Arizona Corporation Commission — Pipeline Safety Interpretation

Page 1April 28, 1993 Mr. Dan Weaklend Chief, Pipeline Safety Arizona Corporation Commission 1200 West Washington Phoenix, Arizona 85007 Dear Mr. Weaklend: This letter is to further clarify my letter of October 22, 1992, in which I tried to clarify the specific inspections and tests the operator should be required to conduct in complying with §192.739. I explained in that letter that regulator stations must be inspected and tested to comply with §192.739 using any practicable method that will demonstrate compliance with paragraphs (a) through (d) of §192.739. Set-point, lock-up, and full-stroke-operation would be part of the inspection and testing if such tests are practicable at the station concerned. Regulator stations that use service-type regulators, such as stations that supply master meter systems, may not be equipped with valving, manifolding, or by-passes. This equipment is needed to preclude interruption of supply to a customer or group of customers while maintenance is performed. Consequently, all the inspections and tests that can be done at some regulator stations may not be practicable at stations with service-type regulators. In addition, to us, practicable inspections and tests do not require the operator to disassemble the regulator, re-pipe the regulator, or cut off the supply of gas to the system. Instead, we suggest that, as a minimum, these service-type regulators be visually inspected, be checked for leaks (including the regulator vent), and be checked for correct set-point. Verifying the correct set- point on a service-type regulator can be done by measuring the pressure of the gas (downstream of the regulator) with a pressure gauge. (We plan to better define "regulator station" in a future rulemaking). dal\192\739\93-04-28 1#

Page 22 I trust that I have further clarified this matter to make it easier to check for compliance with §192.739. If you have any more concerns, please call James Thomas, Southwest Regional Director. Sincerely, Cesar De Leon Director, Regulatory Programs Office of Pipeline Safety dal\192\739\93-04-28 2#