Piping engineering :It is a study and development of Piping layout, material selection and behavior of the piping system under prevailing process conditions and design parameters. It is the study for developing an efficient and economical way for the transport of fluid from the source to the destination as indicated in the Piping and Instrumentation Diagram (P&ID).

Inputs to Piping discipline:

1. Requirement from client:

Plot area and location, statutory requirement, special requirements etc.

2. Process licensor:

Project design basis, plot plan, PFDs(Process Flow Diagram), P&IDs (Process and Instrumentation Diagram), PDS (Process Data

Sheet), process description, equipment list, line list, site data, licensor, capacity etc.

3. Process information:

Process data sheet showing overall dimensions, supporting arrangement, all nozzles location, size, rating, etc. for equipment.

4. Civil/Structural layout, drawing:

Effluent & drain sewers layouts and manholes location.

Civil drawings (plan and elevation) for the facilities within the unit like instrumentation control room, electrical sub-station, and

laboratory.

Pipe racks and technological structure foundation drawings.

Civil drawings for platforms.

Tank settlement data.

5. Instrument drawing:

Tray width requirement on pipe rack/sleepers.

Instrumentation hook-up drawing.

Instruments drawings for control valves, safety valves, inline instruments etc.

6. Electrical layout:

Tray width requirement on pipe rack/pipe sleepers and cable trenches width in units/off-site.

Electrical cable tray layout.

7. Mechanical (Static/Rotary/Package) layout:

Mechanical datasheets for equipment like columns, vessels, tanks etc.

Layout drawing of packages items showing auxiliary equipment.

8. HVAC: (Heating, Ventilation, and Air conditioning)

Layouts showing the HVAC duct size and the location.

Outputs from Piping discipline:

1. Overall plot plan showing location of various units, tankfarms, offsite, package units, non-plant buildings, roads, culverts, piperacks,

sleepers, etc.

2. PMS (Piping Material Specification)& VMS (Valve Material Specification).

3. Equipment general arrangement drawing/layouts indicating the location of all the equipment within the unit, platforms , ladders,

overhead crane elevation, monorail location, cutouts for piping.

4. Piperack general arrangement drawing & structures for equipment support

5. Piping general arrangement drawing/Layouts showing all the piping and equipment.

6. Piping Bill of Materials (BOM) with technical evaluation and technical bid analysis (TBA).

7. Piping stress analysis report for the critical lines.

8. Drawing showing the vessel cleats location for pipe supports and platform/ladder.

9. Layout for underground services.

10. Piping isometrics with bill of material.

11. Support location plan, support schedule, pipe support drawings.

12. Purchase specification for insulation, painting, wrapping and coating.

13. Material handling study.

Code:

A set of general rules or systematic procedures developed for design, fabrication, installation and inspection prepared in such a way

that it can be adopted by legal jurisdiction and made into law.

Standards:

Standards are prepared by professional group or committee. They are set of documents which are believed to be proper and good

engineering practice and which contain mandatory requirement.

Types of pipes:

1. Seamless:

Pipe produced by piercing a billet followed by rolling or drawing or both.

They are used for high pressure applications.

2. Welded:

a. Electric fusion welded (EFW): Pipes carrying a single or double longitudinal but weld joined wherein coalescence is produced by

manual or automatic electric arc welding in the preformed tube.

b. Electric resistance welded: (ERW): Pipe carrying longitudinal but weld joined wherein coalescence is produced by heat obtained

from resistance of the pipe to flow of electric current in a circuit of which the pipe is a part and by application of pressure.

3. Forged and bored:

Pipes prepared by forging and then boring to the desired thickness.

Various methods of pipe joints:

1. Butt weld pipe joints

2. Socket weld pipe joints

3. Screwed pipe joints

4. Flanged pipe joints

5. Spigot socket pipe joints

Generally used pipe materials are Carbon steel:

ASTM A53- welded and seamless pipe, black and galvanised.

ASTM A106- Seamless cs pipe for high temperature services.

ASTM A672- Electric fusion welded steel pipe for high pressure service at moderate temperature services.

Stainless steel:

ASTM A312- Seamless and welded steel pipe for low temperature services.

A409-welded large diameter austenitic steel pipe for corrosive and high temperature services.

ASTM A358- Electric fusion welded austenitic chrome -nickel steel pipe for high temperature services.

Low alloy steel:

ASTM A335- Seamless ferritic alloy steel pipe for high temperature services.

ASTM A691- Carbon and alloy steel pipe, electric fusion welded for high pressure service at high temperature.

Low temperature carbon steel:

ASTM A333- Seamless and welded steel pipe for low temperature services.

ASTM A671- Electric fusion welded steel pipe for atmpospheric and low temperature services(sizes >=16in NB)

In case of Low pressure services the branching off is done by directly pipe to pipe welding. This is called as Stub-in or Stub-on

connection. Depending on the size and the thickness of the branch-off sometime times reinforcement pads are welded on the

main pad for the area compensation purpose.

The requirement of the reinforcement pad is specified in the code ASME B31.3. The branch table or schedule are generally is a part of

each piping specification which gives the type of fitting to be used depending on the size of header and corresponding size of the

branch.

Couplings:

There are three types of coupling available each type is used in the piping system depending upon the requirement

Full coupling:

Used to join small bore plain end pipes where the pipe spec requirement is socket weld

Half coupling:

Used to take a small bore pipe branch-off from a large bore pipe where the pipe spec requirement is socket weld in small bore size

Reducing coupling:

Used to reduce the size of a small bore pipe maintaining the centerline of the pipe.

Pipe full coupling Pipe half coupling

Swage Nipples:

The function of Swage nipples are the same as reducer the only difference is that they are generally used to connect butt welded pipe

to a socket welded or screwed pipe.

There are also available as Concentric and Eccentric type.

The different end connections available are:

PBE-Plain Both Ends

PLE-Plain Large Ends

PSE-Plain Small End

BLE-Beveled Large End

TSE-Threaded Small End

Pipe concentric swage nipples

Pipe eccentric swage nipples

Pipe flanges based on Face Finish:

Stock Finish:

These flanges are used with non-metal gaskets. The allowable roughness for these type of Flanges is 250-500 or 500-1000 micro inch

AARH.

Smooth/Serrated Finish:

These flanges are used with metal or spiral wound gaskets. The allowable roughness for these type of Flanges is 125-250 micro inch

AARH. Extra Smooth Finish:

These flanges are used with metal RTJ and T/G flanges. The maximum allowable roughness for these type of Flanges is 63 micro inch

AARH.

Selection of Pipe Supports: Parameters Considered

The basic parameters considered during the selection of supports are mentioned below:

1) Process design conditions

2) Pipe material of construction

3) Piping Loads including Piping weight, fluid,weight, Valves,inline instruments etc.

4) Insulation material,thickness,density & specification.

5) Piping General Arrangement drawing

6) Thermal forces,moments & displacement of Piping

7) Occasional loads: Hydrotest loads, Sesimic loads, wind loads etc.

The layout and the design of the piping and its supporting elements shall be directed towards preventing the following

1. Piping stresses in excess of those permitted in the code.

2. Leakage at joints.

3. Excessive thrust and moments on connected equipment (such as pumps and turbine).

4. Excessive stresses in the supporting (or restraining) elements.

5. Resonance with impose fluid induced vibrations.

6. Excessive interference with thermal expansion and contraction in a piping system, which is otherwise adequately flexible.

7. Unintentional disengagement of piping from its supports.

8. Excessive piping sag in systems requiring drainage slope.

9. Excessive distortion or rag of piping (e.g. thermo plastics) subject to creep under conditions of repeated thermal cycling.

10. Excessive heat flow, exposing supporting elements to temperature extremes outside their design limits.

The basic type of supports used in refinery are:

Anchors: It restricts all six degree of freedom (i.e,Rotational, Logitudinal & Axial).

Guides: It restricts the longitudinal movements but free to move in rotational and axial.

Line Stops: It restricts the axial movements but free to move in rotational and longitudinal.

Rests: It takes the vertical loads generated due to pipe weight, fluid weight,thermal loads and occasional loads.

1. Non-metallic Gaskets:

Usually composite sheet materials are used with flat face flanges and low pressure class applications. Non-metallic gaskets are

manufactured non-asbestos material or Compressed Asbestos Fibre (CAF). Non-asbestos types include arimid fibre, glass fibre,

elastomer, Teflon (PTFE) and flexible graphite. PTFE or RPTFE are used in high corrosive applications.

Full face gasket types are suitable for use with flat-face (FF) flanges and flat-ring gasket types are suitable for use with raised face (RF)

flanges.

2. Semi-metallic Gaskets:

Semi-metallic gaskets are composites of metal and non-metallic materials. The metal is intended to offer strength and resiliency while

the non-metallic portion of a gasket provides conformability and sealability Commonly used semi-metallic are spiral wound, metal

jacketed, Cam profile and a variety of metal-reinforced graphite gaskets.

Semi metallic gaskets are designed for the widest range of operating conditions of temperature and pressure. Semi-metallic are used

on raised face, male-andfemale and tongue-and –groove flanges.

Spiral wound gaskets are used for high temperature and high-pressure applications. The main parts of spiral wound gasket are metallic

windings and filler material. The criteria for material selection of windings are: corrosive nature, fluid concentration, operating

temperature and material cost. Commonly used material for winding are Stainless steel 304, 316 and 321.Alternate winding materials

also can be used depending upon the services. General filler material used are Asbestos and graphite. Graphite filler are

recommended for very high temperature application.

For proper positioning, spiral wound gaskets are provided with outer centering ring made up of Carbon Steel. In Vacuum service

application they are provided with inner ring. The material of the ring should be compatible with the process fluid.

Spiral wound gasket is recommended with flange face finish of 63-250 AARH.

3. Metallic Gaskets:

Metallic gasket is fabricated from one or a combination of metal to the desired shape and size. Common metallic gasket is ring-joint

gasket and lens rings.

It is suitable for high-pressure and temperature applications and require high bolt load to seal.

Dimensional Standards:

API 601- Metallic Gasket for Refinery Piping

BS 3381- Spiral Wound Gaskets to suit BS 1560 Flanges

ANSI B 16.20- Metallic Gasket for Steel Pipe Flanges, Ring Joint, Spiral Wound and Jacketed

ANSI B 16.21- Non-Metallic flat Gasket for Pipe Flanges

In a chemical plant pipes run from one unit to another unit, lines coming from outside facilities etc. The structure which used for these

purpose is termed as Piperack. So while preparing the plot plan for a plant one of the most important activity is to plan the piperack

through which the piping has to run from one unit to the other.

Generally it is cheaper to run pipes at grade, but only where resulting hindrance to access is unimportant. The arrangement of pipe

rack and structures should be given special attention as savings in structural steel and civil costs can often be greater than increased

cost due to extra pipe length. Piperack constructionablity (structural or concrete) needs to be freezed at early stage of project in

consultation with client & civil . Piping that needs to be free draining or ‘no pocket’ will often dictate the levels for elevated structures.

The following types of Pipe racks may be required:

• Interconnecting/Main piperack (elevated)

• Unit piperack (elevated)

• Pipe track or sleeper way (at grade)

Interconnecting piperacks carry process and utility lines to and from process and utility units. They should not run through process

or utility units. Unit racks connect to the main rack taking lines into the respective units via a battery limits station. These racks should

be at different elevations to the interconnecting rack.

Unit piperacks are the main arteries carrying the pipes into the units, and as such should be centrally located and are usually

elevated. They should be of sufficient height to allow vehicle access beneath. The width of rack will be determined by the number of

lines (plus future requirements) it carries, along with any allocation for cable trays.

In off-site areas or where only a few lines are required to run to an isolated plant area it is more cost effective to run pipes on pipe

tracks or sleepers, at grade. Sleeper spacing will depend on limiting pipe spans. Sleeper piping is also preferred in off-site area as

pipe runs on elevated structure often acts as hindrance for fire protection.

Pipe trenches are used mainly in large off-plot storage areas where pipes need to run at low level and require to pass under plant

roads. However use of unfilled open pipe trenches has to be reviewed considering the draining requirement.

Galvanization (or galvanisation) is the process of applying a protective zinc coating to steel or iron, in order to prevent rusting.In few

services care should be taken to avoid rusting of the pipeline as it might be hazardous to personnel, cause damage, malfunction of

equipment, instrument, etc. so for that reason the piping is galvanized.

Pipe Material Procurement Process for an Oil and Gas Project

Specification engineer than populates the replies of all the vendors/suppliers in a common document which is called the technical bid

analysis (TBA)/ evaluation (TBE). This document will show the highlighting points of the particular enquiry along with the replies from

all the vendors/suppliers. If there are any deviations they are mentioned against applicable points in the TBA/TBE. In the TBA/TBE

Specification engineer has to give a technical acceptance or rejection of each vendor/supplier in the enquiry. This TBA/TBE is then

forwarded to projects/procurement department.

5. After receiving the TBA/TBE, the projects/procurement departments then evaluate the technically accepted vendor for commercial

and delivery schedule. The vendor/supplier which is acceptable in technical, commercial and delivery schedule terms are given

the purchase order (PO).

Key topics which need to be explicitly mentioned in an enquiry specification/Request for quotation (RFQ) are mentioned below:

1. Product fabrication guidelines. (what can be done & what cannot be done, For ex.: cold work / hot work / drawing etc)

2. Product chemical composition control. (For ex.: Codes applicable / Max % of elements etc)

3. Product Governing codes (For ex.: ASME / ASTM / NACE / Chapter IX etc)

4. Product heat treatment / stress relieving requirements. (For ex.: Tempering / Normalizing etc)

5. Product Surface treatment requirements (For ex.: Galvanizing / Pickling / Passivation etc)

6. Product production Quality assurance, quality control & quality management requirements (For ex.: ISO Quality management system

/ Quality plans / Min. info. in Quality record manual etc)

7. Product inspection plan / inspection frequency / (For ex.: Inspection methods / frequency / Inspectors qualifying procedures etc)

8. Product testing requirements (For ex.: Codes applicable / PMI / NDE / Hydrotest / sampling etc)

9. Product certification requirements (For ex.: EN10204 3.1 or 3.2 etc)

10. Product marking requirements (For ex.: Color code / tagging etc)

11. Product Preservation requirements (For ex.: preservation methods / Preservation requirements etc)

12. Products minimum documentation to be submitted for approval (For ex.: As per SDRL)

13. Product packing requirements (For ex.: Packing for sea / land / road transportation etc)

14. Product delivery information (For ex.: Final destination / Delivery period etc)

15. Product shipping information (For ex.: Weight & volume of product / Freight charges etc)

16. Size compatibility between Nominal sizes API 6A Sizes

Corrosion can be defined in a more simplistic way as deterioration of materials under the influence of an environment.

COMMON TYPES OF EXPANSION JOINTS ARE:

Simple Expansion Joint

Universal Expansion Joint

Pressure Balanced Expansion Joint

Hinged Expansion Joint

Gimbal Expansion Joint

SIMPLE EXPANSION JOINT:

The main use of single expansion joint in a piping system is to absorb axial & small amount of lateral & angular movements

in which it is installed.

UNIVERSAL EXPANSION JOINT:

Universal expansion joints contain two bellows with multiple convolutions joined by a center pipe or spool. These joints, also known as

double or tandem bellows expansion joints are used for the purpose of absorbing any combination of axial, lateral, or angular

movements in a piping system.

HINGED EXPANSION JOINT:

Hinged expansion joints are usually used in sets of 2 or 3 elements to absorb lateral deflection in one or more directions in a single

plane.

The gimbal pipe expansion joint is basically same as the hinge type, except that instead of being limited to deflection in only one

plane gimbal Expansion Joints are used to absorb angular rotation in any plane, using two pairs of hinges attached to a common

floating gimbal ring. Gimbal bellows joints are designed to absorb the full pressure thrust load of the expansion joint and thus guard

the adjacent equipment from damage due to thrust loading.

Flame Arrester (also spelled as Flame Arrestor) is a device fitted to the opening of an enclosure or to the connecting pipe work of a

system of enclosures and whose intended function is to allow flow but to prevent transmission of a flame.

Steam Trap is some such automatic draining device, which satisfies all above functional requirements in terms of discharging the

condensate at the required flow rate under varying inlet and back pressure conditions, at the same time allowing a rapid evacuation of

cool air/non-condensible gases from the system.

A trap is therefore required on typically following locations where Condensate is likely to get formed.

1. Steam Distribution Headers:

Where self-draining of the condensate is intercepted by vertical risers/ loops.

At low points and at approximately every 50 – 60 Mts. of distance on horizontal pipe.

Ahead of all possible Dead Ends (e.g. shutoff valves on bypass lines)

2. Steam Tracing/ Jacketing Service:

At the steam supply manifolds for feeder lines.

At the condensate collection manifolds.

3. Steam Operated Equipment:

Ahead of Humidifier, Pumps and Turbines etc.

Condensate outlet from the Equipment using steam (e.g. Condensers, Coils, Heaters, Drier etc.)

Pipe rack piping study:

General arrangement of the piperack is finalized during the development of the overall plot plan.

The following data and drawings are required to be studied before starting the detailed design of pipe rack piping study:

Unit Plot Plan / Overall Plot Plan

Piping and Instrumentation diagrams

Plant layout specification

Client specification

Material of construction

Fireproofing requirements

Normally, the piperack piping study, with its structural and platform requirements is the first priority item for detail engineering of a

process unit.

The points which are finalized during the piperack piping study are:

Exact width of the piperack

Numbers of levels and elevations

Access and maintenance platforms requirements

Pipelines in the pipe rack are classified as process lines, relief-line headers and utility headers.

Process lines:

(a) Which interconnect nozzles on process equipment more than 20ft. apart (closer process equipment can be directly interconnected

with pipelines)

(b) Product lines which run from vessels, exchangers, or more often from pumps to the unit limits to storage or header arrangement

outside the plant.

(c) Crude or other charge lines which enter the unit and usually run in the yard before connecting to exchangers, furnaces or other

process equipment e.g. holding drums or booster pumps.

Utility lines:

Utility lines in the pipe rack can be put in two groups:

(a) Utility headers serving equipment in the whole plant. Such lines are: low and high pressure steam lines, steam condensate, plant air

and instrument air lines. If required, cooling water supply and return and service water can also be arranged on the pipe rack.

(b) Utility lines serving individually one or two equipment items or a group of similar equipment (furnaces, compressors) in the plant.

Such lines are: boiler feedwater, smoothering steam, compressor starting air, various fuel oil lines, lubricating oil, cooling oil, fuel gas,

inert gas and chemical treating lines.

Instrument lines and Electrical cables:

Instrument lines and Electrical cables are often supported in the yard and extra space should be provided for these facilities. The best

instrument line arrangement eliminates almost all elevation changes between the plant and the control room. This can be easily

achieved when instrument lines are supported outside the pipe rack column on a suitable elevation.

STEPS TO PIPE RACK PIPING:

The first step in the development of any pipe rack is the generation of a line-routing diagram. A line routing diagram is a schematic

representation of all process piping systems drawn on a copy of pipe rack general arrangement drawing / or on the unit plot plan

where the pipe rack runs in the middle of the process unit.

Based on the information available on the first issue of P&I Diagram / Process flow diagram i.e. line size, line number, pipe material,

operating temperature etc. the line routing diagram is to be completed.

Once the routing diagram is complete, the development of rack width, structural column spacing, road crossing span, numbers of

levels and their elevations should be started.

After analyzing all the requirements and arrangements, the dimensions are to be rounded off to the next whole number. Based on

the economics, the width and the number levels e.g. two tier of 30 ft. wide or three tiers of 20 ft. wide rack will be decided.

The gap between the tiers shall be decided on the basis of the largest diameter pipeline and its branching. The difference between

the bottom line of pipe in the rack and the bottom of a branch as it leaves the rack shall be decided carefully, to avoid any

interference due to support, insulation, size of branch etc. All branch lines from the main lines on pipe rack shall be taken

aesthetically on a common top of steel (TOS).

INTERFACE WITH OTHER DEPARTMENTS:

The following are the highlights of the major activities where interdepartmental discussions are necessary before the documents are

released for execution.

Piping / Civil:

Civil Skeleton/ Civil Information Drawings of Units, Pipe Rack and Tank Farms.

Civil Drawing review/ release for construction.

Release of HOLDS at subsequent dates.

Piping/ Mechanical:

Nozzle Index and Nozzle Orientation.

Foundation Bolt details and orientation.

Platforms Cleats on Equipment – its orientation and levels etc.

Piping/ Process:

Review/ Markup on PID’s

Package Units Drawings from Vendors – its review fir fixing the Battery Limit supply,

General Arrangement, Civil details etc.

Special Parts List – fixing responsibility for procurement action (i.e. by PI, PE or MQ Group).

Piping/ Procurement:

Issue Enquiry Specification for PI Items.

Issue Revision of MTO at subsequent dates for necessary procurement action.

Issue Order Specification for Valves/ Special Parts. For Piping items like Flanges, Fittings, Fasteners, Gaskets etc. Procurement

Department issues the Order Specifications.

Discussions with various Vendors during bid evaluation.

Piping/ Project Management:

Finalization of Master Plot Plan after getting clearance/ agreement with Licensor, Client, Statutory Bodies etc.

Finalization of Procurement Philosophy/ Spare Philosophy with Client

Monitoring of Project Schedule and updating the month wise activity and follow-up/ coordination with Client, Vendor and Licensor.

Progress Report/ Constraint Report.

Piping/ Electrical:

Finalization of Cable Tray Layout and requirement of Insert Plates on RCC Column/ Beam, Floor opening for Cables etc.

Cable connection/ Push Button supports near the Terminal Box of all motors.

Finalization of location of Switchboards, Lighting Fixtures floor wise.

Piping/ Instruments:

Review of IC comments on the PID revision due to change in any instrument.

Finalization of Instrumentation GES regarding connection details of Instruments and delineation of scope of procurement between

PI and IC.

Details of Instrument mountings/ dimensions.

Review of approved Vendor Drawings for Instruments with respect to Isometrics (released for construction) as well as the piping

arrangement around the Instrument.

Finalization of IC Cable Tray requirement.

Review of field routed instrument Cable Trays, keeping provision of accessibility, free space and interference with piping

arrangement

Nominal Pipe Size (NPS) is a North American set of standard sizes for pipes used for high or low pressures and temperatures.

Pipe size is specified with two non-dimensional numbers: a nominal pipe size (NPS) for diameter based on inches, and a schedule

(Sched. or Sch.) for wall thickness

NB (nominal bore) is the European designation equivalent to NPS is DN (diamètre nominal/nominal diameter/Durchmesser nach

Norm), in which sizes are measured in millimeters.

Tower Piping: Center for equipment layout

Columns, towers and vertical vessels are to be arranged in a row with a common centerline if of similar size. If, however, diameters

vary considerably, lining up with a common face will be found to be beneficial.

Generally, platforms of manholes shall be utilized for operating and maintenance access for valves and instruments. Small valves

and instruments are usually arranged outside the platforms and are operated from the ladder. Additional platforms are required for

operating valves, line blinds, relief valves (3” and above, orifice plates, transmitter of a level controller and handling davit.

Nozzles & Manholes

Temperature connections are usually located in the liquid space of tray downcomers. In some cases, it could be also in vapor space. In

front of thermowell nozzles, a clearance of approximately 600mm is required to remove thermowell.

Pressure connections are usually located on the vapor space just below the trays. All instrument locations are to be confirmed by

process department. Care should be taken with interference such as between two reinforcing pads, one near the other, nozzle baffle

and down comer and weir dams.

Manholes should preferably be placed on road side on tray area so that it is convenient for removal and lowering to grade of tower

internals. Accessibility whether internal or external is very important and is often not given enough consideration. A balance must be

made between the external accessibility of connections from ladders and platforms and internal accessibility from shell manholes,

handholes or removable section of trays.

Platforms, Ladders and Davit

Platforms are considered as work area for manholes and rest area when an intermediate area is added, if the height between two work

platforms exceeds 9 meters.

Generally, layout analysis should be started from the top of the tower and those having reboilers should be started from the bottom,

but with the designer visualizing the layout as a whole. There will be no trouble in dropping the large lines (such as overhead vapour

lines) straight down the side of the column. The lower spaces can then be laid out with piping and nozzles’ knowing what space is

already occupied by these large vertical lines.

Condensers are often located at grade. In such cases, a large overhead lines drop right alongside the tower to the condenser at grade.

Condensers can also be elevated. An elevated condenser is more convenient from a tower piping layout standpoint because the large

overhead line leaves the immediate vicinity of the tower at a high level, leaving the lower section open, say, for a ladder from grade to

the first platform.

Whether the condenser is at grade or at an elevated level, the flexibility and thermal load problems connected with large diameter

overhead lines must be considered.

For valves and blinds, the best location is directly at tower nozzles. Valves in branch connections or at nozzle should be in a

position where the line will be self-draining on both sides of the valve. A dead leg over closed valve collects liquid or solids. The

trapped liquid can freeze, or when opening the valve, without draining the leg, can upset process conditions.

All instruments should be oriented so as not to obstruct the passage way at the ladder exits or entrance. Convenient access and

groupings of instruments and valve will help inspection and plant operation. Instruments should not be located adjacent to manholes.

Bolting: Selection Guide for Bolting Material

As per ASME B16.5, one can use either square head machine bolts or studs for making a joint. Bolts and studs are available in either

fully threaded or partially threaded condition. The fully threaded structure ensures an equal distribution of elongation when the bolts are

tightened and avoid concentration of stresses that exist in partially threaded stock due to varying cross-sections.

Also, studs are preferred over bolts due to ease of insertion during assembly. At places, like bolting of two valves together, there may

not be sufficient clearance available for inserting bolts due to valve body contour and use of studs is the only possible solution

The breather valve also known as pressure/vacuum relief valve is a protective device mounted on the top of a fixed roof

atmospheric storage tank. Its primary function is to conserve the loss of storage tank content when the tank is in out-breathing mode.

The purpose & selection of breather valve is mainly to control the in-breathing and out-breathing of storage tank by protecting the tank

under over pressurization and vacuum and possible rupture or imploding.

Types of Breather Valves

a) Pressure or Vacuum Relief Valve

b) Emergency Vent Valve

c) Gauge Hatch

d) Tank Blanketing Valve

e) Pilot Operated Relief Valve

f) Air Operated Relief Valve

A plug valve is a quarter-turn on-off valve. The plug can be cylindrical or tapered and has a variety of port types. Plug valves are

available in either a lubricated or non-lubricated design. Plug valve ends can be flanged, hub type or butt weld.

TYPES:

1. Non-Lubricated Plug Valve- These valves are not torque seated. Low Maintenance

2. Lubricated Plug Valve- These valves are not torque seated.

3. Eccentric Plug Valve- These valves are torque seated.

4. Expanding Plug Valve- These valves are torque seated.

Storage tank are containers used for storage of fluids for the short or long term. Cluster of tanks together in a same are termed as

“Tank Farms”.

Types of Tanks:

Types of Tanks in Process plant depend on the product to be stored, potential for fire, and capacity to be handled.

Cone roof tank:

Used for countless products including Petroleum, Chemicals, Petrochemicals, Food products & Water

Floating roof tank:

The roof of tank rises and lowers with the stored contents thereby reducing vapour loss &minimizing fire hazard. Commonly found in

Oil refineries.

Low temperature storage tank:

Tanks stores liquefied gases at their boiling point. Products found in such tanks include Ammonia (-28 °F), Propane (-43.7 °F) and

Methane (-258°F).

Horizontal pressure tank (Bullet):

Used to store products under high pressure.

Hortonsphere pressure tank:

Handles large capacity under high pressure.

Underground Tanks:

Commonly used for drain collection of the plant at atmospheric pressure.

FRP Tanks:

Commonly used for corrosive fluid at atmospheric pressure.

Classification based on capacity and diameter:

1. Larger installations: Aggregate capacity of Class A and Class B petroleum product is more than 5000 cu.m or diameter of Class A

or Class B product tank is more than 9m.

2. Smaller installations: Aggregate capacity of Class A and Class B petroleum product is less than 5000 cu.m or diameter of Class A

or Class B product tank is less than 9m.

Dyke Enclosure

Aggregate capacity in one dyke enclosure:

1. Group of Fixed roof tanks: Upto 60,000 m3

2. Group of Floating roof tanks: Upto 120,000 m3

3. Fixed cum floating roof tanks shall be treated as fixed roof tanks.

4. Group containing both Fixed roof tanks & Floating roof tanks, shall be treated as fixed roof tanks.

Class – A and / or Class – B petroleum products :- Same dyked enclosure

Class – C: – Preferably separate dyked enclosures.

Tanks shall be arranged in maximum two rows. Tanks having 50,000 m3 capacities and above shall be laid in single row.

The tank height shall not exceed one and half times the diameter of the tank or 20 m whichever is less.

The minimum distance between a tank shell and the inside toe of the dyke wall shall not be less than half the height of the tank.

1. Height of Dyke (H): 1m < H < 2m

2. Width of Dyke (W): Minimum 0.6m (Earthen dyke) Not Specific (RCC dyke)

Separation distances between the nearest tanks located in separate dykes shall not be less than the diameter of the larger of the

two tanks or 30 meters, whichever is more.

In a dyked enclosure where more than one tank is located, firewalls of minimum height 600mm shall be provided to prevent spills

from one tank endangering any other tank in the same enclosure.

Piping layout for Tank farm

Piping from / to any tank located in a dyked enclosure should not pass through any other dyked enclosure. Piping connected to

tanks should run directly to outside of dyke to the extent possible to minimize piping within the enclosures.

Inside dyked area, earth shall be graded and gravel filled. H.P (High point) level inside the dyked area shall be 300mm above the

outside grade & shall slope towards the drain sump inside dyke.

In dyked area of tankfarm, arrangement shall be made to drain containment to either OWS or storm water drain by providing two

valves. Generally for the first 10 -15 mins of rainwater will be routed through the OWS and subsequently through the storm water.

Pumps & its associated piping shall be located outside the dyke wall.

Pipes Crossing the dyke wall shall pass through a sleeve suitably sealed.

Piping elevation to be fixed considering settlement values.

Spiral stairways shall be provided on each tank considering ease of access and minimizing paving requirement. Wind direction

consideration should be taken into account

Pumps shall be provided in a curbed area (150 mm high) with proper provision for draining either to OWS & storm water drain.

Pump plinth shall be minimum 300mm high from finished floor level.

Carbon Equivalent CE shall not exceed 0.43%

Where CE = C + Mn/6 + (Cr+Mo+V)/5 + (Cu+Ni)/15

The above formula for CE is applicable when the carbon content is greater than 0.12%

Requirements for Pipes

Carbon steel pipes shall be supplied in double random lengths (11 to 13m) for pipe sizes 2″ to 36”, and in single random lengths (5 to

7m) for pipe sizes 1.5″ and smaller.

SS, DSS and CS galvanized pipes shall be supplied in single random lengths (5 to 7m) for all pipe sizes.

CS & LTCS Pipes shall be fully killed, fine grained and shall be supplied in normalized or normalized and tempered condition. All

stainless steel pipes shall be supplied in solution annealed condition.

Welded pipe shall be supplied with single straight seam for sizes upto 36” and double straight seam for sizes greater than 36”

subjected to approval from the contractor.

All DSS welded pipes with a wall thickness greater than 30 mm shall also be 100% ultrasonically examined.

Requirements for Fittings

3.7 Union dimensions shall be in accordance with BS 3799.

3.8 Galvanizing of fittings shall be in accordance with ASTM A153. Threaded portion of fittings shall be supplied with threads

free of galvanizing.

3.9 Swage nipple shall be pipe swaged by forging only. Machining of bar stock, forgings or heavy wall pipe not permitted.

Dimensions shall be in accordance with MSS-SP-95.

3.10 All reduction sizes for tees and reducers to be in accordance with ASME B16.9.

3.11 CS & LTCS fittings shall be fully killed and fine grained and shall be supplied in normalized or normalized and tempered

condition.

3.12 100% of CS & LTCS welded fittings, with wall thickness greater than Sch 80 shall be examined by Magnetic Particle

Examination for weld bevel ends. Acceptance standards shall be in accordance with ASME VIII Division 1, Appendix 6. This shall be

done after final heat treatment.

3.13 100% of CS, LTCS & SS forged fittings, with wall thickness greater than Sch 80 shall be examined by Magnetic Particle /

Dye penetrant examination. Acceptance standards shall be in accordance with ASME VIII Division 1, Appendix 6 / 8. This shall be done

after final heat treatment.

3.14 100% of SS & DSS wrought fittings having wall thickness more than 20mm shall have the bevel and weld end over a width

of 25mm, examined by Dye penetrant Method.

Acceptance standards shall be in accordance with ASME VIII Division 1, Appendix 8.

3.15 100% of DSS welded fittings with a wall thickness greater than 30mm shall be 100% ultrasonically examined in accordance

with ASME VIII Division 1.

3.16 100% of DSS forged fittings weld bevels shall be examined by Dye Penetrant inspection.

the support is classified as:

1.1 Primary Supports:

It is the parts of support assembly which is directly connected to the pipe.

1.2 Secondary Supports:

It is the parts of support assembly which is directly connected to the foundation / structure and is supporting the primary support

attached to the pipe line.

Based on construction details, pipe supports are broadly classified in three types, as

- RIGID SUPPORTS

- ELASTIC SUPPORTS

- ADJUSTABLE SUPPORTS

2.1 Rigid Supports:

This type of support arrangement is generally very simple and has maximum use in piping. It does not have adjustability to the erection

tolerances. It will directly rest on foundation or structure which is supporting the pipe. Common type of RIGID SUPPORTS are shoe

type (welded), shoe type (with clamp) Trunnion type, valve holder type, support brackets (Secondary Support

2.2 Elastic Supports:

This type of support is commonly used for supporting hot piping. It shall be able to support pipes even when the pipe is moving up or

down at support point.Common types of elastic supports are variable type spring supports, constant type spring supports.

2.3 Adjustable Supports:

This type of support is Rigid type in construction but is has few nuts and bolts arrangements for adjusting the supports with respect to

the actual erected condition of pipe. The support can be adjusted for the erection tolerances in the piping. These are required for a

better supporting need at critical locations of pipe supports.Mostly all type of rigid supports can be modified by using certain type of

nuts and bolts arrangement, to make it as an Adjustable support.

Centrifugal Pump Piping Design Layout

The suction pipe should never be smaller than the suction nozzle of the pump and in most cases it should be at least one size larger.

Suction pipes should be as short and as straight as possible. Suction pipe velocities should be in the 1.0 – 1.5 metre per second range,

unless suction conditions are unusually good. Higher velocities will increase the friction loss and can result in trouble some air and

vapour separation.

Changes in direction of suction lines should be at least 600mm away from the pump suction.

Pumps should be arranged in line with drivers facing the access gangway.

With normal piperack column spacing of 6m, it is generally found that only two pumps of average size can be arranged between the

columns, with a preferred clearance of 1m between the pumps.

The clearance between any structure / steel work and the pump discharge line shall be 0.75m minimum. For small pumps upto 18 KW,

clearance between pumps should be 0.9m minimum. A space of 2 – 2.5 m should be provided for working aisle.

Means of lifting should be provided for pumps or motor weighing more than 25Kg.

Pump suction piping shall be as short as possible and shall be arranged so that vapour pockets are avoided.

For end suction pumps, elbows shall not be directly connected to the suction flange. A straight piece 3 times the line size shall have to

be provided at the suction nozzle.

For top suction, pump elbow shall not be directly connected to suction flange. A straight piece of minimum 5 times the nozzle size shall

have to be provided at the suction nozzle.

Design Guide For Heat Exchanger Piping

The main application of heat exchangers is to maintain the heat balance by addition or removal by exchange between streams of

different operating temperatures.

The most common heat exchangers used in process plants are :

a) Shell & Tube Exchanger

b) Plat type Exchanger

c) Spiral Exchanger

d) Double Pipe Exchanger

e) Air Cooler Exchanger

Nozzle Orientation Drawing

Nozzle Orientation are prepared for following equipments,

Columns and Reactors

Horizontal / Vertical vessels

Tanks

Nozzle Orientation is not prepared for Heat Exchangers

Input documents required for preparation of Nozzle Orientation

P&ID

Process Data Sheet

Mechanical Data Sheet / First Pass Vendor drawings

Vendor drawings for Column Internals

Piping Material Specifications

Piping Studies

30% Model review comments

Instrument Level Sketches

Piping requirements for Instruments

Standard details for Platform and ladders.

Brief procedure for preparation of Nozzle Orientation

Nozzle Orientation drawings contain two basic views-

Plan view and

Schematic elevation

Orientation plan views shall include key information viz. nozzles, manholes, shell openings, lifting & tailing lugs, earthing bosses, name

plate and davits with their tag numbers, degrees / locations.

Schematic elevation shall indicate all the manholes, nozzles and their respective platforms / ladders, equipment supports.

For inclined horizontal Vessels only the schematic elevation view shall be furnished and no plan view shall be provided. Reference

point which is the intersection of center line and fixed saddle location will govern for detailing.

Nozzles sizes / schedule and elevations shall not be included in the Nozzle Orientation.

Nozzle Orientation shall be developed with zero (0) degree aligned to the plant North and incremental degrees shall be indicated

clockwise.

Davit and manhole opening shall be indicated in the Nozzle Orientation drawing. Manhole opening shall be oriented such that they are

pushed closed in the escape direction

For all vertical Vessels and Columns, platform extent shall be preferably restricted to 180 degrees.

Ladders with two side exits at the same platform elevation shall be avoided.

Material Used for Rubber Lining of Piping System

Rubber linings are mainly used for protection against corrosion and/or erosion damage.

Material Selection

Material selection is determined by:

- service conditions (pressure, temperature, medium, etc.)

- design

- manufacturing method

The following rubber types are used for lining purposes (classification according to ASTM D 1418):

- Isoprene or natural rubber (NR)

- Synthetic isoprene rubber (IR)

- Styrene-butadiene rubber (SBR)

- Chloroprene rubber (CR)

- Butyl rubber (IIR)

- Broom-butyl rubber (BIIR)

- Chloro-butyl rubber (CIIR)

- Nitrile-butadiene rubber (NBR)

- Ethylene propylene rubber (EP, EPDM)

- Urethane rubber (UR)

- Chlorosulphonated polyethylene (CSM)**

- Fluoro elastomer (FKM)*

Depending on the degree of vulcanization, rubbers can be classified as ‘soft’ rubber or as ‘hard’ rubber. The hardness of soft rubbers is

expressed in Shore A, and the hardness of hard rubbers is expressed in Shore D (ASTM D 2240).

Strainer

It is a device used in Piping Systems, its function being to arrest foreign particles like dirt, weld sputter, scale etc upstream of rotating

equipment such as compressors, turbines, pumps, rotary instruments, steam traps etc.

Distillation Column Piping

The distillation is separation of the constituents of a liquid mixture via partial vaporization of the mixture and separate recovery of

vapour and residue.

Various kinds of devices called plates or trays are used to bring the two phases into intimate contact. The trays are stacked one above

the other and enclosed in a cylindrical shell to form a Distillation Column.

The feed material, which is to be separated into fractions, is introduced at one or more points along the column shell.

Due to difference in gravity between liquid and vapour phases, the liquid runs down the column, cascading from tray to tray, while

vapour goes up the column contacting the liquid at each tray.

The liquid reaching the bottom of the column is partially vaporized in a heated reboiler to provide reboil vapour, which is sent back up

the column. The remainder of the bottom liquid is withdrawn as the bottom product.

The vapour reaching the top of column is cooled and condensed to a liquid in the overhead condenser. Part of this liquid is returned to

the column as reflux to provide liquid overflow and to control the temperature of the fluids in the upper portion of the tower. The

remainder of the overhead stream is withdrawn as the overhead or distillate product.

Introduction to Cooling Tower:

Cooling towers are heat exchangers that are used to dissipate large heat loads to the atmosphere generated in the Process Plants.

There are two types of Cooling Tower:

a) Mechanical Draft

(i) Mechanical Forced Draft

(ii) Mechanical Induced Draft

b) Natural Draft

Introduction to Restriction orifice (RO)

Restriction orifice (RO) is mainly used to achieve controlled or restricted flow of process medium. The orifice offers a restriction to the

process flow and the pressure head drops from the upstream to the downstream.

Types of restriction orifice plates

(i) Single stage restriction orifice.

(ii) Single stage multi-hole restriction orifice.

(iii) Multi-stage restriction orifice plate assembly.

Application of restriction orifice plates

(i) Restriction Orifice (RO) at the downstream of blowdown valves.

(ii) Restriction Orifice (RO) in pump recirculation line.

(iii) Restriction Orifice (RO) to restrict gas blow-by.

(iv) Restriction Orifice (RO) to check excess flow.

(v) Restriction Orifice (RO) for controlled pressurization.

Mitre Elbows:

These are usually used for low pressure, low temperature non critical services having 14” inches and above. They are economical as

compared to elbows in higher sizes and hence preferred.

Mitre bends are usually fabricated at site out of pipe by cutting and re-welding spools as shown in Fig. 7. The Figure is for 5 piece 4

weld mitres. The change in direction at every weld is 22 1/2 °. We may also have 4-piece 3-weld mitre where change in direction at

every weld would be 30°. Usually 5 piece 4 weld mitres are preferred in order to have smooth flow.

Because of high stress intensification factor they are not recommended on high temperature lines.

Pressure-temperature rating for mitre bend is not the same as for pipe and in order to withstand same pressure-temperature conditions

as applicable to pipe, a higher thickness is required for mitre bend.

Stress Analysis: Steps for Stress Analysis

The objective of pipe stress analysis is to ensure safety against failure of the Piping System by verifying the structural integrity

against the loading conditions, both external and internal, expected to occur during the lifetime of the system in the plant.

Steps involved in the stress analysis can be listed as

1.3.1 Identify the potential loads that the piping system would encounter during the life of the plant.

1.3.2 Relate each of these loads to the stresses and strains developed.

1.3.3 Get the cumulative effect of the potential loads in the system.

1.3.4 Decide the allowable limits, the system can withstand without failure.

1.3.5 After the system is designed, to ensure that the stresses are within the safe limits.

Types of loads

All the American code for Pressure Piping classifies the loads mainly into three types.

1.4.1 Sustained Loads: Those due to forces present during normal operation.

1.4.2 Occasional Loads: Those present during rare intervals of operations

1.4.3 Displacement Loads; Those due to displacement of pipe

an offshore engineer you could find yourself responsible for finding ways in which to extract oil and gas from natural reservoirs, in both

an economic and an environmentally sound way, as well as designing offshore installations and offshore drilling equipment, or devising

methods to maximise productivity.

An oil platform, offshore platform, or (colloquially) oil rig is a large structure with facilities to drill wells, to extract and

process oil and natural gas, and to temporarily store product until it can be brought to shore for refining and marketing.

The upstream sector includes the operations involved in searching for underground or underwater oil and gas fields and drilling

exploratory wells and at the same time, operating the wells that recover to re-direct the crude oil or raw natural gas to the surface. This

sector is also referred to as the 'Exploration and Production or E&P sector'.

The midstream sector processes and stores, markets and transports crude oil, natural gas and the various natural gas liquids like

ethane, butane and propane. The midstream sector involves the transportation (by pipeline, rail, barge, oil tanker or truck), storage, and

wholesale marketing of crude or refined petroleum products. Pipelines and other transport systems can be used to move crude oil from

production sites torefineries and deliver the various refined products to downstream distributors

The downstream sector includes all oils refineries and petrochemical plants, petroleum product distribution via the affiliated retail

outlets and natural gas distribution companies, within the operations. The downstream industry markets products such as gasoline and

diesel and jet fuel. This is also the sector responsible for the availability of natural gas and propane.

The need for independent energy supply has spurred many companies to invest heavily in storage facilities of oil & gas and

(petro)chemicals. The downstream sector commonly refers to the refining of petroleum crude oil and the processing and purifying of

raw natural gas,[1][2]

as well as the marketing and distribution of products derived from crude oil and natural gas.

What is Offshore Drilling and Drilling Rigs

A mechanical process where a wellbore is drilled through the seabed is referred to as Offshore drilling.

The main purpose of drilling is to explore for and subsequently extract petroleum which lies in rock formations beneath the seabed.

WHAT IS OFFSHORE DRILLING RIG

A offshore drilling rig is a machine which creates holes(usually called wells or boreholes) and/or shafts in the ground.

Drilling rigs can be massive structures housing equipment used to drill water wells, oil wells, or natural gas wells.

Drilling rigs can be mobile equipment mounted on trucks, tracks or trailers, or more permanent land or offshore-based marine units.

The term “rig” therefore generally refers to the complex of equipment that is used to penetrate the surface of the earth’s crust. THE OFFSHORE DRILLING CONCEPT

The offshore drilling concept is to drill a hole in the ground and stabilize it against collapse of its walls.

The drilling is made using drill bits that penetrate the soil and creates the hole.

Mud (mixed with cement) is injected in the hole to stabilize the sides and prevent it from collapse.

The drilling tower (Derrick) is used to handle the pipes and drilling equipment during drilling.

A blow-out prevention system and/or Christmas Tree is used to cap the well after completing drilling.

Piping Offshore: Main Components of Drilling

The main components involved in theoffshore drilling process are the drilling rig, the mud system, the blow-out preventer (BOP) etc.

THE MUD SYSTEM (BASICS):

This mud scours the bottom of the hole to keep the bit cutters clean and keep a fresh rock surface for the bit to attack.

Three Main Functions of the Mud are: (1) Cleans the bit, (2) Removes the Cuttings from the hole, (3) Keeps the hole from

collapsing.

DRILLING RIG:

The main component of the jack-up rig which is critical for selection in a drilling operation is the drill string.

THE DRILL STRING

The basic drill string is composed of drill bit, drill collars, Bottom Hole Assembly (BHA) and drill pipe.

Each joint of drill pipe is around 30ft long.

Each joint is between 2 3/8” to 6 5/8” in diameter depending on the location and the well type.

The drill string is hollow for the continuous circulation of drilling mud.

BLOW OUT PREVENTORS (BOP):

Sometimes formation fluids do enter the wellbore (the hole that is being drilled) under great pressure. When this happens, a well is

said to “take a kick.” It is especially risky if the fluid is a gas or oil.

To guard against the dangers of such events, rigs are usually equipped with a BOP.

If a well takes a kick and the mud cannot stop or slowly release the pressure, the BOP is the last line of defense.

If done correctly the gas is trapped in a bag type preventer and the mud and kick fluids special chemicals that are released into the

hole to stop the gases/oils from reaching the Surface) are pumped out into a separate pit for disposal.

Methods of Offshore Installations: Lift Barges, Floatover

There are two main methods of marine installation of heavy equipment. The conventional way to install major facilities, such as

topsides and production equipment, is through lift barges, while the other method which is gaining acceptance in offshore installation

is the floatover method.

1. Offshore installation – Lift Barges

For past many years, heavy lift cranes have been deployed in offshore oil and gas fields for installation purposes. Heavy-lift barges are

used to both transport the equipment offshore and lift it into place via powerful cranes.

For ease of installation and to use smaller capacity of crane, major marine installations can be divided into modular lifts. For example, a

processing facility can be fabricated in multiple modules that are then installed offshore one by one as per the construction planning

and scheduling.

2. Offishore installation - Floatover Installation

As the floatover technology is both time- and cost-efficient it is gaining popularity in today offshore industry. Floatover installation

through semisubmersible vessels is a viable option for marine installation operations. A vessel with a hydraulic pumping system is

employed for this method of marine installation that allows the vessel to submerge itself under the water, and then reemerge.

Floatover marine installation allows onshore mating of equipment, and further transporting the equipment to location, as well as

installing it. Here, the semisubmersible vessel floats into place and takes on water to partially descend under water. The equipment is

lowered into place and installed, and the vessel then floats out from under it. Then, hydraulic pumps drive the water out of the vessel,

which reemerges from the water.

There are various kinds of exploration (and drilling) offshore Platforms/Structures

1. Fixed steel structures

2. Tension leg platforms

3. Semi-submersible vessels

4. Floating Production systems

5.

Fixed steel structures

The fixed tower structures are the most common offshore structure. These structures are commonly used in water depths less than 150

meters. However this can be used in water depths up to about 300 meters. Within this category there are 4-leg, 6-leg, and 8-leg towers.

Tension leg offshore Platforms

The Tension Leg Platforms are used in water depths greater than 300 meters. They consist of a floating deck structure anchored to pile

heads on the sea floor by means of long pipes, which are always kept in tension

Semi-submersible vessels

As fixed structures are not practical for water depth greater than around 500 meters, so the offshore drilling operation is required to be

carried out using a floating vessel.

A specialized marine vessel with good stability and seakeeping characteristics is known as semi-submersible vessel. It can be moved

in different locations and anchored to the seabed using mooring system.

In offshore, the specific role for which semi-submersible vessel designs used are: offshore drilling rigs, safety vessels, oil production

platforms and heavy lift cranes.

Floating Production Systems

A floating production system is in-effect a floating Oil rig. It contains all the equipment associated with a fixed installation and is used in

conjunction with sub sea well heads to explore moderate to deep-water oil fields. FPS is particularly suitable for the development of oil

reserves where the installation of a fixed structure would be either impractical or economically not viable.

Piping Systems

Piping systems can be broadly classified into two basic categories of Hydrocarbon Piping and Utility Piping

Cloud point is the temperature at which dissolved solids are no longer completely soluble, precipitating as a second phase giving the

fluid a cloudy appearance.

Pour point is the temperature at which the crude oil becomes semi solid and ceases to flow.

Crude stabilization is a process of removing volatile components from crude oil to reduce its vapour pressure.

Overview Production

The primary function of a production facility is to separate the product from the wells into saleable products and dispose of the rest in

an environmentally friendly manner. The product from the wells typically consists of oil; gas; associated produced water and sediment

Well fluids enter a separation train where the crude oil, gas, and bulk water are separated. The separation train may consist of several

stages of separators. In the separation train, most volatile components of the well fluid will be vaporized. Thus the crude oil will either

be stabilized or partially stabilized. Crude stabilization is performed to achieve the specified RVP

After free water removal, produced oil may contain residual emulsified water. The crude oil is then further processed in a dehydration

unit to reduce the water content to a value that acceptable for transportation or sales. Dilution water must occasionally be added to

reduce the salt content of the residual emulsion to a suitably low level. The addition of dilution water and followed by dehydration is

called desalting process.

Gas separated from the separation train enters the gas processing train. The train normally comprises of gas compression system and

gas dehydration system. Gas dehydration unit is required to remove water from the gas stream to prevent hydrate and corrosion

problem in the pipeline. The most common method for gas dehydration is a TEG contactor unit which is completed with a TEG

regeneration system. The TEG (liquid) absorbs water from the gas stream to achieve the specified water content of the export gas.

Compression of the gas to pipeline pressure is normally required to allow economic transport in reasonable small diameter pipeline.

A more complex gas processing train may include gas sweetening system to remove the acid gases which are CO2 and H2S. Both

gases are very corrosive when liquid water is present. Gas sweetening usually uses aqueous solution of various chemicals. Therefore

a gas sweetening, if required, is normally placed upstream of dehydration unit. However, gas sweetening system is not common for

offshore processing facilities. Generally, any sour gas produced from offshore will be further processed in onshore gas plant.

Separated water from the well fluids is directed to the produced water treatment unit to render the water suitable for disposal to the sea.

Oil removal is the first treatment for produced water. Oil-water emulsions are difficult to clean up due to the small size of the particles,

as well as the presence of emulsifying agents. Hydrocyclone is common equipment for produced water de-oiling purpose.

As an alternate of disposing water into the sea, the produced water could be re-injected into water injection wells. Before re-injection,

produced water is usually filtered and treated with biocides. Booster pumps and injection pumps are normally installed for water

injection system.

This guideline discusses the treatment of the crude oil to meet the product specifications such as vapor pressure, base sediment and

water, salt content, and H2S concentration.

Product Specification

Typical specifications of crude oil are as follow:

Maximum vapor pressure : 10 – 12 psia RVP. Reid Vapour Pressure

BS & W : 0.2 – 1.0% Basic Sediment & Water

Maximum salt concentration : 10 – 30 PTB Pounds of salt per thousand barrels of oil

Maximum H2S : 10 – 100 ppmw Part per million