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Brazing safety guidelines

Health and Safety

Health and Safety guidelines in brazing

When brazing, operators work with temperatures of the filler metal that are higher than of its melting point. This can cause fume release, thus often exposing the operator to fumes and other harmful health risks. During brazing, all products involved in the process, should not be excessively over heated. Overheating is a sign that the brazing technique is not being done correctly since it can cause poor joint characteristics and over production of fumes. The fumes caused by metals or metal oxides can cause irritations and harmful health risks. Possible harmful health risks can occur from the following situations:

Torch brazing technique is the one that can cause the most fume release when compared to other brazing systems such as furnace or automated ones. In order to guarantee safety conditions for the workers involved in brazing, the following safety standards and security guidelines should be strictly observed and followed.

Fumes released from metals and oxides

The following factors can affect the quantity of fumes released during brazing processes:

  • The vapor pressure caused by the elements present in the alloy at a certain temperature;
  • The range melting interval of the alloy;
  • The alloy composition;
  • The surface area of the melted metal exposed to air;
  • The time during which the brazing alloys is kept in its melted stage;

The vapor pressure and the alloy composition are fixed parameters while the temperature, time and surface area can vary. The operator needs to make appropriate evaluation of these parameters in order to avoid fumes.

Copper and Zinc oxides

Usually these fumes do not cause any harm for the health, however if an excessive amount is inhaled they can cause major irritations and can lead to a disease called “metal fume feve” which can result in flu like symptoms such as fever, nausea, headaches etc.. Zinc oxides can cause nose, mouth and throat irritations.

Diphosphorus Pentoxide

tif alloys containing phosphorus are over heated they can generate diphopshorus pentoxide (P2O5). This compound can react with the humidity releasing phosphoric acid (H3PO4), that can cause even at low concentration severe irritations of the mucous membranes, respiratory tract, eyes and skin.

Fluxes

Fluxes are usually made up as a mixture of fluorides, fluoroborates, borates, fluorosilicates and potassium chlorides with the addition of boric acid and borax. They can cause mild skin irritations if prolonged contact occurs. Higher attention is needed when skin presents damages such as cuts or abrasions since immediate skin irritation can occur. It is highly recommended the usage of resistant gloves (e.g. rubber, latex etc) in order to prevent skin contact when handling fluxes both in liquid or powder form. Fluxes are dangerous if ingested, hence it is highly recommended washing hands carefully after handling such products. It is prohibited to smoke when working with fluxes.
During the heating process fluxes can generate hydrogen fluoride, fluoride and boron trifluoride gases. In case of non adequate ventilation or incorrect brazing procedures these fumes can cause irritations to the nose and eyes. The operator should avoid direct contact with the working area.
Be sure to read carefully and understand the safety data sheets in order to avoid dangerous situations when using fluxes; in case of ingestion, irritation or inhalation seek medical aid immediately.

Fumes released from brazing equipment

The following well-tested precautions should be followed to guard against any hazard from these fumes:

  • brazing workstations should be built using non-flammable and adequate refractory materials;
  • hot brazed materials should be handled with appropriate tongs, pliers or heat resistant gloves.

Torch brazing is the technique that releases most fumes when compared to other brazing processes. This is due to the fact that in torch brazing gas combustion such oxy-acetylene or compressed air/natural gas mixtures occurs. Attention should be paid to the correct ventilation/exhaustion systems used during brazing and as well to handling materials in high temperatures.

Personal safety precautions in the workplace

The following basic safety precautions on the job should be observed in order to guarantee workers safety when using brazing alloys:

  • Wear appropriate clothing and gloves (individual protection devices IDP)
  • Wear safety goggles or face masks at all time (for better protection dark ones are recommended)
  • Avoid direct exposure of the face with the working area
  • Use at all time an adequate aspiration system to guarantee good ventilation
  • Ventilate confined areas. Use adequate ventilating fans and exhaust hoods to carry all fumes and gases away from work, and air supplied respirators as required.