-20degF Vessel for PED

[stanrick]

I am redesigning a small vessel for use in Europe at -20F (-29C). Currently it is made of SA53B,E shell, SA414G heads, SA36 machined nozzles. My understanding is that these materials cannot be rated -29C in Europe without impact testing. But I understand that I can achieve -29C if I switch to SA524 shell, SA516-70 (normalized) heads, and SA516-70 (normalized) machined fittings AND FOLLOW THE FOLLOWING STEPS:

1) Limit carbon content to .23%, Phosphorous to .035%, Sulfur to .025%
2) Employ Fig UCS-66 to show -55F at 20J impact
3) Adjust to 27J using API579

I would appreciate hearing comments on how sensible this plan is, and if there are better material choices than I gave.

 

[JackSam]

European regulations require all ferritic materials to be impact tested at or below the minimum operating temperature, but not greater than 20C, with an energy no less than 27J. Sorry but you can't use the charts to get out of the impact test you just have to do it.

 

[vesselfab]

YEP...Gotta impact it all. Just finishing up our first and hopefully last set of PED jobs.

make sure all materials come from ped certified sources.
make sure a ped certified lab does all tests.

make sure your nde contractors are ped certified.

make sure that your weld procedures were or will be witnessed by the PED certifying person.

 

[XL83NL]

I think I once read the PED doesnt apply to vessels that were in use prior to when the PED was issued, and are now repaired.

Not sure if thats your case here, but since u're talking bout redesigning I thought I just mentioned.

As vesselfab indicated, you might want to ask for 3.1 certificates as per EN 10204.
Also, make sure your material is 'PED approved' (Annex I 4.2 (b)), which might require a PMA,
as ASTM material isn't a harmonized standard for the PED.

It might also be useful to read PED guideline 7/17 about when a material requires impact testing per PED (it's not always required).