Bab 13 Operation, Inspection (Maintenance) and Repair

7/27/2019 Bab 13 Operation, Inspection (Maintenance) and Repair

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MAINTENANCE/INSPECTIONMAINTENANCE/INSPECTION

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ObjectiveObjective

Provide requirements for the safe and reliable operation of

pipeline systems for the whole service life

Requirements are given for operation, inspection, modifications

and repair

Basic RequirementsBasic Requirements

Detailed procedures for operation, inspection, and repairs shall be

establish. This procedures provide information about :

Organisation and management;

Start-up and shut-down procedures;

Operational limitation;

Cleaning and other maintenance, e.g pigging;

Corrosion control, including inspection and monitoring;

Inspection;

Emergency procedures;

Reporting procedures.

InIn--Service fileService file An in-service file of historical data shall be established and

maintained for the whole service life

The in-service file shall contain information regarding :

- resu s an conc us on rom e n-serv ce nspec ons;

- accidental events and damages to the pipeline systems;

- repair and modifications; and

- operational data affecting corrosion and other deterioration

The in-service file, together with the design, fabrication, installation

DFI resume shall be the basis for future ins ection lannin


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OperationOperation

The following parameters should be controlled or monitored to ensure

that critical fluid parameters are kept within the specified design limits :

pressure and temperature along the pipeline;

fluid composistion, flow rate, density and viscosity

All safety equipment in the pipeline system shall be tested and inspected

at agreed intervals, including :

pressure control and over-pressure protection devices,

emergency shut down systems, and

automatic shut down valves

Inspection and monitoring philosophyInspection and monitoring philosophy An inspection and monitoring philosophy shall be established, and

this shall form the basis for the detailed inspection and monitoring

program

The philosophy shall be evaluated every 5 to 10 years

Inspections and monitoring shall be carried out to ensure safe and

reliable operation of the pipeline system

All inspection and monitoring requirements identified during the

design phase as affecting safety and reliability during operation shall

be covered in the inspection and monitoring program


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Special inspectionSpecial inspection

A special investigation shall be performed in case of any event which

impairs the safety, reliability, strength or stability of the pipeline

system. This investigation may initiate further inspections

periodic inspection, a proper evaluation of the damage shall be

performed, which may include additional inspections

PIPELINE CONFIGURATION SURVEYPIPELINE CONFIGURATION SURVEYPeriodic SurveyPeriodic Survey

The Start-up inspections shall be completed within one year (1 year)

from start of production

In case of significant increase in temperature or pressure after this

first inspection, the need of additional inspections should be

considered

The following should be considered for a long term inspection

programme reflecting the overall safety objective for the pipeline :

- operation conditions of the pipeline,

- consequences of failure

- likelihood of failure

- inspection methods, and

- design and function of the pipeline


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PIPELINE CONFIGURATION SURVEYPIPELINE CONFIGURATION SURVEY

Periodic Survey (contd)Periodic Survey (contd)

The long term inspection program shall include the entire pipeline

system. The following items, at minimum, should be considered :

- pipeline,

- risers,

- Valves,

- Tee and Y connections,

- mechanical connectors,

- flanges,

- anchors,

- clamp

- protecting structures,

- anodes,

- coating.

PIPELINE CONFIGURATION SURVEYPIPELINE CONFIGURATION SURVEYPeriodic Survey (contd)Periodic Survey (contd)

Inspection shall be carried out to ensure that the design

requirements remain fulfilled and that no damage has occurred. The

inspection program s ou a ress, suc as :

- Exposure and burial depth of buried or covered lines

- Free spans, including mapping of length, height, and support

condition

- Identification of areas where upheaval buckling or excessive

lateral buckling has taken place

- Sand wave movements affecting the pipeline integrity

- Mechanical damage to pipe, coating and anodes

- Leakage

- Etc.


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The risers shall be part of the long-term inspection programme for

the pipeline system. Special attention shall be given to the following

elements for riser inspections :

- Riser displacement due to pipeline expansion or foundation

settlement

- Coating damage

- Technique for corrosion control of any risers in closed conduit of

J-tubes

- Extent of marine growth

- Extent of any previous damage due to corrosion

- Integrity and functionality of riser supports and guides

- Integrity and functionality of protecting structure

PIPELINE CONFIGURATION SURVEYPIPELINE CONFIGURATION SURVEYPeriodic Survey (contd)Periodic Survey (contd)

The frequency of future external inspections shall be determined

based upon an assesment of :

- Degradation mechanisms and failure modes,

- Likelihood and consequences of failure,

- Results from previous inspections,

- Changes in the operational parameters,

- Repair and modifications, and

- Subsequent pipelay operation in the vicinity


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Critical sections of the pipeline system vulnerable to damage or

subject to major changes in the seabed conditions i.e support and/or

burial of the pipeline, shall be inspected at short intervals, normally

on an annual basis

The remaining sections should also be inspected, ensuring a full

coverage of the entire pipeline system within a 5 yo 10 years period

INSPECTION AND MONITORING OF EXTERNAL CORROSIONINSPECTION AND MONITORING OF EXTERNAL CORROSION

GeneralGeneral

In the splash zone and in the atmospheric zone, damaged and/or

disbonded coatings can cause severe corrosion damage. Risers

In the submerged zone, coating malfunctions are not critical unless

they are combined with deficiency in the cathodic protection system

For risers contained in J-tubes filled with non-corrosive fluid

inspection of external corrosion may not be required if adequate

properties of the fluid is verified by periodic testing

corrosion of risers and pipelines in all three zones including risers

conintained in J-tubes, if required


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Severe corrosion damageIn the splash zone

Damage due to corrosionIn atmospheric zone


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Risers in the Splash zone and the Atmospheric zoneRisers in the Splash zone and the Atmospheric zone

In the splash atmospheric zone, visual examination of the coatingshall be performed in order to assess the needs for preventive

Besides visual indications of direct damage to the coating, effects

such as rust discoloration and bulging or cracking of the coating are

indicative of under-rusting

Coating systems which prevent close inspection of under-coating

corrosion shall require special consideration

shall be determined based on :

- the fluid category,

- the line pipe material,- coating properties and

- any corrosion allowance


Pipeline and Risers in the Submerged ZonePipeline and Risers in the Submerged Zone

To a large extent, inspection of external corrosion protection of

pipelines and risers with sacrificial anodes can be limited to

Excessive anode consumption is indicative of coating deficiencies,

except close to platforms, templates and other structures where

curent drain may lead to premature consumption of adjacent pipe

anode

Potential measurements on anodes, and at any coating damage

exposing bare pipe metal, may be carried out to verify adequateprotection

For pipelines with impressed current cathodic protection systems,

measurements of protection potential shall, at minimum, be carried

out at locations closest to, and most remote from, the anode(s)

A survey of the external corrosion protection system, should be

carried out within one year of installation


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INSPECTION AND MONITORING OF INTERNAL CORROSIONINSPECTION AND MONITORING OF INTERNAL CORROSION

GeneralGeneral

Inspection of internal corrosion is carried out in order to confirm theintegrity of the pipeline system, primarily by means of in situ wall

The objective of monitoring internal corrosion :

- to confirm that the fluid remains non-corrosive or,

- to assess the efficiency of any corrosion preventive measures,and,

- to identify requirements for inspection of corrosion

(CRA) do not normally require inspection and monitoring of internal

corrosion

Pipeline internal inspection


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Corrosion InspectionCorrosion Inspection

Internal corrosion inspection shall be carried out with a carrier tool(inspection pig) capable of inspecting the internal surface of the

,

thereof

The technique for detection of internal corrosion (e.g magnetif flux

leakage or ultrasonic examination) shall be selected based on

considerations :

- Linepipe material

- Diameter and wall thickness

- Expected form of damage

- requirements to detection limits and defect sizing capability

Pipeline PigPipeline Pig


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Corrosion Inspection (contd)Corrosion Inspection (contd)

The frequency of internal inspections shall be determined based onfactors such as :

- r ca y o p pe ne

- Potential corrosivity of fluid

- Detection limits and accuracy of inspection system

- Results from previous surveys and monitoring

- Changes in pipeline operational parameters, etc.


Corrosion MonitoringCorrosion Monitoring

The following major principles of corrosion monitoring may be

applied :

-

- Corrosion probes

- In-situ wall thickness measurements

Techniques and equipment for corrosion monitoring shall be selected

based upon :

- Monitoring objectives, including parameters for accuracy and

sensitivity- Fluid corrosivity and the corrosion preventive measures to be

applied

- Potential corrosion mechanisms


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DEFECTS AND REPAIRDEFECTS AND REPAIR

GeneralGeneral

Repair and modification shall not impair the safety level of thepipeline system below the specified safety level

All repairs shall be carried out by qualified personnel in accordance

with agreed specifications and procedures, and up to the standard

defined for the pipeline

All repairs shall be tested and inspected by experienced and

qualified personnel in accordance with agreed procedures

Pipeline systems with defects may be operated temporarily under

defect has been removed or repair has been carried out


General (contd)General (contd)

When a defect is observed, a evaluation of the defect shall be

performed and shall, as a minimum, include :

- Determined details of the defect

- Mechanisms causing the defect

- Accuracy and uncertainties in the inspection results

- Option for further operational conditions of the pipeline system

- Repair method

Depending upon the condition of the damage, a temporary repair

may be accepted until the permanent repair can be carried out

If temporary repair is carried out, it shall be documented that the

pipeline integrity and safety level is maintained either by the

temporary repair itself and/or in combination with other precautions


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Selection of most effective Repair /Rehabilitation methods ) Welded sleeve

Mechanical sleeve

Hot tap fitting

Hot tap and STOPPLE procedure with bypass


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LeaksLeaks

The most suitable method for repairing a leak in the pipe dependsupon e.g :

-

- Pipe dimensions

- Location of leak

- Load conditions

- Pressure

- temperature

The following repair methods may be used :

- The damaged portion is cut out of the pipe as a cylinder and a

new pipe spool is installed either by welding or by an mechanical

connector

- Clamps are installed, and tightness is obtained by either welding,

filler material, friction or other qualified mechanical means

Leak on pipeline


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Leaks (contd)Leaks (contd)

Leaking flanges and couplings may be sealed by :

- Installing a seal clamp covering the leaking flange or coupling,

- Increasing the bolt pre-load, or

- Replacing gaskets and seals

Prior to increasing the pre-load in bolts, it shall be documented by

calculation that no over-stressing occurs in bolts, flange or

gasket/seal

- , .

gasket, new bolts shall be used for the flange connection

All repair clamps, sleeves, pipe spools, and mechanical connectors

shall be qualified prior to installation and leak tested after

installation


Repair by WeldingRepair by Welding

A welding procedures specification shall contain following

information, such as :

- , ,

- Diameter and wall thickness,

- Groove preparationg and design, including tolerances

- Welding process, number and location of welders

- Etc.

For underwater welding the welding procedure specification shall

contain, in addition to the procedure above, such as :- Water depth (max/min)

- Pressure inside the chamber

- Gas composition inside the chamber

- Humidity, maximum level

- Etc.


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Underwater weldingUnderwater welding


Repair by Welding (contd)Repair by Welding (contd)

Repair welding may, in special cases, be carried out on pipelines

while operating, depending on :

- pe ma er a ,

- Pipe wall thickness,

- Product tipe,

- Pressure and Temperature

It shall be documented that safety for carrying out the repair is

acceptable, and a safety procedure shall be established

All repair welds shall be subject to visual and non-destructive

testing. Following the repair, pressure testing may be required for

the repaired section.


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Pipeline Welding RepairPipeline Welding Repair

REMAINING LIFE ASSESSMENTREMAINING LIFE ASSESSMENT

9 A remaining life for the component should be determined

once it has been established that the component containing

flaw is acceptable at the current time,

9 The remaining life is used to establish appropriate inspection

interval and/or in-service monitoring plan, or the need for

remediation

9 The remaining life is not intended to provide a precise

estimate of the actual time to failure.

9 The remaining life can be estimated based on the quality of

,assumptions to provide an adequate safety factor for

operation until the next scheduled inspection


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Remaining life estimates will fall into one of the following three general

categories :

1. The remaining life can be calculated with reasonable certainty

Example : general uniform corrosion. The remaining life is the

future corrosion allowance divided by the assumed corrosion rate

from previous thickness data, corrosion design curves, or

experience in similar services.

2. The remaining life cannot be calculated with reasonable certainty

Example : stress corrosion cracking mechanism where there is no

reliable crack growth rate data available or hydrogen blistering

where a future damage rate cannot be estimated

3. There is little or no remaining life

In this case remediation, such as repair of the damaged component,application of a lining or coating to isolate the environment, and/or

frequent monitoring is necessary for future operation


Type of corrosion found in pipelineType of corrosion found in pipeline


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Estimation of remaining life of pipeEstimation of remaining life of pipenetwork using softwarenetwork using software

REQUALIFICATIONREQUALIFICATIONGeneralGeneral

9 Re-qualification is a re-assessment of the design under

chan ed desi n condition.

9 Re-qualification may be triggered by a changed in the original

design basis, by not fulfilling, or by mistakes or shortcomings

having been discovered during normal or abnormal operation.

9 Possible causes may be:

1) preference to use this standard, e.g. due to requirement

or g er u a on or ex s ng p pe nes pra ng ;

2) changed of the premises;

environmental loads,

Deformation,

Scour.


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REQUALIFICATIONREQUALIFICATION

Design CriteriaDesign Criteria

9 A target safety level below shall apply for a re-qualification

assesment

LimitLimitstatestate

Probability BasesProbability BasesSafety ClassesSafety Classes

LowLow NormalNormal HighHigh

SLS Annual per Pipeline1) 10-2 10-3 10-3

ULS Annual per Pipeline1)

10-3 10-4 10-5FLS Annual per Pipeline2)

ALS Annual per Pipeline2)

1) Or the time period of the temporary phase

2) The failure probability will effectively be governed by the last year

in operation or prior to inspection depending on the adoptedinspection philosophy

3) Refers to the overall allowable probability of severe consequences

REQUALIFICATIONREQUALIFICATIONDesign Criteria (contd)Design Criteria (contd)

System pressure test

System pressure test may be required when

The original mill pressure test or system pressure test does not

satisfy requirement according to this standard at the new

design pressure

A significant part of the pipeline has not been system pressure

tested e.g. new pipeline section

All Relevant deterioration mechanism shall be evaluated. Typical

deterioration mechanism:

- corrosion - accdental loads - fatigue

- erosion - development of free spans - settlement


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REQUALIFICATIONREQUALIFICATION

Design Criteria (contd)Design Criteria (contd)

9 Sufficient reliability or safety measure shall be applied to

account for the accuracy and uncertainities in the inspection

results

9 Accumulated damage experienced prior to the re-qualification

shall be included in the evaluation

9 Operation experience, e.g. change of operational condition,

inspection records and modifications, shall be considered in a

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Documents

Bab 13 Operation, Inspection (Maintenance) and Repair