Welding Precautions on Suspended Scaffolds

Welding on suspended scaffolds occurs more often than is considered. Common scenarios where welding on swing stages takes place are at boilers, power plants, and shipyards; however, a manufacturer and rental company may not always be aware of how the equipment ends up being used.

In one case, equipment was supplied to a contractor who was working on a large project. The rental company asked if welding was to be performed from the stage. The end-user said no, but when the equipment was delivered to the site the customer changed his mind.

The rental company then had to scramble to get the additional required equipment to the site to avoid the job being shut down. The result was a considerable increase in cost because of overtime and airfreight costs; a necessary measure in order to protect the users and to avoid accidents.

OSHA’s Guidelines for Welding from a Swing Stage
OSHA’s website has a significant amount of information, including codes and case reports on welding incidents from a swing stage.

1926.451(f) (17)
“When welding is being performed on suspended scaffolds, the following precautions must be taken, as they apply to reduce the possibility of welding current arcing through the suspension wire ropes.”

The key word here is precautions.  In the above scenario, if the codes had been followed prior to shipment, the fire drill described could have been avoided. Many times the rental company finds that the end-user is unaware of these lifesaving welding codes.

Welding is discussed in detail in the SAIA’s Competent Person Training: Suspended Scaffold course. Most students are not familiar with the additional requirements called for when welding occurs from a suspended scaffold.

OSHA Case Report
Frayed insulation causes arc, damages suspension wire rope:
An employee was arc welding from a suspended scaffold. The work lead on the welder had frayed insulation in one area, leaving the bare conductor exposed. The frayed section of the welding cable was tied around the guardrail of the scaffold. Since the scaffold was not grounded, it became energized. This caused arcing between the scaffold and the building. The welding current passed through the wire rope supporting the scaffold and the wire rope separated. The worker and the scaffold fell 50 ft. to the ground. The worker was hospitalized for his injuries.

This gentleman was lucky. In another similar case, the outcome was fatal.

On the University of Iowa’s public health portion of its website, a detailed accident report from the Des Moines Register describes a 1996 accident in which a 43-year old welder fell 19 stories to his death. The company had an extensive safety manual and on-site, weekly safety talks; and the majority of workers were experienced journeymen.

It is unfortunate that equipment inspections and needed improvements were overlooked. The high amperage welding cable had been improperly repaired using electrical tape. It then came in contact with the suspension wire rope melting it – the result the worker’s fatal 19 story fall.

How could this have been avoided?

Key Precautions
Often key components of this diagram are overlooked. The most commonly overlooked precautions include the following:

  • Insulating the tiebacks
  • Insulating the excess wire rope on the roof when using J-clips (fist grips)
  • Using Non-conductive roller bumpers
  • Ensuring the tail-end of the wire ropes do not touch the ground
  • Jumper cable from stage to structure

1926.451(f) (17) (i)
“An insulated thimble must be used to attach each suspended wire rope to its support (such as a cornice hook or outrigger). Excess suspension wire rope and any additional independent lines must be protected from grounding.

Thimbles, when installed correctly, prevent metal-on-metal contact and break the flow of any current through the suspension lines. They must be in good condition with no cracks or defects. (Common in the older style).

1926.451(f) (17) (ii)
“The suspension wire rope shall be covered with insulating material extending 4 ft. above the hoist. If there is a tail line below the hoist, it shall be insulated to prevent contact with the platform. The portion of the line that hangs free below the scaffold shall be guided or retained, or both, so that it does not become grounded.”

1926.451(f) (17) (iii)
“Each hoist shall be covered with an insulated protective cover.”

A trash bag does not work. Contact your hoist supplier for approved covers.

1926.451 (f) (17) (iv)
“In addition to a work lead attachment required by the welding process, a grounding conductor shall be connected from the scaffold to the structure. The size of the independent conductor shall be at least the size of the welding process work lead, and this conductor shall not be in series with the welding process or the work piece.

1926.451 (f) (17) (v)
“If the scaffold grounding lead is dis- connected at any time, the welding machine shall be turned off.”

1926.451 (f) (17) (iv)
“An active welding rod or uninsulated welding lead shall not be allowed to contact the scaffold or its suspension system.” These two codes are self-explanatory. One must protect the equipment from high amperage and heat in welding applications.

Know for Sure
To ensure that safety precautions are being taken, remember to ask: “Are you welding from a stage?”

  • Manufacturers, ask your rental companies
  • Rental companies, ask your end-user
  • End-user, ask your trades