Sec. 14-9.3. Required openings

(a) All boilers or parts thereof must be provided with suitable manhole, handhole, or other inspection openings for examination or cleaning, except special types of boilers where such openings are manifestly not needed or used. Specific requirements for access openings in certain types of boilers appear in the ASME Code.

(b) An elliptical manhole opening shall be not less than 11 by 15 inches, or 10 by 16 inches in size. A circular manhole opening shall be not less than 15 inches in diameter. A manhole opening in a boiler drum or shell shall be not less than 15 inches in diameter. A handhole opening in a boiler drum or shell shall be not less than two and three-fourths by three and one-half inches, but it is recommended that, where possible, larger sizes be used.

(c) Manhole, handhole, inspection, and washout openings in a shell or unstayed head shall be designed in accordance with the ASME Code.

(d) When a threaded opening is to be used for inspection or washout purposes, it shall be not less than one-inch pipe size. The closing plug or cap shall be of nonferrous material (except for pressures over 250 pounds). The thread shall be a standard tapered pipe thread, except that a straight thread of equal strength may be used to prevent leakage.