How Do Safety and Scheduled Welding Machine Maintenance Protect Your Welding Assets?

Preventive welding maintenance checklist

Because most welding equipment finds its way into the rigors of construction, farming, automotive, fabrication and other "rough use" industries, aspects of routine maintenance are often postponed or even overlooked. This article is intended to provide a practical overview of arc welding equipment maintenance and safety.

Aside from protecting your investment in welding equipment, the best argument for a program of ongoing and thorough maintenance is operator safety. This article addresses some common safety topics but does not address all of them. Always read and follow all labels on the equipment and the Owner’s Manual carefully before installing, operating or servicing the equipment. Remember that only qualified persons should install, operate, maintain and repair welding equipment. A qualified person is defined as one who, by possession of a recognized degree, certificate or professional standing, or who by extensive knowledge, training and experience, has successfully demonstrated the ability to solve or resolve problems relating to the subject matter, the work or the project and has received safety training to recognize and avoid the hazards involved.

1. The power source and primary power line

Properly grounding the equipment is crucial. Welders must be concerned at all times about the possibility of electric shock. Touching live electrical parts can cause fatal shocks or severe burns. The electrode and work circuit are electrically live whenever the output is on. The input power circuit and machine internal circuits are also live when power is on. In semiautomatic or automatic wire welding, the wire, wire reel, drive roll housing and all metal parts touching the welding wire are electrically live. Incorrectly installed or improperly grounded equipment is a hazard.

There are some common best practices for grounding your welding equipment:

• Avoid wet working conditions, because water is an excellent conductor and electricity will always follow the path of least resistance. It's always advised to prevent any physical contact with the work or ground. Insulate yourself from the work and ground by using dry insulating rubber mats, or standing on a dry board when welding outdoors.
• Be sure to check your cables daily, since worn, damaged, undersized or repaired cables can be another source of electric shock.
• Aside from these more obvious electric shock hazards, operators should frequently inspect for a proper supply ground connection to the equipment. A proper supply ground connection is always necessary because it provides a safety connection from a welding machine frame to the earth. One of the connections typically used for grounding an engine-driven welder/generator is a cable connected from a ground stud on the welding machine to a metal ground rod driven into the earth.

The frame or chassis of all electrically powered welding machines must be connected to a good electrical ground. This can happen by connecting it to a properly grounded building frame or other appropriate ground.

The work lead is not the grounding lead. The work lead connects the work terminal on the power source to the workpiece. A separate lead is required to ground the workpiece. Chains, wire ropes, cranes, hoists and elevators must never be used to carry welding current.

The workpiece or metal upon which the operator welds must be grounded independently of the welding leads to a good electrical ground unless a qualified person assures it is safe to work on an ungrounded workpiece, according to the National Electrical Code and to ANSI Z49.1 “Safety in Welding, Cutting, And Allied Processes.” When the work terminal is grounded, care should be taken to see that the workpiece is not separately grounded. Before welding, the operator should check to be sure that the work lead is properly connected. This will eliminate the chance of welding current being misdirected into the grounding conductor system of other equipment. Misdirected welding current can damage conductors, which do not have adequate ampacity.

In addition to the potential problems caused by improper grounding, poor electrical weld circuit connections can also yield a number of problems. These can include excessive resistance in the weld circuit, resulting in arc wander, or an arc that won’t start or is difficult to start.

The following items require routing inspection:

• Power sources: Approximately every six months, disconnect power to the unit and blow out or vacuum the inside of the machine. In heavy service conditions, monthly cleaning may be necessary.
• Wire feeders: Periodically inspect the electrode wire drive rolls. If they are dirty, remove the drive rolls and clean with a wire brush. If the drive rolls are deformed, replace them. Drive rolls should be changed, adjusted or cleaned only when the wire feeder is shut off. In addition, check the inlet and outlet guides and replace them if they are deformed from wire wear. Remember that when power is applied to a wire feeder, fingers should be kept away from the drive roll area.
• Gun and liner assembly: Guns and torches should be kept in good working order and serviced at regular intervals by qualified technicians. A gun or torch must be used only with the gases for which it is designed. Shielding gas pressures should be those recommended for the weld process used. MIG gun liners should be cleaned periodically.
• Electrode holders: Fully insulated electrode holders should be used. Do not use holders with protruding screws.
• Connectors: Fully insulated lock-type connectors should be used to join welding cable lengths.
• Cables: Frequently inspect cables for wear, cracks and damage. Immediately replace those that have excessively worn or damaged insulation to avoid the possibility of electric shock from bare cable. Also, keep cables dry, free of oil and grease, and protected from hot metal and sparks.
• Terminals and other exposed parts: Terminals and other exposed parts of electrical units should have insulating covers secured before operation.
• Electrodes: Welding power sources for use with MIG and TIG welding normally are equipped with devices that permit on/off control of the welding power output. If so, the electrode becomes electrically hot when the power source switch is on and the welding gun switch is closed. Never touch the electrode wire or any conducting object in contact with the electrode circuit unless the welding power source is off. Welding power sources used for shielded metal arc welding (SMAW or stick welding) may not be equipped with welding power output on/off control devices. With such equipment, the electrode is electrically hot when the power switch is turned on. Never touch the electrode unless the welding power source is off.
• Electrical safety devices: Safety devices, such as interlocks and circuit breakers, should not be disconnected or shunted out. Disconnect input power or stop the engine before installation, inspection or servicing of equipment. Lockout/tagout input power according to OSHA 29 CFR 1910.147 to prevent power from being turned on accidentally.

2. Gas cylinder distribution system (shielding gas system)

Cylinders

Cylinders should be securely fastened at all times. Chains are usually used to secure a cylinder to a wall or cart. When a cylinder is moved or stored, a threaded protector cap must be fastened to the top of the cylinder. This protects the valve system should it be bumped or dropped.

Cylinders should not be stored or used in a horizontal position. This is because some cylinders contain a liquid that can leak out or be forced out if the cylinder is laid in a flat position. Also, welding guns and other cables should not be hung on or near cylinders. A gun could cause an arc against the cylinder wall or valve assembly, possibly resulting in a weakened cylinder or even a rupture.

Regulators

Immediately remove a faulty regulator from service for repair (remember to first close the cylinder valve.) The following symptoms indicate a faulty regulator:

• Leaks, if gas leaks externally.
• Excessive creep, if deliver pressure continues to rise with the downstream valve closed.
• Faulty gauge, if the gauge pointer does not move off the stop pin when pressured, or return to the stop pin after pressure release.

Do not attempt to repair a faulty regulator. It should be sent to the manufacturer's designated repair center, where special techniques and tools are used by trained personnel.

Hoses

Use only ferrules or clamps designed for the hose, never ordinary wire or other substitutes, as a binding to connect hoses to fittings. Avoid long runs to prevent kinks and abuse. Suspend hose off the ground to keep it from being run over, stepped on or otherwise damaged. Coil up excess hose to prevent kinks and tangles. Examine hose regularly for leaks, wear and loose connections. Immerse pressured hose in water to check for leaks (bubbles will indicate leaks). Repair a leaky or worn hose by cutting out damaged area and splicing. Do not use tape.

3. Ongoing procedure controls/recommended practices

Cooling of equipment

All operators should understand the duty cycle of the equipment they are using. Duty cycle is based on the number of minutes out of a 10-minute time period an arc welding machine can be operated at its rated output. An example would be 60% duty cycle at 300 amps. This would mean that at 300 amps, the machine can be used for six minutes and then must be allowed to cool with the fan motor running for four minutes.

Preparation of shielding gas hoses

The welding operator should purge the gas hoses to expel all air and moisture condensation from lines before welding. Porosity in the weld bead and poor bead color can result from entrapped gas impurities in the line. Condensation or loose fittings in the gun or TIG torch can also cause porosity in the weld bead, as can a defective gas hose or loose hose connection. These should be checked often.

Proper safety procedures or operator maintenance

Arc rays and eye protection

Arc rays produce intense visible and invisible (ultraviolet and infrared) rays that can burn eyes and skin. Any exposed skin can be burned quickly by these rays. Welding helmets should be fitted with a proper filter shade to protect the operator's face and eyes when welding or watching, and approved safety glasses with side shields must also be worn. Screens or barriers to protect others from flash and glare should be installed where appropriate and maintained.

Clothing

Gloves and clothing should be flame-resistant. Clothing made from a dark-colored, tightly woven material is best suited for welding. Gauntlet-type leather gloves should be worn to protect the hands and wrists. Shirt collars and shirt cuffs should be buttoned, and open front pockets are not advisable as they may catch sparks.

Also, operators should never store matches or lighters in their pockets.

Pants cuffs are not recommended, as they will also catch sparks. Tennis shoes do not qualify as proper foot protection. High-top leather shoes or boots are necessary.

Environment

The area around the welder will be subjected to light, heat, smoke, sparks and fumes. Permanent booths or portable partitions can be used to contain light rays in one area. The heat and sparks given off are capable of setting flammable materials on fire. Therefore, welding should not be done in areas containing flammable gases, vapors or liquids or in dusty locations where explosions are possible. Metals with plating, coatings or paint that come near the region of the arc may give off smoke and fumes during welding.

Breathing welding fumes and gases can be hazardous to your health. Ventilate the work area and/or use local forced ventilation at the arc to remove welding fumes and gases. The recommended way to determine adequate ventilation is to sample for the composition and quantity of fumes and gases to which personnel are exposed. If in doubt, have an industrial hygienist test the air in your facility to ensure adequate protection from contaminants in your environment. For occupational use applications, employers must implement a written respiratory protection program meeting the requirements of OSHA 29 CFR 1910.134 (USA) or CSA Z94.4 (Canada), and other substance specific requirements as applicable.

When welding in confined spaces, such as inside tanks, large containers or compartments of a ship, toxic fumes may accumulate. Also, in an enclosed room, breathable oxygen can be replaced by shielding gases used for welding or purging. Work in a confined space only if it is well ventilated or while wearing an air-supplied respirator. Always have a trained watchperson nearby. Welding fumes and gases can displace air and lower the oxygen level, causing injury or death. Be sure the breathing air is safe.

General schedule for routine maintenance of engine-driven welders

8 hours

• Wipe up oil and fuel spills immediately
• Check fluid levels (oil and fuel)
• Service the air filter (refer to engine manual for specifics)

50 hours

• Service air filter element (refer to engine manual for specifics)
• Clean and tighten weld terminals

100 hours

• Change oil
• Change oil filter (refer to engine manual for specifics)
• Clean and tighten battery connections
• Clean cooling system (refer to engine manual for specifics)

200 hours

• Replace unreadable labels (order from parts list)
• Replace fuel filter
• Check valve clearance (refer to engine manual for specifics)

250 hours

• Check and clean spark arrestor

500 hours

• Tape or replace cracked cables
• Clean/set injectors (refer to engine manual for specifics)

1,000 hours

• Blow out or vacuum inside equipment. During heavy service, do this monthly.

Welding equipment maintenance and safety

By following a regimen of appropriate and thorough maintenance and safety, a good welding power source from a major manufacturer can run dependably for decades. Designed to withstand rough use, these machines typically use high-quality components and are tested for durability and reliability. For more information on welder maintenance or for the Miller distributor/service center nearest you, call 1-800-4-A-MILLER (1-800-426-4553).