N.Y. Comp. Codes R. & Regs. Tit. 12 §§ 14-11.5
Every miniature boiler shall be fitted with not less than three brass washout plugs of one-inch iron-pipe size, which shall be screwed into openings in the shell near the bottom. In miniature boilers of the closed-system type heated by removable internal electric heating elements, the openings for these elements when suitable for cleaning purposes may be substituted for washout openings. Boilers not exceeding 12 inches internal diameter and having less than 10 square feet of heating surface, need have not more than two one-inch openings for cleanouts, one of which may be used for the attachment of the blowoff valve; these openings shall be opposite to each other where possible. All threaded openings in the boiler shall be provided with a riveted or welded reinforcement, if necessary, to give four full threads therein.
N.Y. Comp. Codes R. & Regs. Tit. 12 §§ 14-11.5