Safety in Brazing

Brazing, Welding, and Soldering are hazardous activities that could pose serious health threats to all the workers of these industries. There is always the possibilities of harmful gases and fumes rising from the base metal coverings, cadmium containing filler metals, inks, and also from fluorides present in the fluxes. These dangerous by-products are formed in most of the industries in one form or another. They seriously affect the respiratory and nervous system of the people working in that environment. Apart from it they also affect the skin, eyes, hairs, and other body parts.

There are some well-tested precautions that should be followed to guard against the hazards from these fumes.

 

 

The brazing process produces a large number of hazardous fumes and gases, which are serious threats to human life. These dangerous fumes should be expelled from the working area. So the confined areas should be ventilated properly. You can use ventilating fans and exhaust hoods to expel all fumes and gases away from working area.

The base metals should be cleaned thoroughly before use. The unknown contaminants, of unknown composition, deposited on the surface of base metals can add to fume hazard. They may cause over heating of the flux leading to a rapid breakdown.

The metals should be heated broadly and uniformly. The localized and intense heating of base metals uses up flux and increases danger of fuming.

You should thoroughly know the metals you are going to braze. During heating the cadmium coated base metals tend to volatilize and produce toxic fumes. The galvanized or zinc coated metals also produce fumes when heated. You must learn to recognize these coatings and the hazards. They should be removed before parts are heated for brazing.

The amount of flux should be sufficient. The main use of flux is to protect the base metals and filler metal during the heating cycle. It helps in reducing the fuming.

Don't overheat the assembly when using filler metals or alloys that contain cadmium. You must follow the related material safety data sheet for maximum recommended brazing temperatures of a specific filler metal.

Pickling Solutions for Oxide Removal
The brazing process is hugely affected by the formation of oxides on the surface of metals. The layers of oxides create problems for efficient and strong bonding. The pickling solutions are used to remove oxides from the areas which were not protected by flux during the brazing process. A number of pickling solutions are available for this purpose.

 

Application	Formulation	Comments
Copper, Bronze, Nickel, Silver, Brass and other alloys containing high percentages of copper	10 to 25% hot H2SO4 (Sulphuric Acid) with 5 to 10% K2Cr2O7 (potassium di-chromate) added	Pickling is done after the removal of flux. It will work on carbon steels. If pickle is contaminated with copper, the copper will plate out on the steel, thus needs mechanical removal. This sulphuric pickle is an oxidizing pickle, which will remove copper or cuprous oxide stains from the copper alloys.
Irons and Steels	Hot or cold 50% hydrochloric acid (HCl) solution. Diluted acid (10 to 25%) can also be used at higher temperatures (140°F-160°F).	For Monel and other nickel alloys, a mixture of 1 part hydrochloric acid to 2 parts water can be used. The Pickling solution should be heated to 180°F (80°C). For bright finishing, mechanical finishing is essential.
Stainless steels and Chromium Alloys	20% H2SO4, 20% HCl, 60% water, used at a temperature of 170-180°F(75-80°C.)	This pickle is followed directly by a 10% nitric dip, and then a clean water rinse.

 

General Safety Methods

• Oil, grease, and other combustible materials shouldn't be placed near the gas cylinders. Other substances, such as reserve stocks of carbide and acetylene, other fuel gas cylinders should be kept away from the substance likely to cause or accelerate fire.
• Cylinders shall be stored in a well-ventilated, well-protected, dry location at a minimum distance of 20 feet from highly combustible materials such as oil or excelsior. They should be stored in definitely assigned places away from stairs, gangways, and elevators.
• The storage spaces shall be situated where cylinders will not be damaged by passing or falling objects. It should be saved from tampering by unauthorized persons.
• The empty fuel or gas cylinders shall have their valves closed.
• The workers or other persons nearby the brazing equipment shall be protected by noncombustible or flame-proof screens or shields. The screens mustn't not impede ventilation.
• Cables used shouldn't have damaged insulation or exposed bare conductors.

 

Brazing Safety Equipment
The brazing flames and fumes can emit vicious ultraviolet and infrared rays that might have serious consequences on your eyes. Brazing isn't like welding where you need to wear a big clumsy helmet. You can wear simple sunglasses only for UV protection.

Brazing Goggles During brazing and welding methods, harmful radiations and gases emit from the chemicals and alloys. They are dangerous for human eyes, so goggles are needed.

Heat Resistant Gloves Leather heat resistant gloves are needed to provide safety to your hands from the extensive hot surrounding and chemical compunds, such as fluxes, brazing pastes and powders.

Helmets: Helmets are important safety equipment. They cover your entire head and provide protection. They aren't so essential in the brazing processes but are advantageous to use. However they are must for the welding processes.