Thomas Industrial Library

Trouble Shooting Brazing & Soldering Processes

Problem: No flow or no wetting.

Causes:

• Wrong braze filler

• Temperature too low

• Time at temperature too short

• Parts not properly cleaned

• Parts fit poorly

• Heat source in wrong location

Problem: Excess flow or wetting causing hole plugging or brazing wrong joints.

Causes:

• Temperature too high

• Time at temperature too long

• Too much filler material

• No stopoff used

Problem: Erosion—Braze filler material eats away parent metal.

Causes:

• Temperature too high

• Time at temperature too long

• Excessive braze filler metal

• Cold worked parts

Safety

What special chemical hazards do brazing and soldering present and what precautions must be taken?

Base metals and filler metals may contain toxic materials such as: antimony, arsenic, barium, beryllium, cadmium, chromium, cobalt, mercury, nickel, selenium, silver, vanadium, or zinc. These will be vaporized during brazing or soldering and cause skin, eye, breathing, or serious nervous system problems. Some of these toxic materials are cumulative such as lead and may be absorbed through the skin. The following precautions are essential:

• Keep you head out of the brazing or soldering plume.

• Perform brazing or soldering in a well ventilated area.

• On failure of normal ventilating equipment, use respiratory equipment.

Many brazing and soldering fluxes and heating bath salts contain fluorides. Others contain acids and aluminum salts. The following precautions apply:

• Avoid direct contact with skin.

• Do not eat or keep food near these materials.

• Do not smoke around these materials.

• Insure MSDSs are affixed to containers of these materials and major equipment using them so they are visible to you and others.

What is an excellent source of information about these hazards in addition to the MSDSs?

See the AWS booklet Z49.1-94, Safety in Welding and Cutting.

What eye protection is needed for brazing and soldering?

• For soldering wear safety glasses or face shields to protect the eyes from external injuries caused by sparks, flying metal, or solder splashes.

• For brazing using a number 5 tinted lenses will protect against internal (retinal) eye damage caused by viewing the radiation coming off hot metal. Some brazing requires darker lens shades of up to number 8.

What other safety precautions must be taken while soldering or welding?

• Skin protection from sparks and hot metal prevented by gloves and non-flammable clothing.

• Fires from the welding process can be prevented by moving flammables away from the weld zone and having water or fire extinguishers close at hand.

Use adequate ventilation when using cleaning solvents to prepare the joints; chlorinated hydrocarbons are toxic and may create phosgene gas when heated.

• Always wear chemical-type eye goggles or face shields, rubber gloves, and long sleeves while using cleaning solutions, pickling solutions, or acids. Note that chemical-type goggles do not have ventilation holes above the eyes where splashes could enter.