Last reviewed 28 November 2023
The Health and Safety Executive has issued a safety alert after it and other regulators have found that the non-destructive testing (NDT) process is vulnerable to tampering and falsification.
The alert is targeted at manufacturers, fabricators and end users of critical structures, pressurised equipment and primary containment systems where non-destructive testing is used to assure integrity.
The safety alert notes that radiographic images of welds have been particularly vulnerable to being falsely obtained or tampered with, leading to a significant risk of flaws and defects going undetected with a subsequent risk of structural failure.
Operators undertaking or commissioning NDT for initial integrity or ongoing assurance should note:
the qualification systems for NDT operatives and those assessing NDT output, eg Personnel Certification in Non-Destructive Testing (PCN) and Certification Scheme for Personnel (CSWIP)
the NDT techniques being used and their limitations
the NDT coverage required and defect acceptance criteria, under relevant standards, eg for pressure vessel manufacture
the conditions required to successfully undertake NDT, eg access and cleanliness
the time required to achieve adequate results
the causes of human failure and violations and ways of reducing them, as described in HSG48 Reducing Error and Influencing Behaviour
employer responsibilities under BS EN ISO 9712, eg issuing written authorisation for NDT personnel to operate, and assurance activities
inspection body responsibilities under BS EN ISO/IEC17020 on impartiality and independence
what the output should look like
how to identify suspect results.
For radiography in particular:
“flash identification” of welds should not normally be accepted — unique and permanent identification at the time of exposure is usually part of the relevant construction standard and where this is the case it should be adhered to
double loading should be tightly controlled, and requirements fully documented within the radiography procedure/written NDT instruction
images should be assessed by someone demonstrably competent
alterations of negatives or manipulation or obscuring of the image should not be accepted.
For practitioners of NDT:
individuals have duties under s.7 of the Health and Safety at Work, etc Act 1974 to take reasonable care for the health and safety of themselves and others who may be affected by their acts or omissions
s.7 places important duties on the employee irrespective of the obligations on the employer
an individual’s activity is also governed by a set of ethical principles in line with those published by the Engineering Council and should be adhered to.