NDTnet 1998 Aug, Vol.3 No.8

Full-Text - Abstract

Recent changes in government regulation have given more flexibility to plant operators about where, when and how to inspect. Plant operators and manufacturers must make appropriate decisions on the method, level and frequency of inspection required and balance this against economic and safety benefits. Since inspection is by its nature an investment (pay now, benefit later): it would be ideal if decisions on inspection were carried out, however simply, on standard investment accounting methods.

This paper reports on a performance-based economic model for inspection developed over the last five years by AEA Technology. We call this the Inspection Value (IVM) Method. This provides a simple and consistent framework for making decisions on inspection issues in cost terms, that also takes account of the performance of the inspection technique: sensitivity, speed, coverage and reliability (POD). The method enables different inspection, maintenance, repair and refurbishment options to be simply compared in terms of added-value and cost. The methods have been customised to meet the needs of the oil and gas industry with support from HOIS 1 and adapted to quantify the benefits in terms of reduced risk as well as cost. Similar economic models have been deployed in the US aerospace industry to aid the introduction of new inspection technology.

The economic balance in inspectionF

The IVM method aids decisions on how to inspect and is complementary to other methods such as risk-based inspection (RBI) which are used to prioritise where to inspect. The main applications of the IVM method include: (i) Technique optimisation, (ii) Technique choice: comparing the merit of different techniques, (iii) Absolute value calculation: comparing different inspection options in cost terms, (iv) to support inspection strategy and (v) to aid the introductionof new technology.

The paper describes the method in detail. Examples are included to illustrate the application using simple spreadsheets. These include: comparing candidate techniques for a new application; establishing discardcriteria following inspection, for example repair/replaceoptions on pipelines; ranking techniques for future R&D development; setting appropriate threshold levels for MFE floorscanner inspection of oil storage tanks, optimising periodic inspection of a gas separator vessel, Guidance documents and simple databases are available through AEAT and HOIS* to aid application of the method.

* HOIS Harwell Offshore Inspection R&D Service

Abstract Source:
Book of Abstracts, 7th European Conference on Non-Destructive Testing, 26-29 May 1998, ISBN: 87-986898-0-00

Full-Text Source:
Proceedings of the 7th European Conference on Non-Destructive Testing, 26-29 May 1998, ISBN:

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