Dome Pipeline Corporation — Pipeline Safety Interpretation

Page 1January 17, 1980 Mr. E. Hobson Dome Pipeline Corporation District Office P.O. Box 1430 Plaza Centre One Iowa City, Iowa 52240 Dear Mr. Hobson: This is in reply to your letter dated June 14, 1979. We regret the delay in responding to your letter which we inadvertently mislaid for a period of time. You requested a finding concerning section 195.416(c); specifically, whether equipping rectifiers with transmitters to indicate current flow above a certain level and detecting this operation by a receiver in a patrol aircraft constitutes compliance with this subsection. Please be advised that the intent of section 195.416(c) is to ensure that the rectifiers are functioning and that your proposal meets this intent. We commend you on your resourcefulness in developing methods to monitor cathodic protections. Sincerely, /signed/ Cesar De Leon Associate Director for Pipeline Safety Regulation Materials Transportation Bureau DB C:\WP51\INTERPRT\195\416\80-01-17 1#

Page 2June 14, 1979 Office of Pipeline Safety 911 Walnut Street Room 1802 Kansas City, MO 64106 Gentlemen: This letter is in reference to DOT Regulations for the Transportation on Liquids by Pipeline - Part 195, Section 195, Section 195.416(c) concerning inspection of cathodic protection rectifiers. We are currently studying the feasibility of monitoring the status of our mainline rectifiers by installing a receiver in our weekly patrol plane in conjunction with a transmitter in each rectifier. The transmitter would be preset to turn off if the current output to the groundbed fell below a predetermined acceptable value. The receiver would emit an audible tone if the transmitter were operating. Should a rectifier transmitter be off, its number would be logged on the line flyer report and a man would be dispatched to investigate the problem. We would like to know whether this type of surveillance could be used to satisfy the two month inspection criteria outlined in Section 195.416(c). This type of inspection would greatly reduce the manhours spent in rectifier monitoring. Your prompt response to this inquiry would be appreciated since we would like to implement this program as soon as possible. Your very truly, E. Hobson Electrical Engineer DB C:\WP51\INTERPRT\195\416\80-01-17 2#