# Virginia State Corporation Commission — Pipeline Safety Interpretation

- **operation:** document
- **citation:** PI-92-034
- **title:** Virginia State Corporation Commission — Pipeline Safety Interpretation
- **source type:** guidance
- **agency:** Pipeline and Hazardous Materials Safety Administration
- **status:** guidance
- **official:** true
- **published on:** 1992-07-23
- **effective on:** Not available
- **summary:** PI-92-034 response to Virginia State Corporation Commission concerning 192.175, 192.177, 192.619, 192.621, 192.743.
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- **app url:** https://regulus.evalyn.ai/document/phmsa-interpretation-pi-92-034
- **source url:** https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/legacy/interpretations/Interpretation%20Files/Pipeline/1992/PI92034.pdf
**body:**

<<<PAGE 1>>>

July 23, 1992
Mr. Massoud Tahamtani
Utilities Manager
Division of Energy Regulation
Virginia State Corporation Commission
P.O. Box 1197
Richmond, VA 23209
Dear Mr. Tahamtani:
This responds to your letter of June 29, 1992, asking questions about Part 192.
First, you asked if gas storage vessels used with a valve actuator are bottle-type holders subject to
§§ 192.175 and 192.177. These two standards are based on comparable provisions of the 1968
edition of ASME B31.8 Code. That Code contains the following definitions:
Bottle-type holder is any bottle or group of interconnected bottles installed in one
location, and used for the sole purpose of storing gas.
Bottle * * * is a gas-tight structure completely fabricated from pipe with integral drawn,
forged, or spun end closures and tested in the manufacturer's plant.
Based on these definition, we believe the vessels are not bottle-type holders. Although they may
be bottles that store gas, gas storage is not their sole purpose. The fact, their primary purpose is
to provide power to actuate the valve when necessary. Thus, they are not subject to §§ 192.175
and 192.177.
Next, you asked whether a city gate station must have overpressure protection. If it is required,
you asked whether the station operator may reply on an interstate transmission operator's devices
to protect the station against overpressure. If such reliance is permissible, you asked if you may
request from the station operator information about the devices to demonstrate compliance with
applicable standards, such as § 192.743.
Under Part 192, distribution systems readied for service after March 12, 1971, or replaced,
relocated, or otherwise changed after November 12, 1970, must have overpressure protection
devices under § 192.195. Other distribution systems are not required to have such protection
unless their maximum allowable operating pressure is established under § 192.619(b) or §
192.621(b). If a distribution operator seeks to satisfy these requirements by relying on
overpressure protection devices it does not own or operate, it is still responsible for compliance of
the devices with Part 192. In this case, you may ask the operator to produce evidence that the
devices comply with applicable Part 192 requirements.jt 1
192.175/92-07-23

<<<PAGE 2>>>

Finally, you asked if § 192.625(a) may be met by collecting gas samples throughout a system,
testing the samples for odorant concentration with a gas chromatograph, and reporting
concentrations of odorant in gas as lbs./MMCF. If so, you asked at what odorant concentration
(lbs./MMCF) would a gas in air concentration of one-fifth of the lower explosive limit be readily
detectable by a person with a normal sense of smell.
Section 192.625(a) provides that a combustible gas in a distribution line must contain a natural
odorant or be odorized so that at a concentration in air of one-fifth of the lower explosive limit,
the gas is readily detectable by a person with a normal sense of smell. Also, § 192.625(f) provides
that each operator shall conduct periodic sampling of combustible gases to assure the proper
concentration of odorant. Section 192.625 does not specify how an operator must test the
samples to assure that a pipeline contains the proper concentration of odorant, or the
concentration required by § 192.625(a). So any testing procedure may be used that is capable of
demonstrating the sufficiency of odorant concentration. If a gas chromatograph is used, the
operator must compare the measured odorant concentrations with the proper concentration,
which must be determined separately. Since the proper odorant concentration can vary among
systems, we cannot give you a specific value in lbs./MMCF that meets the standard.
I hope you find this information useful. If you need any further clarification, please call me.
Sincerely,
Cesar De Leon
Director, Regulatory Programs
Office of Pipeline Safety
jt 2
192.175/92-07-23
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