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.

April 24, 2012

Mr. David Pryor
Director of Engineering, Global Gas Equipment
Thermadyne Operations Center
P.O. Drawer 1007
2800 Airport Road
Denton, Texas 76207

Dear Mr. Pryor:

Thank you for email of September 20, 2011, to the Occupational Safety and Health Administration's (OSHA's) Directorate of Enforcement Programs in response to OSHA's letter to you dated January 28, 2011. This letter constitutes OSHA's interpretation only of the requirements discussed and may not be applicable to any question not delineated within your email correspondence and subsequent communication with OSHA.

Your question relates to shielding gas regulators used for gas-shielded arc welding operations performed in construction and general industry workplaces. Your scenario and question are paraphrased below, followed by our response.

Scenario: Your company, Therrnadyne, manufactures shielding gas regulators for use in welding processes, including metal arc welding and gas tungsten arc welding but excluding oxygen-fuel gas welding and cutting. These regulators reduce the pressure of shielding gases-usually argon, carbon dioxide, helium, or a mixture of argon and carbon dioxide-to a safe working pressure. Thermadyne manufactures two types of shielding gas regulators, flowmeter and flow gauge; each type works slightly differently, but both are operated using the energy of pressurized shielding gas. Although the arc welding system is electrically powered, your diagram depicts the shielding gas cylinder and regulator as separated from the arc welder and not connected to any electrical installation. The complete description of the regulators you provided to OSHA, including pictures and diagrams, is attached to this letter.

Question: Must Thermadyne's shielding gas regulators be "approved" or "listed" by a third party (for example, by a Nationally Recognized Testing Laboratory (NRTL)) for use in the workplace?

Response: No. As explained in our January 28, 2011 letter to you, electric-powered equipment used in general industry work, such as the arc welder itself, must be so approved under 29 CFR Part 1910, Subpart S1, 29 CFR §§ 1910.303(a), 1910.399.2 In addition, as you are aware, OSHA requires NRTL approval of regulators and other equipment used for oxygen-fuel gas welding and cutting under 29 CFR Part 1910, Subpart Q, 29 CFR §§ 1910.251(2),1910.253(3). OSHA does not, however, require such approval of the regulators about which you inquired as you have described them because the regulators are not connected to any electrical installation and are not used in oxygen-fuel gas welding or cutting operations.

Nevertheless, OSHA encourages manufacturers such as your company to subject gas regulators to independent testing and inspection, and encourages employers to use products that have been so tested and inspected. There are a number of potential safety concerns about shielding gas regulators that manufacturers and employers should consider, including whether the regulator body and connections, threaded or otherwise, can withstand the expected operating pressures (to 5500 psig) without failing catastrophically. OSHA notes that the Compressed Gas Association has provided guidance in its E-4 Standard/or Gas Pressure Regulators, which contains design and manufacturing requirements relating to materials, construction, performance, test procedures, information, marking, and packaging of pressure regulators. Regulators covered by this standard are intended for use with compressed gases, such as air, carbon dioxide, and inert gases, identified in the scenario.

Thank you for your interest in occupational safety and health. We hope you find this information helpful. This letter is intended to provide information about the standards relating to the arc welding equipment you identified. The Occupational Safety and Health Act requires employers to comply with safety and health standards promulgated by OSHA or by a state with an OSHA approved state plan. However, this letter is not itself a standard or regulation, and it creates no new legal obligations. Note that our enforcement guidance may be affected by changes to OSHA rules. In addition, 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 http://www.osha.gov. If you have any further questions, please feel free to contact the Office of General Industry Enforcement at (202) 693-1850.


Thomas Galassi, Director
Directorate of Enforcement Programs

1 Electric-powered equipment used in general industry must be similarly approved by a "qualified testing laboratory." 29 CFR § 1910.399.   [Return to Text]

2 Section 191Oo403(a) states: "Approval. The conductors and equipment required or permitted by this subpart shall be acceptable only if approved, as defined in Sec. 1926.399." In § 19260449, OSHA defines the terms "approved" and "acceptable" so as to require a safety determination by a NRTL.  [Return to Text]