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Propane pre-heaters used during field welding

Summary A steel construction company asked about propane pre-heaters used outdoors while erecting structures. OSHA said applicable construction welding gas provisions governed that use. The portable heater rule cited in the inquiry did not apply unless the equipment was used inside a building or structure.
Document
Federal opinion letter
Agency
Occupational Safety and Health Administration (OSHA)
Document number
1979-12-10
Date issued
December 10, 1979
Status
Active
Status last verified October 10, 2026
Topics
Workplace Safety OSHA 1926 Welding Flammable Gases
Source
View the official document

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About this page: The full text below is the official document from Occupational Safety and Health Administration (OSHA). Ezel adds the plain-English summary and tracks the document's status. The official source linked on this page is authoritative for any reliance.

December 10, 1979

Mr. E.M. Shoemate
Corporate Safety - Houston
Chicago Bridge & Iron Company
[Recipient address omitted]
Dear Mr. Shoemate:

This is in response to your recent inquiry and telephone communication with a member of my staff requesting clarification of appropriate requirements for propane pre-heaters used to pre-heat steel in field construction.

The use of propane/air pre-heaters for pre-heating metal plate during the field erection of metal structures in conjunction with standard welding operations shall comply with any applicable sections of 29 CFR 1926.350 and 29 CFR 1926.351. You stated in your telephone conversation with Mr. Simms that your pre-heaters are used outside and are attended by an employee at all times. Therefore, 29 CFR 1926.153(h)(8) is not applicable to the Chicago Bridge Iron Company pre-heater, unless the subject equipment is used as a portable heater inside of buildings or structures.

If we may be of any further assistance, please feel free to contact me.

Sincerely,

Grover C. Wrenn Director,
Federal Compliance And State Programs

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