N.Y. Comp. Codes R. & Regs. tit. 12, § 14-9.1 – Tube ends of fire-tube boilers.

(a) Figure 14-9.1 illustrates some of the acceptable types of tube attachments. Such connections shall be:
1. (1) expanded and beaded as in sketches (a), (b), and (d);
2. (2) expanded and beaded and seal welded as in sketch (c);
3. (3) expanded and seal welded as in sketch (e);
4. (4) welded, as in sketches (f) and (g).
  Tube ends attached by expanding and welding are subject to the following provisions:
  Where no bevel or recess is employed, the tube shall extend beyond the tubesheet not less than a distance equal to the tube thickness or ⅛ inch, whichever is the greater, nor more than twice the tube thickness of ¼ inch, whichever is the lesser (see sketch [e]).
(b) The tubesheet hole may be beveled or recessed, the depth of any bevel or recess shall not be less than the tube thickness or ⅛ inch, whichever is greater, nor more than one-third of the tubesheet thickness, except that when tube thicknesses are equal to or greater than 0.150 inch, the bevel or recess may exceed T/3. Where the hole is beveled or recessed, the projection of the tube beyond the tubesheet shall not exceed a distance equal to the tube wall thickness, see Figure 14-9.1, sketches (f) and (g).
(c) On types of welded attachment shown in sketches (c) and (e), the tubes shall be expanded before and after welding. On types shown in sketches (f) and (g), the tubes may be expanded.
(d) Expanding of tubes by the Prosser method may be employed in combination with any beaded or seal welded attachment method (see sketch [b]).
(e) After seal welding as shown by sketches (c) and (e), a single hydrostatic test of the boiler shall suffice.
(f) The inner surface of the tube hole in any form of attachment may be grooved or chamfered.
(g) The sharp edges of tube holes shall be taken off on both sides of the plate with a file or other tool.