# National Transportation Safety Board — Hazardous Materials Safety Interpretation

- **operation:** document
- **citation:** 12-0121
- **title:** National Transportation Safety Board — Hazardous Materials Safety Interpretation
- **source type:** guidance
- **agency:** Pipeline and Hazardous Materials Safety Administration
- **status:** guidance
- **official:** true
- **published on:** 2012-08-16
- **effective on:** Not available
- **summary:** 12-0121 response to National Transportation Safety Board concerning 177.840, 180.416.
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- **markdown:** https://regulus.evalyn.ai/document/phmsa-interpretation-12-0121.md
- **app url:** https://regulus.evalyn.ai/document/phmsa-interpretation-12-0121
- **source url:** https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/legacy/interpretations/Interpretations/2012/120121.pdf
**body:**

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U.S. Department
of Transportation
Pipeline and Hazardous
Materials Safety
Administration
1200 New Jersey Avenue, SE
Washington, D.C. 20590
AUG 16 2012
The Honorable Deborah A.P. Hersman
Chairman
National Transportation Safety Board
490 L'Enfant Plaza, SW
Washington, DC 20594
Ref. No.: 12-0121
Dear Chairman Hersman:
Thank you for your May 4, 2012letter requesting clarification of the inspection and
maintenance requirements for the discharge system on a cargo tank motor vehicle in
liquefied compressed gas service under the Hazardous Materials Regulations (HMR; 49
CFR Parts 171-180). Specifically, you request clarification of the meaning of"in service"
as it applies to the monthly inspection of a delivery hose assembly (i.e., "a cargo transfer
hose assembly") under§ 180.416(d)(l).
As part of an investigation of an accident involving the rupture of a hose used to transfer
anhydrous ammonia, the National Transportation Safety Board (NTSB) included among its
findings the belief that lack of clarity of§ 180.416(d)(l) regarding monthly inspections of
each "in service" hose assembly can lead a cargo tank motor vehicle operator to mistakenly
defer monthly inspections.1 The NTSB concluded that "if a motor carrier does not believe
that [a hose assembly] will be used, it will not necessarily consider it to be 'in service' and
as a result, the hose assembly may not be inspected, as was the case in this accident." It is
the understanding ofNTSB that a hose assembly carried on a cargo tank motor vehicle has
the potential to be used on any given day, and consequently, is "in service." Therefore, in
order to provide greater clarity of the monthly inspection requirement of a hose assembly
installed or carried on a cargo tank, in its Safety Recommendation H-12-5, the NTSB
requests that PHMSA provide an interpretation of when a hose assembly is "in service."
Your understanding is correct. A hose assembly installed or (to be) carried on a cargo tank
motor vehicle in liquefied compressed gas service must be inspected monthly regardless of
whether it is used in any given month. Although a hose assembly must be checked prior to
1 Hazardous Materials Accident Summary Report: Cargo Hose Rupture and Release of Anhydrous Ammonia
During Offloading of a W emer Transportation Services Cargo Tank Motor Vehicle at the Tanner Industries
Plant, Swansea, South Carolina, July 25, 2009.

<<<PAGE 2>>>

each unloading operation, this check involves only those components readily visible (see
§ 177.840(m)). The requirement of§ 180.416(d)(l) ensures that at least once a month each
hose assembly assigned to a cargo tank motor vehicle in liquefied compressed gas service
will undergo a thorough visual inspection whether or not it has been used. "In service" as
used in § 180.416, is associated with qualification and maintenance for purposes of
hazardous materials transportation and should not be misconstrued as "in use." Just as a
cargo tank in liquefied compressed gas service is subject to inspection and testing
requirements and must be removed from hazardous materials service (i.e., placed out of
service) if it fails a test or inspection, a hose assembly must be inspected and tested, and
removed from service according to rejection criteria found in§ 180.416. A repaired hose
assembly successfully retested in accordance with§ 180.416(±) may be placed back in
service and then must again be inspected monthly regardless of whether it is used in any
given month.
If I can provide further information or assistance, please feel free to contact me.

<<<PAGE 3>>>

W1nter-
~ 1 ~o, ttl to(J)
Carao Tun~ .
"'' IZ---012.{
National Transportation Safety Board
Washington, D.C. 20594
Safety Recommendation
Date: MAY 0 4 2012
In reply refer to: H-12-2 through -6
The Honorable Cynthia L. Quarterman
Administrator
Pipeline and Hazardous Materials
Safety Administration
Washington, D.C. 20590
On July 15, 2009, about 8:00a.m., a cargo transfer hose ruptured shortly after transfer of
anhydrous ammonia began from a Werner Transportation Services, Inc. (Werner) cargo tank
truck to a storage tank at the Tanner Industries, Inc. (Tanner) facility in Swansea, South Carolina.
A white cloud of anhydrous ammonia, a toxic-by-inhalation gas,
1 moved from the parking lot of
the facility across U.S. Highway 321 to a largely wooded area, where it eventually dissipated.
About the same time, a motorist traveling north on the highway drove into the ammonia cloud,
apparently tried to get away from the cloud, then got out of her car and died of ammonia
poisoning. Fourteen people reported experiencing minor respiratory problems or dizziness as a
result of the anhydrous ammonia release and were evaluated by emergency medical services
(EMS) on scene. Of those 14, 7 displayed symptoms that required EMS to transport them for
further evaluation at an emergency department; they were treated and released the same day. The
anhydrous ammonia cloud caused temporary discoloration of vegetation in the area, including
the leaves on the trees. Residents in the area sheltered in place, and U.S. Highway 321 was
closed until about 2:00 p.m. on the day of the accident. The Lexington County Fire Service
arrived on scene about 8 :07 a.m. Property damage and losses were limited to the ruptured hose
and about 6,895 pounds of the anhydrous ammonia that was released.2
The National Transportation Safety Board (NTSB) determined that the probable cause of
the accident was Werner Transportation Services, Inc.'s use of a cargo hose assembly that was
not chemically compatible with anhydrous ammonia. Contributing to the accident was the lack of
explicit requirements by the Pipeline and Hazardous Materials Safety Administration (PHMSA)
1 The U.S. Department of Transportation (DOT) classifies anhydrous ammonia as a Hazard Class 2
nonflammable gas. Anhydrous ammonia is a colorless liquid or gas that is both poisonous and corrosive and that has
an intense, pungent, suffocating odor.
2 See Cargo Hose Rupture and Release of Anhydrous Ammonia during Offloading of a Werner Transportation,
Inc. Cargo Tank Motor Vehicle at the Tanner Industries Plant near Swansea, South Carolina, July 15, 2009,
Hazardous Materials Accident Report NTSB/HZM-12/01 (Washington, D.C.: National Transportation Safety Board,
2012) on the NTSB website at <http://www.ntsb.gov>.
8391

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2
that the motor carrier and the facility carrier verify that the cargo hose assembly is chemically
compatible with the product to be transferred before transfer operations begin.
Accident Hose Assembly
The ruptured transfer hose was manufactured by Durodyne, Inc} in 2005. The hose,
Durodyne product number DD-G-220, was designed for liquefied petroleum gas (LPG) transfer
only and was constructed of several different layers of material that are chemically compatible
with LPG, but not with anhydrous ammonia. The innermost layer ofthe hose was made of nitrile
rubber, followed by three sequential layers of polyethylene terephthalate (PET) yarn braids
encased in chloroprene rubber and an outer layer of neoprene rubber. The PET yarn braids are
used to mechanically reinforce the hose, and they provide the hose with the majority of its
strength. The hose had been approved by Underwriters Laboratories Incorporated (UL) and met
the UL 214 standard for LPG hose.
The hose was imprinted with text. One side of the black neoprene cover of the hose
featured a blue Mylar stripe extending along the length of the hose with the Durodyne logo and
"DD-G-220 LPG TRANSFER ONLY 350 PSI MAX WP" printed in black. The phrases "To
prevent serious injury or property damage use for intended purpose only," "Warning: Use of
damaged hose could be hazardous; inspect hose and couplings prior to each use," and "Textile
reinforcements meet UL21" were also embossed along the imprinted blue Mylar stripe. The
opposite side of the hose had "DURODYNE DD-G-220 LPG HOSE UL21 ISSUE E-7874
MH29239 SPEC DD-G-220 TEXTILE BRAID WP 350 PSIG 4Q05 INSPECT HOSE BEFORE
USE" embossed on an imprinted stripe extending the length of the hose. (See figure 1.)
Figure 1. Blue Mylar and imprinted stripes on accident hose.
3 In August 1999, Durodyne was purchased by Argo Tech Costa Mesa. In 2007, Eaton Corporation purchased
Argo Tech, including the Durodyne unit.
4 UL standard 21, for LPG hose, covers hose and hose assemblies in sizes up to and including a nominal internal
diameter of 4 inches for conveying LPG.

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3
Smart-Hose Technologies of Philadelphia, Pennsylvania, purchased the LPG transfer
hose from Durodyne and installed the Smart-Hose safety system to fabricate the complete
accident hose assembly as a Lifeline III LPG Transfer Hose. The Smart-Hose safety system
consists of an internal cable running through the bore of the hose connected to specially designed
unseated flapper valves located on each end of the cable. In the event of hose or coupling
separation, catastrophic hose rupture, or excessive hose stretching, the system is designed to shut
off the flow of LPG in both directions as the flapper valves release and instantly seat.
The Smart-Hose assembly consisted of a 238-inch-long 1/4-inch lxl9 galvanized steel
strand cable with a nylon coating down the bore of a 216-inch-long piece of Durodyne LPG
transfer hose. Each end of the cable was connected to a valve flapper made from 316 stainless
steel. 5 The flappers were connected to 2-inch-diameter 316 stainless steel female national pipe
thread end fittings on each end of the hose. The end fittings were secured to the hose by 2-inch
ferrules crimped onto each end of the hose, which completed the Smart-Hose assembly and held
the cable in compression. Records indicate that the hose assembly was 222 inches (18 1/2 feet)
long. Smart-Hose issued a new hose test certification for this hose assembly, serial number
10573, on October 18, 2005.
Each end of the hose also had a male acme hammer lock coupling made of cast iron and
carbon steel that threaded into each end fitting. This type of coupling is not acceptable in LPG
applications because of sparking issues, but it is appropriate for anhydrous ammonia
applications. According to Smart-Hose Technologies, these couplings were not installed by or
purchased from Smart-Hose at the time Smart-Hose completed the hose assembly. Werner
purchased the transfer hose assembly from Gas Equipment Company, Inc. of Indianapolis,
Indiana, on December 20, 2005. The invoice for the purchase does not include any information
about the couplings, such as whether the couplings were purchased from or installed by Gas
Equipment Company. Additionally, no other records or receipts were found that identified the
company that installed the couplings. As a result, NTSB investigators were unable to determine
when the hammer lock couplings were installed and who installed them.
Postaccident Testing and Analysis of Accident Hose Assembly
On September 9, 2009, the LPG transfer hose assembly was examined at the NTSB's
Materials Laboratory in Washington, D.C., in the presence of the parties to the investigation. The
overall length of the hose assembly was 18 1/2 feet. The measured length of the hose from end
fitting to end fitting was 18 feet. At the time of construction, Smart-Hose certified the length of
the hose assembly, not including the couplings, as 18 112 feet.6 The rupture in the hose was about
5 1/2 inches long. The centerline of the rupture was located 131 inches from the A end7 and
91 inches from the Bend of the hose assembly.
5 Type 316 stainless steel is an austenitic chromium nickel stainless steel containing molybdenum. Because of
its superior corrosion and oxidation resistance, good mechanical properties, and fabricability, 316 stainless steel has
applications in many sectors of industry, including its use for the manufacture of tanks and storage vessels for
corrosive liquids.
6 Smart-Hose literature states that these hoses may contract up to 3 percent when pressurized. Therefore, an
18 I /2-foot hose could contract 6 inches or more (that is, 3 percent of 18 I /2 feet, or 222 inches, is 6.66 inches).
7 The "A" and "B" ends of the hose assembly were arbitrarily chosen and labeled by the NTSB's Materials
Laboratory for reference use only.

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4
The exterior surfaces of the hose assembly contained only superficial abrasions. No
gouges, slices, or other defects were noted on the surface of the hose, including the areas
adjacent to and abutting the rupture area. The black text on the blue Mylar stripe was abraded in
multiple locations so that the stenciling along the length of the hose could not be read; however,
several sections of the hose assembly were free of abrasions or stains, and the text could be read.
The embossed text on the imprinted line could be read along the length of the hose assembly.
Fractographic8 evidence indicates that the rupture in the accident hose assembly initiated
on the interior wall of the hose and propagated outward. The NTSB's Materials Laboratory
identified a definitive fracture origin on the surface of the fracture that was indicative of
relatively slow crack growth. Several secondary cracks were noted in the interior wall of the hose
near the fracture origin; however, the interior surface did not appear to be degraded from
anhydrous ammonia exposure.
The reinforcing fibers in the two innermost PET braid layers of the hose assembly
appeared to be severely damaged on both halves of the fracture surface along the entire length of
the ruptured area. In some parts of the ruptured area, the fibers were clumped together and
appeared to be encased in salt-like particles. Laboratory analysis of the hose assembly revealed
that the fibers in the two innermost PET braid layers were degraded to the point that they were
brittle and friable when strained or mechanically flexed. (See figure 2.)
8 Fractography is the study of the fracture surfaces of materials.

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5
3rdbraid
2"dbraid
l 5tbraid
3rd braid
2nd braid
Figure 2. Cross-section of accident hose showing brittleness of fibers in two innermost PET
braid layers.
The PET used for the yam braids is not chemical~ resistant to anhydrous ammonia or
ammonium hydroxide. As documented in several studies, exposure to anhydrous ammonia or
ammonia-related compounds results in a chemical reaction (ammonolysis) that can cause PET
fibers to degrade and lose strength.
9 (a) C. Lorenzetti, et. a!., "Chemical Recovery of Useful Chemicals from Polyester (PET) Waste from
Resource Conservation: A Survey of State of the Art," Journal of Polymers and the Environment, vol. 14, no. 1
(2006), pp. 89-101. (b) V. Sinha, et. a!., "PET Waste Management by Chemical Recycling: A Review," Journal of
Polymers and the Environment, vol. 18, no. I (2008). (c) M. Khaddaj, et. al., "Processing of New Materials Using
Thermal and Thermo-Vaporous Treatment of Terephthalates," Journal of Physics, Conference Series 121 (2008).
(d) R. Lamparter, et. a!., "Process for Recovering Terephthalic Acid from Waste Polyethylene Terephthalate, United
States Patent 4542239, September 17, 1985. (e) W. Murdoch, "Production ofTerephthalic Acid and Ethyl em: Glycol
from Polyethylene Terephthalate by Ammonolysis," United States Patent 6723873, April20, 2004.

<<<PAGE 8>>>

6
The outer rubber layer of the accident hose had an array of small pinpricks along its
length that was intended to allow the product that it was transferring to permeate through the
rubber layers of the hose and escape to the atmosphere. The purpose of this is to prevent gas
from becoming trapped in the hose wall and damaging the hose; this pinprick design is standard
in rubber hoses for LPG and anhydrous ammonia service. When the anhydrous ammonia
permeated through the rubber layers of the accident hose, it collected in the interstitial spaces of
the fibers within the PET braids. Also, the accident hose was likely exposed to moisture,
including humidity and rain, throughout its life cycle. Any absorbed and dissolved moisture
contained in the accident hose likely would have converted the trapped anhydrous ammonia to
ammonium hydroxide, leading to chemical degradation of the PET fibers.
Testing completed by both the NTSB 's Materials Laboratory and an independent
laboratory10 confirms that the PET fibers in the accident hose had sustained chemical degradation
that dramatically reduced the strength of the PET fiber. The NTSB concluded that the accident
hose failed because it was not chemically compatible with the anhydrous ammonia in the cargo
tank and that caused the chemical degradation, loss of mechanical strength, and ultimate failure
ofthe cargo hose.
Use of Chemically Incompatible Hose
When making deliveries, Werner drivers sometimes used facility-owned hoses instead of
the hose on the cargo tank vehicle. It is not known how many times the accident hose assembly
was used to transfer anhydrous ammonia before it failed.
Following the accident, a NTSB investigator discovered that the accident hose was the
LPG transfer hose that was originally assigned to trailer 2322, not the accident trailer (that is,
trailer 3002). Further investigation revealed that an anhydrous ammonia transfer hose
manufactured by Goodall Canada Inc. was carried on board trailer 2322 at the time of the
accident. According to records and statements from Werner, trailers 2322 and 3002 were stored
on the same secure lot in Tampa, Florida, for a several hours on May 17, 2009. Although Werner
stated that neither of its drivers had admitted to exchanging the transfer hoses, no other
opportunity existed for the LPG transfer hose to be placed on the accident trailer. Based on its
records, Werner estimated that the accident hose was used to unload anhydrous ammonia
between 2 and 12 occasions.
The physical properties of hazardous materials vary so greatly that cargo hoses are
constructed and intended for use with specific products and cannot be used interchangeably. As
previously noted, the hose in the accident hose assembly had internal fibers made of PET, which
is not chemically compatible with anhydrous ammonia. Therefore, any cargo hose containing
P.ET fibers would not be suitable for anhydrous ammonia service. The need for chemical
compatibility applies not only to the hose material, but to all components of the completed hose
assembly, including end fittings and couplers. The accident hose assembly had cast iron and
carbon steel couplings that were appropriate for anhydrous ammonia service but inappropriate
for LPG service, which requires spark-resistant materials such as brass, bronze, and stainless
steel.
10 Trace Laboratories also tested the accident hose.

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7
Therefore, the NTSB concluded that because of the chemical incompatibilities of the
hose material with anhydrous ammonia and of the couplers with LPG, Werner Transportation
Services, Inc.'s hose assembly was not suitable for use with either anhydrous ammonia or LPG
and should not have been carried on the cargo tank motor vehicle that was involved in this
accident. The PHMSA Office of Hazardous Materials Safety issues safety advisory notices to
help the public understand significant safety risks. PHMSA's safety advisories are published in
the Federal Register and provide a description of the safety issue and a recommended action to
resolve the issue. The Federal Motor Carrier Safety Administration (FMCSA), in conjunction
with its duties enforcing rules and regulations, conducting inspections, and licensing hazardous
materials carriers, also issues safety advisory notices pertinent to cargo tank safety. The two
agencies working together could provide the necessary outreach to assist carriers and facility
operators in avoiding the hazards associated with the use of chemically incompatible hoses and
couplers during loading and unloading operations. Therefore, the NTSB recommends that
PHMSA, with the Federal Motor Carrier Safety Administration, jointly issue a safety advisory
bulletin to inform cargo tank motor vehicle owners and operators, registered inspectors of these
vehicles, and transfer facility operators about the circumstances of this accident and actions
needed to prevent the occurrence of a similar accident.
Facility and Carrier Information
Tanner, of Southampton, Pennsylvania, owned and operated the Swansea,
South Carolina, facility at which this accident occurred. Tanner was registered with the FMCSA
and PHMSA as a private carrier, transporter, and shipper of various hazardous materials,
including anhydrous ammonia.
The cargo tank truck involved in this accident was owned and operated by Werner, of
Gainesville, Georgia. ·The company's business consists primarily of bulk transportation of
anhydrous ammonia to its customers. Werner also transports flammable gases, including LPG
and butane. At the time of the accident, all 21 of Werner's hazardous materials cargo trailers
were DOT specification MC 331 cargo tanks that are authorized for the transportation of
liquefied compressed gases, including both LPG and anhydrous ammonia.
Actions Preceding the Accident
About 7:40a.m. on July 15, 2009, after the Werner cargo tank truck arrived at the Tanner
facility in Swansea, South Carolina, the driver parked the truck, picked up the vapor hose
assembly that was lying on the ground next to the manifold, and connected the hose assembly to
the vent line on the cargo tank. He then removed the cargo transfer hose assembly from the
storage tube on the trailer, checked the pressure valves on the tank, and connected the hose
assembly to the liquid discharge fitting on the tank. A Tanner plant employee fastened the other
end of the transfer hose assembly to the facility piping manifold. The driver then engaged the
power take-off unit, turned on the pump, and checked the tank volume gauge on the side of the
cargo tank to make sure product was flowing from the cargo tank to the storage tank. The driver
watched the reading on the cargo tank volume gauge drop from 71 percent full to 64 percent full,
at which point he told the trainee to oversee the unloading while he completed paperwork in the
tractor. A driver trainee, who was accompanying the cargo tank truck driver, watched the gauge
to make sure the unloading was proceeding correctly. The last gauge reading observed by the

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8
trainee before the accident indicated that the cargo tank was about 53 percent full. The trainee
later estimated that at that time, 1 ,500 gallons had been transferred.
Just before 8:00a.m., about 7 or 8 minutes after the transfer had begun, the trainee heard
a pop sound followed by a loud rush of gas. He looked underneath the truck and saw a rupture in
the transfer hose assembly directly in front of him. He stated that he saw anhydrous ammonia
pluming upward from the rupture, forming a dense white cloud. The trainee immediately pushed
the emergency shutdown button on the rear of the cargo tank. Upon doing this, he noticed that
movement of the ammonia cloud quickly shifted in the direction of highway 321. He then turned
to the facility manifold to find a shutdown switch, but did not see one because the white
ammonia cloud was surrounding the manifold. He then evacuated through the south gate and ran
west into a wooded area. Eventually he heard the hose stop and saw the cloud lift soon after.
The driver stated that he also heard a loud pop about 8:00 a.m. and saw a cloud of gas
outside the driver's side window. He then turned off the engine to stop the trailer pump; put on
his half-face respirator; got out of the truck on the passenger side; and escaped through the white
cloud in front of the building along the fence, and exited through a gate.
To reduce the likelihood of using a hose assembly that is not chemically resistant to the
hazardous material to be loaded into or unloaded from a highway cargo tank, the motor carrier
and/or the facility carrier should not only visually inspect the cargo hose assembly for defects,
but also verify the chemical products that can be safely transferred through the hose assembly.
Verification can be accomplished by noting markings on the hose assembly or through a written
certification that lists acceptable products for the hose assembly and/or restrictions provided by
the owner of the hose assembly. Verification that a cargo hose assembly is appropriate for its
intended use also should be incorporated into the required pretransfer procedures. The NTSB
recommends that PHMSA require cargo tank motor vehicle carriers and transfer facilities to
verify (1) that cargo transfer hose assemblies, whether carried on the vehicle or provided by the
facility, are chemically compatible with the hazardous material to be transferred and (2) that
drivers verify hoses are marked as compatible with the material to be transferred before either
loading or unloading operations begin.
Inadequate Passive Emergency Discharge Requirements
Title 49 CFR 173.315(n)(2) requires that bulk transport vehicles transporting certain
liquefied compressed gases, including anhydrous ammonia, be outfitted with passive emergency
shutdown control equipment. The passive shutdown system serves as a means to shut off
automatically the flow of product from the cargo tank motor vehicle-without the need for
human intervention-within 20 seconds of an unintentional release caused by "a complete
separation of a liquid delivery hose." The two types of passive shutdown systems commonly
used in industry to satisfy this requirement are the Smart-Hose system found on the accident
hose and a permanently mounted, computer-controlled leak detection/shutdown system. The
computer-controlled leak detection/shutdown system activates in the event of pressure change,
whereas the Smart-Hose system activates as a result of mechanical failure of the hose assembly
that leads to the internal cable's being stretched to a predetermined length. Consequently, a
computer-controlled leak detection/shutdown system can shut off the flow of product as a result
of either partial or complete hose separation, whereas the Smart-Hose system can do so only in

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9
the event of complete hose separation and the tensioning of the internal cable. Both systems
satisfy the current requirement to stop the flow of product from the cargo tank if there is a
complete separation of the cargo hose assembly. However, in this accident, the hose assembly
did not experience a complete separation, and the internal cable inside the hose assembly was
unaffected. As a result, the internal cable was not stretched to the predetermined length necessary
and the flow rate was insufficient to activate the flapper valves in the ends of the hose assembly,
which would have cut off the flow of anhydrous ammonia in all directions.
The current regulation does not take into account a rupture of a cargo hose without
complete separation. For toxic or flammable gases, such as anhydrous ammonia and LPG, the
consequences of a hose rupture without separation can be just as severe as the consequences of a
complete hose separation. The outcome of either scenario is the uncontrolled and free flow of the
toxic or flammable gas from the cargo tank. The impact of the hose rupture in Swansea was
slightly mitigated because the driver trainee was able to trip the emergency shut-off valve on the
cargo tank and thereby prevent the complete release of ammonia from the cargo tank. Even so,
the cloud of ammonia gas generated by the accident was sufficient to cause a passing motorist to
suffer a fatal injury.
The current requirement11
was established to prevent catastrophic human loss and
property destruction that may result from the failure of a hose assembly while hazardous
liquefied compressed gases are loaded into and unloaded from highway cargo tank vehicles.
However, emergency discharge control should function under all-rather than only select-
circumstances; that is, any hose assembly failure rather than only failures that result in complete
hose separations. The NTSB concludes that given the unique hazards of toxic and flammable
liquefied compressed gases, the requirements in 49 CFR 173.315(n)(2) for passive emergency
discharge systems on highway cargo tanks fail to provide an acceptable level of protection
against all types of cargo hose assembly ruptures.
This accident demonstrates that hose assemblies do not always separate completely if
they fail, and the NTSB believes that passive shutdown systems designed to function as a result
of a complete separation of a hose assembly alone should not be permitted to satisfy the
emergency discharge control requirement. Therefore, the NTSB recommends that PHMSA
amend the provisions of 49 CFR 173 .315(n)(2) to require that passive emergency shutdown
control systems for highway cargo tanks activate in the event of a partial or complete failure of a
cargo hose assembly.
Hose Assembly Inspection and Testing Requirements
Title 49 CFR 180.416 establishes standards for inspecting and testing cargo hose
assemblies that are installed or carried on specification MC 330 and MC 331 cargo tank motor
vehicles that transport liquefied compressed gases such as anhydrous ammonia and LPG.
11 On September 8 1996, in Sanford, North Carolina, during delivery ofpropane to a bulk storage facility by an
MC 331 bulk transport, more than 35,000 gallons of propane were released. The discharge hose separated from its
hose coupling at the delivery end of the hose. Mos~ of the !ransport's 9,800 gallon~ o~propane and mo:~ than ~0,000
gallons from the storage tanks were released. Ifth1s quant1ty of released propane 1gmted, local authontles estimated
that about 125 emergency response personnel could have been injured or killed. Federal Register Volume 62,
Number 159 (Monday, August 18, I 997). http://www.gpo.gov/fdsys/pkg/FR-1997-08-18/html/97-21865.htm
(accessed July 5, 2011).

<<<PAGE 12>>>

10
Elements of the inspection and testing program include requirements for monthly inspections,
annual leak tests, testing of new and repaired hose assemblies, and a safety check of each hose
after unloading.
Under section 180.416( d), cargo tank motor vehicle carriers must visually inspect each
delivery hose assembly at least once each calendar month in which the hose is in service and
record the inspection date, the inspector's name, the identification number of the hose, the
company name, the test date of the transfer hose assembly, and the result of the inspection (that
is, pass or fail). The monthly hose inspection records are to be retained by the motor vehicle
carrier until the next test of the same type is completed.
Although section 180.416( d) specifies that a hose assembly must be inspected each
month it is in service, the regulation does not define what is meant by "in service." It seems
logical that a hose assembly carried on a cargo tank motor vehicle has the potential to be used on
any given day, and, therefore, it should be considered to be "in service." If a motor vehicle
carrier does not believe that it will be used, it will not necessarily consider it to be in service and
as a result, the hose assembly may not be inspected, as was the case in this accident. The intent
of this regulation presumably was to ensure that each hose assembly carried on a cargo tank
motor vehicle is inspected on a monthly basis. However, the wording in the regulation seems to
have created a loophole, because the term "in service" could be interpreted differently by various
motor vehicle carriers. Because monthly inspections are an important preventive measure for the
identification of physical deterioration, damage, and excessive wear, it is critical that these
inspections are performed routinely.
Typically, if PHMSA receives an industry inquiry regarding a specific hazardous
materials regulation, it publishes a formal interpretation of the regulation in question to clarify or
explain the intent of the regulation. These interpretations are disseminated to the respective
parties and posted on the PHMSA website. PHMSA has not published an interpretation on this
subject matter. The NTSB concludes that the lack of clarity of 49 CPR 180.416(d) regarding
monthly inspections of "in service" cargo hose assemblies can lead motor carriers to mistakenly
defer monthly inspections of transfer hose assemblies that are carried on cargo tank vehicles but
believed not to be used regularly. Therefore, the NTSB recommends that PHMSA publish and
disseminate a formal interpretation of 49 CPR 180.416( d) that includes the criteria that determine
when a cargo transfer hose assembly is "in service."
Inadequate Annual Hose Assembly Leakage Test Requirements
Title 49 CFR 180.407 specifies the requirements for annual leakage tests for specification
MC 330 and MC 331 cargo tanks that are used to transport liquefied compressed gases such as
anhydrous ammonia and LPG. In accordance with section 180.407(h)(l), the leakage test is to
include product piping "with all valves and accessories in place and operative."
Section 180.407(h)(4) requires registered inspectors of MC 330 and MC 331 cargo tanks to
inspect visually the delivery hose assembly for noticeable defects while the hose assembly is
under the same test pressure as the tank. This paragraph further states that hose assemblies that
are not permanently attached to the cargo tank motor vehicle can be inspected separately from
the cargo tank motor vehicle. Title 49 CPR 180.416( e) requires that the "owner of a cargo hose
assembly that is not permanently attached to a cargo tank motor vehicle must ensure that the

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hose assembly is annually tested" in accordance with section 180.407(h)(4).12 Under section
180.407(h)(4), in addition to the written record of the inspection of the cargo tank motor vehicle,
the registered inspector conducting the leakage test of the hose assembly must record the hose
identification number, the date ofthe test, and the condition of the hose assembly.
The most recent annual external visual inspection and leakage test records for Werner's
nine cargo tank motor vehicles that were equipped with hose assemblies were reviewed by
NTSB investigators; these records were found to be incomplete. Those tests were performed by
(1) L&L Repair and Testing, Inc., and (2) Boyd Service, Inc. Although each of the reports
indicated that the hose assembly had been visually inspected and found to be in an acceptable
condition, only three of the reports included a separate leakage testreport. The test reports for the
other six trailers indicated that the hose assemblies had been visually inspected and found to be
in acceptable condition; however, no indication existed that any of these hose assemblies had
been leak tested, and none of the required hose identification information was included in any of
the reports.
Additionally, although none of the 12 other vehicles that Werner owned at the time of the
accident were equipped with hose assemblies, the test records for those cargo tank vehicles
indicated that they were carrying hose assemblies that had been visually inspected and, in some
cases, the test records included hose identification numbers. The inconsistencies found in the
inspection and testing records strongly indicate that the registered inspectors had not been
consistently conducting leakage tests on the cargo hose assemblies on the cargo tank vehicles nor
were they completing annual leakage test reports as required.
The FMCSA also uncovered deficiencies in Werner's test records. During a posta,:cident
facility review, the FMCSA cited one of the companies contracted by Werner to perform
inspections because it failed to include required information on test and inspection reports and to
retrain hazardous materials employees every 3 years. The FMCSA reviewed 50 test and
inspection records and found that all of them were missing some ofthe required information. The
NTSB concludes that Werner's incomplete and incorrect inspection records of cargo tank and
hose testing suggests that the accident cargo hose assembly may not have been inspected and
tested properly before the accident. The NTSB believes that the compliance reviews conducted
by the FMCSA following this accident, and its subsequent enforcement actions, satisfied the
need for an audit of Werner and its contracted registered inspectors. Therefore, the NTSB is not
issuing any safety recommendations for this purpose at this time.
Notwithstanding the hose inspection deficiencies of Werner and its contracted registered
inspectors, the lack of clarity of the regulation (section 180.407(h)(4)) is also a factor in this
accident. After stating the requirement for registered inspectors to inspect the hose assemblies
while under leakage test pressure, the regulation states that "Delivery hose assemblies not
permanently attached to the cargo tank motor vehicle may be inspected separately from the cargo
tank motor vehicle." Although PHMSA has not published a formal interpretation of this
language, it has indicated to investigators that "inspected separately" is intended to mean that a
hose assembly does not have to be physically attached to the cargo tank to be tested for leaks. As
12 These leakage tests include visual inspection of the hose assemblies while they are under leakage-test
pressure (that is, 120 percent of maximum working pressure).

<<<PAGE 14>>>

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is the case with the language contained in section 180.416 regarding monthly hose inspections
being completed on hose assemblies that are in service, the NTSB believes that this language
could also be interpreted differently depending on the individual. One possible misinterpretation
would be that a hose assembly may be tested for leaks at a time other than during the annual
inspection of a cargo tank motor vehicle. PHMSA told investigators that a cargo tank motor
vehicle should not pass an annual inspection without its hose assembly being leakage tested,
since the hose assembly is considered to be part of the vehicle. However, the fact that registered
inspectors allowed 12 of Werner's vehicles to pass annual inspection when none of them were
equipped with hose assemblies indicates that industry and the regulators do not agree on the
scope and procedures for leakage testing. Therefore, the NTSB concludes that the lack of clear
requirements for testing cargo hose assemblies and cargo tank motor vehicles for leaks has
adversely affected the accuracy of the test records. The NTSB recommends that PHMSA issue
guidance to motor carriers and registered inspectors that clarifies the testing and the
recordkeeping requirements of 49 CFR 180.407 for cargo hose assemblies and cargo tanks that
are used to transport liquefied compressed gases to ensure that all hose assemblies are tested for
leaks on an annual basis.
Therefore, the National Transportation Safety Board makes the following safety
recommendations to the Pipeline and Hazardous Materials Safety Administration:
With the Federal Motor Carrier Safety Administration, jointly issue a safety
advisory bulletin to inform cargo tank motor vehicle owners and operators,
registered inspectors of these vehicles, and transfer facility operators about the
circumstances of this accident and actions needed to prevent the occurrence of a
similar accident. (H-12-2)
Require cargo tank motor vehicle carriers and transfer facilities to verify (1) that
cargo transfer hose assemblies, whether carried on the vehicle or provided by the
facility, are chemically compatible with the hazardous material to be transferred
and (2) that drivers verify hoses are marked as compatible with the material to be
transferred before either loading or unloading operations begin. (H-12-3)
Amend the provisions of Title 49 Code of Federal Regulations 173.315(n)(2) to
require that passive emergency shutdown control systems for highway cargo tanks
activate in the event of a partial or complete failure of a cargo hose assembly.
(H-12-4)
Publish and dissemi
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