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Re: [MW:12229] Hairline cracks in stellite 6 coating (HF) - A216 WCB

By Materials & Welding
Any experience with barrier layer of Inconel or stellite 21 and then
with stellite 6?

On Mon, Aug 15, 2011 at 2:32 PM, tong tong <tong2je@gmail.com> wrote:
> 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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