Hot Work

Nearly all metals generate fume and a few of the risks are listed below.

1. Lung cancer is related to exposure to certain metals, especially nickel and chromium which are found in different grades of steel.
2. Metal fume fever from nearly all metals during cutting and welding, can cause vomiting, chills and headache. Effects may be delayed several hours and last 24 hours. Zinc fume from galvanized iron is most severe, though copper and tin fume are nearly as bad.
3. Fume poisoning - from such metals as lead, zinc and cadmium, can enter through the nose and mouth through smoking or eating with contaminated hands. Continuous exposure may lead to long term blood disorders, nerve damage and kidney disease.
4. Gases and fume fluoride emitted from coating on low hydrogen rods can damage the lungs and cause general poisoning.
5. Ozone, a highly toxic gas, produced from any arc-type welding, can cause long term respiratory problems. Ozone has a characteristic irritating pungent odour and can cause short term headaches and nausea.
6. Heated coatings and paints can release toxic substances such as cyanide, formaldehyde and isocyanates.
7. Fluxes may give off hazardous substances when heated. A Material Safety Data Sheet should be obtained from suppliers to determine hazards of each flux.

To reduce exposure to the various inhalation hazards associated with welding and cutting, adequate local and general ventilation is essential.

General ventilation

Welding areas should have good general ventilation (about 10 to 12 air changes per minute) that is not re-circulated back into the building.

Weld out of the plume. Use a tight fitting welding helmet to shield you from the plume.

A well-designed welding helmet can help reduce a welder's exposure to welding fumes by diverting the plume away from the welder's breathing zone.

Local exhaust ventilation

Local ventilation should be used in conjunction with adequate general ventilation to reduce the amount of welding contaminants entering the area.

Downdraft bench

A downdraft bench has an open grid work surface. Air is drawn downward through the grid, drawing contaminants into exhaust ducting. Air speed must be great enough to keep contaminants from rising into your breathing zone. If work pieces are too large they may block the ventilation airflow or cause pockets of high velocity air (which could affect shielding gases).

Moveable hood

Flexible ducting allows the capture hood to be moved where required. Provide an air velocity of at least 100 ft/min (0.5 m/s) across the welding arc. Place the hood as close as practical to the work. The optimal location for the hood is about 1 duct diameter from the arc.

All combustible material must kept more than 15 Meters from the welding or cutting process.

The following fire extinguishers must be available:

• Two 10 lb water fire extinguishers (type 2A)
• One 5 lb dry powder (type ABC)

• Equipmentmustmeet the requirements of the CSA Standards C22.2 No.60 or be acceptable to the regulatory authority.
• Evidence of equipment approval must be visible near the name plate of the equipment
• Open circuit voltages of arc welding and cutting machinesmust be specified as in CSA Standard C22.2 No. 60.
• Remote portable control devices carried by operatormust be connected to an AC circuit lower than 120 V.

• Welding machines must not be used above the current rating that corresponds to the rated duty cycles as specified by the manufacturer.
• Installation of equipment must be installed according with CSA Standards C22.1, or as specified by the regulatory authorities and the manufacturer’s instructions.
• Installation, maintenance, and repair of equipment must only be done by a qualified person.

The requirements of section 5.2 of the W117.2-94 Safety in Welding, Cutting, and Allied Processes Standards must be well understood by the operators. The following is a brief summary of them.

• 
  Never allow skin or wet clothing to touch any live metal parts. Always ensure that gloves are dry.
• Never stand on metal or operate in a damp area without protective insulation. Wear gloves and rubber soled shoes and stand on a dry board or platform.
• 
  Replace damaged cables. Never overload them.
• Turn off equipment when not operating.
• Never coil or loop cable around parts of the body.
• Connect the proper size work lead cable to the work piece as close to the work area as possible.
• Keep clothing, work-area, cables, electrode holder, and power supply dry.
• Never use water-cooled electrode holder, and guns if any water leak exists.
• Welding machinesmust always have the output electrically de-energized when electrodes are removed from gas tungsten arc and plasma welding or plasma cutting electrode holders.
• Take precautions to prevent shock-induced falls.
• Wearers of pacemakers or other electronic equipment vital to life must check with the life support manufacturer and their physicians to determine whether or not a hazard exists.
• Never carry matches or lighters near welding area.

Wear eye and face protection in welding workplace to protect against radiation and weld spatter. Appropriate eye and face protection shall be selected in accordance with CSA Standard Z94.3.

• Goggles or safety glasses with side shields shall be worn by all welding personnel at all times in the workplace, even when other eye and face protection is also worn.
• Do not wear contact lenses because foreign bodies in the eye may cause irritation.

• Wear woolen clothing as opposed to cotton which is easily ignited. All clothing should be free from oil or grease.
• Where ventilation alone does not protect the welder, appropriate respiratory protection must be worn as it is required by CSA Standard Z94.4

Eye protection

Shades for shielded metal arch welding (SMAW) CSA W117.2.94

Electrode size	Arc current in ampere	Shade number
3/23	Less than 60	7
3-5/32	60-160	10
5-8/32	160-250	12
8/32	250-550	14

Shades for oxygen cutting

Type of cutting	Material thickness in inches	Shade number
Light	Under 1	4
Medium	1-6	5
Heavy	Over 6	6

• Torch must be pointed away from persons or combustible material.
• Use a friction lighter, stationary pilot flame, or other suitable source of ignition for lighting it.

• Metal parts which have been degreased must be completely free of solvents.
• Degreasing and welding operationsmust be located in different rooms.
• Store chlorinated hydrocarbon solvents far from welding areas.
• Do not use chlorinated hydrocarbon solvents (e.g. perchloroethylene, trichloroethylene) for degreasing at welding stations.
• Other industrial operations (e.g. acid pickling, plating, painting)must be done in areas away of the welding operation area.

• Gas contentmustbe identified with either its chemical name or its trade name.
• Only the gas supplier or authorized person must fill a cylinder.

• Onlythe gas supplier must mix gases in a cylinder or transfer gases from one cylinder to another.
• Compressed gas cylindersmust be equipped with connections complying with the Compressed Gas Association Standard V-1.
• Cylinders with water weight capacity over 13 kg (30 lb)must be equipped with a means of connecting a valve protection cap or with a collar or recess to protect the valve.
• Temperature of the cylinder contentsmust not be allowed to exceed 55°C (note: hot gases expand and may increase pressure above allowable limits).
• Cylinders showing damage, corrosion, or fire exposure mustnot be used.
• Cylinders must only be used with a pressure-regulating device.

See the Compressed Gas Standard for more information.

• Personal operating or maintaining laser beam welding and cutting equipment musthave been properly instructed by a manufacturer's representative or by a qualified instructors.
• A laser safety officer (LSO) mustbe appointed at each facility using lasers for welding or cutting heat sources. The LSO is responsible for ensuring that all operators are properly trained and fully aware of the safe operation and hazards in respect to operation of a laser welding or cutting system.
• Appropriate eye protection mustbe worn to protect against reflections of laser radiation.
• Caution: Laser welding and cutting process produce visible and /or invisible radiation. Reflections of the laser beam itself pose an additional potential hazard. The two areas of greatest concern are eye damage and skin damage.

• Personal assigned to operate or maintain plasma arc welding and cutting, and gouging equipment must have been properly trained by a manufacturer’s representative or by a qualified instructor.
• Do not operate equipment where gas leaks are suspected.
• Be aware that plasma arc cutting and gouging equipment presents a greater hazard than typical welding equipment because of the higher voltages and high frequency ignites.
• Make
  
  certain that primary power supply or power to the control circuitry is disconnected before replacing torch parts.
• Hearing protection must be worn where the noise level exceeds limits as specified by the regulatory authority.
• Eye and skin protection mustbe worn when exposure to radiation is
  
  unavoidable.
• Radiation exposure may also be reduced by mechanical barriers such as walls or welding curtains.