[Federal Register Volume 62, Number 182 (Friday, September 19, 1997)]
[Rules and Regulations]
[Pages 49171-49172]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-24974]
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DEPARTMENT OF TRANSPORTATION
Research and Special Programs Administration
49 CFR Part 171
[Docket No. RSPA-97-2133 (HM-225)]
RIN 2137-AC97
Hazardous Materials: Cargo Tank Motor Vehicles in Liquefied
Compressed Gas Service; Advisory Guidance for Leak Testing Discharge
Systems
AGENCY: Research and Special Programs Administration (RSPA), DOT.
ACTION: Advisory guidance.
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SUMMARY: On August 18, 1997, RSPA published in the Federal Register a
final rule adopting certain safety standards applicable to cargo tank
motor vehicles used in liquefied compressed gas
[[Page 49172]]
service. This advisory guidance identifies a potential safety problem
when leak testing a cargo tank motor vehicle's discharge system and
clarifies a pressure test requirement for new or repaired transfer
hoses. It is responsive to a petition for reconsideration and a request
for clarification.
FOR FURTHER INFORMATION CONTACT: Ronald Kirkpatrick, Office of
Hazardous Materials Technology, RSPA, Department of Transportation, 400
Seventh Street, SW., Washington, DC 20590-0001, telephone (202) 366-
4545, or Nancy Machado, Office of the Chief Counsel, RSPA, Department
of Transportation, 400 Seventh Street, SW., Washington, DC 20590-0001,
telephone (202) 366-4400.
SUPPLEMENTARY INFORMATION: On August 18, 1997, RSPA published a final
rule in the Federal Register (62 FR 44038) that adopts temporary
requirements for cargo tank motor vehicles in certain liquefied
compressed gas service. It requires a specific marking on affected
cargo tank motor vehicles and requires motor carriers to comply with
additional operational controls intended to compensate for the
inability of passive emergency discharge control systems to function as
required by the Hazardous Materials Regulations. The interim
operational controls specified in the rule are intended to assure an
acceptable level of safety while the industry and government continue
to work to develop a system that effectively stops the discharge of
hazardous materials from a cargo tank if there is a failure of a
transfer hose or piping.
Following publication of the August 18, 1997 final rule, The
Fertilizer Institute (TFI) filed a petition for reconsideration
seeking, in part, a revision to a requirement in Sec. 171.5(a)(1)(i)
which specifies that an operator must subject the transfer hose to full
transfer pressure before commencing the first transfer of each day.
TFI's petition stated, in pertinent part:
In the final rule, RSPA adopts a requirement concerning the
pressure testing of the transfer hose prior to the first transfer
each day. Specifically, RSPA requires that ``prior to commencing the
first transfer of each day, the transfer hose shall be subjected to
full transfer pressure.'' 49 CFR 171.5(a)(1)(i). No further guidance
concerning this requirement is found in the regulations or the
preamble to the final rule. TFI is concerned that RSPA or Federal
Highway Administration (FHWA) inspectors may interpret this
requirement to mandate pressurizing the hose, after opening the
vapor valves on the cargo tank and customer tank, and engaging the
power take-off (PTO) without opening the product valve on the
customer's tank. Under such an interpretation, this requirement is
unreasonable and not in the public interest. To explain why such a
requirement is unreasonable and not in the public interest, it is
necessary to describe a typical anhydrous ammonia unloading
operation.
To unload a cargo tank containing ammonia, the operator first
connects the vapor line from the cargo tank to the customer's tank
and opens the valve at each end of the line. Next, the operator
connects the product transfer hose to the cargo tank and customer's
tank. After making this connection, the operator opens the internal
valve on the cargo tank to flood the pump and, after the pump is
flooded, opens the discharge valve on the pump to charge the
transfer hose. At this point in the delivery process, the transfer
hose is charged with the product pressure. Next, if there are no
signs of leakage, then the operator opens the product valve on the
customer's tank. Finally, the operator engages the PTO to commence
product transfer.
If Sec. 171.5(a)(1)(i) is interpreted to require engagement of
the PTO and pumping against a closed product valve at the customer's
storage tank, TFI asserts that such a requirement is unreasonable.
This requirement is unreasonable because pumping against a closed
valve could cause the vanes in the transfer pump to break. Also, the
PTO, which is rotating at 650 revolutions per minute, could be
damaged and break. Because of the likely potential for damage to the
pump and PTO, it is unreasonable for RSPA to require an ammonia
cargo tank operator to pump against a closed product valve to ensure
the integrity of the transfer hose.
In addition to being unreasonable, such a requirement is not in
the public interest because failure of the pump or PTO may result in
injury to the cargo tank operator and public in proximity to the
unloading operation. If the vanes in the pump break, it is possible
that the integrity of the pump casing may be compromised, resulting
in flying debris. Also, a PTO which breaks, while rotating at 650
revolutions per minute, may cause injury, including death, to those
within proximity of the cargo tank.
TFI understands RSPA's concern with ensuring the integrity of
the transfer hose prior to commencing product transfer. As RSPA is
aware, TFI has consistently been a proponent through this rulemaking
of measures designed to ensure the integrity of the transfer hose
and couplers. TFI believes that RSPA's goal of ensuring that a hose
is sound prior to commencing transfer may be accomplished through
the daily visual inspection of the discharge system, including the
transfer hose and couplers, and charging of the transfer hose with
product at the pressure within the closed system. This is especially
true when RSPA considers the safety implications of engaging the PTO
with the customer's storage tank product valve closed.
For these reasons, TFI requests that RSPA modify the language in
49 CFR 171.5(a)(1)(i) to read:
In addition, prior to commencing the first transfer of each day,
the transfer hose shall be subjected to product pressure without
mechanical influence (e.g., engaging the power take-off).
The provisions of Sec. 171.5(a)(1)(i) are intended to ensure that a
cargo tank's discharge system, including transfer hose and couplings,
is subjected to pressure prior to beginning transfer of product from a
cargo tank motor vehicle to a receiving tank. It is not intended that
any components of the discharge system should be subjected to pressures
greater than full transfer pressure as part of this leak test.
RSPA believes that the problem described by TFI is common to larger
cargo tank motor vehicles, known as transports, which may not have
separate back-to-tank bypass valves; smaller cargo tank motor vehicles,
known as bobtails, generally do have separate back-to-tank bypass
valves, and during delivery the transfer hose is charged with pump
discharge pressure all the way to the hose end valve, which tests the
integrity of the transfer system at each delivery.
RSPA agrees with TFI's concern that some cargo tank pumping systems
are not capable of pumping against a closed product valve without being
damaged. Therefore, operators may determine the leakproofness of a
delivery system, before beginning transfer of product from a cargo tank
motor vehicle to a receiving system, by flooding the pump and charging
the transfer hose with product pressure before the receiving system is
opened.
RSPA will publish a response to TFI's petition for rule change and
petition to extend the termination date of the final rule in the near
future.
Section 171.5(a)(1)(ii) requires, in part, that prior to commencing
transfer using a new or repaired transfer hose or a modified hose
assembly for the first time, the hose assembly must be subjected to a
pressure test performed at no less than 120 percent of the design
pressure or maximum allowable working pressure (MAWP) marked on the
cargo tank motor vehicle, or the pressure a hose is expected to be
subjected to during product transfer, whichever is greater. In response
to a recent telephone inquiry, RSPA noted that this requirement is
based on the MAWP marked on a cargo tank motor vehicle, not the maximum
working pressure marked on a transfer hose.
Issued in Washington, DC on September 16, 1997.
Alan I. Roberts,
Associate Administrator for Hazardous Materials Safety.
[FR Doc. 97-24974 Filed 9-18-97; 8:45 am]
BILLING CODE 4910-60-P
