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The material for the occupational safety training course in electric and gas welding equips workers with safety knowledge and prevention of hazards when performing electric and gas welding tasks, ensuring fire prevention and safety.

Table of Contents

I. BASIC CONCEPTS IN THE SAFETY DOCUMENT FOR ELECTRIC AND GAS WELDING

Welding Shielded Metal Arc Welding (SMAW/MMA): is a common welding method with a consumable electrode coated in flux. During welding, the outer coating melts, creating a gas and a protective layer over the weld bead. This method is often used for steel and stainless steel structures. Aluminum, nickel, and copper alloys can also be welded using this method. The diameter and length of the welding rods vary and are typically made of aluminum bronze, brass, steel, nickel, and stainless steel.
Flux-Cored Arc Welding (FCAW): this method is more widely used, the welding process is fast, and there is no need to change electrodes.
- FCAW uses a tubular wire reel with a core containing a mixture of flux, deoxidizers, denitrifiers, and alloying elements, which increase adhesion, strength, wear resistance, and stabilize the arc.
- The welding core typically consists of aluminum, calcium, carbon, chromium, iron, manganese, and other elements.
- To protect the weld, a shielding gas or gas mixture can be supplied; this method is often used for welding stainless steel.
Gas Metal Arc Welding: (MIG and MAG). This method is suitable for welding metal sheets. This form of welding creates a molten weld pool, and the weld is protected from oxidation by a gas such as argon or CO₂.
Tungsten Inert Gas (TIG) welding: the welding electrode is non-consumable, and the shielding gas is usually argon.
Plasma welding and cutting: similar to TIG welding, it uses a tungsten electrode and an inert gas that is forced through a nozzle. The arc is constricted by the plasma stream, thus concentrating the energy.

II. SAFETY IN ELECTRIC WELDING WORK

1. FORMATION OF WELDING FUMES AND TOXICITY

Welding fume particles are mainly formed from the vaporization of the metal and the welding consumables when they melt. As these vapors cool, they condense and react with oxygen in the atmosphere to form fine particles. About 90% of the fumes are generated from the consumable material.

The fumes generated also differ among welding processes: in MMA and FCAW welding, a higher proportion of fumes comes from the burning of the flux coating and the electrode rather than from the base metal. In gas welding, the concentration of fumes generated is higher from the base metal.

These particles range in size from 0.01 – 1 micron. These particles are highly toxic to workers. The smaller the particles, the more dangerous they are. Other gases produced during welding are also dangerous if the workshop is not safely ventilated.

The substances generated include:

Ø Beryllium Ø Cadmium Oxides Ø Chromium
Ø Copper Ø Fluorides Ø Iron Oxide
Ø Lead Ø Manganese Ø Molybdenum
Ø Nickel Ø Vanadium Ø Zinc Oxides
Ø Carbon Monoxide Ø Hydrogen Fluoride
Ø Nitrogen Oxide Ø Ozone

Particle size affects worker health:

Welding fume particles range from less than 0.01 to over 1 micron at the source and 1-2 microns in the worker’s breathing zone. The size of these particles affects the respiratory system. Particles larger than 5 microns will be deposited in the upper respiratory tract, while particles from 0.1-5 microns will enter the lungs and deposit there.
Diseases that workers may contract from prolonged exposure to welding fumes include: Bronchitis, pneumonia, asthma, lung cancer, eye diseases, skin diseases…

The danger from welding fumes.

Welding fume particles are small enough to enter and deposit in the lungs. Over time, these particles can affect the bloodstream. Welding fumes from MMA and FCAW often contain very large amounts of Chromium (VI) and manganese, nickel, and some other elements. Stainless steel contains a chromium content of about 10.5%.
The concentration limits for Cr(VI), manganese, and nickel in the US are set low by OSHA.

2. HAZARDS DURING WELDING IN THE SAFETY DOCUMENT FOR ELECTRIC AND GAS WELDING

Before starting any welding work (outside of work conducted in an approved workshop), an assessment must be made to ensure there are no hazards in the welding area, as well as adjacent areas (above, below, beside).
In confined spaces, it is not permitted to use a step-down transformer from 220V to 24V (e.g., for portable lighting, grinders, or handheld drills).
Special attention must be paid to high-risk jobs, among others, which can increase the risk of workplace accidents, cause permanent health damage, and pose fire or explosion hazards.
High-risk welding work, among others, includes working in damp, wet, or hot environments where humidity or sweat significantly reduces the electrical resistance of the human skin.
High-risk welding work, among others, includes working in enclosed and confined spaces.
A fire watch must be present when welding with a high risk of fire or explosion.
Ensure good ventilation in enclosed and tight spaces when performing welding work to minimize the concentration of contaminants and to ventilate the welding area.
The fire watch’s duty when welding in a confined space is to monitor and maintain a safe area, continuously observe the welder’s activities, and be ready to respond to incidents when there is a risk of fire or explosion.
When welding with a high risk of poisoning or suffocation, there must be at least one welder and one other fire watch personnel.
When welding containers that have been used to store unknown substances, the welder must perform the work as if welding a container with hazardous substances.
To prevent fires in the welding area and surrounding areas, flammable and explosive materials must be removed or covered with non-combustible materials, and the worksite must be ventilated to ensure a safe level is maintained.
The welding location and adjacent areas, after finishing high-risk welding work, must be inspected after the final cooling period, and welding can only resume after at least 8 hours.

When welding with a high risk of suffocation or poisoning that cannot be ensured by necessary safety measures, the welder must be supplied with clean air from outside.
The welding location and adjacent area, i.e., the area above, below, and beside the welding area, must be checked for flammable and combustible materials before starting work; if any are found, they must be removed.
Before starting work at the location, the welder must inspect all holes and ducts in all walls, ceilings, and floors leading to adjacent areas, including energy conduits, unsealed ends of welded pipes, and the possibility of heat transfer through the welded structure via walls, floors, or ceilings.

3. HAZARDS DURING ELECTRIC WELDING IN THE SAFETY DOCUMENT FOR ELECTRIC AND GAS WELDING

Welders working with a high risk of electric shock, especially in confined spaces and adjacent areas, must not wear clothing with metal objects in contact with the human body and must have an insulated floor.
In areas with a high risk of electric shock, if technical measures cannot place the welding machine outside this area, electric welding may be permitted, but additional safety measures must be ensured in writing.
When welding in an enclosed container, insulating and heat-resistant pads must be used to prevent contact between the welder’s body parts and the metal.
It is strictly forbidden to weld with alternating current (AC) in an enclosed container.
When welding with a high risk of fire or explosion, turning the welding machine or welding circuit on and off must be done by another worker (the fire watch) who is not present in the welding area, according to regulations for the welder before determining the work position and being ready to weld.
Before a welder enters a confined or narrow space, a thorough inspection of the insulation of the welding cables and connections within that space must be conducted.

4. WORKING WITH HIGH-RISK SAFETY

High-risk jobs are performed based on a written production order from an authorized person and can only be carried out after additional safety measures have been included.
Welding in high-fire-risk locations is performed after a production order from an authorized person in which additional safety measures have been included.
High-risk welding work is started after implementing additional safety measures according to a written production order issued by an authorized person.
The authorized person is responsible for issuing the written production order for high-risk welding work.
The authorized person is responsible for issuing additional safety measures for high-risk welding work.
The safety measures in the production order are developed by professionals in the relevant fields (safety technician, fire prevention technician, electrical technician, or electrician).
An essential part of a written production order for high-risk welding work is the limitation of working time and the assignment of safety supervision personnel.
Permission to start welding and the control of additional safety measures when welding with high risk is carried out by the authorized person.

5. ELECTRIC WELDING MACHINE IN THE SAFETY DOCUMENT FOR ELECTRIC AND GAS WELDING

Welders must disconnect the power cord from the power source in all cases when moving the electric welding machine.
Welding machines should only be cleaned during periodic inspections, as specified by the machine manufacturer.
Welders working in open areas must protect the welding machine against atmospheric effects, mainly rain.
The storage location for the welding machine when not in use must be dry and have low dust.
Welding equipment stored for six consecutive months must be inspected by an electrical maintenance technician before being put back into use.
Before using the welding machine, the welder must also check that the welding cables are connected as close to the welding position as possible.
Electric welding machines used or stored in dusty or humid environments must be inspected once a month.
Disconnecting the electric welding equipment when moving is done by turning off the main switch.
Welders may only use the welding machine as specified by the manufacturer for the intended use, in accordance with officially approved safety regulations, and maintained according to regulations.
When work is temporarily interrupted, the welder must turn off the power to the welding machine or take measures to prevent unauthorized use.
If a welder notices that a welding machine poses a threat to the health or life of workers, the equipment must be taken out of service and measures taken to secure it against use.
Maintenance of the welding machine is performed by a professional technician under permissible conditions according to the maintenance, operation, and repair instructions.
Repair of the welding machine is performed by a professional technician under permissible conditions according to the maintenance, operation, and repair instructions.
Cleaning of the welding machine is performed by the technician according to the maintenance, operation, and repair instructions, usually during periodic inspections.
During work at the welding position, the welder must turn off the machine when connecting welding cables to the terminals.
Welders must take precautions against the welding machine being turned on by strangers when handling the machine’s terminals.
When welding in corresponding locations using multiple electric welding machines, each machine must have a separate source, and the controls, connecting cables, and welding leads must be clearly distinguished.
When welding with direct current on a workpiece using multiple machines, the welding equipment must have the same polarity with respect to the workpiece.
Multiple welding power sources with different current ratings are not allowed to be connected to one workpiece so that a hazardous total voltage greater than the no-load voltage of the source with the highest potential does not occur between two machines.
When simultaneously connecting a DC welding machine and an AC welding machine to one electrode holder, welding can be done separately by using only one power source and the other sources are turned off or disconnected from the holder.
Welders must ensure the welding machine is turned off or disconnected from the power source when leaving the workstation.
Electric welding equipment should only be connected to a designated outlet or by an authorized operator.
Welders are obliged to regularly check that the electrical circuit is not connected to the welding leads before plugging into an electrical outlet.
Welders are obliged to regularly check that the electric welding machine is turned off before plugging into an electrical outlet.
Welders are obliged to regularly check the tightness of the terminal wire ends before plugging into an electrical outlet.
Welders are obliged to regularly check that the electrical circuit is not directly connected to the welding machine casing before plugging into an electrical outlet.
Welders must check the insulation of the electrode holder before use.
An overheated electrode holder should never be cooled by immersing it in water.
At the welding station, welders may only change the electrode in the holder while wearing dry and undamaged welding gloves.
Welders must place the electrode holder on an insulating plate or on an insulated stand.

6. CONDUCTORS IN THE SAFETY DOCUMENT FOR ELECTRIC AND GAS WELDING

The size of the welding current, by which we can load a rubber-insulated conductor, depends on the cross-section of the conductor, the permissible load by the welding current, and the ambient temperature.
The maximum operating temperature of a rubber-insulated welding cable is 60°C.
Welders are not allowed to wrap the welding cable around their body while welding.
Welders must inspect the welding cable daily before starting work.
If, upon inspecting the welding cable, the welder finds visible damage to the cable insulation, the damaged cable must not be used and must be given to a professional for repair.
When connecting the work equipment to the workpiece, only a welding cable specified for the corresponding welding current may be used.
The contact surfaces of the welding cable and the terminals must be conductive.
The connection of conductors to the welding machine terminals must be made to prevent accidental contact with the machine’s terminals.
The terminal for connecting to the welding cables must be securely fastened as close to the welding point as possible.
When welding with a high risk of electric shock, welders can only change the electrode after turning off the power or using gloves.
Welders are responsible for regularly checking the safety of the insulation of conductors and welding cables before plugging into an outlet.
Welders are responsible for regularly checking the safety of the outlet, plug, and welding machine before plugging into an outlet.
The welding cable must have intact insulation, and its cross-section must be suitable for the size of the welding current and the length of the cable.
Welding cables in use must be stored to prevent damage from bending, other objects, transport vehicles, and the effects of the welding process.
If it is necessary to use a welding cable longer than its length limit, a cable with a larger cross-section must be used.
Repairing visible damage to the welding cable, identified by the welder during the daily inspection before starting work, is the responsibility of a qualified professional (expert).
If there are metal objects within the welder’s and their machine’s range, the electrical conduction must be connected to the workpiece or the possibility of conductive contact must be avoided.
The welding current conductor to the workpiece must be attached as close as possible to the welding point or to a metal welding table.
When connecting the workpiece to the protective terminal of the electrical network, the protective wire must have a cross-section similar to or larger than the welding cable.
The condition for connecting the welding cable to the welding machine is that the welding current source must be turned off during connection.
The condition for connecting the welding cable to the workpiece is that the welding current source must be turned off during connection.
Connecting the welding cable to the welding machine’s terminals must be done to prevent accidental or unintentional contact by strangers with the machine’s terminals.

7. UNSAFE CURRENT

The maximum permissible no-load voltage for a direct current (DC) electric welding machine is 113V.
The risk of electric shock from the no-load voltage (up to 113V) for a DC welding machine used in normal areas can be a cause of electric shock.
The maximum permissible no-load voltage for an alternating current (AC) electric welding machine is 80V.
The risk of electric shock from the no-load voltage (up to 80V) for an AC welding machine used in normal areas can be a cause of electric shock.
The safe direct current value is 25mA.
The safe alternating current value is 10mA.
Areas considered normal for electric shock risk are those with a normal, cool environment or with insignificant humidity.
Areas considered hazardous for electric shock risk are outdoor environments, with a relative humidity greater than 15%, hot with moderate vibration, or with conductive dust.
Areas considered hazardous for electric shock risk are those with a conductive surrounding environment, hot environments, or with conductive dust.
Areas considered hazardous for electric shock risk are those with an environment of conductive dust, moderate vibration with a relative humidity greater than 15%.
Areas considered hazardous for electric shock risk are those with a damp environment and enclosed metal compartments.

8. ELECTRIC WELDING POSITION IN THE SAFETY DOCUMENT FOR ELECTRIC AND GAS WELDING

For welding positions, we need to consider restricted areas for long-term or temporary welding.
For a welder performing continuous manual welding, a minimum work area volume of 15m³ must be ensured.
For a welder performing continuous manual welding, a minimum floor work area of 2m² must be ensured.
The minimum height of the cabin wall is 2m, made of non-combustible or flame-retardant material.
There must be a gap of 0.15-0.20m between the cabin wall and the floor to bring air into the cabin.
The work floor of the welding position must be made of non-combustible material.
At locations where workers perform continuous welding of heavy or light metals or their alloys (e.g., lead, mercury, cadmium, beryllium, manganese, zinc, chromium, and their compounds…), it must be ensured that the workplace has ventilation equipment to aerate.
Work positions for electric welding are placed in cabins equipped with means to protect the welder and the surrounding area from hazards that may arise during welding.
The walls and ceiling at the welding position must be adjusted in shape and color as much as possible to reduce the reflection of radiation.
Natural ventilation is only permitted at locations for regular, variable, and short-term welding, if the work area volume per welder is more than 100m³ and there are no toxic gases.
At the workplace, before starting to weld, the welder must check that there are no flammable substances at the welding position.
At the workplace and surrounding area, before starting to weld, the welder must wear full personal protective equipment.
The welder is responsible for installing screens to prevent radiation.
Radiation-preventing screens must be made of non-combustible or flame-retardant material.

Compressed gas cylinders at the electric welding work site must not have welding cables wrapped around them.
At an electric welding site where multiple welding machines are used, in case of an incident, the power to the machine causing the incident must be quickly disconnected.
Flammable, explosive materials, and substances harmful to health should not be kept near the electric welding area.

9. PROTECTING THE WELDER FROM HAZARDS

Accidents from molten metal spatter and welding slag are prevented by personal protective equipment specified for the defined welding method.
Protection against the harmful effects of radiation to the area surrounding the workplace is achieved by using shields, screens, curtains…
Protection against contaminants during welding is achieved by installing a ventilation system so that pollutants do not pass through the welder’s breathing zone.
In areas with a high risk of poisoning or suffocation, in addition to the implemented safety precautions, the welder must also wear a safety harness with one end of the line brought outside.
Welders are obligated to use personal protective equipment for electric welding as regulated and not to wear dirty clothes stained with oil, grease, or other flammable materials.
The employer is obligated to provide personal protective equipment for electric welders as regulated and require welders to use them, while also checking the use of this personal protective equipment.

When there is an accumulation of toxic gases in confined and restricted spaces, ventilation equipment must be used and clean air supplied or air conditioning provided for the welder’s breathing zone.
At welding positions in confined and restricted spaces with a risk of poisoning and suffocation, it is not permitted to bring in oxygen.
A basic protective component for welders during electric welding is the use of clear safety glasses when chipping slag.
When welding at heights, measures must be taken to prevent the welder from falling, even in the event of an electric shock.

The protective welding filter on the helmet is selected according to the welding method and the welding current intensity.

Protection against electric shock during electric welding is achieved by eliminating the possibility of the welder’s contact with the live parts of the welding machine and the welding cables connected to it.

10. FIRST AID FOR ELECTRIC SHOCK FROM WELDING

A mild electric shock without serious consequences: immediate treatment by medical personnel.
It is necessary to ascertain the first aid knowledge of everyone at the electric welding work site.
Sequence: separate the victim from the power source, perform artificial respiration, cardiac massage (until medical personnel arrive), while immediately notifying medical personnel, report the accident.
Alternative to artificial respiration: mouth-to-mouth resuscitation.
If the patient is not breathing after being separated from the power source – immediately perform artificial respiration; if no pulse is detected, simultaneously perform cardiac massage.

11. PRINCIPLES FOR USING A MANUAL ARC WELDING MACHINE

To use a welding machine safely, note the following principles:

Preventing electric shock when operating the welding machine.
- Absolutely do not touch the live components of the machine directly as it is very easy to get an electric shock or burn.
- Be sure to insulate yourself from the workpiece and the ground with sufficiently large insulating materials.
- Before removing or installing machine accessories, turn off the power.
- Regularly check the safety of the power cable; if the cable is worn, undersized, or scratched, it must be replaced with a new one.
- Turn off all equipment when not in use.
- Always wear occupational safety protective gear to prevent risks.
- Be careful when welding in a damp environment or having to work in difficult positions such as kneeling, lying down…
- When buying a welding machine, pay attention to its anti-shock capability.

Preventing welding burns
- Many novice welders have to “give up” due to issues like eye pain or skin burns from the effects of the welding arc. Almost every welder encounters this problem, even professionals with many years in the trade if they are not careful with protection.
- Therefore, when operating a welding machine, wear a mask or welding goggles to prevent the welding arc from damaging the eyes. For protective clothing, choose types made of thick, flame-retardant material.
- In case of a mild eye injury, you should apply ice to reduce swelling and then apply 1-2 drops of 1% cyclopentolate.
Avoid inhaling welding fumes and gas
- Welding produces fumes and gas vapor. Welding fumes are harmful to health when inhaled over a long period. Therefore, when operating a welding machine, you should sit or position yourself to avoid directly inhaling the fumes. Wear a mask to both prevent eye burns and avoid inhaling welding fumes.
Fire and explosion safety when using a welding machine.
- It is easy to see that during welding, slag often splatters around. This poses a very high safety risk when welding is performed in an environment with flammable or explosive materials nearby. Therefore, before welding, it is necessary to survey and assess the safety level of the surrounding welding environment. Move flammable or explosive objects and equipment out of the welding area. If they cannot be moved, cover them with fire-resistant materials.

12. OCCUPATIONAL SAFETY AND HEALTH FOR ELECTRIC WELDERS

Only individuals who meet the following conditions are allowed to perform electric welding work:
- Within the working age prescribed by the state.
- Have passed a health examination by a medical authority.
- Have been trained in the electric welding trade and have an accompanying certificate, have undergone OSH training, have been issued a safety card, and have been assigned tasks by a superior.
- Use the correct and sufficient personal protective equipment provided according to regulations: canvas clothing, heat-resistant gloves with low conductivity, high-top leather boots with insulated soles, canvas leggings, a welding helmet with the correct code and uncracked welding lens; in necessary cases, also provided with a hard hat, safety harness, and respirator.
During electric welding, the metal parts of the electric welding equipment (casing of the welding transformer, welding generator, etc.) must not be live under normal conditions. The welding machine casing, welding jigs, and the parts and structures to be welded must be grounded before the equipment is connected to the power source.
Welding generators and transformers, as well as tools and accessories for welding parts outdoors, should be placed in a small room or under a shelter. It is forbidden to carry out electric welding outdoors in the rain.
- The no-load voltage of a manual and semi-automatic arc welding transformer must not exceed 75 volts; for automatic welding, it must not exceed 80 volts. The voltage of a welding generator must not exceed 80 volts. If several welding transformers or generators serve one arc welding machine, their electrical connection diagram must ensure that the welding circuit voltage does not exceed the above limits.
The length of the cable from the power source to the mobile welding equipment must not exceed 10m. The insulation of the cable must be protected from mechanical damage when laid on the ground. It is forbidden to use a cable with damaged insulation or covering.
- Before starting electric welding and during work, one must monitor the integrity of the conductor’s insulation, the insulation and heat resistance of the electrode holder’s handle, and the secure connection of all contacts. Care must be taken to prevent the conductor from coming into contact with water, oil, or steel cables. Welding cables must be placed at least 1 meter away from oxygen and acetylene hoses, open flames, gas, hot welded parts, and hot water pipes.
It is not allowed to supply power directly to the welding arc from the power grid, lighting network, or contact network.
- Connecting and disconnecting electric welding equipment from the grid, changing fuses, as well as monitoring their perfect condition during use, must be carried out by a professional electrician. Welders are strictly forbidden from performing these tasks.
- When moving welding equipment, it is essential to disconnect them from the power source.
Both the outgoing and return electrical conductors in a mobile welding transformer must be insulated.
- It is strictly forbidden to use grounding circuits, parts of electrical equipment, sanitary engineering pipes (water, heating, hot gas and liquid pipes), as well as metal structures of buildings and technological equipment as return conductors. It is permissible to use the hulls of barges, tanks, metal structures, and pipes as return conductors if they are the object being welded.
The electrode holder must have a handle made of insulating, heat-resistant material that allows for quick electrode replacement without touching live parts.
- It is strictly forbidden to use an electrode holder with a damaged handle insulation.
- There must be a stand for the electrode holder next to the welding spot: It is forbidden to place the electrode holder on the ground or rest it on the workpiece.
When welding in high-risk electrical conditions (inside ship compartments, containers, boiler bodies, metal boxes, etc.), the welder must be provided with insulating protective gear (gloves, boots, and mats) and must be supervised by a second person from the outside. (In some special cases, the supervisor’s hand holds the end of a rope tied to the waist of the person welding inside the confined space, and communication between the two is agreed upon by pre-arranged rope pulls in an emergency).
- It is strictly forbidden for an electric welder and a gas welder (or cutter) to work simultaneously in enclosed containers.
The welding equipment must have an interlock to automatically connect the circuit upon electrode contact and a device to limit the no-load voltage to 12 volts, not slower than 1 second after breaking the welding circuit when welding in hazardous places.
When performing electric welding on wooden scaffolding, its floor must be covered with a metal sheet, asbestos cardboard, or other flame-retardant materials. Electric welding is not permitted if fire prevention measures have not been implemented.
When performing electric welding on several floors of a building (vertically), measures must be taken to protect people working on the lower floors from being hit by drops of metal, partially burned electrode pieces falling or splashing onto them or flammable objects below.
- If working at height without scaffolding, the welder must use a heat-resistant safety harness, with a bag for tools, electrodes, and spent stubs.
When performing electric welding in damp locations, the welder must be on a dry platform or a platform covered with an insulating mat.
To prevent illness and respiratory damage from frequent inhalation of welding fumes, local and general ventilation (exhaust, supply) must be organized at the welding station. When welding in enclosed containers, one must:
- Provide the welder with a respirator with a flexible air hose.
- Organize breaks to go outside and breathe fresh air.
It is strictly forbidden to weld tanks and equipment that have previously contained explosive oil and gas products without first being thoroughly cleaned (sprayed/washed) with hot water, a soda solution, or steamed with subsequent ventilation.
It is strictly forbidden to use and store flammable substances: gasoline, acetone, white spirit, etc.) near the welding location.
- It is strictly forbidden to perform welding within 5m of where flammable and explosive substances are stored.
When using multiple single-station welding power sources simultaneously, they must be placed at least 0.35m apart.
- The walkway between single-station power sources must have a width of 0.8m.
- When placing single-station sources near a wall, the distance between the source and the wall must not be less than 0.5m.
During breaks, the welder must disconnect the welding converter or transformer from the power grid.
- It is strictly forbidden to leave the electrode holder unattended while it is still energized.
At the end of the work, after disconnecting power from the welding equipment, the workspace must be tidied up, cables and protective gear collected and carefully stored in their designated places. It must be certain that no smoldering objects such as rags, wood chips, or insulating materials are left behind after work.

III. SAFETY IN WELDING AND CUTTING

1. Introduction

Compressed gas can be in a physical state, contained in tanks and supplied to factories for production purposes or stored in compressed gas cylinders.

Oxygen cylinder with pressure regulator
Acetylene cylinder with pressure regulator
Pre-adjustment device
Oxygen gas hose (air)
Acetylene gas hose
Welding torch
Welding rod
Filler rod
Welded part
Welding/cutting flame

This document will help us focus on the safety aspects of handling, storing, and using various types of compressed gas cylinders in the field of welding and cutting.

The most obvious and primary danger of a compressed gas cylinder is that the gas inside is under pressure, with some cylinders having pressures as high as 2,200 pounds per square inch. A damaged cylinder or a faulty valve can cause a sudden gas leak, making the cylinder roll and become like a rocket projectile with enough force to penetrate a brick wall.
Another danger is the type of gas contained within the cylinder. There are hundreds of types of gases and mixtures used in compressed gas cylinders. Gases like acetylene, propane, butane, and hydrogen are highly flammable and potentially explosive. Oxygen itself is not flammable, but in the presence of a fire, it will make the fire burn more intensely. Gases like ammonia and chlorine are very toxic; even a small leak can require everyone to evacuate the workplace. Gases like argon, nitrogen, and helium are inert, but they are still dangerous because they displace air, causing people to suffocate due to a lack of air to breathe.

This document includes the following contents:

Properly storing compressed gas cylinders
Safely moving compressed gas cylinders
Handling cylinders during welding and cutting (gas welding)
Storing Acetylene gas

2. How to properly store compressed gas cylinders?

Observe and determine if this is right or wrong.

What is the sign above the compressed gas cylinders like? Is there enough information?
Are the compressed gas cylinders stored properly?
Are the compressed gas cylinders placed upright or lying down?
What will happen if the compressed gas cylinders collide with each other?
What should be done to prevent the compressed gas cylinders from tipping over?
Are the compressed gas cylinders clearly labeled and painted with appropriate color codes?
Should different compressed gas cylinders be stored close to each other or must they be placed far apart?

Arrow 1: The sign “Compressed Gas Cylinder Storage Area” tells us which compressed gases are stored in this area, but it does not indicate the potential hazards that workers need to know. More information should be added to indicate the possible existing hazards. For example, add warning signs like “Danger! Compressed Gas, No Smoking…”
Arrow 2: Placing an oxygen cylinder next to other compressed gas cylinders is unsafe; the minimum distance between oxygen cylinders and flammable gas cylinders (like acetylene) should be 20 feet (6 meters). Oxygen does not ignite on its own, but it provides oxygen to make other substances burn faster (especially oils, greases…) and creates ignition sources when combined with other compounds like gasoline to form a flammable/explosive mixture.
Arrow 3: The cylinders can tip over at any time. Injury or death is possible when a compressed gas cylinder falls and hits another object and breaks. At that moment, the compressed gas cylinder acts like a rocket as gas rushes out. Compressed gas cylinders, whether full or empty (used up), must be secured with chains to prevent them from tipping over.
Arrow 4: The valve cap on the cylinder is missing. The valve cap is a safety device that prevents the valve from being damaged if it tips over. The valve cap must always be on except when in use.
Arrow 5: Note that the compressed gas cylinders in the “Empty” area do not necessarily mean they are empty. Empty cylinders must be marked with the word “Empty” or “MT” on the cylinder body.

Correct design of cylinder placement area:

The signs above the cylinder placement have been revised to indicate the potential hazards in the area to warn workers not to smoke or use open flames in the storage area.
The oxygen cylinders have been removed from the area and placed 20 feet away.
A chain system is in place to prevent the cylinders from tipping over.
All compressed gas cylinders have their valve caps on.
The gas cylinders in the “Empty” row are clearly marked with a sign.

What did we learn?

Post hazard warning signs.
Keep oxygen cylinders at least 20 feet (~6 meters) away from other compressed gas cylinders.
Prevent compressed gas cylinders from tipping over.
Always keep valve caps on and label empty cylinders.

3. Moving compressed gas cylinders in the safety document for electric and gas welding

Observe and determine if this is right or wrong.

Is this hand truck the correct type for transporting compressed gas cylinders?
Besides using a hand truck, is there another safe way to move compressed gas cylinders?
What should be done to prevent the compressed gas cylinder from falling off the hand truck?
What will happen if the compressed gas cylinder falls off the hand truck? What can be used to protect the valve?
The worker’s hands are greasy, and he is holding the valve assembly. What hazard will occur?

Arrow 1: This hand truck should not be used to transport compressed gas cylinders. When handling or transporting, ensure the cylinder does not tip over and get damaged. This hand truck has a flat backrest suitable only for moving square boxes, crates, or flat objects.
Arrow 2: Note that the cylinder should not be secured with tape to prevent tipping. The hand truck should be designed with a chain and hook to secure the cylinder to the cart during movement.
Arrow 3: The valve cap is not on. The valve assembly is a part of the compressed gas cylinder that is very easily damaged if the cylinder tips over. Protect the valve by always keeping the valve cap on, especially when handling or moving the cylinder.
Arrow 4: Since the cart has nothing to secure the cylinder, this worker has to hold the cylinder by hand. Note that the worker’s hands are greasy; never touch the valve assembly with greasy hands. Of course, the cylinder is very likely to slip out of his hands, and a greater danger is the reaction of the gas in the cylinder with the grease (oxygen), which has the potential to cause a fire or explosion.

Correctly moving a compressed gas cylinder:

The worker is transporting the compressed gas cylinder using a specially designed hand truck for cylinders.
A chain is in front to secure the cylinder, preventing it from tipping over during movement.
This worker also put the valve cap on before transporting the cylinder.
The worker’s hands are not greasy when working with compressed gas cylinders.

What did we learn?

Use a specially designed hand truck for compressed gas cylinders.
Protect the valve with its cap.
Keep hands, gloves, and gas cylinders free of oil and grease.

4. Handling gas cylinders during welding and cutting (gas welding)

Observe and determine if this is right or wrong.

Is the worker performing gas welding/cutting wearing appropriate PPE for the job?
What kind of gloves are they wearing?
What kind of eye protection are they wearing?
Is it safe to smoke around an area with compressed gas cylinders?
If the cylinder valve is stuck, is it safe to use a wrench to open it?
Are the cylinders secured against tipping over?
Is it safe to remove the valve cap?
Are the compressed gas cylinders clearly labeled?
What information should be on the label?
A forklift is passing through the area with the compressed gas cylinders. This could be a main traffic route in the work area. Is this a safe area to place compressed gas cylinders?

Arrow 1: Smoking around an area with compressed gas cylinders is very dangerous, especially with flammable gas. It is very difficult to detect leaks from the cylinder or valve; a gas leak is a dangerous ignition source when you smoke nearby.
Arrow 2: Only open the valve by hand or use another gas cylinder (if it cannot be opened by hand). A wrench can put pressure on the valve assembly and break the valve. Set aside the cylinder that cannot be opened and return it to the gas supplier for them to repair.
Arrow 3: The cylinder is not clearly labeled to identify what gas it contains and the associated risks. The worker cannot know if they have selected the correct type of gas needed.
Arrow 4: Do not place compressed gas cylinders in areas with heavy foot or vehicle traffic. If unavoidable, place barriers around the cylinders to ensure the safety of the cylinders, equipment, and people.

Correct handling:

The worker is no longer smoking.
He has securely attached the valve, and the valve can be opened by hand.
The gas cylinder has been properly marked and labeled; he has taken the correct gas cylinder he wanted.
The worker has restricted the area with cones to warn vehicles and people to stay away from the area where the compressed gas cylinders are placed.

What did we learn?

Use appropriate PPE.
Do not smoke where compressed gas cylinders are stored and handled.
Only open valves by hand.
Compressed gas cylinders must be clearly labeled.
Avoid placing compressed gas cylinders in traffic areas.

Ensure you select and use the correct PPE for work involving compressed gas cylinders. When welding, wear gloves to protect against heat and use appropriate goggles to protect your eyes from the welding light (ultraviolet rays).
Do not smoke near the compressed gas cylinder area, especially when opening the gas valve.

Only use cylinders that can be opened by hand. Never open a valve with a metal tool; excessive pressure can break the valve and cause a gas leak, leading to fire, explosion, or poisoning.

Only use cylinders that have been inspected and are clearly labeled, even if you think an unlabeled cylinder contains the gas you need. Mark it “Contents unknown” and return it to the cylinder supplier. Keep compressed gas cylinders away from high-traffic areas; it is very easy to cause an accident due to a collision.

5. Storing Acetylene Gas in the safety document for electric and gas welding

Observe and determine if this is right or wrong.

The worker is transporting a cylinder from the storage area to the workplace.
Is the compressed gas cylinder being handled carefully and correctly?
Are there any warning signs on the cylinder?
Is the compressed gas cylinder placed near an exit (exit door)?
Are flammable materials like oil, grease, and rags near the acetylene cylinder?
Are the cylinders chained to prevent tipping?
Are the cylinders clearly labeled?
Is the cylinder’s valve properly protected?
Is the worker using PPE?
Is the worker opening the valve safely?
What will happen to this worker if gas pressure bursts out of the valve assembly?

Arrow 1: Placing the cylinder right next to an exit door is unsafe. It is important that hazardous and flammable materials are cleared away from exit doors so that people can get out during a fire or explosion. The cylinder could be hit because it is near a high-traffic area, and the exit door and fire extinguisher are obstructed.
Arrow 2: Flammable materials must be placed far from compressed gas cylinders, including oil containers, pallets, paper, cardboard…
Arrow 3: The chain securing the cylinder is too low; the cylinder could tip over. It should be at least 2/3 of the cylinder’s height.
Arrow 4: The worker is opening the valve with the valve assembly pointing towards them. This worker could lose a hand or be seriously injured if the valve flies out of the assembly. The person opening the valve must stand to one side and point the valve and assembly away from their body.
Arrow 5: This worker is not wearing safety glasses. He is at risk of eye injury if gas leaks or the pressure gauge shatters and blinds him. Always wear safety glasses when working with compressed gas.

The acetylene cylinder area is placed far from the exit door and oil containers.
Hazard warnings are posted above the cylinder storage area.
The chain secures the cylinder at 2/3 of its height.
The worker is wearing safety glasses.
He is standing to one side of the valve and ensuring the opening direction of the valve is away from his body to prevent any unforeseen incidents.

What did we learn?

Keep compressed gas cylinders away from exits.
Keep compressed gas cylinders away from sources of fire or explosion.
Secure the cylinder with a chain at 2/3 of its height. Always open the valve so that it points away from you.
Wear eye protection.
Avoid tipping or dropping compressed gas cylinders.
Cap the compressed gas cylinder valve.
Store compressed gas cylinders carefully.
Transport compressed gas cylinders safely.
Follow safety instructions when using compressed gas cylinders.

IV. Further Reference

1. Group 3 certification safety training service

Occupational Safety Training for Group 3

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Safety Document Group 3

Occupational Safety Training Document for Electric and Gas Welding

I. BASIC CONCEPTS IN THE SAFETY DOCUMENT FOR ELECTRIC AND GAS WELDING

II. SAFETY IN ELECTRIC WELDING WORK

1. FORMATION OF WELDING FUMES AND TOXICITY

2. HAZARDS DURING WELDING IN THE SAFETY DOCUMENT FOR ELECTRIC AND GAS WELDING