Dear All,
I have a problem with PVElite program. When I select ‘Air/Water/Steam’ in Service Type (Design Data), the program gives immediately a minimum thickness for heads and shells of 2,5 mm. Having a look on the ASME Code, I understand the minimum thickness is 1,5 mm (per UG-16). The paragraph UG-16 mentions some exceptions. If you see UG-16 (4) [the minimum thickness of shells and heads used in compressed air service, steam service, and water service, made from materials listed in Table UCS-23, shall be 3/32 inches (2,5 mm approx.)]. UCS-23 is carbon and low alloy steel. I have considering in the program different material as A-240 and A-312 in 316 material (table UHA-23). Consequently I understand this exception doesn’t apply and the minimum thickness should be 1,5 mm as mentioned by the general rule.
I have checked the rest of the exceptions mentioned in UG-16 and they don’t apply to the equipment in this case.

Could you please clarify this? Do we need really a minimum thickness of 2,5 mm (as results from PVElite) or 1,5 mm will be valid?

Thanks in advance!

Hi cmna,
I think you are correct. Minimum thickness requirement of 2.5 mm only applies to vessels constructed of materials listed in table UCS-23 used in compressed air service, steam service, and water service; as per UG-16(4).

Dear PVElite Moderators, what is your opinion on below conclusion.

Agree or disagree on the forum member's conclusion?

My opinion is the same. UG-16(b)(4) shall not affect High Alloy material since they are not listed in Table UCS-23.

If it is a recognized bug, when PVElite will fix it ? The discussion took place past few years already.

We have a recent case. By knowing UG-16(b)(4) applicable to Table UCS-23, we used 316L Tube with wall thickness greater than 3/32" on a water service application since PVElite did not accept 1/16" as minimum.

We hope this can be resolved as soon as possible, good for every PVElite users.

Please enlighten if there is a valid Code reason to apply 3/32" minimum wall thickness for High Alloy ASME material in PVElite.

Thank you!

Hello SK Tan

The statement in UG-16(b)(4) states this:

"(4) the minimum thickness of shells and heads used
in compressed air service, steam service, and water service,
made from materials listed in Table UCS-23, shall be 3⁄32
in. (2.5 mm) exclusive of any corrosion allowance."

If we go to Table UCS-23, we find the list of materials to which UG-16(b)(4) refers. There are no austenitic or high alloy steels listed there as far as I can see. So the simple answer to the question is this:

UG-16(b)(4) refers to Table UCS-23. If the material does not appear in that Table, then that clause does not apply.

Dear Ray,

Thanks for your reply and confirmation.

Will this over-conservative on UG-16(b)(4) be improved on next update of PVElite ?

We do hope Intergraph will rectify this promptly. I only continue this subject initiated by other forum members which was few years back. PVElite should have removed the 2.5 mm from UHA material and let UG-16 (b)(4) solely govern material listed on Table UCS-23.

We hope this day will come soon. Thanks again!

Hello SK

You are of course right in that the requirement should not apply to materials that appear in the UHA section of the code. I have discussed this with the development staff, and they too agree. We are going to look into this situation.

We thank you for your interest, and input. We need feedback from the customers.

Dear Ray,

Thanks for your effort to discuss with PVElite development staff and get their agreement to set continuous improvement plan on it.

Regards!