Why MDMT must be correspond to the coincident pressure MAWP ?
Why MDMT must be correspond to the coincident pressure MAWP ?
(OP)
as the statement of ASME VIII-1 UG20(b)
“The minimum metal temperature used in design shall be the lowest expected in service expect xxx”,
The MDMT marked on the nameplate shall correspond to a coincident pressure equal to the MAWP”
Background: a pressure vessel,the internal pressure is direct proportional to the temperature, when temperature increased,the pressure increased, simultaneously the pressure will reduce when the temperature reduced.
when the temperature at 50℃(highest),the coincident pressure will be 1.6 Mpa, and the pressure will be 0.1Mpa at the lowest temperature 0 ℃. The MDMT can’t occurs at the WAMP.
How can i stamp the MDMT at WAMP in the nameplate ?
“The minimum metal temperature used in design shall be the lowest expected in service expect xxx”,
The MDMT marked on the nameplate shall correspond to a coincident pressure equal to the MAWP”
Background: a pressure vessel,the internal pressure is direct proportional to the temperature, when temperature increased,the pressure increased, simultaneously the pressure will reduce when the temperature reduced.
when the temperature at 50℃(highest),the coincident pressure will be 1.6 Mpa, and the pressure will be 0.1Mpa at the lowest temperature 0 ℃. The MDMT can’t occurs at the WAMP.
How can i stamp the MDMT at WAMP in the nameplate ?





RE: Why MDMT must be correspond to the coincident pressure MAWP ?
Stamp by Code instructions.right, you can stamp per design MDMT at xxx calculated designed pressure. It can be lower than the MAWP at xxx temp.
By design...good luck.
RE: Why MDMT must be correspond to the coincident pressure MAWP ?
What is the WAMP ? Also to answer your question "How can i stamp the MDMT at WAMP in the nameplate ?"
Use a minimum of 6mm high metal stamps on the nameplate. Impact other end of stamp with a 2Lb hammer!!
RE: Why MDMT must be correspond to the coincident pressure MAWP ?
That would ONLY be true of a pressure vessel filled to some initial pressure with an ideal gas, with no gas then being fed or removed.
That is NOT how most pressure vessels are used!
RE: Why MDMT must be correspond to the coincident pressure MAWP ?
RE: Why MDMT must be correspond to the coincident pressure MAWP ?
Regards,
Mike
The problem with sloppy work is that the supply FAR EXCEEDS the demand