Tennessee Public Service Commission — Pipeline Safety Interpretation

Page 1PI-74-0142 Mr. John Searcy Engineering Division Tennessee Public Service Commission Cordell Hull Building Nashville, TN 37219 Dear Mr. Searcy: Your letter of September 23, 1974, asked two questions concerning Part 192 Section 192.197, Control of the pressure of gas delivered from high-pressure distribution systems. In response to these we offer the following: (1) Question: Where an industrial customer requires and receives a minimum of 10 psi, reduces this with his own regulators within his plant to 5 psi at each piece of utilization equipment, is 10 psi or 5 psi considered the safe gas utilization equipment pressure as referred to in 192.197(b)? Answer: The safe utilization pressure in such a case would be 10 psi and the individual regulators provided by the consumer would be considered similar to appliance regulators that are often used on domestic appliances. (2) Question: If a maximum allowable operating pressure is 50 psi and a service regulator that does not have all of the characteristics listed in 192.197(a) is used to provide the 10 psi described above, is it a correct interpretation that, in accordance with 192.197(b), suitable protective devices must be installed? Answer: The condition described would fall within the requirements of 192.197(b) and thus an additional suitable protective device would be required for the gas operator to comply with this section. Thank you for your interest in pipeline safety. Sincerely /signed/ Joseph C. Caldwell Director Office of Pipeline Safety#

Page 2Mr. Joseph C. Caldwell, Director Office of Pipeline Safety Department of Transportation 2100 Second Street, SW Washington, D. C. 20590 Dear Mr. Caldwell: Where an industrial customer requires and receives a minimum of 10 psi, reduces this with his own regulators within his plant to 5 psi at each piece of utilization equipment, is 10 psi or 5 psi considered the safe gas utilization equipment pressure as referred to on 192.197(b)? If a maximum allowable operating pressure is 50 psi and a service regulator that does not have all of the characteristics listed in 192.197(a) is used to provide the 10 psi described above, is it a correct interpretation that, in accordance with 192.197(b), suitable protective devices must be installed? Sincerely, John Searcy Engineering Division#