American Meter Company — Pipeline Safety Interpretation

Page 1Mr. H. F. Kruzan Chief Engineer Regulators American Meter Company 300 North Gilbert Avenue Fullerton, California 92633 Dear Mr. Kruzan: Thank you for you letter of October 28, 1970, requesting an official interpretation of certain sections of 49 CFR, Part 192. The interpretation requested are furnished herewith: Question 1: Section 192.145 and others: Are pressure regulators to be classified as valves? Answer: Generally speaking pressure regulators are valves and as such must meet the general requirements of this section. The requirements of API-6A and API-6D are limited to steel gate valves, plug valves, ball valves and check valves 2" and larger in size and MSS-SP-52 is limited to cast iron gate valves, plug valves and swing check valves 2" and larger in size. The omission of specification for other types of valves does not exempt them from the general requirements of this section. Question 2: Section 192.195(b)(1)(2): Distribution System. What is the intent of the special requirement for Distribution Systems? What type of installation will meet this requirement: Monitor, Parallel Stand-By Regulator, or What? Answer: The intent of Section 192.195(b). Additional requirement for distribution systems is to prevent subjecting a distribution system to pressures above the maximum allowable operating pressure of the distribution system. For example, this could be accomplished by use of a monitor type of installation, by a series cut in pressure where the pressure ahead of the downstream regulator is less than the MAOP or the distribution system or by use of relief or automatic over pressure shut-offs. The relief or automatic shut-off may be either built in to the regulator or separate units. Question 3: Section 192.197(a)(6): Please define the term "Control Line." It is synonymous with static line? There are certain pilot loaded pressure regulators that do not require a static line, but do require a pilot inlet supply line. If this line is broken, the regulator will close. An overpressure condition cannot be experienced due to breakage of this line. Please comment. Answer: The term "Control Line" used in paragraph 192.197(a)(6) is considered synonymous with "Static Lines." This is taken verbatim from the B31.8 - 1968, paragraph 845.51(f). A pilot jt/dal/192.3 70-10-28#

Page 2supply line may be necessary to the operation of a pilot controlled regulator but is not considered as prohibited by this paragraph. Question 4: Section 192.197(b): Concerns gas content of materials that could interfere with the operation of a service regulator. Question: Does this mean normal content, or is the operator responsible for any abnormal interpretation, this could mean the end of service regulators that are not equipped with an approved type safety device, could it not? Answer: In Section 192.197(b) the phrase "or if the gas contains materials that seriously interfere with the operation of service regulators" is meant only to apply to those conditions that can be reasonably anticipated. As examples: a. Some gases being distributed may contain excessive amounts of sulfur compounds. b. Systems that were formerly operated on manufactured gas may contain tars, oils and dust. c. If new lines are not cleaned before being placed in service they may contain foreign materials that were introduced during construction. Question 5: Section 192.197(a)(1): Paragraph specifies a regulator "capable" of reducing distribution pressure, etc. If such a regulator also has the capability of being adjusted for higher pressures, does this mean that it doesn't meet the requirements of this paragraph? Answer: In Section 192.197(a)(1) the phrase "cable of reducing distribution line pressure to pressures recommended for household appliances" is in no way a restriction on the capability that may be designed into a regulator. Question 6: Section 192.201(c) and Others: The deletion of 2 psig W.P. so as to conform to "performance-type" specifications, leaves interpretation of "safe pressure" wide open. There will undoubtedly be many opinions as to the proper pressure limitation. On what basis will DOT determine compliance? Answer: The phrase "the safe operating pressure for any connected and properly adjusted gas utilization equipment" in Section 192.201(c) is intended to place the burden on the operator to prevent unsafe conditions. There are some appliances that may be adjusted for normal operation at 4 to 6 inches water column that would be dangerous with a 1 1/2 to 2 psig inlet while some others would take 4 to 5 psig and be safe. The operator must determine the maximum safe operating pressure and install appropriate relief devices. jt/dal/192.3 70-10-28#