[Federal Register: July 26, 1994]
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DEPARTMENT OF TRANSPORTATION
Research and Special Programs Administration
[Notice No. 94-7]
Safety Advisory; High Pressure Aluminum Seamless and Aluminum
Composite Hoop-Wrapped Cylinders
AGENCY: Research and Special Programs Administration (RSPA), DOT.
ACTION: Safety advisory notice.
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SUMMARY: RSPA is aware of ruptures involving two DOT-3AL cylinders made
of aluminum alloy 6351-T6. Cylinder ruptures pose a risk of death,
serious personal injury, and property damage. The purpose of this
notice is to advise owners of certain cylinders made of aluminum alloy
6351-T6 to follow the precautionary measures outlined in this notice.
RSPA also seeks information on ruptures involving other cylinders made
of aluminum alloy 6351-T6.
FOR FURTHER INFORMATION CONTACT: Charles H. Hochman or Gopala K.
Vinjamuri, telephone (202) 366-4545, Office of Hazardous Materials
Technology, Research and Special Programs Administration, U.S.
Department of Transportation, 400 Seventh Street SW, Washington, DC
20590-0001. Office hours are: 8:30 a.m. to 5 p.m., Monday through
Friday, except holidays.
SUPPLEMENTARY INFORMATION: RSPA has been notified of the rupture of two
DOT-3AL aluminum cylinders made of aluminum alloy 6351-T6. The first
cylinder rupture occurred in Deer Park, Texas. This cylinder was
manufactured in 1977 and was part of a self-contained breathing
apparatus (SCBA) unit. It ruptured while being filled to its marked
service pressure of 2216 pounds per square inch gauge (psig). The
second cylinder rupture occurred in North Miami, Florida. This cylinder
was manufactured in 1982 and was part of a self-contained underwater
breathing apparatus (SCUBA) unit. It ruptured while being filled to its
marked service pressure of 3000 psig. The person filling the SCUBA
cylinder sustained serious injury. In both ruptures, a piece of the
cylinder neck separated from the cylinder.
RSPA estimates that approximately seven million cylinders have been
manufactured using aluminum alloy 6351-T6. RSPA presently does not know
which cylinders among this population have the potential for similar
failure. Cylinders made of aluminum alloy 6351-T6 are known to be
susceptible to sustained load cracking (SLC) in the neck and shoulder
area of the cylinder. Extensive research, testing and analysis have
been performed on cylinders made of aluminum alloy 6351-T6 to determine
any correlation between SLC and the probability of rupture. Findings
indicated that cylinders with a marked service pressure below 4000 psig
failing due to SLC would leak and not rupture. Present data are
inconclusive as to why the two cylinders noted here ruptured instead of
leaked. RSPA is continuing to investigate the incidents.
Aluminum cylinders are widely used in industrial, medical, SCUBA
and SCBA services. Aluminum alloy 6351-T6 has been used in the
manufacture of the following DOT high pressure cylinders:
1. Cylinders (seamless aluminum) marked ``DOT 3AL'', including
those marked with ``DOT 3AL'' above or near one of the following
exemption or special permit numbers:
6498
7042
8107
8364
8422
2. Composite cylinders (aluminum-lined with hoop-wrapped, fiber-
reinforced plastic) marked with one of the following exemption numbers:
7235
8023
8115
To RSPA's knowledge, no cylinders have been manufactured under the
exemption or special permit numbers listed above, except DOT-E 7235,
since 1984. Any cylinder marked with one of these exemption or special
permit numbers most likely is made of aluminum alloy 6351-T6. (DOT-E
7235 cylinders are discussed more fully below.) If in doubt, contact
the cylinder manufacturer or distributor to identify the material of
construction.
The primary domestic manufacturers of DOT-3AL cylinders currently
in service are Luxfer USA; Walter Kidde Co.; Cliff Impact Division of
Parker Hannifer Corporation; and Catalina Cylinders, a division of
Aluminum Precision Products Inc. Luxfer USA is the only manufacturer of
DOT-E 7235 cylinders. Between 1987 and 1989, Luxfer USA discontinued
using alloy 6351-T6 and changed to alloy 6061-T6 for DOT-3AL cylinders
and DOT-E 7235 cylinder liners. Cylinders manufactured from alloy 6061-
T6 are not believed to be susceptible to SLC; therefore, they are not
subject to this advisory notice. According to Luxfer USA data, the
following types of cylinders stamped as manufactured by Luxfer USA
before the dates indicated below likely are made from alloy 6351-T6.
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DOT Service and type cylinder Part no. Date mfd.
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CO<INF>2
Spec. 3AL....... 1.2 and 1.5 lb........................................ C1.2, C1.5 1-89
Do.............. 2.18 lb............................................... C2-18 11-88
Do.............. 10 lb................................................. C10 8-88
Do.............. 5 lb.................................................. C5 6-88
Do.............. 15 lb................................................. C15 11-87
Do.............. 20 and 35 lb.......................................... C20, C35 4-88
Do.............. 50 lb................................................. C50 2-88
SCBA
Do.............. 7, 8 and 13 cu. ft.................................... L7, L8, L13 9-87
Do.............. 13.3 cu. ft........................................... L13-30 5-88
Do.............. 15 cu. ft............................................. L15 1-89
Do.............. 26 cu. ft............................................. L26 2-88
Do.............. 45 cu. ft............................................. L45 11-87
SCUBA
Do.............. 30 and 63 cu. ft...................................... S30, S63 5-88
Do.............. 40 cu. ft............................................. S40 6-88
Do.............. 50 and 92 cu. ft...................................... S50, S92 4-88
Do.............. 72 and 100 cu. ft..................................... S72, S100 8-87
Do.............. 80 cu. ft............................................. S80 1-88
Do.............. 80.8 cu. ft........................................... S80.8 5-87
Medical O<INF>1
Do.............. C..................................................... M9 1-88
Do.............. D and E............................................... MD, ME 12-87
Industrial
Do.............. 22 and 150 cu. ft..................................... N22, N150 5-88
Do.............. 33 cu. ft............................................. N33 11-88
Do.............. 60 and 122 cu. ft..................................... N60, N122 12-87
Do.............. 88 cu. ft............................................. N88 12-88
Do.............. Service Pressures 2016 and 3000 psig.................. 8-89
E-7235.......... Service Pressure 4500 psig............................ See below.
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All Walter Kidde DOT-3AL cylinders, of which production ceased in
January 1990, are made of alloy 6351-T6. Cliff Impact DOT-3AL cylinders
were made from alloy 6351-T6 before July 1990, at which time Cliff
Impact changed to alloy 6061-T6. Catalina Cylinders did not produce any
DOT-3AL cylinders from alloy 6351-T6; therefore, cylinders manufactured
by Catalina are not subject to this notice.
Until determined otherwise, any DOT-3AL or DOT-E 7235 cylinder
should be assumed to be made of alloy 6351-T6, if it was:
1. Manufactured by Luxfer USA before the applicable date listed in
the chart above;
2. Manufactured by Cliff-Impact before July 1990;
3. Manufactured by any other company in the United States,
excluding Catalina, before February 1990; or
4. Manufactured outside the United States.
For aid in determining whether a cylinder is constructed with alloy
6351-T6, contact the cylinder manufacturer or distributor. RSPA will
provide further information as it becomes available.
Any person who owns, uses, fills or retests an affected cylinder
should take the following precautions:
1. Do not fill the cylinder to greater than the marked service
pressure, except during a hydrostatic test.
2. Do not fill a cylinder that is beyond its required retest date.
3. Do not use a SCUBA or SCBA cylinder that is beyond its required
retest date.
4. Whenever you remove the cylinder valve, visually inspect the
interior of the cylinder neck and shoulder area for cracks. Any
evidence of a crack or crack-like defect may require further
evaluation. Contact the cylinder retester, distributor or manufacturer
for the procedure to be used in performing the visual inspection and
for rejection criteria. For guidance on inspecting Luxfer USA
cylinders, contact Luxfer USA Limited, Customer Service Department, PO
Box 5300, Riverside CA 92517, telephone (909) 684-5110.
RSPA wishes to reiterate two previous advisories it has issued
regarding DOT-E 7235 cylinders. On August 15, 1985, RSPA published an
exemption-related notice [Notice 85-4, 50 FR 32944] to alert users that
any cylinder marked DOT-E 7235, with a service pressure of 4500 psig
and not equipped with a neckring was required to be removed from
service by October 1, 1985. On March 24, 1993, RSPA published a safety
advisory notice [Notice 93-8, 58 FR 15895] after being notified of the
rupture of a cylinder authorized under DOT-E 7235 that had not been
fitted with a neckring. Cylinders properly fitted with the required
neckring are not susceptible to rupture. That notice stated in part:
Persons finding cylinders without the required neckring should
immediately take the following precautions.
1. If a cylinder has been filled, its entire contents should be
vented in order to relieve internal pressure.
2. The vented cylinders should be segregated from all other
cylinders by being placed in a secured area and marked conspicuously
with a tag bearing the notation ``Do Not Use'' or similar warning.
3. Under no circumstances should any of the cylinders in question
be sold or otherwise transferred, filled, refilled or used for any
purpose.
Once the above procedures have been taken, persons finding
cylinders without neckrings should contact the company, or distributor
from whom they were purchased, for their disposition.
Any person who is aware of the rupture of any DOT-3AL cylinder or
any other cylinder manufactured from aluminum alloy 6351-T6, whether
the incident was domestic or foreign, is requested to contact RSPA as
soon as possible.
Issued in Washington, DC on July 20, 1994.
Alan I. Roberts,
Associate Administrator for Hazardous Materials Safety.
[FR Doc. 94-18192 Filed 7-25-94; 8:45 am]
BILLING CODE 4910-60-P