Impact Tested Without PWHT 1

[sxz]

If a heat exchanger is made from SA-516 Gr70N, 1-1/2", MDMT at -45C for both tube and shell sides, the plate, tubesheet and nozzles are impact tested at -45C, and satisfied with energy specified, the PWHT will not be required for the exchanger. Not sure if it is true. Any comments are welcomed. Thanks.

 

[SnTMan]

Maybe, maybe not. You should review Table UCS 56-1.

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[weldstan]

With a 200 F minimum preheat, P No.1 materials may be welded up to and including 1.5" thick under ASME VIII, Div 1.

 

[sxz]

When running COMPRESS on the above exchanger, it says PWHT is mandatory for the thickness over 1-1/4",even if Impact test is selected. I couldn't exempt the PWHT by using COMPRESS.

 

[NBrink]

Going to go ahead and echo SnTMan here. Review UCS 56-1, specifically note (b).

Software like Compress is a useful tool, but it does not supplant knowledge of the code.

Nathan Brink

 

[sxz]

1. As per Note (b), Table UCS-56-1,no PWHT is required if preheat over 95C is performed.
2. As per UCS66 and 68: SA-516 Gr70N on curve D will have -26C impact test exemption temperature. if PWHT is performed, 17C can be credited, subtotal of MDMT will be -43 C(-26-17). If stress ratio designed gives some MDMT reduction, say -2C, then final MDMT can reach -45C. In this calculation, PWHT is required.
3. If all pressure components are impact tested at -45C, no PWHT is required.
Based on the knowledge of code, PWHT is required or not? Maybe or Maybe not? or both are acceptable?

 

[SnTMan]

PWHT provisions of UCS-66, 67, 68, etc. do not affect PWHT required by UCS-56.

IF required preheat is performed AND if ALL materials are impact tested at -45C, I'd say no PWHT required PROVIDED qualified lo-temp weld procedures are used.

Regards,

Mike



The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[sxz]

SnTMan, thanks for your clarification!
Weldstan and NBrink, thanks for your inputs!

 

[israr1]

SZX,

Also if you see code, preheating is required for thickness within range of 1.25 to 1.5in and above 1.5in PWHT is mandatory.

In compress as far i know there is no provision to consider Pre-heating for thickness within 1.25in to 1.5in.
Hence, it might be considering PWHT directly for thickness above 1.25in which is you case i guess.

Secondly,if PWHT is mandatory as per code than you cannot take the advantage of it for impact testing (to determine MDMT)

 

[r6155]

If both impact test and preheat are required then specimen test shall be preheat.

r6155
Regards

 

[marty007]

Compress does have an option somewhere that accounts for preheating material from 1.25-1.5" thickness.

I can't remember where it is, I think it's in the "Set Mode Options" dialogue somewhere. Unfortunately all of our Compress licenses are currently in use, so I can't look it up for you...

Edit: Here it is: