Hi All,
I have a question regarding the impact test requirement for austenitic stainless steel material, 321H and 304H.
Due to the high design temperature requirement, those materials are chosen, as high carbon content will provide high strength characteristic.
The pressure vessel will be manufactured by cold forming with post-fabrication strain limit below the one listed in Table UHA-44. Therefore, no heat treatment is required as per Table UHA-44. But, however, to ensure the dimensional stability for the cold formed pressure vessel, the pressure vessel will still be heat treated (stress relieved) to remove the residual stress. The pressure vessel will be warming to the temperature up to 475 C and hold for 4 hours per 25 mm of section.
This temperature is just below than the temperature range indicated in UHA-51(c), and the stainless steel material need NOT to be impact tested after the heat treatment process. See the UHA-51 (c) below for your reference.
“UHA-51 (c) Required Impact Testing When Thermal Treatments Are Performed. Impact tests are required at the test temperature in accordance with (a) but not warmer than 70oF (20oC) whenever thermal treatment within the temperature ranges listed for the following materials are applied:
(1) austenitic stainless steels thermally treated at temperatures between 900 F (480 C) and 1650 F (900 C); however, Types 304, 304L, 316, and 316L that are thermally treated at temperatures between 900 F (480 C) and 1300 F (705 C) are exempt from impact testing provided the MDMT is -20 F (-29 C) or warmer and vessel (production) impact tests of the thermally treated weld are performed for Category A and B joints.”
The manufacturing process as prescribed above have clearly concluded that impact test is NOT required.
HOWEVER, the operating temperature for the pressure vessel could reach up to 566 C (design temperature is 600 C) and is within the heat treatment temperature range as prescribed above UHA-51 (c). In this case, is there a need to have impact test for material Type 321H and 304H as per UHA-51(c)?
I deeply appreciate if anyone could advise me on these and see if my interpretation on UHA-51(c) is correct.
I have a question regarding the impact test requirement for austenitic stainless steel material, 321H and 304H.
Due to the high design temperature requirement, those materials are chosen, as high carbon content will provide high strength characteristic.
The pressure vessel will be manufactured by cold forming with post-fabrication strain limit below the one listed in Table UHA-44. Therefore, no heat treatment is required as per Table UHA-44. But, however, to ensure the dimensional stability for the cold formed pressure vessel, the pressure vessel will still be heat treated (stress relieved) to remove the residual stress. The pressure vessel will be warming to the temperature up to 475 C and hold for 4 hours per 25 mm of section.
This temperature is just below than the temperature range indicated in UHA-51(c), and the stainless steel material need NOT to be impact tested after the heat treatment process. See the UHA-51 (c) below for your reference.
“UHA-51 (c) Required Impact Testing When Thermal Treatments Are Performed. Impact tests are required at the test temperature in accordance with (a) but not warmer than 70oF (20oC) whenever thermal treatment within the temperature ranges listed for the following materials are applied:
(1) austenitic stainless steels thermally treated at temperatures between 900 F (480 C) and 1650 F (900 C); however, Types 304, 304L, 316, and 316L that are thermally treated at temperatures between 900 F (480 C) and 1300 F (705 C) are exempt from impact testing provided the MDMT is -20 F (-29 C) or warmer and vessel (production) impact tests of the thermally treated weld are performed for Category A and B joints.”
The manufacturing process as prescribed above have clearly concluded that impact test is NOT required.
HOWEVER, the operating temperature for the pressure vessel could reach up to 566 C (design temperature is 600 C) and is within the heat treatment temperature range as prescribed above UHA-51 (c). In this case, is there a need to have impact test for material Type 321H and 304H as per UHA-51(c)?
I deeply appreciate if anyone could advise me on these and see if my interpretation on UHA-51(c) is correct.
