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ASME VIII Div 1 2019 and temperature limit of steel cast valves
- Thread starter engrom
- Start date
The Obturator
Mechanical
I've not seen that change in any of the "Summary of Changes" reviews done by various people relating to ASME VIII 2019. It would impact a few other standards such as ASME B16.34, API 526 etc., not to mention PRV manufacturers own sizing and selection software, and their issuing of advise to specifiers and the like.
Can you at least obtain the specific part of ASME where this has been raised for further review and comment?.
Per ISO-4126, only the term Safety Valve is used regardless of application or design.
Can you at least obtain the specific part of ASME where this has been raised for further review and comment?.
Per ISO-4126, only the term Safety Valve is used regardless of application or design.
- Thread starter
- #3
The Obturator - Not entirely sure about the explicit reference. However, this is the response I got from the supplier:
"ASME BPVC UG-136 (b)(3) states that materials for “bodies, bonnets or yokes, and body-to-bonnet or body-to-yoke bolting shall meet all applicable requirements of Subsection C.”
The wordings in 2017 version that was removed "Carbon and low alloy steel bodies, bonnets, yokes and bolting subject to in-service temperatures colder than -20F (-30C)shall meet the requirements of UCS-66 unless exempted by the following......." which is now changed to refer Subsection C. However, subsection C for cast steel is referring to ASME II Part D Subpart 1 Table 1A. The low temperature section in the ASME BPVC UCS-65 and UCS-66 have not changed between 2017 and 2019 in respect to cast steel A216 WCA, WCB, WCC. The notes 1 & 2 as part of MDMT curve specifies the application of Curve A and B for different grades which depends on heat treatment, normalized vs fine grain etc.
I am still not sure whether it is an industry wide change as there will be other implications, however, I have only heard from one relief valve supplier regarding this so far. They are limiting their cast steel body (WCB) which were previously good for -29C is now rated to -8C and asking clients to select low temperature carbon steel (LCC) body if the temperature is below -8C.
It would be good to know if any others are facing similar discussions by the valve manufacturers.
"ASME BPVC UG-136 (b)(3) states that materials for “bodies, bonnets or yokes, and body-to-bonnet or body-to-yoke bolting shall meet all applicable requirements of Subsection C.”
The wordings in 2017 version that was removed "Carbon and low alloy steel bodies, bonnets, yokes and bolting subject to in-service temperatures colder than -20F (-30C)shall meet the requirements of UCS-66 unless exempted by the following......." which is now changed to refer Subsection C. However, subsection C for cast steel is referring to ASME II Part D Subpart 1 Table 1A. The low temperature section in the ASME BPVC UCS-65 and UCS-66 have not changed between 2017 and 2019 in respect to cast steel A216 WCA, WCB, WCC. The notes 1 & 2 as part of MDMT curve specifies the application of Curve A and B for different grades which depends on heat treatment, normalized vs fine grain etc.
I am still not sure whether it is an industry wide change as there will be other implications, however, I have only heard from one relief valve supplier regarding this so far. They are limiting their cast steel body (WCB) which were previously good for -29C is now rated to -8C and asking clients to select low temperature carbon steel (LCC) body if the temperature is below -8C.
It would be good to know if any others are facing similar discussions by the valve manufacturers.
The Obturator
Mechanical
Hi again engrom and thanks for the pointers.
I followed the ASME BPVC 2019 revision only references you provided. Subsection C (of ASME VIII), if I follow the dialog, the curves do suggest limitations of WCB/C cast carbon steel to -8C without impact test. I had to stop there since any welding and/or wall thickness etc., of a cast pressure containing part has an effect, as well as various other ASME section references that are very present in Subsection C. I have never found ASME BPVC easy to follow.
Clearly this is for the manufacturers engineering people to advise on. I will ask some of my contacts at factories at what their interpretation of this revision is.
If anyone else on this Forum has a better explanation, please enlighten us. Thanks.
Per ISO-4126, only the term Safety Valve is used regardless of application or design.
I followed the ASME BPVC 2019 revision only references you provided. Subsection C (of ASME VIII), if I follow the dialog, the curves do suggest limitations of WCB/C cast carbon steel to -8C without impact test. I had to stop there since any welding and/or wall thickness etc., of a cast pressure containing part has an effect, as well as various other ASME section references that are very present in Subsection C. I have never found ASME BPVC easy to follow.
Clearly this is for the manufacturers engineering people to advise on. I will ask some of my contacts at factories at what their interpretation of this revision is.
If anyone else on this Forum has a better explanation, please enlighten us. Thanks.
Per ISO-4126, only the term Safety Valve is used regardless of application or design.
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