What is the reliability of in service non-destructive testing (NDT)?

Lloyd’s Register services to the energy industry

November 11-14, 2014 Adipec

Speaker information

Reliability of In-Service NDT



Introduction

• NDT is a critical tool in our Integrity Management Toolbox

• The majority of In-Service Inspection we do is NDE

• Piping, vessels, exchangers, tanks, pipelines & structures

• We place a lot of FAITH in the NDT results and use it to determine FFS

• Is our FAITH justified?



Reliability of In-Service NDT

INDEPENDENTINTEGRITY

HEALTHCHECK

Corrosion Management

RBI Adequacy

IM Gap Analysis

In-Service NDT Adequacy

Integrity Database & CMMS Utilisation

IM Procedure Compliance

IM Strategy Compliance

Anomaly & Repair Management Process



Types of NDT applied for In-Service Inspection

• Ultrasonic

• Radiography

Advanced techniques –

• ToFD, Phased Array,……

• Digital / Computerised RT

• Slofec / MFL



Analysis

Build comprehensive Asset Register

Perform detailed Risk Based Inspection (RBI) studies

Determine applicable damage mechanisms

Great lengths – but can we detect, can we measure, does technician know what he is looking for????

HIGH

MED HIGH

MEDIUM

LOW



Construction NDT v In-Service NDT

• Training and Certification to support Oil & Gas Construction activity

• Increasing % of NDT in O&G is In-Service NDT / Non-Intrusive Inspection (NII)

• However most NDT training still reflects looking for weld flaws rather than in-service damage mechanism

• Often Opco’s not rigorous enough in specifying requirements



In-Service NDE – so what’s different?

• Different skills & mindset required

• Techniques / responses / interpretation differ greatly

• Corrosion and Erosion – random

• Defect locations and orientation and morphology not readily predictable………



Weld Root Corrosion & Erosion/Corrosion *



Co2 Corrosion & SRBs



Erosion & Crevice Corrosion



Corrosion Under Insulation (CUI) *



Pipelines



Influencing Factors for Consideration

• PANI (Programme for Assessment of NDT in Industry) requirements

• Take account of Human factors & enviromental conditions

• Training on specific samples

• Knowledge of damage mechanisms

• Appropriate Written Procedures and Reporting requirements

• Suitable POD to give desired Confidence Level



Typical Issues Observed

Competence – not received correct training for actual task

Experience / knowledge – no appreciation of what inside of pipe may actually look like!

Procedures – do not reflect in-service application (no DAC curve!)

Reporting – not clear & concise, poor layout and lack detail to support FFS

Appropriate technique – will not find and measure actual expected damage



New Inspection Technology

• Not always available in MEA region

• Sometimes equipment is available, but the Operator??

• In-Service training & experience with technique is still essential



What of Other Techniques?

Radiography

• Trained to interpret andidentify weld flaws

• Measurement ofremaining ligament

• Scale, sand, heat,vibration, debris…..



In-Service Radiographs



Inspection Technique Selection

• Consideration is required to ensure selection of most appropriate technique(s)

• Random deep, isolated, localised pitting on 6”dia piping – long lengths of straight pipe

• Manual ultrasonic scanning with 0 degree compression probe – is this the best approach?

• Looking for needle in a haystack! Applied Magnetic Flux Leakage (MFL) as a rapid screening, with detailed UT assessment of limited areas of interest



Typical Areas for Improvement

• In-Service orientated NDE Procedures

•Consider inspection conditions (access, weather, boredom, etc.)

• Make use of “hard copy” techniques

• Mix and match techniques (Slofec/TOFD/PE)

• Assurance/ x-checks on high criticality

• Ensure relevant training and awareness



Summary

- In-Service NDT is an essential tool in maintaining the Integrity of our Assets

- In-Service NDT requires specific skills, training, experience & procedures

- Be wary of putting too much FAITH in NDT results unless you also have the appropriate controls and assurance activities in place

- LR can help you have greater confidence in this critical data

What is the reliability of in service non-destructive testing (NDT)?

Technology

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