56.30-20—Threaded joints.
(a)
Threaded joints may be used within the limitations specified in subpart of this chapter and within other limitations specified in this section.
(b)
(Reproduces 114.1.) All threads on piping components must be taper pipe threads in accordance with the applicable standard listed in 46 CFR 56.60-1, Table 56.60-1(b). Threads other than taper pipe threads may be used for piping components where tightness of the joint depends on a seal weld or a seating surface other than the threads, and where experience or test has demonstrated that such threads are suitable.
(c)
Threaded joints may not be used where severe erosion, crevice corrosion, shock, or vibration is expected to occur; or at temperatures over 925 °F. Size limitations are given in Table 56.30-20(c) of this section.
| Maximum nominal size, inches | Maximum pressure, p.s.i.g. |
|---|---|
| Above 2″ | (Not permitted in Class I piping service.) |
| Above 1″ up to 2″ | 600. |
| Above 3/4″ up to 1″ | 1,200. |
| 3/4″ and below | 1,500. |
| 1 Further restrictions on the use of threaded joints appear in the low temperature piping section. | |
| 2 Threaded joints in hydraulic systems are permitted above the pressures indicated for the nominal sizes shown when commercially available components such as pumps, valves and strainers may only be obtained with threaded connections. | |
(d)
No pipe with a wall thickness less than that of standard weight of ASME B36.10M (incorporated by reference; see 46 CFR 56.01-2) steel pipe may be threaded regardless of service. For restrictions on the use of pipe in steam service more than 250 pounds per square inch or water service over 100 pounds per square inch and 200 °F (938C), see part 104.1.2(c)(1) of ASME B31.1 (incorporated by reference; see 46 CFR 56.01-2 ). Restrictions on the use of threaded joints apply for low-temperature piping and must be checked when designing for these systems.
[CGFR 68-82, 33 FR 18843, Dec. 18, 1968, as amended by CGFR 69-127, 35 FR 9978, June 17, 1970; CGD 73-254, 40 FR 40164, Sept. 2, 1975; CGD 77-140, 54 FR 40606, Oct. 2, 1989; USCG-2003-16630, 73 FR 65178, Oct. 31, 2008]