John,

My opinion is: Although nowhere explicitely shown in WRC 107 ,a perforation in the wall, I think the intent of WRC 107 is to calculate the stresses at nozzle openings only.The WRC 107 document calculates stresses in shell only and the thickness of the nozzle comes to play ( at least to a great extent)stresses in the nozzle only. So although the attachment parameter in WRC 107 does not mention nozzle thickness for cylindrical attachments, it really does not play an important role in the shell stress calculation.

So WRC 107 basically addresses a real life nozzle connection ( and not a rigid plug connection on an unperforated shell) and hence the trunnion attachment cannot be analyzed with WRC 107.

This is as per my view on WRC 107 and based on numerous discussions I had with COADE in this aspect.

Looking forward to your view and view of other forum members.

Best regards