HSE issues stern warning against falsifying NDT records

“HSE has investigated a number of instances where the NDT has been falsified, mainly at the fabrication stage. Welds have not been thoroughly tested and/or the results have been misrepresented,” said the regulatory body in its statement.

The cases appear to centre on radiographic images of welding work and involve duplicate images of welds, images cropped to remove evidence of defects and potential misrepresentation of image quality. Undetected flaws could create a subsequent risk of structural failure warns the HSE.

“Metallic structures fabricated by welding are prone to defects, such as inclusions, porosities and cracking.  The absence of significant defects is assured, at the construction phase, by non-destructive testing (NDT) of the welded joints. This is often achieved by radiography. The weld can be examined for internal defects using an X-ray or radioactive source and a suitable medium (plate or film),” it stated.

Quality assurance at the fabrication stage was essential for ensuring the integrity of structures such as pressure vessels, pipework and tanks, it insisted.

The executive released details of two unidentified cases, one involving a steam boiler project, the other concerning film radiographs of completed work.

In the case of the large-scale steam boiler, incidences of film duplication were noticed by inspectors. The construction had involved hundreds of internal tube welds and generated thousands of radiograph images.

The submissions also included an unusually number of welds claimed to have been radiographed in one working shift. Estimates of capability varied from between 10 welds to 20 welds per shift yet in one instance the firm cited104 weld butts (312 images).

However, none of the parties accountable in the initial supervision process appeared to recognise the implications of the large number recorded, while the weld inspector appointed was not qualified to interpret radiographs.

In a second case, some film radiographs were noted to be slightly smaller than the majority submitted by a firm for approval, post-fabrication. It was discovered that those negatives had been cropped to omit defects that would have required further work and amendment.

As both submitting firms were UKAS-accredited they would have to conform to the BS EN ISO/IEC 17020 standard that stipulates commercial, financial or other pressures should not compromise impartiality. In addition BS EN ISO 9712 defines the requirements placed on those responsible for performing NDT; it also permits certification bodies to withdraw certification from transgressors warned the HSE.

Pic: Filipa Saldanha