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: