Thanks to both of you.

Tried check off and PVElite calculated a lower achievable MDMT.

Anyway, per ASME Code requirement, do not think we shall check it off. MDMT still need to be evaluated at MAWP unless design concept is using design pressure as MAWP (Rate MAWP = DP supported by UG 99 b with note 34).

Manual calculation for tr with MAWP(1536.05 KPa) + liquid head (41.85 KPa) get around 33.9 mm, close to PVElite reported 34 mm.

My doubt is clear now, it is not bug.

Regards!

S K Tan