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RF pad to RF padSpacing requirement as per API 650

RF pad to RF padSpacing requirement as per API 650

RF pad to RF padSpacing requirement as per API 650

For an API 650 tank, with dimension 12(D)m x 20(H)m. Bottom shell course of A36 with 10mm thickness.

Tank is provided with anchor chair and also RF pad considered for this anchor chair. and there are two nozzle N1 & N3 (let say inlet as N1 and Outlet as N2).

My concern is that the clearance between the nozzle RF pad and anchor chair RF pad is only 75 mm. When i check in API 650, as per clause 5.8.1 the requirement is mentioned for shell material for group IV and higher. and i haven't find any clause for weld clearance for shell material I, II, III and IV.

Kindly advise with clause i have to follow for weld clearance.

RE: RF pad to RF padSpacing requirement as per API 650 requirements are applicable only to materials in Groups IV, IVA, V or VI and are NOT required to meet for I, II, III and IIIA. See below interpretation (it will provide the intent that requirements are only for the material groups IV or higher), old reference of clause was in 10th Edition of API-650.

Please see the below interpretation No. 650-I-53/00

Question: Referring to API 650, is magnetic particle testing applicable for inspecting permanent attachments to the shell and at temporary attachment removal areas, when the material group is of Group I (A 283, Grade C)?

Reply: No. See and

Javed Nasir
Inspection Engineer
Technip-France Abu Dhabi

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