orion952
Industrial
- Feb 13, 2006
- 8
What is required for a radiographic examination level of RT-2 and RT-4?
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Levels of radiographic examination
- Thread starter orion952
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orion,
Refer to UG 116 and UW 11(a). UG 116 defines the rules for marking a vessel constructed in accordance with ASME Sec VIII, Div 1, and UW 11(a) outlines the rules for the extent of radiography to be performed. You'll also want to be familiar with UW 3 for definitions of the various categories of joints in a vessel and UW 12 which allows one to determine a joint efficiency based on the type of joint and the extent of volumetric examination performed on that joint. Summarizing, one would apply RT-2 to a vessel when the entire vessel meets the requirements of UW 11(a) and the spot RT requirements of UW 11(a)(5)(b) have been applied. Typically this means vessel long seams are radiographed 100% while spot radiography is applied to the round seams.
RT-4 is kind of a catch all and is used where none of the other markings RT-1, RT-2, & RT-3, apply. Typically, RT-4 is used when one section of the vessel is 100% radiographed and another section is not fully radiographed.
Refer to UG 116 and UW 11(a). UG 116 defines the rules for marking a vessel constructed in accordance with ASME Sec VIII, Div 1, and UW 11(a) outlines the rules for the extent of radiography to be performed. You'll also want to be familiar with UW 3 for definitions of the various categories of joints in a vessel and UW 12 which allows one to determine a joint efficiency based on the type of joint and the extent of volumetric examination performed on that joint. Summarizing, one would apply RT-2 to a vessel when the entire vessel meets the requirements of UW 11(a) and the spot RT requirements of UW 11(a)(5)(b) have been applied. Typically this means vessel long seams are radiographed 100% while spot radiography is applied to the round seams.
RT-4 is kind of a catch all and is used where none of the other markings RT-1, RT-2, & RT-3, apply. Typically, RT-4 is used when one section of the vessel is 100% radiographed and another section is not fully radiographed.
Inspector1964
Mechanical
Hi,
Thanks for this post, one point I want to add, the joint efficiency for both RT1 and RT2 is 1, and we know when we have full radiography we can consider joint efficiency to be 1, but in RT 2 we have not done full radiography but our joint efficiency is 1 so why code has given this concession?
Because in RT1 full radiography is mandatory either the service is lethal, or the thickness is higher than a specific value, or our vessel is unfired steam boiler so manufacture is mandated to do full radiography.
But in RT-2 manufacture by his own option select UW-12(a) for full radiography so the code given this concession for circumferential joints (spot for circumferentials)
For more on this you may review following article
ASME Pressure Vessel Joint Efficiencies
Regards
and thanks again
Thanks for this post, one point I want to add, the joint efficiency for both RT1 and RT2 is 1, and we know when we have full radiography we can consider joint efficiency to be 1, but in RT 2 we have not done full radiography but our joint efficiency is 1 so why code has given this concession?
Because in RT1 full radiography is mandatory either the service is lethal, or the thickness is higher than a specific value, or our vessel is unfired steam boiler so manufacture is mandated to do full radiography.
But in RT-2 manufacture by his own option select UW-12(a) for full radiography so the code given this concession for circumferential joints (spot for circumferentials)
For more on this you may review following article
ASME Pressure Vessel Joint Efficiencies
Regards
and thanks again
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