Regarding difference in temperature limits mentioned in Deg F and Deg C in ASME B 16.5 2

[ATUL KHATRI]

Dear Experts,

1. ASME B 13.4 and 16.5 do have tables for P-T ratings in imperial as well as metric unit. So can we take advantage of conversion factors. For example Table 2-3.4 of ASME B 16.5 (for group 3.4 materials) allows the maximum temperature till 475 deg C but parallely table II-2-3.4 allows to go with maximum temperature till 900 deg F which actually comes as 483 deg c. So can we take the benefit for this conversion and use group 3.4 materials till 483 deg c instead of 475 deg c?

2. In any circumstances can we go beyond the temperature limits for particular pressure rating if its fulfill the requirement of non-mandatory Appendix A ? for example if for group 3.4 materials, my process design temperature is 485 deg C and design pressure is 49.5 barg , so can i go with this temperature and pressure and check whether it fulfills the conditions of equation (3) of Nonmandatory appendix A of 16.5 ?


Thanks
Atul Khatri

 

[XL83NL]

So can we take the benefit for this conversion and use group 3.4 materials till 483 deg c instead of 475 deg c?

No. You either work with SI, or imperial, and dont switch to take credit for something that actually isnt there. Consult your construction code (e.g. ASME VIII-1 or ASME B31.3), which speels this out. If you go for imperial, you do that all the way. See e.g. ASME VIII-1 U-4. Furthermore, see ASME B16.5 para 1.6, where the second last sentence spells this out as well.

In any circumstances can we go beyond the temperature limits for particular pressure rating if its fulfill the requirement of non-mandatory Appendix A ?

If you do so, it becomes a non-standard flange, which needs to be calculated, e.g. using appendix 2 of ASME VIII-1.

for example if for group 3.4 materials, my process design temperature is 485 deg C and design pressure is 49.5 barg , so can i go with this temperature and pressure and check whether it fulfills the conditions of equation (3) of Nonmandatory appendix A of 16.5 ?

No

 

[ATUL KHATRI]

First off all thanks Mr. XL83NL.
Appreciated..

Regarding your first reply to refer the construction code. While referring ASME B 31.3-2016, Table A-1M (pg-296) for spec no.564 -Forging and Fittings (UNS no. N04400),it mentions the maximum use of temperature as 482 deg C . So can i go with this temperature compared to 475 deg C as mentioned in ASME B16.5 against the same UNS number ?

 

[XL83NL]

Hi, you can use
[ul]
[li]B127 plate, sheet and strip to the limits of table A-1[/li]
[li]B164 rod, bar and wire to the limits of table A-1[/li]
[li]B165 pipe and tube to the limits of table A-1[/li]
[li]B366 wrought fittings to the limits of table A-1[/li]
[li]B564 forgings to the limits of table A-1[/li]
[li]B725 pipe to the limits of table A-1[/li]
[/ul]

B31.3, per 323.2.1 even allows you to go beyond those limits.

If you have a forged flange, material per B564, you may use it beyond the limits of table A-1. However, this only applies to flange that dont conform to B16.5. Anything conforming to B16.5, may only be used to B16.5 limits, when it's applied within those limits.

 

[ATUL KHATRI]

Thanks again.
I found your replies reasonably logical.
If something else comes to my knowledge than I will share.

 

[XL83NL]

I found your replies reasonably logical.

Welcome to the world of codes and standards.
Just read the Code, and youll understand yourself. ASME = Always, Sometimes, Maybe, Except.