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The Advent of NDT at TWI

Thu, 16 February, 2023

As part of the 100th anniversary celebrations for The Welding Institute we have been reaching out to our Professional Members for their memories of the Institute.

One of those we spoke to, Fellow CEng Alan Gifford, offered an interesting story of how the company he was working with in the 1960s, International Combustion Ltd, were influential in bringing non-destructive testing to TWI Ltd.

Alan revealed how International Combustion Ltd were accepted a contract to supply a 140 ton boiler drum in 4.5 inch thick low alloy steel for a client who was overseas. A British inspection body was appointed to oversee the manufacture and testing of the drum.

However, as Alan explained, “We had, as an error of judgement, also unfortunately accepted a 100% ultrasonic testing procedure of the seams to an exacting ultra-high sensitivity scan.”

The circumferential welds of the drum were created with submerged arc welding at a pre-heat of a minimum of 100°C. The ultrasonic testing showed numerous small inclusions, with the repair involving the excavation of a 4” deep groove before preheating and hand welding.

This repair was expensive, unnecessary and time consuming, while the drum itself took up a large area of International Combustion’s shop floor.

Alan revealed, “We appealed to the client for a relaxation of the standard but, as we later found out, he did not require the drum due a change of programme,” adding, “Whilst this was in hand we came across a similar reflector in a welded test plate associated with one of the seams. By careful cutting and machining we managed to expose the fault - it was a very small slag inclusion (maybe 1.5mm across the section) and about 80mm from the outer surface and it would have required a big excavation.”

Discussing the problem with his own company directors, Alan was told to check with TWI forerunner the British Welding Research Association (BWRA), so he set up a meeting with BWRA director Doctor Richard Weck. Dr Weck stated that the BWRA did not deal with non-destructive testing as it was the job of NDT specialists.

However, Alan was not to be dissuaded, as he revealed, “I said NDE was an integral part of manufacture and then produced the polished and etched section and asked him to comment on it.”

Dr Weck believed that it was a ‘very good weld,’ at which point Alan explained that it was a reject, pointing out the inclusion. This led to the realisation that the BWRA should investigate NDT further so as to be able to locate and explain such small defects. In 1965, the BWRA and the Non-Destructive Testing Society of Great Britain united to form the School of Applied Non-Destructive Testing, pioneering formal training in areas like ultrasonic weld testing and radiographic interpretation.

Despite this ground-breaking revelation, Alan revealed that his client did not want the drum to be delivered, meaning that the work had no impact on improving their product.

However, the work was influential in progressing NDT at TWI Ltd, creating an important part of our work ever since.

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