API 579-1 Fitness for Service Part 3 - Brittle Fracture of Existing Valves and Carbon Steel Gaskets

[MechanicalEng2015]

I am preparing an API 579-1 (Fitness for Service) Part 3 (Assessment of Existing Equipment for Brittle Fracture) Level 2 analysis of an existing carbon steel piping system to determine if the piping system can operate safely during an auto refrigeration condition.

The procedure does not address valves or gaskets.

Is there a separate procedure to analyze valves and gaskets, similar to the procedure for flanges, or are valves not considered in the scope of Part 3?

 

[akpipelineengr]

For valves that include integral flanges, the flange methodology is applicable, especially if it is manufactured from a typical flange material grade. Alternatively, other material grades may be considered to be a part of the "piping system". At the high level of a Level 1 or even a Level 2 assessment, the differences between valves and other piping components are probably negligible and don't warrant a separate analysis methodology. If you get into specific stress states of a specific valve design, you are in the Level 3+ FEA realm.

Gaskets are totally out of scope. Typical spiral wound and metallic gaskets are made from materials that are not susceptible to brittle fracture (or at least have a much lower transition temperature than carbon steel piping materials). Nonmetallic gaskets are too varied in their temperature performance to be analyzed by any standardized methodology. Generally, you have to rely on manufacturer data to assess the acceptability of gaskets at a given exposure temperature.

 

[SJones]

Please don’t double post

Steve Jones
Corrosion Management Consultant

http://www.linkedin.com/in/drstevejones

All answers are personal opinions only and are in no way connected with any employer.

 

[SJones]

Also, gaskets are generally too thin to be prone to the causes of brittle fracture.

Steve Jones
Corrosion Management Consultant

http://www.linkedin.com/in/drstevejones

All answers are personal opinions only and are in no way connected with any employer.

 

[MechanicalEng2015]

I am new to eng-tips and did not realize double posting was against the rules. My question applied to both forums (Piping and BPVC) so I posted it in both forums. Thanks for letting me know.

 

[GD2]

MAT for B16.5 and B16.47 Flanges are set at -29 degree C. Use tg (governing thickness) for valves to determine MAT. As other colleagues said gaskets are too thin and not considered in FFS.

GDD
Canada

 

[MechanicalEng2015]

Is there any mention of valve governing thickness in API-579-1 or UCS-66 (BPVC)? I cannot find any mention of valve governing thickness in these references.

 

[GD2]

Start with ASME B16.34.

GDD
Canada