(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.