(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 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 should be considered.

(b) The brazing material used must have a shearing strength of at least 10,000 psig. The maximum allowable working pressure for brazing piping must be determined by this part.

(c) Fluxes that are fluid and chemically active at the brazing temperature must be used when necessary to prevent oxidation of the filler metal and of the surfaces to be joined and to promote free flowing of the filler metal.

The clearance between surfaces to be joined must be no larger than is necessary to allow complete capillary distribution of the brazing alloy or solder.

(a) The joint must 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 must be in accordance with the requirements of Part C, Section IX of the ASME Code (incorporated by reference; see § 56.01-2) 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) The surfaces to be brazed must be clean and free from grease, oxides, paint, scale, and dirt of any kind.

(c) After the parts to be joined have been thoroughly cleaned the edges to be brazed must 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 must be cut or machined square and the edges must 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 must be not less than 90° where the wall thickness is three-sixteenths of an inch or greater. The annular clearance of socket joints must be held to small clearances.

(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 must be not less than 60°.

(c) Brazing, general. (1) Heat must be applied evenly and uniformly to all parts of the joint in order to prevent local overheating.

(2) The members to be joined must 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 must 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 must be used to cause the brazing material to appear promptly after reaching the brazing temperature.