NDT of Welds by Ultrasonic Techniques
National Grid Gas Transmission
Alan Kirkham; box.GT.Innovation@nationalgrid.com
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Network Innovation Allowance
Electricity Transmission Networks
To enable the project to demonstrate that the defects can be located within the welds of interest the initial work will be to design and produce suitable test blocks which adequately represent the circumferential welds within the hot tap operation. Once the test blocks have been manufactured and artificial defects introduced, the next stage will be to carry out controlled inspections on the test blocks to determine if the artificial defects introduced can be detected and the size and position determined accurately using a manual ultrasonic technique and the more advanced manual phased array system.
The objective of the project will be to determine that with the selection of a suitable non-destructive ultrasonic system and using suitably controlled technique that it is possible to detect defects within the circumferential weld of hot tap operations which could be detrimental to the integrity of that weld.
The project will inform the debate concerning the suitability of the latest ultrasonic techniques for weld integrity assessments. The success criteria will be if following the work suitable equipment, National Grid will be able to integrate their use for inspection of the circumferential welds on hot tap operations for detecting weld defects.