Re: [MW:12223] Hairline cracks in stellite 6 coating (HF) - A216 WCB

Same with my situation. During our last TA, the stellite 6 was overlaid on jet nozzle of regen. standpipe after minor repair on it. After the weldment was cooling down, DPT was carried on that particular area and revealed a hair line crack.

On Fri, Aug 12, 2011 at 4:00 PM, Materials & Welding <materials-welding@googlegroups.com> wrote:

Is it true that stellite 6 HF will leave hairline cracks on the
surfece?, one of the reputed valve vendor is quoitng that

"Seat overlay made of Stellite 6 is possible but not recommended by
us. We clearly mention that it is not possible to perform a Stellite 6
completely free of hair cracks. Probably after final machining the
surface will show hair cracks which is normal in case of using
Stellite 6 and this do not affect the sealing functiont We normally do
not use Stellite 6 because of this fine cracks and because of much
better experience with Stellite 21. If you insist on Stellite 6
seating surface showing hair cracks will not be a reason not to accept
the valves if seat tightness test is ok"




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