United States Nuclear Regulatory Commission - Protecting People and the Environment

Information Notice No. 95-01: Dot Safety Advisory: High Pressure Aluminum Seamless and Aluminum Composite Hoop-Wrapped Cylinders

                                 UNITED STATES
                         NUCLEAR REGULATORY COMMISSION
                   OFFICE OF NUCLEAR REACTOR REGULATION AND
               OFFICE OF NUCLEAR MATERIAL SAFETY AND SAFEGUARDS
                          WASHINGTON, D.C. 20555-0001

                                January 4, 1995


NRC INFORMATION NOTICE 95-01:  DOT SAFETY ADVISORY:  HIGH PRESSURE ALUMINUM 
                               SEAMLESS AND ALUMINUM COMPOSITE HOOP-WRAPPED    
                               CYLINDERS


Addressees

All U.S. Nuclear Regulatory Commission licensees.

Purpose

The U.S. Nuclear Regulatory Commission (NRC) is issuing this information
notice to alert addressees to a safety concern for workers identified in the
safety advisory (see Attachment 1) recently issued by the Research and Special
Programs Administration of the U.S. Department of Transportation (DOT).  The
DOT notice advises users of certain high pressure cylinders made of aluminum
alloy 6351-T6 to follow precautionary measures to prevent or mitigate cylinder
ruptures.  It is expected that recipients will review the information for
applicability to their facilities and consider actions, as appropriate, to
avoid similar problems.  However, suggestions contained in this information
notice are not NRC requirements; therefore, no specific action or written
response is required.

Description of Circumstances

On July 26, 1994, the Research and Special Programs Administration of DOT
issued a safety advisory, "High Pressure Aluminum Seamless and Aluminum
Composite Hoop-Wrapped Cylinders," in the Federal Register (Volume 59,      
No. 142, pages 38028-38030).  The advisory contains a description of two
catastrophic cylinder failures.  The first occurred at a chemical plant in
Texas, where a self-contained breathing apparatus aluminum alloy air cylinder
ruptured while being filled to its rated pressure of 15.4 MPa [2216 psig]. 
The second failure was the rupture of a self-contained underwater breathing
apparatus cylinder also made of the same type alloy that also occurred while
the cylinder was being filled.  The rupture caused serious injury to the
attending technician.  In both events, a piece of the cylinder neck separated
and was blown away with great force.  Ruptures like these are unexpected for
aluminum alloy 6351-T6, since current metallurgical findings and modeling
predict only leaking at pressures below 27.7 MPa [4000 psig].  The DOT
investigation of these failures is continuing.

The DOT advisory applies to seamless aluminum cylinders marked "DOT 3AL,"
manufactured under one of the following exemption or special permit numbers:
6498, 7042, 8107, 8364, or 8422; composite cylinders affected are marked with
one of the following exemption numbers:  7235, 8023, or 8115.

9412270314.                                                            IN 95-01
                                                            January 4, 1995
                                                            Page 2 of 3


Discussion

These two events are the first known ruptures of aluminum alloy 6351-T6 in the
seamless (non-composite) cylinder neck and shoulder area at pressures below
27.7 MPa [4000 psig].  Previous problems with the same alloy in composite
cylinders (hoop-wrapped aluminum cylinders) have been described in various
National Institute for Occupational Safety and Health, DOT, and NRC generic
communications, which all dealt with ruptures or cracking of cylinders rated
at 31.1 MPa [4500 psig] or cracking (leaking) of cylinders with a service
rating of 15.4 MPa [2216 psig].  

DOT cautions users to take reasonable precautions as described in its advisory
when using or handling affected cylinders, and to call the manufacturer or
distributor if they have any questions about that particular unit.  Anyone
aware of the rupture of any DOT 3AL cylinder made of aluminum alloy 6351-T6
can call the technical contacts at DOT, as DOT is collecting information and
insight on this matter, and is planning to consider additional advisories.

Licensees may wish to share this information with other potential users, such
as local fire departments.

Related Generic Communications

.     NRC Information Notice 83-68, "Respirator User Warning:  Defective Self-
      Contained Breathing Apparatus Air Cylinders"

.     NRC Information Notice 84-34, "Respirator User Warning:  Defective Self-
      Contained Breathing Apparatus Air Cylinders"

.     NRC Information Notice 85-48, "Respirator User Notice:  Defective Self-
      Contained Breathing Apparatus Air Cylinders"

.     NRC Information Notice 86-24, "Respirator User Notice:  Increased
      Inspection Frequency for Certain Self-Contained Breathing Apparatus Air
      Cylinders"
.                                                            IN 95-01
                                                            January 4, 1995
                                                            Page 3 of 3


This information notice requires no specific action or written response.  If
you have any questions about the information in this notice, please contact
one of the NRC technical contacts listed below, the DOT contacts mentioned in
the subject DOT safety advisory, or the cylinder manufacturer.

/S/'D BY RFBURNETT                        /S/'D BY BKGRIMES


Robert F. Burnett, Director               Brian K. Grimes, Director
Division of Fuel Cycle Safety             Division of Project Support
  and Safeguards                          Office of Nuclear Reactor Regulation
Office of Nuclear Material Safety
  and Safeguards

Technical contacts:  Jim Wigginton, NRR
                     (301) 504-1059

                     Jerry Roth, NMSS
                     (301) 415-7257

Attachments:
1.  DOT Safety Advisory, "High Pressure Aluminum Seamless 
      and Aluminum Composite Hoop-Wrapped Cylinders"
2.  List of Recently Issued NMSS Information Notices 
3.  List of Recently Issued NRC Information Notices

.      The following is an electronic copy of Attachment 1, the Federal
      Register notice containing the DOT Safety Advisory.  The content
      is identical to the paper copies of the attachment, although the
      format is somewhat different..������������������
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.
������������������
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. 
...


�������������������������������������������������������������������������������
     DOT     �   Service and type cylinder   �     Part no.    �   Date mfd.    
�������������������������������������������������������������������������������
             �                               �                 �                
             �             CO2               �                 �                
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 O1                    �                 �                
   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.     
             �                               �                 �                
�������������������������������������������������������������������������������
.
   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


Page Last Reviewed/Updated Monday, November 18, 2013