Pipeline regulations in §192.3 provide definitions for transmission and distribution lines. Determining a distribution line seems relatively easy as the definition is simply “Distribution Line means a pipeline other than a gathering or transmission line.”
The difficulty lies in identifying transmission lines. The definition has 3 separate criteria, meeting any one condition will make a pipeline a transmission line. The regulatory definition is:
Transmission line means a pipeline, other than a gathering line, that: (1) Transports gas from a gathering line or storage facility to a gas distribution center, storage facility, or large volume customer that is not down-stream from a gas distribution center; (2) operates at a hoop stress of 20 percent or more of SMYS; or (3) transports gas within a storage field.
Note: A large volume customer may receive similar volumes of gas as a distribution center, and includes factories, power plants, and institutional users of gas.
It all seems pretty straightforward but questions do arise. Can one change the classification from transmission to distribution where the SMYS drops below 20%? Just how does this “large volume customer” concept work?
The following interpretation from 2010 explores these questions and provides some answers.
Interpretation 192.3 45
March 22, 2010
U.S. Department of Transportation
Pipeline and hazardous materials Safety Administration
1200 New Jersey Avenue, SE
Washington, D.C. 20590
March 22, 2010
New Mexico Public Regulation Commission
Pipeline Safety Bureau
Joe M. Johnson
Acting Bureau Chief
1120 Paseo de Peralta
Santa Fe, New Mexico 87504
Dear Mr. Johnson:
In a letter to the Pipeline and Hazardous Materials Safety Administration (PHMSA) dated September 15, 2009, you requested an opinion/interpretation on whether the following pipelines operated by New Mexico Gas Company (NMGC) should be regulated as transmission pipelines or distribution pipelines (as described by New Mexico Public Regulation Commission):
1. Animas Power Plant 6″ diameter – an intrastate natural gas pipeline that transports natural gas from a transmission line to a large volume customer (Animas Power Plant).
2. Farmington (Bluffview) Power Plant 8″ diameter – an intrastate natural gas pipeline that transports natural gas directly from a transmission line to large volume customers (Animas and Bluffview power plants).
3. Tucumcari Mainline – an intrastate natural gas pipeline that transports natural gas directly from a transmission to distribution centers (Tucumcari Townplant, Northeast Regulator Station, and Baker Kelso Regulator Station). This pipeline is a continuation of the Clovis Transmission Line that transports natural gas from EI Paso Natural Gas Company’s intrastate pipeline system to New Mexico Gas Company’s Northeast Area distribution centers, and is not downstream of a distribution center.
4. NMGC has designated a valve at the Clovis Border Regulator Station as the end point of the Clovis Transmission Line and the beginning of the Tucumcari and Cannon mainlines. The Clovis Transmission line and the Tucumcari and Cannon mainlines all operate at 300 psig. The Tucumcari Mainline runs approximately 62 miles from Mile Post 0 at the Clovis Border Regulator Station to the Tucumcari Townplant distribution center.
5. Cannon Mainline – an intrastate natural gas pipeline that transports natural gas directly from a transmission to distribution centers (Northwest Regulator Station, Mixon lane Regulator Station, Hayfield Farmers Regulator Station, 6084 Regulator Station, Port Air Dairyman Regulator Station, Port Air Farmers Regulator Station, and Clovis Expansion Regulator Station). This pipeline is a continuation of the Clovis Transmission line that transports natural gas from EI Paso Natural Gas Company’s Intrastate pipeline system to New Mexico Gas Company’s Northeast Area distribution centers, and is not downstream of a distribution center.
6. Northeast Distribution Mainline – an intrastate natural gas pipeline. The pipeline is a loop line that can be used to: (a) transports natural gas from EI Paso Natural Gas Company’s interstate pipeline via NMGC’s Clovis Transmission line to the Tucumcari Townplant distribution center without going to the Clovis Border Regulator Station, or (b) transport natural gas to the Clovis Townplant distribution center via the Tucumcari Mainline.
7. Portales Mainline – an intrastate natural gas pipeline that transports natural gas from the Clovis Transmission line, and Transwestern’s interstate transmission line to distribution centers (Portales Townplant, Grinder Regulator Station, Baxter Regulator Station, Midway Regulator Station, and Cameo Regulator Station). Pressure on the pipeline is regulated at 200 psig just downstream of the Transwestern interconnect at the Clovis Transmission line. There are no service lines on the Portales Mainline and the pipeline runs approximately 20 miles to the Portales Townplant distribution center.
Based on the provided information, we agree with the New Mexico Public Regulation Commission – Pipeline Safety Bureau (PSB) determinations and PHMSA’s responses to the PSB requests are as follows:
1. Regarding the Animas Power Plant 6″ line, we believe this line is a transmission line because under the first definition of a transmission line this line transports gas from a transmission line to a large volume customer that is not downstream from a distribution center.
2. Regarding the Farmington (Bluffview) Power plant 8″ line, we believe this line is a transmission line because under the first definition of a transmission line this line transports gas from a transmission line to a large volume customer that is not downstream from a distribution center.
3. Regarding the Tucumcari Mainline, we do not consider a decrease in pressure to below 20 percent SMYS at a transmission line to be a “distribution center” and lines downstream of that point to be distribution lines – this would violate the intent of the pipeline safety regulations. We consider a “distribution center” to be the point where gas enters piping used primarily to deliver gas to customers who purchase it for consumption as opposed to customers who purchase it for resale. Therefore, in our opinion, this line is an extension of the Clovis transmission line.
4. Regarding the Cannon Mainline, we do not consider a decrease in pressure to below 20 percent SMYS at a transmission line to be a “distribution center” and lines downstream of that point to be distribution lines – this would violate the intent of the pipeline safety regulations. We consider a “distribution center” to be the point where gas enters piping used primarily to deliver gas to customers who purchase it for consumption as opposed to customers who purchase it for resale. Therefore, in our opinion, this line is an extension of the Clovis transmission line.
5. Regarding the Northeast Distribution Mainline, we do not consider a decrease in pressure to below 20 percent SMYS at a transmission line to be a “distribution center” and lines downstream of that point to be distribution lines – this would violate the intent of the pipeline safety regulations. We consider a “distribution center” to be the point where gas enters piping used primarily to deliver gas to customers who purchase it for consumption as opposed to customers who purchase it for resale. Therefore, in our opinion, this line is an extension of the Clovis transmission line or the Tucumcari Mainline as described by PSB.
6. Regarding the Portales Main line, we do not consider a decrease in pressure to below 20 percent SMYS at a transmission line to be a “distribution center” and lines downstream of that point to be distribution lines – this would violate the intent of the pipeline safety regulations. We consider a “distribution center” to be the point where gas enters piping used primarily to deliver gas to customers who purchase it for consumption as opposed to customers who purchase it for resale. Therefore, in our opinion, this line is an extension of the Clovis Transmission line and Transwestern transmission line.
I hope that this information is helpful to you. If I can be of further assistance, please contact me at (202) 366-4046.
Sincerely,
John A. Gale
Director, Office of Regulations
All this and more including the latest on pipeline safety in WinDOT, The Pipeline Safety Encyclopedia.
The WinDOT Report 
So if I understood PHMSA’s response correctly, a pipeline containing segments that are below or, equal to or greater than 20 percent SMYS can still be considered a DOT defined transmission pipeline in its entirety despite those sections below 20 percent SMYS based on meeting the first criteria in the regulatory definition – “(1) Transports gas from a gathering line or storage facility to a gas distribution center, storage facility, or large volume customer that is not down-stream from a gas distribution center”
Yes, that is my understanding of this interpretation.