When EDF Branche Energies were assessing sub-contractor bids for penstock construction, the first people they called were TWI.
It was likely that high strength steel would be used for the penstock plate material. This is a relatively new development and there is only a small body of knowledge on such applications. EDF were concerned that not enough was known about hydrogen cracking and other welding problems in these materials so TWI was asked to carry out a review of the sub-contractor's proposal.
TWI experts looked at the information on the material proposed with respect to metallurgical, weldability and structural integrity factors. Issues such as moisture, delay time, carbon equivalent levels, preheat, control of welding materials and NDT were examined.
The impartial recommendations supplied by TWI were of great assistance to EDF when deciding on the suitability of the bids.