OSHA requirements are set by statute, standards and regulations. Our interpretation letters explain these requirements and how they apply to particular circumstances, but they cannot create additional employer obligations. This letter constitutes OSHA's interpretation of the requirements discussed. Note that our enforcement guidance may be affected by changes to OSHA rules. Also, from time to time we update our guidance in response to new information. To keep apprised of such developments, you can consult OSHA's website at https://www.osha.gov.

December 10, 1979

Mr. E.M. Shoemate
Corporate Safety - Houston
Chicago Bridge & Iron Company 8900 Fairbanks North Houston Road
P.O. Box 40066
Houston, Texas 77040

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.





Grover C. Wrenn Director,
Federal Compliance And State Programs