Preparation Before Paint Coating”.

3.2.2 This clause is based on related contents of chapter 4 “Derusting by tools”, chapter 5

“Derusting by jetting (impeller blasting)”, and chapter 6 “Acid cleaning” of “Specification for Steel Surface Preparation Before Paint Coating”, and add the requirements for compressed air used by dry spray facility, temperature on steel surface during Surface preparation, and chemical treatment process.

3.2.2.2 This paragraph has made reference to related items of chapter 12 “Surface preparation” of “Recommended Practice Corrosion Control of Steel Fixed Offshore Platforms Associated With Petroleum Production”, “Technical instruction on painting” of “Detail Design of Test Platform for single well and triple -well at Liaohai Oilfield” and related items of chapter 3 of “Applied Corrosion Protection Technology”.

3.2.2.3 This paragraph is a requirement of chemical treatment process. Chemical treatment is different from general surface preparation, each process of chemical treatment shall be conducted consecutively with pause, otherwise, it will affect the quality of next process and whole treatments. Any moisture left on metal surface after passivation will lead to rusty very easily so metal surface shall be dried immediately after passivation.

3.3 Protection after surface preparation

3.3.1 This clause is the requirement of primer painted on steel surface after treatment. In order to ensure the quality of surface preparation, avoid redo treatment, steel surface shall be painted with primer immediately after treatment. The requirement painting time is mainly related to relative humidity, environment temperature, temperature on steel surface; The standard of “The Design Specification on Corrosion Protection for Chemical Facilities and External Surface of Pipeline” defines that “Steel surface shall be painted with a primer immediately after treatment, general no more than 6 hours”. 3.3.2 This clause is the temperature requirement of steel surface. Only when the temperature on steel surface is above dew point by 3, it can be assured that water drop can not be formed on the steel surface, so as to facilitate operation of surface preparation.

4. Overburden protection 4.1 General requirements

4.1.1 Overburden (coating/cover) has many types. This clause is the technical requirements of painting, coating, spray metal and plating. 4.1.2 This clause is a general rule for selecting overburden. Different overburden (coating) protection shall be applied to different steel structure steel, pipeline, oil and gas production plant under different environments. When selecting coating types, related surface preparation grade and construction method, it is necessary to consider technical factor as well as economic factor. 4.1.3 This clause is the general requirements of overburden material characteristics

4.2 Protection of painting coating

4.2.1 This clause is the general requirements for selecting paint type. Painting coating system in beach-shallow sea general include priming, intermediate paint and surface paint coating. There are many types of paint, but not all of them are suitable for the corrosive environment of petroleum engineering in beach-shallow sea. Environment conditions will affect the selection of paint material, so different types of paint will be used for atmospheric zone, splash zone, continuous immersion zone and beach zone.

4.2.1.1 This paragraph is the general requirements of paint selection. 4.2.1.2 This paragraph is the performance requirement of paint used at atmospheric zone. Paint

used at atmospheric zone shall have good weather resistance. “Technical Specification for Engineering Steel structure Anticorrosion of Seaport” defines that “Paint used in atmospheric zone shall have good weather resistance”, this specification adds “Paint subject to more than one year weather resistance test, overall evaluation grade shall be above Middle”, which specifies the index of paint weather resistance.

4.2.1.3 This paragraph is the performance requirement of paint used at splash zone. Environment in splash zone is adverse, so the paint performance in splash zone should be higher, Anticorrosion grade of selected paint shall achieve “good” or “conformance” after the tests of resistance of salt-spray, aging resistance, humidity and heat resistance for a period of set time. 4.2.1.4 This paragraph is the paint performance requirement for continuous immersion zone and beach zone. When selecting the paint for continuous immersion zone and beach zone, it is necessary to consider the matching effect (compatibility) between paint and cathode protection; the selected paint used for continuous immersion zone and beach zone shall match with cathode protection, have good ability to resist cathodic peeling and alkali resistance. Cathode protection characteristics objective of paint is quoted from chapter 7 section 2 “protection of painting and plating” of “Specification of Classification and Construction of Fixed Offshore Platform” (1992) issued by China Classification Society; Peeling period of painting test sample will be defined according to the actual engineering. 4.2.1.5 Application of anti pollution paint shall be based on the pollution status of marine growth.

4.2.2 This clause recommends the paint coating systems applicable to different zones and provide the design requirements for paint protection. The standard of American National Association of Corrosion Engineers and standard of Det Norske Veritas (DNV) have recommended the paint coating system for each zone; There is no practice example for paint protection system in China during current petroleum development in beach-sallow sea, but anticorrosion for seaport engineering has experienced a long period examination, so the recommended paint system table 4.2.2-1, table 4.2.2-2 and table 4.2.2-3 in this specification are quoted from chapter 4 section 2 “selection of paint” of “Technical Specification for Engineering Steel Structure Anticorrosion of Seaport” . 4.2.2.4 Paint system for submarine pipeline and riser is quoted from Det Norske Veritas (DNV) standard “Evaluation of Paint Protection”. Environment of pipeline in beach zone is between onshore and offshore environment, so when selecting protection coating, reference can be made to the paint protection system for continuous immersion zone or to the standard for onshore zone. 4.2.2.5 This paragraph is the requirement for selection of high temperature resistance paint. High temperature resistance paint could be chlorosulfonated polyethylene modified high temperature resistance paint, organosilicon high temperature resistance paint, etc. 4.2.2.6 This paragraph is the requirement for surface paint color. Currently, there is no standard for surface paint color for pipeline, equipment and others used in offshore environment, so the requirement of this specification for color of steel structure surface paint used in beach-shallow sea is quoted from “Design Specification of Coating Protection for Steel Platform in Offshore Oil Field” issued by China National Offshore Oil Corporation Bohai Engineering Design Company. As for surface paint color of pipeline, equipment, and oil and gas production plant on platform, reference can be made to onshore standard “Standard of Painting Color for Surface Pipelines and Equipments in Oil/Gas Field”.

4.2.3 This clause is the general requirement for painting 4.2.3.1 This paragraph is the requirement for surface preparation prior to painting. The quality of surface preparation will directly affect painting protection effects; therefore it is required to control the quality of surface preparation prior to painting. 4.2.3.2 This paragraph is the requirement for painting method. The detailed painting methods

shall be selected according to the physical characteristics of the paint, application conditions, environment conditions and surface conditions to be painted.

4.2.3.3 This paragraph is the requirement for painting condition. This paragraph is based on related requirement of “Design Specification of Painting Protection for Steel Platform in Offshore Oil Field”.

4.2.4 This clause is the requirement for painting quality inspection. Painting quality inspection is an important part to ensure the quality of the surface coating.

Quality inspections include quality of surface preparation before the painting, inspection of painting equipments, materials, and process inspection of painting operation and paint quality inspection after painting. This clause is based on related items of chapter 4 section 4 “quality inspection” of “Technical Specification for Engineering Steel structure Anticorrosion of Seaport”.

4.2.5 This clause is the general requirement for coating protection hand over acceptance

inspection.

4.3 Protection of spray metal This clause is the technical specifications for selection of spray metal material, protection design, operation spray, and so on. The main reference standards include chapter 5 “spray metal system protection” of “Technical Specification for Engineering Steel Structure Anticorrosion of Seaport”, “Coating of Thermal Spraying Zinc and Zinc Alloy”, “Experiment Method for Coating of Thermal Spraying Zinc and Zinc Alloy”, “Coating of Thermal Spraying Aluminum and Aluminum Alloy”, and “Experiment Method for Coating of Thermal Spraying Aluminum and Aluminum Alloy”.

4.4 Protection of plating Although plating layer protection is not as widely as used painting protection, spraying protection, it is an effective method for complicate steel structure, such as barrier, rail, ladder, instrument box and base of skid.

4.5 Protection of cladding This clause is the technical specification for selection of cladding material, the quality of surface preparation prior to cladding, and quality of cladding layer. Cladding is usually used for reinforced protection of structural components in spray zone; detail cladding structure cladding shall be determined by environmental conditions, application conditions and so on.

5. Cathode Protection

5.1 General requirements

5.1.1 This clause is the requirement for selection of cathode protection. Two kinds of cathode protection (sacrificial anode and impressed current) have their own advantages and disadvantages; As in practice, the selection of either one shall be determined according to the engineering scale, construction condition, environment, and application condition. As for cathode protection design for pipeline at beach-shallow zone, the design standard for onshore cathode protection can be used as reference. 5.1.2 This clause is the requirement for assessment the cathode protection effecting. Most widely used method is protection potential rule; visual inspection rule and test block rule can also be used in special situations. This clause is quoted from chapter 4 “cathode protection rule” of “Recommended Practice Corrosion Control of Steel Fixed Offshore Platforms Associated With Petroleum Production”; table 5.1.2 is quoted from chapter 6 section 3 “cathode protection” of petroleum and natural gas industry standard SY/T 4804-92 “Specification of Submarine Pipeline System”, and for the convenience, the “anode limit”, “cathode limit” in original specification are changed into “minimum value” and “maximum value”.

5.1.3 This clause is the selection requirement for protection current density. The main reference for this clause includes Appendix D: “guideline on corrosion control” of “Specification of Submarine Pipeline System”, and DNV standard RP B401 “Cathode Protection Design”. As for protection current density of bared steel, please refer to table 1.

Generally used initial stage protection current density value Table 1

Environment medium Surface conditions of

steel structure Protection current density

(mA/mP

2P)

Still seawater Bared steel 80 ~ 100 Flowing seawater Bared steel 100 ~ 150

Still seawater Have painting 10 ~ 20

Flowing seawater Have painting

(complete) 15 ~ 30

Flowing seawater Have painting

(cracked) 30 ~ 50

Flowing fresh seawater Bared steel 70 ~ 100 Under mud Bared steel 10 ~ 25

Seawater rockfill Bared steel 40 ~ 60 Polluted seawater Bared steel 150 ~ 200

5.2 Sacrificial anode protection 5.2.1 This clause is the selection requirement for anode material.

5.2.1.1 This paragraph is the selection requirement for anode material type. Currently, sacrificial anode material of marine cathode protection mostly use zinc alloy and aluminum alloy. Due to the advantages of light weight and large capacitance, aluminum alloy becomes more and more popular.

5.2.1.2 This paragraph is the requirement for anode material performance. Anode materials will directly affect the effect of cathode protection, and since no external power supply is available for

protection by sacrificial anode, anode material performance must meet the required objective for application.

5.2.1.3 This paragraph is the selection requirement for anode material under different working temperatures. Due to the threat of corrosion between crystals, zinc anode could not be used under environment in which working temperature is above 50.

5.2.1.4 Chemical composition, electrochemistry performance of sacrificial anode will directly affect the solution performance and protection effect of sacrificial anode under seawater and mud, this paragraph is the requirement for chemical composition, electrochemistry performance and its test method.

5.2.1.5 As for the requirement of appearance (visual) quality, quality deviation, dimensional tolerance of sacrificial anode, reference has been made to DNV standard “Cathode Protection Design”.

5.2.2 This clause is the calculation formula of sacrificial anode protection. Main reference standards for this clause are “Specification of Classification and Construction of Fixed Offshore Platform” and “Specification of Submarine Pipeline System”. 5.2.4 This clause is the requirement for installation of anode. This clause is mainly referred to related items of chapter 6 section 7 “construction of sacrificial anode protection system” of “Technical Specification for Engineering Steel Structure Anticorrosion of Seaport”. 5.2.6 This clause is the requirement for examination of cathode protection effect. Requirement of examination time is quoted from chapter 4 section 3 “cathode protection” of “Safety Rules on Offshore Fixed Platform” issued by Ministry of Energy.

5.3 Impressed current protection

5.3.1 This clause is about the requirement for power supply facility. In beach-shallow sea, the cathode protection requirement for power supply facility has no obvious difference from that of onshore situation, but adaptability to environment and operability of power supply shall be higher than that of onshore situation. 5.3.2 This clause is about the selection requirement for auxiliary anode materials. Main reference standards for this clause are “Specification of classification and Construction of Fixed Offshore Platform” and “Recommended Practice Corrosion Control of Steel Fixed Offshore Platforms Associated With Petroleum Production”. 5.3.3 This clause is about selection requirement for insulation shield materials. This clause refers to related item of chapter 8 “insulation shield layer” of “Recommended Practice Corrosion Control of Steel Fixed Offshore Platforms Associated With Petroleum Production”. 5.3.4 This clause is about the requirement for design of protection system.

5.3.4.1 Referred standard and documentation including: “Specification of Classification and Construction of Fixed Offshore Platform”, “Technical Specification for Engineering Steel Structure Anticorrosion of Seaport” and “Submarine Oil and Gas Pipeline Engineering” (compiled by Ma Liang). 5.3.4.2 This paragraph is the requirement for auxiliary anode design. Main reference includes

chapter 6 section 2 “cathode protection design of impressed current system” of “Technical

Specification for Engineering Steel Structure Anticorrosion of Seaport”. 5.3.4.4 This paragraph is about the requirement for setting of reference electrode and its

performance. It is quoted from chapter 6 section 1 General requirements of “Technical Specification for Engineering Steel Structure Anticorrosion of Seaport”.

5.3.4.5 This paragraph is the requirement for cathode cable and anode cable. It is quoted from chapter 6 section 2 “cathode protection design of impressed current system” of “Technical Specification for Engineering Steel Structure Anticorrosion of Seaport”.

5.3.5 This clause is the requirement for installation of protection system. It refer to chapter 6 section 3 construction and quality inspection for cathode Impressed current protection system” of “Technical Specification for Engineering Steel structure Anticorrosion of Seaport”. 5.3.7 This clause is the requirement for examination of cathode protection effect. Requirement of examination time is quoted from chapter 4 section 3 “cathode protection” of “Safety Rules on Offshore Fixed Platform”.

Appendix A: Assessment criterion for anticorrosion of film coating

Appendix A is an assessment criterion for anticorrosion of film coating after salt spray, aging,

humidity and heat resistance testing. In the applicable national standard, there is only specification

on weather resistance for film coating; Comprehensive assessment criterion of this type is not

available yet; Appendix A is quoted from Appendix 2 “inspection method for coating and spraying

metal” of “Technical Specification for Engineering Steel Structure Anticorrosion of Seaport”.

Appendix B: Material Characteristics of Common Auxiliary Anode and The Geometrical Shape of Anode

This Appendix is quoted from Appendix 3 “Material Characteristics of Common Auxiliary

Anode and the Geometrical Shape of Anode” of “Technical Specification for Engineering Steel

Structure Anticorrosion of Seaport”.

Technical specification of anticorrosion for petroleum engineering in beach-shallow sea

SY/T 4091-95