California Public Utilities Commission — Pipeline Safety Interpretation

Page 1August 19, 1993 Mr. Russell W. Copeland Chief, Utilities Safety Branch California Public Utilities Commission 505 Van Ness Avenue San Francisco, CA 94102-3298 Dear Mr. Copeland: This responds to your letter of July 16, 1993, concerning the corrosion control requirements in 49 CFR Part 192. Answers to your questions are stated below. 1. Section 192.467(a) requires each pipeline on which external corrosion control is required to be electrically isolated from other underground metallic structures, unless the pipeline and the other structures are electrically interconnected and cathodically protected as a single unit. Under this requirement, the electrical interconnection must be designed and installed as apart of the cathodic protection system to enable the pipeline and other structures to be cathodically protected together. Subsequent "pipe-to-soil" readings on the other structures indicating adequate protection would also indicate the electrical interconnection is functioning as designed. 2. Section 192.467(b) requires one or more insulating devices to be installed where electrical isolation of a portion of a pipeline is necessary to facilitate the application of corrosion control. Under this section, insulating devices are required only when the portion of pipeline being protected is electrically isolated to achieve the required level of cathodic protection. If the required protection is achieved without isolation, no insulating devices are required. 3. We agree that if a pipeline is not required to have cathodic protection, §192.467(b) does not require the pipeline to have insulating devices. Sincerely, Cesar De Leon Director, Regulatory Programs Office of Pipeline Safety dal\192.467\93-08-19#