Applying SA 333-6 for MDMT of -49 C
Applying SA 333-6 for MDMT of -49 C
(OP)
Dear all,
I am currently working on a Process heater which has Nitrogen as the operating medium and operating temp. is -49C. Required MDMT is also -49C.
Vendor has proposed to apply SA 333-6. However, as per ASME Section II Part A, SA 333-6 is impact tested at -45C , so standard SA 333-6 cannot be used for MMDMT of -49C
.
Vendor says that they can impact test the material at -49C and demonstrate the absorbed energy same as mentioned in Table 4 of SA 333 material specification.They are reluctant to apply other grades (which are impact tested for lower temperature, and should ideally have been used...)due to cost and sourcing issues.
Could the esteemed forum members let me know if Vendor's proposal can be accepted?
I read through SA 333 specification, but could not find anything which would suggest that testing at colder temperature is acceptable.
Kindly let me know your valuable opinions.
Thanks,
D2HANDLE
I am currently working on a Process heater which has Nitrogen as the operating medium and operating temp. is -49C. Required MDMT is also -49C.
Vendor has proposed to apply SA 333-6. However, as per ASME Section II Part A, SA 333-6 is impact tested at -45C , so standard SA 333-6 cannot be used for MMDMT of -49C
.
Vendor says that they can impact test the material at -49C and demonstrate the absorbed energy same as mentioned in Table 4 of SA 333 material specification.They are reluctant to apply other grades (which are impact tested for lower temperature, and should ideally have been used...)due to cost and sourcing issues.
Could the esteemed forum members let me know if Vendor's proposal can be accepted?
I read through SA 333 specification, but could not find anything which would suggest that testing at colder temperature is acceptable.
Kindly let me know your valuable opinions.
Thanks,
D2HANDLE





RE: Applying SA 333-6 for MDMT of -49 C
You can actually use SA-333-6 to -48 C per UCS-66(g). It shouldn't be difficult to obtain a 1 degree UCS-66(b) reduction.
Regards,
Mike
The problem with sloppy work is that the supply FAR EXCEEDS the demand
RE: Applying SA 333-6 for MDMT of -49 C
Their approach is otherwise completely fine per ASME VIII-1.
RE: Applying SA 333-6 for MDMT of -49 C
Regards
r6155
RE: Applying SA 333-6 for MDMT of -49 C
RE: Applying SA 333-6 for MDMT of -49 C
RE: Applying SA 333-6 for MDMT of -49 C
RE: Applying SA 333-6 for MDMT of -49 C
Thanks for your opinion...
This is an Electrical Heater and shall be used intermittently only when a Compressor on the downstream starts and needs to be supplied with Nitrogen before start-up.Once the Compressor is up and runnning, the Heater will be shut down.
MDMT of -49 has been specified by the Process guys in our team and they said they have considered all possible operating scanarios....
@SnTMan , @marty007
Thanks for your post and valuable opinions...
Yes this Heater is designed asper ASME Sec VIII Div. 1., and of couse I can take credit for UCS-66 (g) and impact test this dowm to -48C... But somehow i think the application of coincident stress ratio is not appropriate.
Please read through UCS-66(b)(1)(a)...
(1) See below. (-a) For such components, and for a MDMT of −55°F (−48°C) and warmer, the MDMT without impact testing determined in (a) above for the given material and thickness may be reducedSo, do you really think this can be applied to this case where MDMT is -49 C??
Regards,
D2HANDLE
RE: Applying SA 333-6 for MDMT of -49 C
The main question that i wanted to have answer to is ....what is the limit????
If there is a case where MDMT is say...-55C or -60C or -75C, can I still apply Gr. 6 if the Vendor is confident of passing the impact test ?
Kindly enlighten me...
Regards,
D2HANDLE...
RE: Applying SA 333-6 for MDMT of -49 C
See UCS-66(i) for reduction of impact tested materials using UCS-66(b).
Regards,
Mike
The problem with sloppy work is that the supply FAR EXCEEDS the demand