The National Inspection Testing and Certification Corporation (NITC) is an impartial provider of certification services to a wide range of businesses. NITC tests and certifies workers in Fire Protection & Safety Systems, HVACR Medical Gas, Pipefitting, Plumbing, and associated industries. The craft and process of Advanced HVAC Brazing is an area of focus for NITC’s certifications.
Soldering is the act of joining two metals by melting a third filler metal between them, without melting the two metals.
Brazing is like soldering, but the filler metal melts above 840 degrees Fahrenheit, so is much hotter than soldering. An oxygen-acetylene torch is most frequently used for brazing, as it gets hotter than the types of torches used for soldering. The higher temperature creates a stronger bond.
Welding is the amalgamation of two metals by melting them together. It involves even hotter temperatures than both soldering and brazing. Welded joints are the strongest of the three.
Why Brazed Joints Are Preferred in HVAC
While welds offer the strongest bond, they are not needed in the copper lines used in HVAC. A brazed joint is considered strong enough. The primary reason a brazed joint is often preferred in HVAC work is that it is virtually leak-proof.
Health & Safety Hazards
Health hazards from brazing operations involve exposure to metal fumes and ultraviolet (UV) radiation.
Safety hazards experienced from these operations are burns, eye damage, electrical shock, cuts, and crushed toes and fingers.
Health & Safety tips include:
- Ventilate confined areas
- Clean base metals thoroughly
- Heat metals broadly and uniformly
- Know your base metals, coatings, and filler metals, and consult the SDS for maximum brazing temperatures
While Brazing training can be taught in a classroom, hands-on practice and professional instruction are needed to become proficient. It must be taught not only by someone with extensive hands-on brazing experience over many years but must also be taught by someone who communicates very clearly, and very well. Training should include:
- Proper adjustment and metering of acetylene and oxygen.
- Personal Protective Equipment (PPE) is required (leather gloves, leather apron, gauntlets, safety glasses with side shields, welders’ helmets, or welders’ goggles).
- Proper Ventilation and Safety Procedures.
- Brazing filler metals. Each filler metal carries a warning label for maximum temperature; look for it and follow the instructions carefully.
- Braze-prep and cleaning methods.
- Fitting and designing supporting joints.
- Degree of heating, cleaning tubing, and necessary parts to be employed.
- Waiting for the flame to turn green.
- How to heat evenly by continuously moving the flame.
- Applying the brazing rod while avoiding melting it with the torch.
- Cooling the joints.
- Quality assurance/control systems, including inspection processes.
- How to avoid the most common mistakes made in brazing today that lead to poor brazements and rejected parts.
For more information about The National Inspection Testing and Certification Corporation (NITC) testing programs, and procedures visit https://nationalitc.com/.