The material, construction and workmanship of compensating rings and doors shall comply with the appropriate Regulations of Chapters II, III and XII.

Connections to shell shall be made by means of branches, pressed plate saddles, forged pads or bosses. Alternatively, where the thickness of the shell is sufficient to allow a suitable surface to be obtained, connections may be attached directly to the shell, provided that the minimum thickness at the hole in the shell is not less than the thickness required for the design pressure and temperature, considering the shell as being unpierced and that the diameter of the hole does not exceed the maximum diameter of an uncompensated hole as defined in Regulation 170 and 279. Studs for securing such connections shall have a full thread holding in the shell for a length of at least one diameter and the stud holes shall not penetrate the whole thickness of the shell. All holes for bolts, studs and rivets in branches, saddles and forged pads shall be drilled. Where such connections are secured by welding alone, a minimum of two runs of metal shall be deposited at each weld, except for seal welds. Each run of weld metal shall be thoroughly cleaned and free from slag before the next run is deposited. The final finish of the welds shall be such that change of section from shell to branch is gradual and free from sharp notches. Where the diameter of the shell is 24 inches and over, welding shall be from both sides of the plate. Where the internal diameter of the shell is less than 24 inches, external and the internal welds shall be applied unless it is considered that efficient welding from both sides is impracticable. This does not apply to the methods of attachment shown in Figures 365/6 and 367/7 in which the welding shall always be from both sides.