http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=STANDARDS&p_id=9854OSHA
• Part Number: 1910
• Part Title: Occupational Safety and Health Standards
• Subpart: Q
• Subpart Title: Welding, Cutting, and Brazing
• Standard Number: 1910.253
• Title: Oxygen-fuel gas welding and cutting.
1910.253(d)(1)(i)(A)
Piping and fittings shall comply with section 2, Industrial Gas and Air Piping Systems, of the American National Standard Code for Pressure Piping ANSI B31.1-1967, which is incorporated by reference as specified in Sec. 1910.6, insofar as it does not conflict with paragraph (d)(1)(i)(A)(1) and (d)(1)(i)(A)(2) of this section:
1910.253(d)(1)(i)(A)(1)
Pipe shall be at least Schedule 40 and fittings shall be at least standard weight in sizes up to and including 6-inch nominal.
1910.253(d)(1)(i)(A)(2)
Copper tubing shall be Types K or L in accordance with the Standard Specification for Seamless Copper Water Tube, ASTM B88-66a, which is incorporated by reference as specified in Sec. 1910.6.
1910.253(d)(1)(i)(B)
Piping shall be steel, wrought iron, brass or copper pipe, or seamless copper, brass or stainless steel tubing, except as provided in paragraph (d)(1)(ii) and (d)(1)(iii) of this section.