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Luxfer 6531 Tanks The Luxfer 6351 aluminum alloy
was used in tanks that predate 1989. In a very few of those
tanks there has been found sustained-load cracking in and
around the neck and threads of the tank. Out of 30,000,000
6351 tanks, 17 ruptured. That is 0.00006%! Out of 6,100,000
6351 tanks, 0.37% were found to have sustained-load
cracking. It takes an average of approximately 6 years for a
tank with sustained-load cracking to begin to leak. The
tanks that have developed sustained-load cracking are ones
that have been abused, damaged, or over-filled.
RIVERSIDE, Calif. (December 9, 2002)-Luxfer Gas Cylinders
has announced a new scuba tank trade-in program to enable
owners of older Luxfer scuba tanks manufactured in the U.S.
from 6351 aluminum alloy to trade in their tanks and receive
a $50 credit for each tank toward the purchase of new scuba
tanks made from Luxfer's proven, proprietary 6061 alloy.
Luxfer implemented the simple four-step program outlined
below on January 1, 2003. The program ended on December 31,
2003. That was a limited one-year offer!
To determine whether your Luxfer scuba tank is made from
6351 aluminum alloy, check the original hydrostatic test
date (the earliest date) stamped on the crown. (Look for a
month/year combination, such as 3/75.) If the stamped year
is 1972 through 1987, the tank is made from 6351 alloy. A
limited number of Luxfer scuba tanks were also made from
6351 alloy during the first half of 1988. If you have a 1988
tank with an original hydrostatic test date of 6/88 or
earlier, Luxfer assumed that it was a 6351-alloy tank and
issued an RG number. Tanks with an original hydrostatic test
date of 7/88 or later are made from 6061 alloy and were not
eligible for the trade-in program.
Why did Luxfer sponsor this program? Is something wrong
with these older tanks made from 6351 aluminum alloy?
As long as these older tanks are properly inspected and
requalified as required by U.S. Department of Transportation
(DOT) and Luxfer, you may continue to use them. DOT requires
that the tanks be requalified every 5 years. In addition,
Luxfer requires that the tanks receive a visual inspection
by a properly trained inspector and an eddy-current test at
least every 2˝ years. (Please note as well that an annual
visual inspection is a standard practice in the U.S. scuba
industry, and Luxfer endorses this practice for all scuba
tanks, not just those made from 6351 alloy.)
Luxfer sponsored this trade-in program for commercial
purposes. The program operates much like a coupon for a
commercial product. The intent is to increase demand and
brand awareness in the marketplace by offering a trade-in
discount on a new Luxfer scuba tank. This trade-in program
also enables divers to upgrade tanks made from older-
technology aluminum alloy to newer tanks made from Luxfer's
proprietary 6061 aluminum alloy.
How do I know if it is a Luxfer tank?
You can tell by several markings on the tank. The serial
number will begin with a prefix. (For example, in the case
of an 80-cubic-foot tank, the prefix will be a P.) The
serial number line should also contain Luxfer's name.
| TANK SIZE |
PREFIX |
TANK SIZE |
PREFIX |
TANK SIZE |
PREFIX |
| S030 |
UU |
S063 |
PP |
S808 |
UV |
| S040 |
LS |
S072 |
Y |
S092 |
US |
| S050 |
R |
S080 |
P |
S100 |
UT |
The US Government has determined that no recall is
warranted for the Luxfer 6351 tanks. No scuba cylinders have
been recalled! The Luxfer 6351 tanks are not to be condemned
unless they show evidence warranting such. There is no
reason for a dive shop to refuse to fill them. There is the
potential to wrongly convince a customer they should be
replacing the cylinder with a new one.
Luxfer scuba cylinders were manufactured from 6351 aluminum
alloy during the following periods:
• United States : 1972 through mid-1988
• England : 1967 through 1995
• Australia : 1975 through 1990
Luxfer requires that every Luxfer 6351-alloy all-aluminum
scuba cylinder be visually inspected at least every 2.5
years by a properly trained inspector. As part of this
inspection, Luxfer further requires that the cylinder neck
be tested with an eddy-current device such as Visual Plus™,
Visual Plus 2™, Visual Plus 3™,Visual Eddy™ or equivalent
non-destructive testing equipment. When properly used,
eddy-current devices contribute significantly to early
detection of difficult-to-observe sustained-load cracks in
the necks of 6351-alloy cylinders. If the cylinder passes
the inspection, the inspector will document that fact. If
the cylinder fails the inspection, it must be removed from
service immediately. Do not use Luxfer 6351-alloy scuba
cylinders that have not been both visually inspected and
eddy-current tested and then properly documented.
This Luxfer-required visual and eddy-current inspection
is in addition to periodic requalifications (including
retesting and inspections) required or recommended by
various regulatory agencies around the world. The intervals
between retests and inspections vary from country to
country.
In addition to the required inspection and testing
described above and in keeping with U.S. scuba industry
standards, Luxfer recommends that all Luxfer 6351-alloy
scuba cylinders be visually inspected at least once each
year by a properly trained inspector.
For cylinders in heavy use (for example, those filled
five or more times a week, Luxfer recommends visual
inspection every four months. For more information, refer to
Luxfer's Scuba Cylinder Inspection Guide, which is available
by calling Luxfer at 800-764-0366 or by visiting the Luxfer
web site at
www.luxfercylinders.com.
Cylinders made from Luxfer's proprietary 6061 alloy are
not susceptible to sustained-load cracks. Therefore, Luxfer
does not recommend the use of earlier-generation
eddy-current devices-e.g., Visual Plus, Visual Plus 2, and
Visual Eddy-with Luxfer 6061-alloy cylinders because field
experience has shown that using these devices can result in
misleading "false-positive" readings and erroneously
condemned cylinders.
However, Luxfer does approve the use of the Visual Plus
3™ eddy-current device with Luxfer 6061-alloy cylinders.
After laboratory testing, Luxfer has determined that
properly calibrated VisualPlus 3 equipment eliminates the
"false positive" problem, accurately measures features in
the neck area of aluminum cylinders, and generally provides
correct pass or fail assessments with cylinders made from
Luxfer's 6061 alloy. As of the date of this Luxfer Policy
Statement, VisualPlus 3 is the only eddy-current testing
device suitable for use with Luxfer 6061-alloy cylinders.
(During a visual tank inspection (VTI) at Deep-Six, the
VisualPlus 3 is used on all aluminum cylinders and a full
report is given to the owner!)
Luxfer emphasizes that the use of eddy-current devices to
improve the quality and accuracy of inspections does not
eliminate the need for a thorough visual inspection by a
properly trained and qualified inspector.
In keeping with U.S. scuba industry standards, Luxfer
recommends annual visual inspection of Luxfer 6061-alloy
cylinders by a properly trained inspector. For cylinders in
heavy use (for example, those filled five or more times a
week) Luxfer recommends visual inspection every four months.
These recommended inspections are in addition to periodic
requalifications (including retesting and inspections)
required or recommended by various regulatory agencies
around the world. The intervals between retests and
inspections vary from country to country. |