MDMT PV Elite
MDMT PV Elite
(OP)
Hi guys, please what can i do to reduce the MDMT of a pressure vessel. I have this warning at the end of the design "Warning: Computed overall MDMT was higher than the required value !".
Although ok with client spec but i there anything i can do to influence the value
Although ok with client spec but i there anything i can do to influence the value





RE: MDMT PV Elite
If you need help furthur, you need to provide the furthur details so that others can understand the problem better.
RE: MDMT PV Elite
I am assumining it is a carbon steel vessel and you don't give the materials you selected.
You can add normalization to the materials.
You can add PWHT.
If the problem is self reinforced nozzles you can go to SA-350-LF2
if all else fails you can add CLVN to the materials and do production impact testing.
Without your requirements or you materials selected, not much else cand be said.
RE: MDMT PV Elite
The MDMT is showing a warning for the computed. the selected is -20 deg C, the computed is 35 deg C.
the warning is as highlighted above, that the computed is higher than required. So i don't know what to do.
RE: MDMT PV Elite
At 33 bar (3401 kPag) and 8 ft diameter, with 1/16" C.A., I computed a vessel shell thickness of 1.5"; if you are getting a computed 35 C MDMT then you probably have specified a Curve A material (ASME Section VIII Division 1 Figure UCS-66 / Table UCS-66). You can almost get to the MDMT you want by specifying a Curve D material such as SA-516-70 N.
RE: MDMT PV Elite
RE: MDMT PV Elite
The problem appears to be in the material selection window, make sure to select the correct heat treatment (normalized or not) and the correct impact test curve.
Cheers,
gr2vessels
RE: MDMT PV Elite
RE: MDMT PV Elite
What are the computed shell / head / nozzle neck thicknesses and materials? Some component or other is limiting.
Are you sure the material that the program is working with is Curve D? I somehow doubt it. Are things 4.5 inches thick?
If a piping component is limiting, see also ASME B31.3 323.
RE: MDMT PV Elite
Refer to UCS-68(c) for PWHT and impact test exemption temperature reduction.