Page 42 - Occupational Health & Safety, April 2018

WELDING
Steering Clear of the Fire and Shock Hazards
Hot work should not be done where flammable vapors or combustible materials exist. Both the work and the equipment being used by the welder should be placed outside any hazardous area.
BY JERRY LAWS
Fires, burns, electric shock, and exposure to welding fume and gases are some of the lead- ing hazards to which welders may be exposed. The protections they require are spelled out
in OSHA’s 29 CFR 1910.252, the welding, cutting, and brazing standard; its section (b)(2) specifies eye protection that must be provided. The standard refers to OSHA’s 1910.133, which contains charts listing the minimal shade numbers needed for protecting weld- ers’ vision and says welders’ lenses must comply with the ANSI/ISEA Z87.1-2015 standard, the American National Standard for Occupational and Educational Personal Eye and Face Protection Devices.
Hot work such as welding, cutting, and grinding can expose workers to the risk of fires when flamma- ble or combustible materials nearby are ignited. Hot work should not be done where flammable vapors or combustible materials exist, and both the work and the equipment being used by the welder(s) should be placed outside any hazardous area, according to OSHA. The 1910.252 standard says personnel should act as a fire watch while hot work is being done in lo- cations where:
■ appreciable combustible material is closer than 35 feet from the work
■ appreciable combustible material is more than 35 feet away but is easily ignited by sparks
■ wall or floor openings within a 35-foot radius will expose combustible materaisl in adjacent areas, including concealed locations in walls or floors
■ combustible materials are adjacent to the op- posite side of metal partitions, walls, ceilings, or roofs and are likely to be ignited
The most common injuries sustained by welders are burns and eye injuries. The right PPE for them— protective apparel, gloves, welding helmets, respira- tory protection—is addressed in both 1910.252(b)(3) and by 1910.132, OSHA’s general PPE standard. It calls for employers to perform a hazard assessment, before PPE is selected and worker training commences.
Shock Hazards
An accident report still available on OSHA’s website describes a fatality in 2005, an electrocution of an em- ployee who was welding trailer gates:
“He was welding using a Wire Feed, Arc Weld- ing Machine. Employee #2 was in the room, but did not observe what happened. He stated he heard Em- ployee #1 cry out. When he turned around, Employee
36 Occupational Health & Safety | APRIL 2018
#1 was on the floor. Other coworkers ran to see what happened and two coworkers started administering CPR. Emergency services arrived, took over CPR, and transported Employee #1 to the hospital, where he later died. An investigation into the incident found that the welding machine was in the ‘on’ position, and that the 50 Amp electrical breaker, which served the circuit to the welding machine, had been tripped. It was noted that Employee #1 did not have his weld- ing hood on. He did have his work gloves on, but the welding gun was not in his hand. The OSHA investi- gation revealed that the electrical conductors (2 hot and 1 neutral), inside of the male attachment plug for the welding machine, were not securely connected to their terminal points. The visible evidence of burns inside of the attachment plug and the melting of the individual strands of the neutral conductor indicated that the neutral conductor came out of its terminal point inside of the attachment plug and it made con- tact with a hot (energized) wire that was also inside of the attachment plug. This contact allowed current to flow through the neutral conductor and back down to the equipment grounding attachment location, which was on the metal frame inside of the welding machine. The frame of the welding machine became energized and so did any metal parts of the welding machine that were in contact with the metal frame. The weld- ing machine was sitting on the floor next to a tin wall, when the incident occurred. There were two electrical burn marks on the tin wall, which matched up per- fectly with two electrical burn marks that were on the side of the welding machine which was facing towards the tin wall. It was believed that Employee #1 made contact with the energized welding machine and he received an initial electrical shock. He either fell against the welding machine, causing it to hit the tin wall or both Employee #1 and the welding machine hit the tin wall. When the energized welding machine made contact with the tin wall, an electrical short cir- cuit would have been created that would be sufficient to cause the fifty (50) Amp circuit breaker to trip out.”
The OSHA page titled “Controlling Electrical Haz- ards” (https://www.osha.gov/Publications/3075.html) is a good resource for understanding the causes of electric shock and how to protect workers from elec- trical hazards through equipment de-energization, PPE, training, and work practices.
Jerry Laws is the editor of OH&S magazine. www.ohsonline.com