PIMS Integrity Evaluation 0109 - PIMS of London Ltdpimsoflondon.com/PIMS Integrity...

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Integrity Evaluation PIMS of London website download 2009 Integrity Evaluation : Version 0109

Transcript of PIMS Integrity Evaluation 0109 - PIMS of London Ltdpimsoflondon.com/PIMS Integrity...

Integrity Evaluation

PIMS of London website download 2009

Integrity Evaluation : Version 0109

Integrity Evaluation 1 Copyright © PIMS of London Ltd

Summary Integrity Evaluations perform a critical role within the Integrity Management cycle –they aim to precisely identify,

locate & quantify features & patterns of threats. They shape the decisions you take to manage risk & maintain

performance within your system.

PIMS works with you to ensure that the evaluations provide appropriate information to support the correct

remediation & response decisions. We do this by building a “functional specification” for the features you need

to find, then determining which method/s that may best meet that specification. We help you fully exploit this

information, beyond your immediate requirements, using it to strengthen the basis upon which subsequent Risk

Assessments are performed.

If you are unfamiliar with evaluation technologies & techniques, or you are resource-constrained, PIMS can

project manage integrity evaluations on your behalf. Beyond standard pressure testing techniques, we have

personal track record in managing thousands of kilometres of in-line inspection (ILI: metal loss, crack detection

& geometric); we can set-out the structured process required to ensure you get value out of direct assessment

(DA: external corrosion, internal corrosion and stress corrosion cracking). Alternatively, we can locate &

supervise those contemporary evaluation techniques that are appropriate to your pipeline or facility.

Once the integrity evaluation information has been captured, PIMS’ support is invaluable. We can take this

information and, combining it with other relevant data, perform immediate integrity assessments to determine

critical corrective actions that must be executed as a priority. With these priorities met, we can then extend

study focus to produce future integrity assessments. Not only does this give you a further, business-case

justified, schedule of corrective actions over time, it also identifies preventative actions that you can take to

maintain sustainable system improvements. Within the clear path set-out to ensure the fitness-for-purpose of

your pipeline or facility, we then propose recommendations for re-inspection intervals and techniques.

Our goals-led approach, framing each task within your overall integrity management objectives, ensure that you

are empowered with an Integrity Evaluation that helps to make your business better.

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Objectives that can be Achieved Provided that the type of threat in question is one that can be detected by an Integrity Evaluation, the

information required to support correction of that threat before it causes failure can be provided by an Integrity

Evaluation. Furthermore, all information arising from an Integrity Evaluation can be used to ensure that

subsequent Risk Assessments performed are increasingly robust and fed from more quantitative data.

Potential Consequence of Improper Execution In themselves, Integrity Evaluations do nothing to prevent failure. Only when supported by a subsequent set of

corrective and preventative actions, do Integrity Evaluations prove to be of value in reducing Risk. Furthermore,

Operators must understand the precise capabilities of each Integrity Evaluation method in order to safeguard

against false assurance on Threats that may not be detected by that particular method.

Selecting the most appropriate Integrity Evaluation method When determining which methods are to be applied for the pipeline Integrity Evaluation, it is essential that

operators consider a “functional specification” for the features they wish to detect and characterise and then

challenge which method may best satisfy that specification. The evaluation methods seek to identify features on

a pipeline that are symptomatic of a particular threat or threats being present.

With regard to the threats that are to be evaluated (or the features that are symptomatic of that threat being

present) the following evaluation methods may be considered:

Evolutionary Threats (Time-related)

• Corrosion

• Stress-corrosion Cracking (SCC)

• Fatigue - an accelerant to failure, eg, after a dent has been inflicted.

• Product-related - threats such as Hydrogen Induced Crack (HIC) and Blistering

Inherent Threats (Stable/Binary)

• Fabrication Defects - during the manufacture of the pipe itself.

• Welding or Construction Defects - during the pipe-laying process.

• Out-of-Specification Ancilliaries

Event-led Threats (Time Independent)

• Mechanical Damage

• Operational Aspects

• Climatic & External Force

Integrity Evaluation 3 Copyright © PIMS of London Ltd

Deployment of the selected Integrity Evaluation technique In-line inspection

Before performing a pipeline in-line inspection, the requirement must be documented to ensure that the

equipment, staff, processes and software that will be part of the inspection are qualified to achieve the desired

specification as set out in the Integrity Evaluation Programme. This documentation must include consideration

for at least the following items:

• The goals and objectives to be achieved, and the accuracy required in the inspection.

• The physical and operational characteristics, and pipeline restrictions.

• The requirements and criteria established in the specifications or standards the department,

organization or company has set to that purpose. In the event that such standards or

specifications are not available, the criteria established in NACE-RP-0102-2002 should

apply.

• The selection of an appropriate inspection tool, based on the inspection requirements and

on the equipment capacities.

The in-line inspection involves the passage of a tool (commonly referred to as a pig) through the pipeline

segment. The tool gathers information on pipeline characteristics during the passage or run. There are three

main categories of inspection tool:

I. Metal Loss tools

- - Magnetic Flux Leakage: Both Standard & High Resolution tools

- - Ultrasonic Wall measurement (Straight Beam)

II. Crack Detection tools

- - Ultrasonic Crack Detection (Angle Beam)

- - Magnetic Flux Leakage: Transverse Flux tools

III. Geometric tools

- - Internal profiling and calliper tool

- - Inertial mapping unit Geopositioning tool

Pressure test (including Hydrotest) Pressure testing – whether conducted using water (fluid), air (gas) or product - must be used as a substitute to

the In-line Inspection method, or in combination with the In-line Inspection method if In-line Inspection is not

practicable. Pressure tests enable the localization of the following features when they result in a loss of enough

magnitude to be recorded by the pressure record tools installed:

a) Localised total metal loss (external/internal)

Integrity Evaluation 4 Copyright © PIMS of London Ltd

b) General total metal loss (external/internal)

c) Stress Corrosion Cracking (SCC)

d) Manufacturing defects (seal or defective metal)

e) Defective girth weld

Acceptable test methods, minimum necessary equipment and other additional requirements of pipeline

hydrotest shall observe the criteria established in the standards or specifications the department, organization

or company has set to that purpose. In the event that such standards or specifications are no available, the

criteria established in standard API-RP-1110-1997 should apply.

Direct Assessment (DA)

Direct Assessment is an integrity evaluation method that can be applied to buried pipelines to consider defects

that are related to some time-dependent threats (internal corrosion, external corrosion, stress corrosion

cracking). The Direct Assessment method should be applied in pipeline systems where pressure testing or the

available internal inspection technologies are not adequate or cost-effective. The Direct Assessment constitutes

a structured process that should not interrupt pipeline operation. Thus, it may be used when the pipeline

operational schedules and product flow rate limit the use of other methods.

Direct Assessment can be used as a solo evaluation method or in combination with other assessment methods.

As a solo evaluation method, it can be used to address external corrosion threats in liquid and gas pipelines,

internal corrosion threats in gas pipelines, and may be considered as an option to understand SCC threat

susceptibility in liquid and gas pipelines.

Other methodologies of Integrity Evaluation

Where In-line inspection, Pressure testing and Direct Assessment cannot be applied, alternative methods of

proven and equivalent technology will be used to evaluate integrity.

Integrity Evaluation report format Regardless of the methodology utilised – be it through In-line inspection, pressure testing, direct assessment or

other methodology – it is important that results are reported in a consistent manner.

The first element that requires consistency is that of the pipe tally. A consistent pipe tally enables an efficient

approach to be taken towards all pipe segments. It also enables alignment of data from disparate sources or

different Integrity Evaluation techniques on any particular segment.

The second element that requires consistency is that of Integrity Evaluation technique accuracy and confidence.

The purpose of expressing accuracy and confidence in a consistent manner enables a degree of span to be

Integrity Evaluation 5 Copyright © PIMS of London Ltd

applied to risk assessments. It also prevents operators from unnecessarily discounting a threat should that

feature lie beyond the reporting threshold.

The third element that requires consistency is that of feature classification. Though feature classification is well

documented with regard to Metal Loss and Cracks, it is important to ensure that other features such as dents or

even pipeline fittings are described in a consistent manner.

It is up to the operator to determine whether the Integrity Evaluation report should include recommendations on

stages to be followed to mitigate the risk represented by features identified as being beyond acceptable limits.

Should this element be required, it is important that the operator determine the manner in which acceptable

limits are defined.

Post Evaluation Assessment The primary purpose of an Integrity Evaluation is to identify what immediate response is required to prevent

imminent pipeline failure resulting from the presence of critical defects.

As with the criteria for the Integrity Evaluation technique itself, it is important that the operator clarifies the exact

purpose of the Post Evaluation assessment. This clarification must be geared towards the manner in which the

information gathered from the evaluation and the Post Evaluation assessment will be used to determine:

• Corrective actions to address a present and identified threat before it causes failure

• Preventative actions to either eliminate consequence or remove the possibility for a threat

to re-occur.

• Reactive actions scheduled as a last line of defence to limit consequence should failure

occur

Though the Post Evaluation Assessment in itself forms a conclusion of a Predictive action, to monitor and

model threat occurrence and location, it is quite likely that the results of such an assessment will also identify

the type and frequency of subsequent evaluations that may be considered appropriate for that pipeline

segment.