46 C.F.R. Subpart 56.75—Brazing
Title 46 - Shipping
(a) The filler metal used in brazing must be a nonferrous metal or alloy having a melting point above 1,000°F. and below that of the metal being joined. The filler metal must meet and flow freely within the desired temperature range and, in conjunction with a suitable flux or controlled atmosphere, must wet and adhere to the surfaces to be joined. Prior to using a particular brazing material in a piping system, the requirements of §56.60–20 of this part should be considered. (b) The brazing material used shall have a shearing strength of at least 10,000 pounds per square inch. The maximum allowable working pressure for brazing piping shall be determined by this part. (c) (Reproduces 128.1.2.) Fluxes that are fluid and chemically active at the brazing temperature shall be used when necessary to prevent oxidation of the filler metal and the surfaces to be joined and to promote free flowing of the filler metal. [CGFR 68–82, 33 FR 18843, Dec. 18, 1968, as amended by CGD 77–140, 54 FR 40615, Oct. 2, 1989] (a) The clearance between surfaces to be joined shall be no larger than is necessary to insure complete capillary distribution of the filler metal; between 0.002–inch minimum and 0.006-inch maximum. (b) [Reserved] (a) The joint shall be brought to brazing temperature in as short a time as possible to minimize oxidation. (b) [Reserved] (a) The qualification of the performance of brazers and brazing operators, shall be in accordance with the requirements of part C, section IX of the ASME Code and part 57 of this subchapter. (b) Manufacturers shall perform those tests required by paragraph (a) of this section prior to performing production brazing. (a) Pipe may be fabricated by brazing when the temperature to which such connections may be subjected does not exceed 425 °F. (For exception refer to §56.30–30(b)(1).) (b) (Reproduces 128.2.1.) The surfaces to be brazed shall be clean and free from grease, oxides, paint, scale, and dirt of any kind. Any suitable chemical or mechanical cleaning method may be used to provide a clean wettable surface for brazing. (c) After the parts to be joined have been thoroughly cleaned the edges to be brazed shall be given an even coating of flux prior to heating the joint as a protection against oxidation. (a) Silver brazing. (1) Circumferential pipe joints may be either of the socket or butt type. When butt joints are employed the edges to be joined shall be cut or machined square and the edges shall be held closely together to insure a satisfactory joint. (b) Copper-alloy brazing. (1) Copper-alloy brazing may be employed to join pipe, valves, and fittings. Circumferential joints may be either of the butt or socket type. Where butt joints are employed, the included angle shall be not less than 90° where the wall thickness is three-sixteenths of an inch or greater. The annular clearance of socket joints shall be held to small clearances which experience indicates is satisfactory for the brazing alloy to be employed, method of heating, and material to be joined. The annular clearance shall be shown on drawings submitted for approval of socket joints. (2) Copper pipe fabricated with longitudinal joints for pressures not exceeding that permitted by the regulations in this subchapter may have butt, lapped, or scarfed joints. If of the latter type, the kerf of the material shall be not less than 60°. (c) Brazing, general. (1) Heat shall be applied evenly and uniformly to all parts of the joint in order to prevent local overheating. (2) The members to be joined shall be held firmly in place until the brazing alloy has set so as to prevent any strain on the joint until the brazing alloy has thoroughly solidified. The brazing shall be done by placing the flux and brazing material on one side of the joint and applying heat until the brazing material flows entirely through the lap and shows uniformly along the seam on the other side of the joint. Sufficient flux shall be used to cause the brazing material to appear promptly after reaching the brazing temperature.
Title 46: Shipping
PART 56—PIPING SYSTEMS AND APPURTENANCES
Subpart 56.75—Brazing
§ 56.75-5 Filler metal.
§ 56.75-10 Joint clearance (reproduces 128.2.2).
§ 56.75-15 Heating (reproduces 128.2.3).
§ 56.75-20 Brazing qualification.
§ 56.75-25 Detail requirements.
§ 56.75-30 Pipe joining details.
