46 CFR 56.25-20 - Bolting.
(1) Bolts, studs, nuts, and washers must comply with applicable standards and specifications listed in 46 CFR 56.60-1. Unless otherwise specified, bolting must be in accordance with ASME B16.5 (incorporated by reference; see 46 CFR 56.01-2).
(2) Bolts and studs must extend completely through the nuts.
(3) See § 58.30-15(c) of this chapter for exceptions on bolting used in fluid power and control systems.
(b) Carbon steel bolts or bolt studs may be used if expected normal operating pressure does not exceed 300 pounds per square inch gauge and the expected normal operating temperature does not exceed 400 °F. Carbon steel bolts must have heavy hexagon heads in accordance with ASME B18.2.1 (incorporated by reference, see 46 CFR 56.01-2) and must have heavy semifinished hexagonal nuts in accordance with ASME/ANSI B18.2.2 (incorporated by reference, see 46 CFR 56.01-2), unless the bolts are tightly fitted to the holes and flange stress calculations taking the bolt bending stresses into account are submitted. When class 250 cast iron flanges are used or when class 125 cast iron flanges are used with ring gaskets, the bolting material must be carbon steel conforming to ASTM A 307 (incorporated by reference, see 46 CFR 56.01-2), Grade B.
(c) Alloy steel stud bolts must be threaded full length or, if desired, may have reduced shanks of a diameter not less than that at the root of the threads. They must have heavy semifinished hexagonal nuts in accordance with ANSI B18.2.2.
(d) All alloy bolts or studs and accompanying nuts are to be threaded in accordance with ANSI/ASME B1.1 (incorporated by reference; see 46 CFR 56.01-2), Class 2A external threads, and Class 2B internal threads (8-thread series 8UN for one inch and larger).
(e) (Reproduces 108.5.1) Washers, when used under nuts, shall be of forged or rolled material with steel washers being used under steel nuts and bronze washers under bronze nuts.