rbi initiative

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RBI Initiative

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Table of Contents

PART 1: GENERAL INFORMATION 3

PART 2: THREATS AND RISKS: 5

PART 3: FACTS NOT FICTION 6

PART 4: SUSCEPTABILITIES TO FAILURE 7

PART 5: CONSEQUENCE OF FAILURE 11

PART 6: CRITICALITY 14

PART 7: REMNANT LIFE CALCULATIONS 17

PART 8: INSPECTION PLAN 22

3

MODULE 31 V-3010

VT-30002-9341X

24"

558

mm 16

60 m

m

1743

mm

Low Low Level Trip

HIGH High Level Trip

10"4"6"

10"

8"3"3"3"3"

6-PO-30019-9341X 6-PO-30019-3145X

6-CD-40007-9341X

3-OW-40013-9143X 3-OW-40013-9341X

10-PO-30018-9145X

10-VF-42056-1341X

4-VF-42057-1341X 4-VF-42057-9341X

10-PG-30002-AA02

PART 1: GENERAL INFORMATION Unit Name: High Pressure Oil Production Separator

Unit Description: Horizontal cigar shape gravity separator, with one bottom weir.

Process Description: 3 phase (oil, gas, water) mix from high pressure oil producing

wells enters the vessel via 10” inlet nozzle, inside the vessel the product separates with

the assistance of the spreader, gas occupies the upper half of the vessel while oil and

water goes to the lower half of the vessel while oil and water goes to the lower half

behind the weir. By gravity (density difference). Oil passes over the weir when reaches

the desired level to the front compartment.

Unit Design Parameters:

Design Pressure 100 BARG

Design Temperature 90/-50 DEGC

4

Unit Operating Parameters:

Maximum Operating Pressure 89 BARG

Maximum Operating Temperature 78 DEGC

Unit Construction Parameters:

Volume: 53m3

Material: Carbon Steel

Shell Thickness: 71mm

Head Thickness: 38 mm

Corrosion Allowance: 6 mm

Inner Surface Area: 135 m2

Inner Surface Coating: Amine Adduct Crude Epoxy 75 mic, + 300 Glass

flake Epoxy 300 mic

Outer Surface Area: 150 m2

Outer Surface Coating: Zinc Silicate 100 mic.

Year Built: 1989

Attached Piping:

10-PO-30018-9145X 3 PHAZE PRODUCT INLET LINE

10-PG-30002-AA02 GAS TO GAS TRAINS

4-VF-42057-9341X GAS TO FLARE HEADER



6-CD-40007-9341X WATER TO CLOSED DRAIN

3-OW-40013-9341X WATER TO OILY WATER NET

3-OW-40013-9143X WATER TO OILY WATER NET

6-PO-30019-3145X OIL TO V-3020

6-PO-30019-9341X OIL TO V-3020

5

PART 2: THREATS AND RISKS: Vessel Threats:

External Corrosion:

External corrosion is caused by surrounding environment impact on the vessel material.

External corrosion forms as general, pitting and crevice corrosion.

Internal Corrosion:

Internal corrosion is caused by processed product impact on the vessel material,

exacerbated by elevated pressure and temperature.

Internal corrosion forms as general, pitting, galvanic, crevice and stress corrosion.

Associated Piping Threats:

External Corrosion:

External corrosion is caused by surrounding environment impact on the piping material.

External corrosion forms as general, pitting and crevice corrosion.

Internal Corrosion:

Internal corrosion is caused by processed product impact on the vessel material,

exacerbated by elevated pressure and temperature.

Internal corrosion forms as general, pitting, galvanic, erosion, crevice and stress

corrosion.

Saddles, Supports, Walkways and Concrete Foundation Threats:

Saddles, supports and concrete foundation reinforcing steel suffer from general and

crevice corrosion. Walkways, platforms and ladders are more susceptible to mechanical

damage and bolting looseness.

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PART 3: FACTS NOT FICTION Date Ref Description

26.09.94 94-398 • Coating problems exist since the beginning of the vessel

• Coating failure reported since September 1992

14.03.95 POC/0282/95 • Recommendations for wall thickness survey on water outlet line after

the level control valve on 3-OW-40013-9341X line.

23.03.95 TI95-111 • Wall thickness survey carried out, no thickness degradation revealed.

21.01.95 TI95-024 • External wall thickness survey on the vessel showed no thickness

degradation.

24.02.96 TI96-024 • External wall thickness survey on the vessel and attached piping

showed no thickness degradation.

15.07.96 TI96-117 • Internal visual inspection reported internal coating deterioration, and

2mm pitting corrosion distributed allover the vessel surface.

27.02.98 TI98-047 • External wall thickness survey showed no significant degradation

• Low readings obtained on 10-VF-42056-1341X.

13.08.2K TI2K-196 • Clusters of sound blistered areas along the vessel coating with no

corrosion or rusting beneath.

• Cracks in the internal paint reported.

• Paint flecking in the nozzles reported.

• Internal painting condition considered acceptable until the next

recoating activity on July 2002.

26.05.2K TI2K-126 • External wall thickness survey showed no significant degradation.

22.04.02 TI02-120 • External wall thickness survey showed no significant degradation.

29.08.03 Painting Report • Vessel internally painted with 75 mic TankGuard primer and 300 mic

Marathon top coat system.

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PART 4: SUSCEPTABILITIES TO FAILURE Extreme High Medium Low Negligible

5 4 3 2 1 Vessel Failure

Failure due to External General corrosion:

External general corrosion is eliminated by the external coating, in addition, the absence

of severe environmental conditions due to the lack of pollution and desert dry weather

eliminates the probability of general external corrosion to occur or propagate rapidly.

Rating 1

Failure due to External Pitting corrosion:

External pitting corrosion is associated with insulation that can be damped with water. It

is unlikely to be found within the vessel as it is not insulated by any means.

Rating 1

Failure due to External Crevice corrosion:

External crevice corrosion is formed due to moisture and dirt coalition at dead points

within the unit construction, especially platform supports and attached nameplates.

The cylindrical shape of the vessel is eliminating the existence of the dead points, as well

as the nameplate is not directly attached to the vessel body but to a special holder.

The attached platforms supporting may be collecting dirt and moisture, the moisture is

not likely found for long times in desert environment, but there is a low possibility of

generating corrosion cells there.

Rating 2

Failure due to Internal General corrosion:

Internal general corrosion is being controlled and eliminated by internal coating system

applied. 6 mm corrosion allowance is also added to the designed wall thickness. Taking

into consideration the design lifetime of 25 years, this gives 0.24 mm for lose per year.

Internal coating has been re-applied in several occasions according to painting material

manufacturer’s recommendations. During that, internal visual inspections had been

carried out revealed with a confidence that no general corrosion mechanism is taking

place.

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There is always a possibility of changing the operation conditions what may lead to the

appearance of general corrosion, although it is very rare.

Rating 2

Failure due to Internal Pitting corrosion:

Internal pitting corrosion is also controlled by the internal painting; the corrosion spices

may consume the corrosion allowance throughout the lifetime. It had been recorded the

occurrence of spreaded pitting with a depth of 2 mm but no propagation was reported

afterwards.

Partial deterioration of internal coating has been reported, what may increase the

possibility of pitting occurrence

Rating 3

Failure due to Internal Galvanic corrosion:

Galvanic corrosion may occur between the vessel stainless steel internals and the carbon

steel vessel, but the internal coating and the insulation installed between them make it

unlikely to be found.

Rating 1

Failure due to Internal Crevice corrosion:

Crevice corrosion is most likely to happen in the vertical attached nozzles and their

flanges. Adequate painting is being applied internally what may reduce the probability of

the occurrence, but previous experience with painting deterioration inside the attached

nozzles increases the possibility of such mechanism to take place.

Rating 3

Failure due to Internal Stress corrosion:

Stress corrosion cracking occurs mainly within the welds heat affected zones, but the

possibility of happening within the main vessel body exists. The vessel is mainly

designed to withstand the stresses caused by the internal pressure, although the

overpressurising conditions may occur from time to time. The existence of internal

coating reduces the possibility of such mechanism, in addition it has not been reported

before within the area.

Rating 2

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Associated Piping Failure:

Failure due to External General corrosion:

External general corrosion on associated piping is controlled by the application of

protective painting system, the absence of severe environment conditions and pollution

eliminates the possibilities of occurrence or propagation.

Rating 1

Failure due to External Pitting corrosion:

External pitting corrosion is associated with insulation existence, and the existence of

chlorides for stainless steel piping. Associated piping of the vessel is not insulated, and

the stainless steel piping is painted, in addition to lack of chlorides existence.

Rating 1

Failure due to External Crevice corrosion:

External crevice corrosion for piping occurs mainly at supporting points and within the

external side of flange connections due to moisture and dirt trap. There is a fair chance to

occur although the general environment conditions are not so helpful.

Rating 2

Failure due to Internal General corrosion:

Internal general corrosion is a result of the flowing media reaction with the pipe metal. It

is most likely to happen within the carbon steel portions rather than the stainless steel.

The routine wall thickness survey carried out on the attached piping throughout the last

few years did not show any significant wall thickness loss.

Rating 1

Failure due to Internal Pitting corrosion:

Internal pitting corrosion is mainly happening due to the presence of particular agents,

like chlorides and sulfides. No history of such failure within the vessel piping, but threat

exists.

Rating 2

Failure due to Internal Galvanic corrosion:

Internal galvanic corrosion occurs between dissimilar metal connections with the

existence of suitable electrolyte. There are causes of galvanic corrosion between carbon

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steel and stainless steel connections within BED area, but none of them within the vessel

skid.

Rating 1

Failure due to Internal Erosion corrosion:

Internal erosion corrosion occurs at or after flow restrictions and direction changes. In

general it shows up within carbon steel piping, with a possibility of occurrence within

stainless steel piping.

Rating 2

Failure due to Internal Crevice corrosion:

Internal crevice corrosion is more combined with slow flow piping. It is unlikely to

happen within the vessel piping due to high pressure and flow rate.

Rating 1

Failure due to Internal Stress corrosion:

Internal stress corrosion within piping system is usually combined with excess vibration

rather than over pressurizing.

Rating 2

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PART 5: CONSEQUENCE OF FAILURE Extreme High Medium Low Negligible

5 4 3 2 1 Vessel Failure Consequence:

Consequence of failure due to External General corrosion:

External general corrosion leads to general wall thickness loss exposing the vessel to be a

subject to collapse or fracture under internal pressure, what will lead to a large amount of

oil and gas release, massive production loss and cost of new vessel.

Rating 5

Consequence of failure due to External Pitting corrosion:

External pitting corrosion leads to low amount of oil or gas release, low production loss

and low cost of vessel repair.

Rating 2

Consequence of failure due to External Crevice corrosion:

External crevice corrosion leads to low amount of oil or gas release, low production loss


Rating 2

Consequence of failure due to Internal General corrosion:

Internal general corrosion leads to general wall thickness loss exposing the vessel to be a

subject to collapse or fracture under internal pressure, what will lead to a large amount of

oil and gas release, massive production loss and cost of new vessel.

Rating 5

Consequence of failure due to Internal Pitting corrosion:

Internal pitting corrosion leads to low amount of oil or gas release, low production loss


Rating 2

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Consequence of failure due to Internal Galvanic corrosion:

Internal galvanic corrosion leads to no oil or gas release, low production loss and low

cost of vessel repair.

Rating 1

Consequence of failure due to Internal Crevice corrosion:

Internal crevice corrosion leads to low oil or gas release, medium production loss and

medium cost of vessel repair.

Rating 3

Consequence of failure due to Internal Stress corrosion:

Internal stress corrosion cracking leads to high oil or gas release, high production loss

and high cost of vessel repair.

Rating 4

Associated Piping Failure Consequence:

Consequence of failure due to External General corrosion:

External general corrosion on associated piping leads to medium oil or gas release,

medium production loss and low repair cost.

Rating 3

Consequence of failure due to External Pitting corrosion:

External pitting corrosion on associated piping leads to low oil or gas release, negligible

production loss and low repair cost.

Rating 2

Consequence of failure due to External Crevice corrosion:

External crevice corrosion on associated piping leads to low oil or gas release, negligible


Rating 2

Consequence of failure due to Internal General corrosion:

External general corrosion on associated piping leads to medium oil or gas release,

medium production loss and low repair cost.

Rating 3

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Consequence of failure due to Internal Pitting corrosion:

Internal pitting corrosion on associated piping leads to low oil or gas release, negligible


Rating 2

Consequence of failure due to Internal Galvanic corrosion:

Internal galvanic corrosion leads to low oil or gas release, negligible production loss and

low repair cost.

Rating 2

Consequence of failure due to Internal Erosion corrosion:

Internal erosion corrosion leads to low oil or gas release, negligible production loss and

low repair cost.

Rating 2

Consequence of failure due to internal Crevice corrosion:

Internal crevice corrosion leads to negligible oil or gas release, negligible production loss

and negligible repair cost.

Rating 1

Consequence of failure due to Internal Stress corrosion:

Internal stress corrosion leads to high oil or gas release, medium production loss and

medium repair cost.

Rating 4

14

PART 6: CRITICALITY

Extreme High Medium Low Negligible 5 4 3 2 1

Vessel Failure Criticality

Criticality of failure due to External General corrosion: Susceptibility Rating 1

Consequence Rating 5

Criticality Rating 4

Criticality of failure due to External Pitting corrosion: Susceptibility Rating 1



Criticality of failure due to External Crevice corrosion: Susceptibility Rating 2



Criticality of failure due to Internal General corrosion: Susceptibility Rating 2



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Criticality of failure due to Internal Pitting corrosion: Susceptibility Rating 3



Criticality of failure due to Internal Galvanic corrosion: Susceptibility Rating 1



Criticality of failure due to Internal Crevice corrosion: Susceptibility Rating 3



Criticality of failure due to Internal Stress corrosion: Susceptibility Rating 2



Associated Piping Failure Criticality:

Criticality of failure due to External General corrosion: Susceptibility Rating 1



Criticality of failure due to External Pitting corrosion: Susceptibility Rating 1



Criticality of failure due to External Crevice corrosion: Susceptibility Rating 2



Criticality of failure due to Internal General corrosion: Susceptibility Rating 1



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Criticality of failure due to Internal Pitting corrosion: Susceptibility Rating 2



Criticality of failure due to Internal Galvanic corrosion: Susceptibility Rating 1



Criticality of failure due to Internal Erosion corrosion: Susceptibility Rating 2



Criticality of failure due to internal Crevice corrosion: Susceptibility Rating 1



Criticality of failure due to Internal Stress corrosion: Susceptibility Rating 2



17

PART 7: REMNANT LIFE CALCULATIONS Vessel Remnant Life Calculations:

1- Shell Remnant Life

Calculation:

Year Built: 1989

Year Start in Service: 1990

Corrosion allowance: 6 mm

Original wall thickness: 71 mm

Minimum accepted wall

thickness: 71 – 6 = 65 mm

Design Corrosion Rate: 6mm/25years = 0.24 mm/year

Actual up to date Corrosion Rate (based on internal inspection reports): 2mm/15years

= 0.133 mm/year

2- Heads Remnant Life

Calculation:

Year Built: 1989



Original wall thickness: 38 mm

Minimum accepted wall

thickness: 38 – 6 = 32 mm

Design Corrosion Rate:

6mm/25years = 0.24 mm/year

Assumed up to date Corrosion Rate (no corrosion reported on heads): 2mm/15years =

0.1 mm/year

Shell Thickness Degradation Chart

60

65

70

75

1990

1995

2000

2005

2010

2015

2020

2025

2030

2035

2040

Service Years

Thic

knes

sMin Design Actual

Heads Thickness Degradation Chart

30

35

40

1990

1995

2000

2005

2010

2015

2020

2025

2030

2035

2040

Service Years

Thic

knes

s

Min Design Actual

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Piping Remnant Life Calculation:

A- 10-PO-30018-9145X



Original wall thickness: 18.24mm

Minimum accepted wall thickness:

17.24mm

Design Corrosion Rate: 1mm/25years

= 0.04 mm/year

Assumed up to date Corrosion Rate (no corrosion reported on this piping): 0.04

mm/year

B- 10-PG-30002-AA02





9.27mm

Design Corrosion Rate: 0

Assumed up to date Corrosion Rate (no corrosion reported on this piping): 0

C- 4-VF-42057-9341X





8.56mm

Design Corrosion Rate: 0mm/year

Assumed up to date Corrosion Rate (no corrosion reported on this piping): 0 mm/year

10-PO-30018-9145X

16

16.5

17

17.5

18

18.5

1990

1995

2000

2005

2010

2015

2020

2025

2030

2035

2040

Years

Thic

knes

s

Min Design

10-PG-30002-AA02

0

2

4

6

8

1019

90

1995

2000

2005

2010

2015

2020

2025

2030

2035

2040

Years

Thic

knes

s

Min Design

4-VF-42057-9341X

0123456789

1990

1995

2000

2005

2010

2015

2020

2025

2030

2035

2040

Years

Thic

knes

s

Min Design

19

D- 4-VF-42058-1341X





3.05mm


Assumed up to date Corrosion Rate (no corrosion reported on this piping): 0mm/year

E- 10-VF-42056-1341X





4.19mm

Design Corrosion Rate: 3mm/25years =

0.12 mm/year


mm/year

F- 6-CD-40007-9341X





10.79mm


Assumed up to date Corrosion Rate (no corrosion reported on this piping): 0mm/year

4-VF-42058-1341X

0

0.5

1

1.5

2

2.5

3

3.5

1990

1995

2000

2005

2010

2015

2020

2025

2030

2035

2040

Years

Thic

knes

s

Min Design

10-VF-42056-1341X

00.5

11.5

22.5

33.5

44.5

1990

1995

2000

2005

2010

2015

2020

2025

2030

2035

2040

Years

Thic

knes

s

Min Design

6-CD-40007-9341X

0

2

4

6

8

10

12

1990

1995

2000

2005

2010

2015

2020

2025

2030

2035

2040

Years

Thic

knes

s

Min Design

20

G- 3-OW-40013-9341X





7.62mm


Assumed up to date Corrosion Rate

(no corrosion reported on this piping): 0mm/year

H- 3-OW-40013-9143X





6.62mm



Assumed up to date Corrosion Rate (no corrosion reported on this piping):

0.04mm/year

I- 6-PO-30019-3145X





6.11mm




mm/year

3-OW-40013-9341X

0123456789

1990

1995

2000

2005

2010

2015

2020

2025

2030

2035

2040

Years

Thic

knes

s

Min Design

3-OW-40013-9143X

0123456789

1990

1995

2000

2005

2010

2015

2020

2025

2030

2035

2040

Years

Thic

knes

s

Min Design

6-PO-30019-3145X

012345678

1990

1995

2000

2005

2010

2015

2020

2025

2030

2035

2040

Years

Thic

knes

s

Min Design

21

J- 6-PO-30019-9341X





10.97mm


Assumed up to date Corrosion Rate

(no corrosion reported on this piping): 0mm/year

6-PO-30019-9341X

0

2

4

6

8

10

12

1990

1995

2000

2005

2010

2015

2020

2025

2030

2035

2040

Years

Thic

knes

s

Min Design

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PART 8: INSPECTION PLAN A- Vessel Inspection:

1- Internal Inspection:

Vessel Highest Criticality rating: 5 (Extreme)

Inspection Confidence Rating: High

Inspection Interval Factor: 0.3

Maximum Internal Inspection Interval = Remnant Life X Inspection Interval Factor

= 240 months X 0.3

= 72 months (6 years)

(Last Internal Inspection was in 2002, next to be in 2008)

2- External Inspection: Technique Application Area Interval

Failure to be monitored

X-Ray Shooting Attached Horizontal nozzles and bottom

vertical nozzles

Yearly Wall thinning

Ultrasonic Wall

Thickness

Measurements

Bottom area of the vessel with height up

to 1660mm, covering the water phase

area, with a 150mm grid

2 Yearly Wall thinning

Visual Inspection All flange connections Yearly Flange Leakage

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B- Associated Piping Inspection:

External Inspection:

Piping Highest Criticality rating: 4 (High)

Inspection Confidence Rating: High

Inspection Interval Factor: 0.4

Maximum External Inspection Interval = Remnant Life X Inspection Interval Factor

= 120 months X 0.4

= 48 months (2 years)

(Last Inspection was in 2004, next to be in 2006)

Application Area Material Corrosion

Allowance

Inspection Technique Interval

Failure to be monitored

10-PO-30018-9145X Carbon Steel 1mm UT wall thickness measure 2 Yearly Wall thinning

10-PG-30002-AA02 Duplex Stainless Steel 0mm Visual Inspection Yearly Flange leakage

4-VF-42057-9341X 316L Stainless Steel 0mm Visual Inspection Yearly Flange Leakage



6-CD-40007-9341X 316L Stainless Steel 0mm Visual Inspection Yearly Flange Leakage

3-OW-40013-9341X 316L Stainless Steel 0mm Visual Inspection Yearly Flange Leakage

3-OW-40013-9143X Carbon Steel 1mm UT wall thickness measure 2 Yearly Wall thinning

6-PO-30019-3145X Carbon Steel 1mm UT wall thickness measure 2 Yearly Wall thinning

6-PO-30019-9341X 316L Stainless Steel 0mm Visual Inspection Yearly Flange Leakage

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