Standard Interpretations - Table of Contents Standard Interpretations - Table of Contents
• Standard Number: 1910.101; 1910.101(a)


September 26, 2002

Hank Seiff, P.E.
Director of Technology
The Natural Gas Vehicle Coalition
400 North Capitol Street, NW
Washington, DC 20001

Dear Mr. Seiff:

Thank you for your November 9, 2001 letter to the Occupational Safety and Health Administration's (OSHA's) [Directorate of Enforcement Programs (DEP)]. You have questions regarding OSHA's Compressed Gases (General Requirements) Standard, §1910.101. Please be aware that this response may not be applicable to any question or situation not delineated within your original correspondence. Your specific questions are related to inspection and maintenance requirements for compressed natural gas (CNG) cylinders at vehicular fueling stations and the application of a latter version of a document which is incorporated by reference into OSHA standards.

Scenario: U.S. Department of Transportation (DOT) 3AA cylinders are used for storage of high pressure gas at some CNG vehicular refueling stations.

Question: Does OSHA have any requirements or guidelines for station operators on the inspection and maintenance of these fuel storage cylinders?

Reply: First, OSHA would have jurisdiction over the situation you describe. The DOT 3AA cylinders are not involved in the movement of materials involved with interstate commerce; the cylinders are used merely for on-site storage of CNG. Since DOT has no authority to enforce its regulations over the storage of CNG in cylinders at the described locations, there is no pre-emption of OSHA authority, and OSHA would enforce its workplace health and safety regulations over the situation you describe.

OSHA/DOT Requirements

While OSHA has not published any guidelines on the situation you describe, we do have regulations related to the inspection and maintenance of compressed gas cylinders, which include CNG cylinders. OSHA has incorporated by reference DOT Hazardous Materials Regulations, 49 CFR Parts 171-179 (amended January 1, 1970).

Part of OSHA regulation §1910.101(a)
1 requires station operators/employers to determine that compressed gas cylinders under their control are in a safe condition to the extent that the cylinders' mechanical integrity can be determined by visual inspection. Additionally, OSHA and DOT recognize that, based on the service of the cylinder, i.e., material, pressure, etc., a visual inspection alone may be insufficient to determine the mechanical integrity of a compressed gas cylinder.

Since employers may not be able to adequately determine the cylinder condition based merely on a visual inspection, OSHA and DOT require visual and other inspections as prescribed in the referenced DOT regulations. DOT has a regulation, 49 CFR 173.34, Qualification, Maintenance and Use of Cylinders (a copy of this section of the 1970 incorporated standard is attached), which is applicable to your question.

In particular, 49 CFR 173.34(e), Periodic retesting and reinspection of cylinders, requires retesting of DOT 3AA cylinders every five years. This requirement would be applicable to DOT 3AA cylinders containing CNG. Further, 49 CFR 173.34(e)(1) specifies criteria to be included in a periodic retest which includes a visual internal and external examination together with a test by interior hydrostatic pressure in a water jacket or other apparatus of suitable form.

Please be advised that in this case, the exceptions found in the OSHA-incorporated standard, 49 CFR 173.34(e)(10), are not applicable to CNG cylinders because your CNG cylinders do not meet the listed service criteria ("...listed in the table below and used exclusively in the service indicated [emphasis added]..."). The table in 49 CFR 173.34(e)(10) lists only the services of liquefied petroleum gas, anhydrous ammonia,fluorinated hydrocarbons, butadiene, and liquefied hydrocarbon gas; CNG is not one of these specified service materials.

Question #2: What is OSHA's position on whether an employer may follow later versions of the Compressed Gas Associations (CGA) pamphlets?

Response: Employers may use the current revision of a national consensus standard relative to a previous revision which was incorporated, usually with changes, into OSHA regulations. This, however, is predicated on compliance with a current national consensus standard which provides at least the same level of safety and health protection as would otherwise be provided by complying with the previous national consensus standard adopted into OSHA regulations. Therefore, OSHA recommends that employers comply with later versions of CGA pamphlets which provide at least the same level of safety and health protection as would otherwise be provided by complying with previous CGA pamphlets that have been incorporated by reference into OSHA standards.

Thank you for your interest in occupational safety and health. We hope you find this information helpful. 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
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.

Sincerely,



Richard E. Fairfax, Director
Directorate of Enforcement Programs

Attachment: 49 CFR 173.34, Qualification, Maintenance and Use of Cylinders, 1970


129 CFR 1910.101(a) "Inspection of compressed gas cylinders. Each employer shall determine that compressed gas cylinders under his control are in a safe condition to the extent that this can be determined by visual inspection. Visual and other inspections shall be conducted as prescribed in the Hazardous Materials Regulations of the Department of Transportation (49 CFR parts 171-179 and 14 CFR part 103). Where those regulations are not applicable, visual and other inspections shall be conducted in accordance with Compressed Gas Association Pamphlets C-6-1968 and C-8-1962, which is incorporated by reference as specified in Sec. 1910.6." [Back to Text]


Standard Interpretations - Table of Contents Standard Interpretations - Table of Contents