NDT for Annular plates for API 650 storage tanks

[mechazm]

Dear Experts,
Case 1) As per API 650 2013ed. para. 8.1.2.9 "When bottom annular plates are required by 5.5.1, or by M.4.1, the radial joints shall be radiographed". If annular plates were required as per Seismic calculation instead of 5.5.1 or M.4.1, Radiographic examination is still Mandatory?

Case 2) As per para. 7.3.2.1 and Annex T (NDE requirements summary), Shell plate butt welds if approved by Purchaser could be subjected to Ultrasonic testing in lieu of Radiographic examination as per requirements of Annex U. Do this requirement (UT instead of RT) applicable to Annular plate Radial joints?
Regards,

 

[Samm17]

API 650 does not require RT on the annular plate butt welds if the annular plate is used for reasons other than 5.5.1 or M4.1.

See attached for an old 650 interpretation that alludes to this. If the annular is there to satisfy 5.5.1 or M4.1 then RT is required. If the annular is there for another reason then RT is not required.

 

[valleytank]

1. It is acceptable to perform shearwave UT on annular ring radial joints. Very common on existing annular ring repairs. Remember this is very operator dependent so get someone who knows what they are seeing or you'll be hurting.

2. In regards to the RT requirements as Samm17 mentioned it wouldn't be required. Usually the client will ask you to perform either 10% or 50% RT/MT depending on the joint style per 650 regardless unless they're the ones not wanting to do the RT.