See UCS-66. First establish which curve 516-70N falls under (curve D) then look up the thickness you have in Table UCS-66 and read the temp for Curve D.
OP could ask the question in a different way.
Is the 30 mm thick plate exempted from impact testing for required MDMT of -29 deg C?
MDMT is a design parameter, not material property.[pre][/pre]
Spot on. There is a difference between MDMT and lowest temperature that avoids Charpy testing. Wonder what the process temperature actually is versus the nominated -29 deg C
Hello
the MDMT is the Minimum Design Metal Temperature, which definition is the minimum (cold) temperature at which a pressure equipment will be pressurized at pressure levels comparable to design pressure (we use 25% of design pressure). The MDMT is a process parameter, not a material's parameter.
I agree with SJones, UCS-66 tells you whether or not you need to perform impact test, i.e. impact tests required as per ASME BPVC when you operate below the curve for a given grade : the curve UCS 66 is minimum allowable MDMT without additionnal impact testing for a given grade.
From the answers above and reading the ASME Code Sec. VIII Div. I 2021 UG-20(f), figure UCS-66 and UCS-66.3 Sketch e, I came to a conclusion that first we need to identify the governing thickness then go to the UCS-66 Curve and see the rated MDMT corresponds to governing thickness and Curve D
In my case two plates are making a corner joint, Plate 1 (35 mm) Plate 2 (30mm). I was confused which thickness is governing thickness which is now clear.
Thanks to all once again. really found your comments supportive.
Chumpes (Petroleum)12 Jul 22 14:31
Hello
the MDMT is the Minimum Design Metal Temperature, which definition is the minimum (cold) temperature at which a pressure equipment will be pressurized at pressure levels comparable to design pressure (we use 25% of design pressure). The MDMT is a process parameter, not a material's parameter.
Minor clarification: MDMT rating corresponds to the vessel's MAWP, not Design Pressure.
Tolerance is the virtue of the man without convictions -GK Chesterton