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1Pipework Integrity

Neil Henry

Senior Consultant

ABB Engineering Services

OPERA Meeting

Pipework Integrity.

March. 2006

Deterioration Management

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! Eutech Engineering Solutions Ltd. established in 1993 as a subsidiary of

ICI. Domain knowledge from:

! Chemicals

! Oil and Gas

! Speciality and Fine Chemicals

! Pharmaceuticals

! Power and Utility

! Sustained growth and development

! 300 plus customers world-wide

! Over 750 staff in Europe, America and Asia

! Over £50 million turnover

! Accredited by Investors in People, Lloyds and UKAS

(ISO 9001)

! Feb 2001, ABB buys Eutech

ABB Engineering Services

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3ABB Engineering Services offering

! Expert and consultancy & technical services

! Project management & design service

! Integrated solutions

! Unique breadth & depth of services

! Innovative approach

! Rapid & effective response

! Local and global delivery

! One-stop shop

CapitalCapital

InvestmentInvestment

LicenceLicence

toto

OperateOperateManufacturingManufacturing

ImprovementImprovementAssetAsset

ManagementManagement

Throughout the asset lifecycle

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4ABB Engineering Services customers

Paints

®

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5Materials Engineering

Why is it important ?

Ageing process plant

Life prediction

Reliability

Repair methods / costs

Corrosion

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6Materials Engineering

What does a materials engineer do ?

Specify materials of construction

Evaluate performance in service

Investigate failures

What are the benefits ?

Optimised materials of construction (cost, life cycle,

maintenance & inspection repairs)

Integrity management for process plant

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7Materials Engineering

Regulatory requirements

PSSRCOMAHIPPC

Competitive business pressure

Assets working harder (for longer)Confidence in condition / availabilityOptimising materials for environment

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8Materials Engineering

Why do materials deteriorate ?

Exposure to excessive severe conditions

e.g. Temperature

Load / Pressure

Process operations

Flow rates

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9Failure Statistics

0

5

10

15

20

25

30

35

Nu

mb

er

of

fail

ure

s

Types of failure

Failure Mechanism: Frequency rate UK.N.W.

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Failure Statistics

0

10

20

30

40

50

60

70

80

Nu

mb

er

of

occu

ran

ces

Operation Design Maintenance Fabrication Repair Ageing

Reason for failures

Cause of failure: Frequency rate UK. N.W.

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Pipework degradation

In order to control degradation processes it is necessary to

understand them

! What are the mechanisms?

! Where do they arise?

! What factors influence rate?

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Pipework degradation

! How can they be detected

! How it can be managed

! Holistic approach to address root

causes

! Examples from our archives

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Mechanisms

Deterioration mechanisms

! Corrosion

! Internal

! External

! Dissolving metal - reducing thickness

! Internal corrosion is related to operating regime

! Specification is usually good

! Deterioration may occur from weakness in design

! Fabrication & Commissioning

! Operation “changes”

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Mechanisms

Deterioration mechanisms

! External corrosion is from moisture (or external leak)

! “Water” is electrolyte for corrosion process

! Material dependant (c steel, austenitic & duplex ss)

Other common mechanisms:

! Environmental cracking, Fatigue, Erosion, Mechanical

overload, “Metallurgical” changes

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Mechanisms

Most common problems

! Corrosion under “insulation” (carbon steel)

! Stress corrosion cracking (stainless steel) under insulation

! Corrosion at supports

! General corrosion

! Local environments

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Corrosion damage

! Corrosion at support

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Figure 5: Defect indications previously located using ECT

and revealed by LPFD.

ECT measured the depth at 1mm.

Spool 1, Area 2

3” Pipe

External Pitting & SCC in Stainless Steel

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Internal corrosion

96% Sulphuric Acid

316 Stainless Steel

Failed after < 6 month operation

Pitting through wall

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Mechanisms

Failure of small bore branches

! External corrosion (small size, thinner wall)

! Unusual internal corrosion process (stagnant condition)

! Cyclic loading leading to fatigue

High vulnerability:

! Thermal or mechanical fatigue or process changes in

local environment

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Managing the Problem

Criticality Reviews}

} Used to set priorities

“RBI” Evaluations }

BUT NEED TO HAVE KNOWLEDGE OF:

• potential for deterioration

• highest vulnerability

• environment and operating regime to optimise the task

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The Deterioration Rview (examples)

Item /

Line

Process stream

composition +

contaminants

Temp C/

Press psi

Materia

lsDeterioration Process

Current condition

monitoring

Future

cond.

Monitor-

ing

Future effect

on material

3001

Mainly Platfinder

prod +reformate

from 8000 unit,

N2 blanketed. S

free.

Amb C steel General PVI PVINone

anticipated

HHS-066-

011

Pipework to

vessel

Sulphuric Acid

98%

100

3.2 / FV

psiSS316

L

Issues about nozzles! As per 03-

113-00. H2SO4 pipework pulses

(pulsation damper) and moves at

high level (investigate why) – dye

pen welds on bands to look for

fatigue

PM 12 month

Clean off deposits

and inspect

branches. Internal

inspection through

m/way

Acid

concentration

changes.

Vibration on

vessel & pipe

supports

HHS-066-

11

Heat exchanger –

Plate cooling

Acetonised

Solution

10 psi

100 / -30

SS316

L

Small potential for det. Pitting

leakage would be CTW into process.

No evidence of corrosion in filters

before heat exchanger

Examine during

routine maintenance

No other

inspection

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Rates of attack

Accelerating factors

! Nominal corrosion rate, c steel in atmosphere, 0.1 to

0.2mm/yr. external corrosion

! Limited risk of pitting in S Steel

! Examples of direct influences

! Temperature of surface; 10°C rise, 2 x rate

! Design features; crevices, supports

! Graph & table, on next slide

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Rates of attack

insulated

insulated & steam

carbon stl/ traced

temperature bare ferritic / ferritic carbon/ferritic

deg C alloys/steel alloys alloys

0 0 0 0

10 0.07 0.06 0.1

20 0.15 0.11 0.19

30 0.17 0.17 0.28

40 0.185 0.22 0.37

50 0.2 0.31 0.46

60 0.22 0.43 0.55

70 0.24 0.54 0.64

80 0.26 0.66 0.73

90 0.28 0.78 0.82

100 0.3 0.89 0.91

110 0 1 1

120 0 0.75 0.75

130 0 0.5 0.5

140 0 0.37 0.37

150 0 0.25 0.25

160 0 0 0

corrosion under insulation rates

0

0.2

0.4

0.6

0.8

1

1.2

0 10 20 30 40 50 60 70 80 90 100

110

120

130

140

150

160

temperature deg C

co

rro

sio

n r

ate

mm

/an

nu

m

bare ferritic steels/alloys insulated carbon/ferritic alloy steels

insulated and steam traced

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Factors Influencing Corrosion Rates

For example

! Time in contact with surface -

drying out

! Deposition of solids

! Contaminants in the “water”;

acidity / alkalinity

! Concentration mechanisms (for s

steel)

! Cooling tower drift

! Steam traps

! Leaks

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Detection methods

Prioritisation of Activities – “confidence in condition”

! Standards of fabrication

! Evaluation of operating conditions & materials

! History

! Sampling examination & thickness testing

! Establish basis of examination process

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Detection methods

External Corrosion

! Thorough visual examination first

! Screening techniques

! Moisture detection

! Long range U/S

! Profile radiography

! Eddy current testing

! Selective thickness testing / Dye penetrant

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Control of deterioration

Managing integrity

! The extent of pipework systems is

very large & difficult to manage

! Prioritisation based on

! Fluid hazard

! Potential for deterioration

! Hazard related to fluid escape

! Potential for deterioration is a function of

! Pipe Material, conditions & temperature

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Evaluation of outfall line

! 10 years old

! Limited history

! Not inspectable:

part buried, part submerged

! Review of design, coatings and protection

! Evaluation of environment internally and externally

! Conclusion of low risk of failure in 10 years

and improvements to extend life

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Heat transfer fluid line

! Operating temp 410°C

! Carbon steel, insulated

! 10 years service

! No nominal risk of corrosion

When inspected:

! Metal loss of half wall thickness

found

! Line was a by pass - only used

at start up

! Actual operating temp at mid

point 80°C

! Pipe was a convenient access

point for maintenance

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High temperature hot water

! System 20 years old

! Lagged carbon steel and (some) stainless

steel

! Operating temperature circa 110°C

! Numerous leaks over several years

! Intent to replace at £550K minimum capital

! Review identified CUI at poor lagging and cyclic duty items

! System was zoned into categories of risk

! Sampling NDT by Neutron back scatter & eddy current

techniques + sample removal

! Resultant replacement was <10% of system,

managed in shutdowns

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Actions to Manage Corrosion

Know what is important

Understand the relationship to the problem

Focus on expenditure for optimum results

Tackle the true root causes

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EXTRACT FROM REPORT of 12 PAGES

Conclusions

• Pipe failed due to chloride-induced stress corrosioncracking (SCC)

• Cracking originated on the outer surface of the pipe

• Lagging had clearly been wetted producing an acidchloride solution

• Pipe material Type 302 or 304 not the specifiedType 316 alloy

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EXTRACT FROM REPORT of 12 PAGES

Recommendations

• Recommendations were made after failed pipe in2000. Same advice applies

• Hot lagged pipes must have a protection system

• The NACE1 document, RPO198-98

• Epoxy/phenolic or high temperature amine-curedcoal tar epoxy

• Notwithstanding the fact that Type 316 stainlesssteel would probably have failed in the same manner

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ABB Recommendations

(Mechanism was agreed as correct)

Maintenance standards

" Correct gaskets

" Missing bolts

" Refit supports

" Repair external leaks

" Renew lagging and aluminium foil

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ABB Recommendations

Operating Review

" Identify leaks on process “rounds”

" Change flow controls and temperatures

" Identify redundant equipment / systems

" Operating controls for valves

(Repair and maintenance training required)

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Pipework integrity - conclusions

Confidence in pipework condition by:

! Review to identify vulnerable areas

! Selective replacement only on problem areas

! Elimination of root causes eg

! Operation and maintenance issues

! Design faults

! Inadequate lagging

! MANAGEMENT OF DETERIORATION STRATEGY – USING

KNOWLEDGE TO SAVE MONEY