AWS C3.6-MC3.6:2016 pdf download.Specification for Furnace Brazing
1.1 Scope. This specification presents the minimum fabrication and quality requirements for the furnace brazing of materials such as steels, stainless steels, nickel, nickel alloys, copper, copper alloys, and heat- or corrosion-resistant materials as well as other materials that can be adequately furnace brazed. Note that the furnace brazing of aluminum alloys is addressed in AWS C3.7M/C3.7, Specification for Aluminum Brazing.
The purpose of this specification is to standardize furnace brazing process requirements and brazed joint quality requirements for all applications requiring brazed joints of assured quality. This document establishes minimum require-ments for processes and products with a minimum of explanatory information so that sources of ambiguity are mini-mized. It assigns responsibility for the ultimate quality of the brazed product to a single organization and permits that organization to modify requirements if appropriate to the application. It requires proper documentation of any such modifications.
5.2.6 Furnace Qualification. In equipment for which SAE AMS 2750 is not used in its entirety, the provisions of 5.2.6 shall apply. AIll furmaces shall be qualfied for temperature uniformity and control prior to initial use for production brazing. Furmaces used for brazing above 1093°C [2000°F] shall be requalified at least every three months. Furmaces used only for brazing below 1093°C [2000°F] shall be requalified every six months.
All furnaces shall be requalified after any repairs or alterations to the furnace that might affect furnace temperature con-trol or uniformity (e.g.. new heating elements, new control thermocouple(s), burner tubes, replacement of shielding for burner tubes). Requalification is not required when the repair or alteration has previously been documented not to affect the temperature control or uniformity of the furnace.
5.2.6.1 Furnace Qualification Procedure. Temperature uniformity tests may be conducted empty or with a furnace load representative of production parts, material, racks, and using a typical production atmosphere or vacuum level. The test shall be conducted using new or recalibrated thermocouples. The potentiometric measuring equipment or equivalent shall meet the requirements of 5.2.2.
Instruments used to control the furnace during production brazing shall not be used to monitor the qualification thermo-couples. A minimum of three thermocouples shall be used to determine the temperature uniformity of furnaces having a work zone volume of 0.085 m3 (cubic meters) [3 ft3 (cubic feet)] or less. A minimum of five thermocouples shall be used to determine the uniformity of furnaces having a work zone between 0.085 m3 to 0.28 m3 [3 ft3 to 10 ft]. A minimum of nine thermocouples or one thermocouple per 0.71 m3 [25 ft] of working zone, whichever is greater, shall be used to determine the uniformity of furnaces having a work zone larger than 0.28 m3 [10 ft]. No more than 40 thermocouples shall be required to determine the temperature uniformity in the work zone of any furnace.AWS C3.6-MC3.6 pdf download.