Thursday, September 6, 2018

Re: [MW:28246] Which Stainless steel bolts to be used between A193 and A320 based on the temperature conditions?

Dear Atul,
Based on my experience in valve industry,I recommend to use B8 for CF8 grade n B8M for CF8M grades.You go with A 193 standard which is for stainless steel bolting

On Thu 6 Sep, 2018, 11:16 AM ATUL KHATRI, <atul.mnnit@gmail.com> wrote:
Hello Experts,
I need some clarification regarding the selection of bolting material between A193 and A320 specifically for stainless steel grades i.e B8,B8C,B8T,B8M etc.
  • Standard specifications A193 and A320 , are for alloy-steel and stainless steel bolting materials intended to be used in high temperature and low temperature services respectively.

  • For alloy-steel bolts its quite evident that A320 clearly highlight the requirement of impact test for low temperature conditions whereas A193 refers A320 for the lower temperature condition. Also the minimum and maximum temperature limits are different for both, as per ASME B31.3. So no confusion in selecting the alloy bolt material specification as per temperature conditions.

  • But for stainless steel grades of these specifications ,for the same grade and same class (for example A193 GrB8M cl2 and A320 GrB8M cl2), the maximum and minimum temperature limits along with their material composition (As per ASME B31.3), mechanical properties (yield and tensile strength ),  is  identical. So on what basis (mainly the temperature limits) we can identify which material to be used ?


  • I am not sure that is there any specific difference of heat treatment and manufacturing process in both the specifications specifically for stainless steel grades ? I tried to find out for the individual specifications but couldn't get it .

  • Also if there is a limit of use of A193 at lower temperature than what is that limit ? is that below -29 deg C we should go for A320 ?

  • Also if there is a limit of use of A320 at higher  temperature than what is that limit ? is that above  125 deg C we should go for A193 ?

I again want to highlight that my query is related to stainless steel grades not alloy grades.

Thanks in advance.

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