Fire safe welded ball

[Tuttoesaurito]

Hi all,
I would like to ask you the following question. According to API 6FA, API 607, ISO 10497, could a welded closure valve be qualifed (as extension criteria) from a fire-safe certified bolted closure valve, assuming that internals are the same?

 

[PeterIgg]

IMO I would say: No. The valve is not the same basic design; I would consider the fact that the body shell is joined differently to disqualify based on this clause. In my experience, the way the body expands and contracts with heating and subsequent cooling affects the performance of the valve, I would expect the welded shell to be reduced in section compared to the bolted version and perform differently. That said, I would expect that once you have successfully achieved certification of the bolted version, the welded version should not be too much of a challenge.

 

[gerhardl]

Hi Tuttoesaurito and PeterIgg

I'm thinking along the same lines as PeterIgg here. There is also a question about the welding itself, if this could possibly have some influence on inner parts.

 

[Tuttoesaurito]

Thanks to both!