OFFSHORE TECHNOLOGY REPORT 2000/018

1 HSEH ealth & SafetyExecutivePOD/POS curves fornon-destructive examinationPrepared byVisser Consultancy Limited for the Health and Safety ExecutiveOFFSHORE TECHNOLOGY REPORT2000/018 HSEH ealth & SafetyExecutivePOD/POS curves fornon-destructive examinationDr W (Pim) VisserVisser Consultancy Limited3 Valiant RoadWeybridgeSurrey KT13 932 United KingdomHSE BOOKSii Crown copyright 2002 Applications for reproduction should be made in writing to:Copyright Unit, Her Majesty s Stationery Office,St Clements House, 2-16 Colegate, Norwich NR3 1 BQFirst published 2002 ISBN 0 7176 2297 5 All rights reserved.

2 No part of this publication may bereproduced, stored in a retrieval system, or transmittedin any form or by any means (electronic, mechanical,photocopying, recording or otherwise) without the priorwritten permission of the copyright REPORT is made available by the Health and SafetyExecutive as part of a series of reports of work which hasbeen supported by funds provided by the the Executive, nor the contractors concernedassume any liability for the reports nor do theynecessarily reflect the views or policy of the of contents Summary Glossary of terms 1.

3 Introduction 1 2. Main findings 2 3. Fundamental aspects Description of defects 5 Calibration & sizing 5 Definitions 5 Inspection methods 6 Statistics of POD/POS 9 Codes and guidance 12 4. Six major projects PISC II & III 13 Nordtest 13 NIL

4 14 UCL underwater inspection 15 ICON 15 TIP 16 5. Major findings of each project Methods of presentation 17 Principal findings for each project 17 Overview of principal findings 21 Differences between surface flaws and buried flaws 21 Collection of general observations

5 22 6. Other aspects Human factors 23 Flooded member detection 24 Acoustic emission 24 Pipelines 25 Workmanship

6 25 Potential areas for future developments 26 7. References 28 Tables Table 1 Definitions of terms Table 2 Overview of acceptance standards Table 3 Overview of NDT methods and the main NDT projects Table 4 Flow diagram for defect detection and assessment Figures iii Appendices Detailed reviews of main projects Appendix A PISC-II and III Appendix B Nordtest Appendix C NIL Appendix D UCL Appendix E ICON Appendix F TIP Appendix G Flooded

7 Member detection Appendix H Potential areas for future developments ivv Summary On behalf of the HSE a review has been made of relevant results on POD (probability of detection) and POS (probability of sizing) of defects in welded structures. The aim is to obtain quantitative information on these topics which can subsequently be used in a probabilistic defect assessment and fitness for purpose (FFP) evaluations in the context of the Brite Euram project SINTAP, co-ordinated by British Steel. In total six major projects on non-destructive examination (NDE) were identified as having potential for this information.

8 These projects are in historical order: PISC Project on Inspection of Steel Components for nuclear components Nordtest a series of Scandinavian projects on fundamental issues in NDE NIL a series of Dutch projects on fundamental issues in NDE UCL a joint industry project on underwater NDE of OFFSHORE structures ICON Inter-Calibration of OFFSHORE NDE, a large underwater NDE project TIP Topsides Inspection Project on NDE of OFFSHORE topsides components The main reports of these six projects have been reviewed in detail.

9 The emphasis of these reviews was on information on POD/POS of surface breaking defects but relevant information on buried defects has been extracted as well. This REPORT does not address the issue of how this information can be used, and which information is still required, to carry out fitness for purpose (FFP) evaluations. vi Glossary of terms abbr. explanations ACFM alternating current field measurement ACPD alternating current potential drop AE acoustic emission AEA.

10 UK Atomic Energy Authority ASME American Society of Mechanical Engineers CAF correct acceptance frequency CAP correct acceptance probability CAT computer assisted telemanipulator CRF correct rejection frequency CRP correct rejection probability CRR correct rejection rate CTOD crack tip opening displacement DAC distance amplitude curve DCPD direct current potential drop method DDF(R or T) defect detection frequency (rejectable defects or total number of defects) DDP defect detection probability DDT defect detection trials DNV Det Norske Veritas DP dye penetrant (technique)