The selection and limitation of piping joints must be as required by this subpart rather than as required by 110 through 118 of ASME B31.1 (incorporated by reference; see § 56.01-2); however, certain requirements are marked “reproduced” in this subpart.

The type of piping joint used must be suitable for the design conditions and must be selected with consideration of joint tightness, mechanical strength and the nature of the fluid handled.

(a) General. Welded joints may be used for materials for which welding procedures, welders, and welding machine operators have been qualified in accordance with part 57 of this subchapter.

(b) Butt welds—general. Butt welds may be made with or without backing or insert rings within the limitations established in § 56.70-15. When the use of backing rings will result in undesirable conditions such as severe stress concentrations, corrosion or erosion, then:

(1) The backing rings must be removed and the inside of the joint ground smooth, or

(2) The joint must be welded without backing rings, or

(3) Consumable insert rings must be used. Commonly used types of butt-welding end preparations are shown in ASME B16.25 (incorporated by reference; see § 56.01-2).

(4) Restrictions as to the use of backing rings appear for the low temperature piping systems and should be checked when designing for these systems.

(c) Socket welds. (Modifies 127.3.3A.)

(1) Each socket weld must conform to ASME B16.11 (incorporated by reference; see § 56.01-2), to applicable standards listed in table 2 to § 56.60-1, and to Figure 127.4.4C in ASME B31.1 (incorporated by reference; see § 56.01-2) as modified by § 56.30-10(b)(4).

(2) Restrictions on the use of socket welds appear in § 56.70-15(d)(3) for Class I service and in § 56.50-105 for low temperature service. See § 56.70-15(d)(4) for Class II service.

(d) Fillet welds. The size of a fillet weld is determined as shown in Figure 127.4.4A of ASME B31.1. Fillet-weld details for socket-welding components must meet § 56.30-5(c). Fillet-weld details for flanges must meet § 56.30-10 (see also § 56.70-15(d)(3) and (4) for applications of fillet welds).

(e) Seal welds. Seal welds may be used but must not be considered as contributing any strength to the joint.

(a) Flanged or butt-welded joints are required for Classes I and I-L piping for nominal diameters exceeding 2 inches, except as otherwise specified in this subchapter.

(b) Flanges may be attached by any method shown in figure 1 to § 56.30-10(b) or by any means approved by the Marine Safety Center. Pressure temperature ratings of the appropriate ASME standard must not be exceeded.

(1) Figure 1 to § 56.30-10(b), Method 1. Flanges with screw threads may be used in accordance with table 1 to § 56.30-20(c).

(2) Figure 1 to § 56.30-10(b), Method 2. ASME B16.5 (incorporated by reference; see § 56.01-2) Class 150 and Class 300 low-hubbed flanges with screw threads, plus the addition of a strength fillet weld of the size as shown, may be used in Class I systems not exceeding 750 °F or 4 NPS, in Class II systems, and in Class II-L systems not exceeding 1 NPS. If 100 percent radiography is required by § 56.95-10 threaded flanges are not permitted and buttwelding flanges must be provided.

(3) Figure 1 to § 56.30-10(b), Method 3. Slip-on flanges meeting ASME B16.5 may be used in piping systems of Class I, Class II, or Class II-L not to exceed the service pressure-temperature ratings, and not to exceed 4-inch Nominal Pipe Size (NPS) in systems of Class I and Class II-L. If 100 percent radiography is required by § 56.95-10, slip-on flanges are not permitted and butt-welding flanges are required. Restrictions on the use of slip-on flanges appear in § 56.50-105 for low-temperature piping systems.

(4) Figure 1 to § 56.30-10(b), Method 4. ASME B16.5 socket welding flanges may be used in Class I or II-L systems not exceeding 3 NPS for class 600 and lower class flanges and 2 1/2 NPS for class 900 and class 1500 flanges within the service pressure-temperature ratings of the standard. Whenever full radiography is required by § 56.95-10 socket welding flanges are not permitted, and a butt weld type connection must be provided. For Class II piping, socket-welding flanges may be used without diameter limitation. Restrictions on socket welds appear in § 56.50-105 for low temperature piping systems.

(5) Figure 1 to § 56.30-10(b), Method 5. Flanges fabricated from steel plate meeting the requirements of part 54 of this subchapter may be used for Class II piping for pressures not exceeding 150 psig and temperatures not exceeding 450 °F. Plate material listed in UCS-6(b) of Section VIII of the ASME BPVC (incorporated by reference; see § 56.01-2) may not be used in this application, except that material meeting ASTM A36/A36M (incorporated by reference; see § 56.01-2) may be used. The fabricated flanges must conform at least to the ASME B16.5 class 150-flange dimensions.

(6) Figure 1 to § 56.30-10 (b), Method 6. Steel plate flanges meeting the material and construction requirements listed in paragraph (b)(5) of this section may be used for Class II piping for pressures not exceeding 150 psig or temperatures not exceeding 650 °F. The flange must be attached to the pipe as shown by figure 1 to § 56.30-10(b), Method 6.

(7) Figure 1 to § 56.30-10 (b), Method 7. Lap joint flanges (Van Stone) may be used for Class I and Class II piping. The ends of the pipe must be heated from 1,650 to 1,900 °F based on the size of the pipe. Extra thickness of metal built up in the end of the pipe must be machined to restore the pipe to its original diameter. The width of the lap flange must be at least three times the thickness of the pipe wall and the end of the pipe must be properly stress relieved after the flanging operation is completed. Manufacturers desiring to produce this type of joint must demonstrate to a marine inspector that they have the proper equipment and personnel to produce an acceptable joint.

(8) Figure 1 to § 56.30-10(b), Method 8. Welding neck flanges may be used on any piping provided the flanges are butt-welded to the pipe. The joint must be welded as indicated by Figure 1 to § 56.30-10(b), Method 8, and a backing ring employed which will permit complete penetration of the weld metal. If a backing ring is not used, refer to § 56.30-5(b) for requirements.

(9) Figure 1 to § 56.30-10(b), Method 9. Welding neck flanges may also be attached to pipe by a double-welded butt joint as shown by Figure 1 to § 56.30-10(b), Method 9.

(10) Figure 1 to § 56.30-10 (b), Method 10. Flanges may be attached by shrinking the flange on to the end of the pipe and flaring the end of the pipe to an angle of not less than 20°. A fillet weld of the size shown by figure 1 to § 56.30-10(b), Method 10, must be used to attach the hub to the pipe. This flange is limited to a pressure of 300 psig and a temperature not exceeding of 500 °F.

(11) Figure 1 to § 56.30-10(b), Method 11. The flange of the type described and illustrated by figure 1 to § 56.30-10(b), Method 10, except with the fillet weld omitted, may be used for Class II piping not exceeding 150 psig and temperatures not exceeding 450 °F.

(12) Figure 1 to § 56.30-10(b), Method 12. High-hub bronze flanges may be used for temperatures not exceeding 425 °F. A preinserted ring of silver brazing alloy having a melting point not less than 1,000 °F must be inserted into the groove. A suitable flux must be applied to the surfaces to be joined to produce a satisfactory joint.

(13) Figure 1 to § 56.30-10(b), Method 13. The type of flange as described for Figure 1 to § 56.30-10(b), Method 12, may be employed and in lieu of an annular groove being machined in the hub of the flange for the preinserted ring of silver brazing alloy, a bevel may be machined on the end of the hub and the silver brazing alloy introduced from the end of the hub to attach the pipe to the flange.

(14) Figure 1 to § 56.30-10(b), Method 14. Flanges may be attached to nonferrous pipe by inserting the pipe in the flange and flanging the end of the pipe into the recess machined in the face of the flange to receive it. The pipe must be securely brazed to the wall of the flange.

(15) Figure 1 to § 56.30-10(b), Method 15. The flange of the type described and illustrated by Figure 1 to § 56.30-10(b), Method 14, except with the brazing omitted, may be used for Class II piping and where the temperature does not exceed 250 °F.

(a) Expanded or rolled joints may be used where experience or test has demonstrated that the joint is suitable for the design conditions and where adequate provisions are made to prevent separation of the joint. Specific application for use must be made to the Commandant.

(b) [Reserved]

(a) Threaded joints may be used within the limitations specified in subpart 56.15 of this chapter and within other limitations specified in this section.

(b) (Modifies 114.1.) All threads on piping components must be taper pipe threads in accordance with the applicable standard listed in table 2 to § 56.60-1. 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 1 to § 56.30-20(c).

(d) No pipe with a wall thickness less than that of standard weight of ASME B36.10M (incorporated by reference; see § 56.01-2) steel pipe may be threaded. For restrictions on the use of pipe in steam service more than 250 psig or water service over 100 psig and 200 °F (93.3 °C), see part 104.1.2(c)(1) of ASME B31.1 (incorporated by reference; see § 56.01-2).

(a) This section applies to pipe fittings that are mechanically connected to pipe by such means as ferrules, flared ends, swaging, elastic strain preload, crimping, bite-type devices, and shape memory alloys. Fittings to which this section applies must be designed, constructed, tested, and marked in accordance with ASTM F1387 (incorporated by reference, see § 56.01-2). Previously approved fittings may be retained to the satisfaction of the Officer in Charge, Marine Inspection.

(b) Flared, flareless and compression fittings may be used within the service limitations of size, pressure, temperature, and vibration recommended by the manufacturer and as specified in this section.

(c) Flared, flareless, and compression type tubing fittings may be used for tube sizes not exceeding 50 millimeters (2 inches) outside diameter within the limitations of applicable standards and specifications listed in this section and § 56.60-1.

(d) Flareless fittings must be of a design in which the gripping member or sleeve must grip or bite into the outer surface of the tube with sufficient strength to hold the tube against pressure, but without appreciably distorting the inside tube diameter. The gripping member must also form a pressure seal against the fitting body.

(e) For fluid services, other than hydraulic systems, using a combustible fluid as defined in § 30.10-15 of this chapter and for fluid services using a flammable fluid as defined in § 30.10-22 of this chapter, flared fittings must be used; except that flareless fittings of the nonbite type may be used when the tubing system is of steel, nickel copper or copper nickel alloy. When using copper or copper zinc alloy, flared fittings are required. (See also § 56.50-70 for gasoline fuel systems, § 56.50-75 for diesel fuel systems, and § 58.25-20 of this subchapter for hydraulic systems for steering gear.)

Caulked joints may not be used.

(a) General (refer also to subpart 56.75). The minimum socket depth must be sufficient for the intended service. Brazing alloy must either be end-fed into the socket or must be provided in the form of a preinserted ring in a groove in the socket. The brazing alloy must be sufficient to fill completely the annular clearance between the socket and the pipe or tube.

(b) Limitations. (1) Brazed socket-type joints must not be used on systems containing flammable or combustible fluids in areas where fire hazards are involved or where the service temperature exceeds 425 °F. Higher temperature service must be approved by the Commandant.

(2) Brazed joints depending solely upon a fillet, rather than primarily upon brazing material between the pipe and socket are not acceptable.

(a) This section applied to pipe fittings that form a seal by compressing a resilient gasket onto the pipe joint primarily by threaded fasteners and where joint creep is only restricted by such means as machined grooves, centering pins, or welded clips. Fittings to which this section applies must be designed, constructed, tested, and marked in accordance with ASTM F1476 and ASTM F1548 (both incorporated by reference, see § 56.01-2). Previously approved fittings may be retained to the satisfaction of the Officer in Charge, Marine Inspection.

(b) Gasketed mechanical couplings may be used within the service limitations of pressure, temperature and vibration recommended by the manufacturer, except that gasketed mechanical couplings must not be used in—

(1) Any location where leakage, undetected flooding, or impingement of liquid on vital equipment may occur; or

(2) In tanks where the liquid conveyed in the piping system is not chemically compatible with the liquid in the tank.

(c) Gasketed mechanical couplings must not be used as expansion joints. Positive restraints must be included, where necessary, to prevent the coupling from creeping on the pipe and uncovering the joint. Bite-type devices are generally not accepted for this purpose. Machined grooves, centering pins, and welded clips are considered positive means of protection against creep.

(a) Flexible pipe couplings of the compression or slip-on type must not be used as expansion joints. To ensure that the maximum axial displacement (approximately 3/8″ maximum) of each coupling is not exceeded, positive restraints must be included in each installation.

(b) Positive means must also be provided to prevent the coupling from “creeping” on the pipe and uncovering the joint. Bite type devices are not generally accepted for this purpose. Machined grooves or centering pins are considered positive means.

(c) The installation must be such as to preclude appreciable difference in the vibration magnitudes of the pipes joined by the couplings. The couplings must not be used as a vibration damper. The vibration magnitude and frequency should not exceed that recommended by the coupling manufacturer.

(d) Flexible couplings made in accordance with the applicable standards listed in table 2 to § 56.60-1 and of materials complying with subpart 56.60 may be used within the material, size, pressure, and temperature limitations of those standards and within any further limitations specified in this subchapter. Flexible couplings fabricated by welding must also comply with part 57 of this subchapter.

(e) Flexible couplings must not be used in cargo holds or in any other space where leakage, undetected flooding, or impingement of liquid on vital equipment may occur, or in tanks where the liquid conveyed in the piping system is not compatible with the liquid in the tank.

(f) Damaged or deteriorated gaskets must not be reinstalled.

(g) Each coupling must be tested in accordance with § 56.97-5.