Solution & Implementation
Furmanite offered an engineered six step controlled process as a solution, which was reviewed and accepted by the owner.
Step one: An On-Site machining clean up cut utilizing a Furmanite manufactured Silk® portable facing machine of the 22” diameter sealing surface of the heads commenced, with periodic PT until it was verified that all indications of discontinuity (cracks) were removed. The pre-machining excavation depth was roughly twice client expectations, due to the errant weld methods used previously—certain indications were deep enough to require hand grinding, to preserve as much parent metal as possible.
Step two: The fill and purge head blocks were preheated and the temperature held.
Step three: The critical 22” diameter sealing surfaces of the heads were welded with the proper low hydrogen electrodes, per weld procedure requirements. Sufficient material was applied raising the sealing surface higher than the OEM finish surface height.
Step four: The facing machine was repositioned to the datum points and the overlay of weld was machined to a
flatness tolerance of 0.001” overall.
Step five: The sealing surfaces were honed to create a surface finish of 32 RMS, which was required to satisfy the sealing criteria.
Step six: The fill and purge head blocks were post weld stress relieved and then ambient air quenched.