granthammer:
What is the average life span of aluminum tanks? Yes of coarse they were stored properly with air in them...I found a set in the local paper, but they havn't been used in 10 years! Should It be a problem?
Check the MFG and date of MFG before you buy. There are a lot of AL tanks out there made of an alloy 6351-T6 that DOT has issued a safety notice on. Small problem with them exploding.
http://www.connected.bc.ca/~baquatics/explode.html
http://www.scubabomb.freeservers.com/
Before you buy have them HYDRO tested and an EDDY CURRENT (VIS PLUS) Test on the neck. Personally, if they are of the suspect AL alloy, I would pass on them.
Check these DOT websites
http://hazmat.dot.gov/3al_toc.pdf
http://hazmat.dot.gov/3al_mainreport.pdf
I have quoted the DOT informtion on the alloys to avoid below:
LUXFER, who mfg a lot of these tanks did NOT issue a recall, but did offer a $50.00 rebate to anyone who turned in an AL 6351-T tank made by them (essentially ther pre Jul 1990 AL tanks). That rebate offer ended Dec 31, 2003.
From DOT
http://hazmat.dot.gov/rules/68fr-53314.htm
Cylinders manufactured of aluminum alloy 6351-T6 prior to July 1990
include seamless aluminum cylinders 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, and 8422. In addition,
unless determined otherwise, affected individuals should assume that a
DOT 3AL or DOT-E 7235 cylinder manufactured outside the United States
is constructed of aluminum alloy 6351-T6.
On August 8, 2002, we published a final rule (Docket HM-220D, 67 FR
51626) that amended the requirements of the HMR applicable to the
maintenance, requalification, repair, and use of DOT specification
cylinders. In that final rule, we added the following amendments
pertaining to DOT specification cylinders made with aluminum alloy
6351-T6:
[sbull] We removed the authorization for the manufacture of DOT
specification cylinders from aluminum alloy 6351-T6 because cylinders
manufactured with this aluminum alloy have a greater risk of failure
than other aluminum cylinders.
[sbull] We prohibited these cylinders for Hazard Zone A materials
effective on October 1, 2002. After that date, cylinders made of
aluminum alloy 6351-T6 may not be filled and offered for transportation
in toxic inhalation hazard service.
[sbull] We prohibited the use of cylinders manufactured of aluminum
alloy 6351-T6 for gases having pyrophoric properties.
[sbull] We required a DOT specification or exemption cylinder made
of aluminum allow 6351-T6 to be inspected for evidence of sustained
load cracking in the neck and shoulder area.
As stated earlier, the majority of the SLC-related ruptures
occurred in SCUBA, SCBA and oxygen services. Additionally, for these
services, the probability of cracking increases due to the increased
frequency with which cylinders in these services are filled. We
recognize that cylinders used in beverage service are also filled on a
frequent basis. However, beverage service cylinders typically are
filled to lower pressures than cylinders used in SCUBA, SCBA, and
oxygen services, thereby reducing the stress levels to which beverage
service cylinders are subjected. Moreover, in SCUBA and SCBA services,
the cylinder is attached to the back of a diver or firefighter, which
substantially increases the risk of injury or fatality in the event of
a rupture. Similarly, an oxygen cylinder may be placed close to a
patient in the hospital or home. SLC could also result in an oxygen
leak that may cause an explosion. Therefore, because of the higher risk
in SCUBA, SCBA and oxygen services, this rulemaking (HM-220F) proposes
to adopt a standard for early detection of SLC to reduce the risk of a
cylinder rupture.