- Standard Number:
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.
March 7, 2022
Constangy, Brooks, Smith, and Prophete, LLP.
230 Peachtree Street, N.W.
Atlanta, GA 30303-1557
Dear Mr. Principe:
Thank you for your letter to the Occupational Safety and Health Administration (OSHA) regarding the applicability of 29 CFR § 1910.147, the Control of Hazardous Energy, and the maintenance and operations of cathodic protection (CP) rectifiers. This letter constitutes OSHA's interpretation only of the requirements discussed and may not be applicable to any questions not delineated within your original correspondence. The questions and background information you provided in your inquiry are paraphrased below. OSHA's responses follow your questions.
Background: CP rectifiers protect pipes against corrosion. Their use is mandated on liquid and gas pipelines by the Department of Transportation's (DOT), 49 CFR § 195.573 (liquid pipelines) and § 192.465 (gas pipelines). While 29 CFR 1910.147 standard may control the hazards associated with the operation of CP rectifiers, it does not eliminate the other sources of electrical current employees may be exposed to in the work area, such as telluric current and/or induced AC or DC current (i.e., multiple and often unidentifiable power sources such as high voltage AC power lines or DC commuter rail systems). Additionally, de-energization of the CP rectifiers during these efforts causes noncompliance with the aforementioned DOT regulations, requiring the uninterrupted functionality of the systems.
Based on industry related research, it is believed that the use metallic bonding cable on pipeline components being separated will protect employees and maintain the integrity of the pipeline during maintenance or repair activities by eliminating potential voltage differences that may exist in an more effective and safer manner than compliance with 29 CFR § 1910.147.
You provided a common scenario and diagram of the work operation that your inquiry was based upon involving pipeline maintenance for the removal of a section of pipe, a valve, or any other piece of inline equipment. You explained the typical work procedures involved were as follows:
- During this type of maintenance work, the energy isolation procedure would require all sources of hazardous energy to be isolated and locked out or tagged out prior to pipeline maintenance work.
- In the below scenario, the pump has been locked out due to energy that it can impart on the fluid being transported and a valve is closed and locked out or tagged out. (Diagram below is not all inclusive of all energy sources, it is representative of the concept of lockout/tagout.)
- As proposed, the rectifier would remain energized but any electrical potential that may build up between the separated metallic pipe is controlled by installing bond cables. The touch potential imposed on the pipeline by the CP system is less than 50 volts, so the risk of shock is not present.
- The bond cables control any hazardous energy sources imposed on the piping, such as stray current, telluric current, interference current from other CP systems, and induced currents from parallel AC transmission lines, all of which cannot be isolated.
In consideration of the above scenario, you had the following questions:
Question 1: Is LOTO of a CP rectifier required when working on a pipeline?
Response: The application of lockout/tagout (required under 29 CFR 1910.147) during servicing and/or maintenance activities depends on whether the employees are exposed to the unexpected energization or start up of machines or equipment, or release of stored energy. "Energy,", as defined by standard, 29 CFR 1910.147(b) means mechanical motion; potential energy due to pressure, gravity, or springs; electrical energy; or thermal energy resulting from high or low temperature. Some energy sources can be turned on and off, some can be dissipated, some can be eliminated, and some can only be controlled.
Based on the information you provided, OSHA cannot give you a definitive response to your question, which is based on assumptions that may or may not be true. Since OSHA has not examined the equipment and physical location you describe and does not know the precise nature of the environments in which the device would operate, OSHA cannot determine the applicability of, and compliance with, the OSHA standards about which you inquire. If the CP rectifier possesses hazardous energy as defined above, then § 1910.147 would apply. Hazardous energy at a workplace may include, but is not limited to, any telluric energy or electrical currents recognized as a hazard. These workplace hazards need to be dissipated or controlled (through grounding and/or other methods). Determinations regarding the presence of hazardous energy must take into account all factors pertaining to the use of such devices at a particular worksite with respect to employee safety and health. This must include an evaluation, through direct observation, of employee work practices and all conditions of use in the workplace.
Question 2: Is the use of a metallic bonding cable an acceptable practice in lieu of CP rectifier lockout/tagout?
Response: Please note that OSHA does not test, approve, certify, or endorse any equipment, product, or procedure, including machine design and risk assessment techniques. The final determination of compliance with OSHA's standards can only be based on an evaluation of the equipment or devices alone. Such a determination must also take into account all factors pertaining to the use of such devices at a particular worksite with respect to employee safety and health. This must include an evaluation, through direct observation, of employee work practices and all conditions of use in the workplace.
Thank you for your interest in occupational safety and health. We hope you find this information helpful. OSHA's requirements are set by statute, standards, and regulations. Our letters of interpretation do not create new or additional requirements but rather explain these requirements and how they apply to particular circumstances. This letter constitutes OSHA's interpretation of the requirements discussed. From time to time, letters are affected when the Agency updates a standard, a legal decision impacts a standard, or changes in technology affect the interpretation. To assure that you are using the correct information and guidance, please consult OSHA's website at http://www.osha.gov. If you have any questions, please feel free to contact the Directorate of Enforcement Programs at (202) 693-2100.
Kimberly Stille, Director
Directorate of Enforcement Programs