blkhwkfxer
Guest
Can these tanks still have hydro procedure done, refilled and used and worth the money spent on it or should I send it to the recycled bin?
U.S. Divers Tank DOT SP6493 Question
- Thread starter blkhwkfxer
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Greg Barlow
Contributor
If the cylinder is a Luxfer version manufactured from 6351 alloy then I would recommend selling it as scrap aluminum. They are the cylinders that have been associated with sustained load cracking. This occurs in the neck region where the threads are found.
Catalina aluminum tanks were never manufactured from 6351, so they do not suffer from the same fate.
Cylinders composed of 6061 alloy don't seem to have any problems.
Greg Barlow
Catalina aluminum tanks were never manufactured from 6351, so they do not suffer from the same fate.
Cylinders composed of 6061 alloy don't seem to have any problems.
Greg Barlow
Scared Silly
Contributor
Please do a search on SP6498 or AL6351 cylinders as this question has been discussed ad nauseum.
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See below
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Are you sure it's not SP 6498???
Ditto...SP6498 was a special permit granted to Luxfer for Alcan 6351-T6 alloy aluminum tanks.
There were several Exemption/Special Permit tanks that were brought into the 3AL standard in 1982 - SP6498, E6498, E7042, E8364 and E8422 and they are legal to fill if in current hydro, but they must be stamped 3AL when they come in for a hydro test. Even though this rule has been in effect since 1982, it is still common to see them come in without a 3AL stamp even though they have been hydro tested a few times since that date.
There were other aluminum special permit tanks that did not fall under the 3Al standard - SP6688, E6688, SP6576, SP7039 and E7235. These tanks must be removed from service and cannot be legally hydro tested or returned to service (in the US at least, in Canada they are I think grand fathered in and can still be used.)
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That is separate from the 6351-T6 sustained load cracking (SLC) issue. There is lots of information out there if you do a search, but in short:
1) There has not been a single documented catastrohpic failure of a properly inspected (current hydro test and current Visual Plus/Eddy Current inspection) since 2000 when Visual Plus/Eddy Current inpsection protocols were implemented.
2) There are still millions of 6351-T6 alloy tanks in service in SCUBA, SCBA, medical O2 and CO2 service, so when you combine 1 and 2 the statistical risk of having one blow up on you is virtually zero. (I crunched the most onerous and threatening numbers available in a past thread and came up with something to the effect that if you filled 200 6351T-6 tanks per day, you'd have to fill them for 242 years before you had one blow up. The odds are very very small.)
3) It is fairly comon for the average hydrotest/requalification facility to have several 6351-T6 tanks per month fail due to SLC.
4) One group uses #3 as evidence that the test protocols work and they cite #1 and #2 .
5) The other group uses #3 as evidence that 6351-T6 tanks are dangerous and they ignore #1 and #2.
6) Test data and field reports since 2000 clearly indicates that SLC cracks progress slowly from the point they are first detectable until catastrophic failure occures. Consequently the DOT only requires Visual Plus/Eddy Current inspection every 5 years as part of the hydro test/requalification process. A crack not visible then will not progress to the point of failure before the next hydro test. The scuba industry standard of a Visual Plus/Eddy Current every year as part of the VIP, ensures you have 5 more chances to catch any crack missed at the hydro test.
7) Despite all of the above, many shops fixate on #5 and refuse to fill 6351-T6 alloy tanks.
8) Many shops refuse to fill any tank made before 1990, even though Catalina tanks have always used 6061-T6 alloy and that most tanks switched to 6061-T6 alloy by mid 1988, meaning they refuse to fill a lot of 6061-T6 alloy tanks as well.
9) Some shops refuse to fill any tanks made more than 20 years ago. I don't normally do business with those shops as I find that kind of ignorance often pervades the entire operation and I have a low tolerance for ignorance and stupidity. On the other hand, you have to be realistic - it is their shop and if they feel it is a risk to fill 6351-T6 tanks, you are not going to be able to talk them out of it as it is an emotional or in some cases authoriitarian argument rather than a rational or scientific one.
There were several Exemption/Special Permit tanks that were brought into the 3AL standard in 1982 - SP6498, E6498, E7042, E8364 and E8422 and they are legal to fill if in current hydro, but they must be stamped 3AL when they come in for a hydro test. Even though this rule has been in effect since 1982, it is still common to see them come in without a 3AL stamp even though they have been hydro tested a few times since that date.
There were other aluminum special permit tanks that did not fall under the 3Al standard - SP6688, E6688, SP6576, SP7039 and E7235. These tanks must be removed from service and cannot be legally hydro tested or returned to service (in the US at least, in Canada they are I think grand fathered in and can still be used.)
-------
That is separate from the 6351-T6 sustained load cracking (SLC) issue. There is lots of information out there if you do a search, but in short:
1) There has not been a single documented catastrohpic failure of a properly inspected (current hydro test and current Visual Plus/Eddy Current inspection) since 2000 when Visual Plus/Eddy Current inpsection protocols were implemented.
2) There are still millions of 6351-T6 alloy tanks in service in SCUBA, SCBA, medical O2 and CO2 service, so when you combine 1 and 2 the statistical risk of having one blow up on you is virtually zero. (I crunched the most onerous and threatening numbers available in a past thread and came up with something to the effect that if you filled 200 6351T-6 tanks per day, you'd have to fill them for 242 years before you had one blow up. The odds are very very small.)
3) It is fairly comon for the average hydrotest/requalification facility to have several 6351-T6 tanks per month fail due to SLC.
4) One group uses #3 as evidence that the test protocols work and they cite #1 and #2 .
5) The other group uses #3 as evidence that 6351-T6 tanks are dangerous and they ignore #1 and #2.
6) Test data and field reports since 2000 clearly indicates that SLC cracks progress slowly from the point they are first detectable until catastrophic failure occures. Consequently the DOT only requires Visual Plus/Eddy Current inspection every 5 years as part of the hydro test/requalification process. A crack not visible then will not progress to the point of failure before the next hydro test. The scuba industry standard of a Visual Plus/Eddy Current every year as part of the VIP, ensures you have 5 more chances to catch any crack missed at the hydro test.
7) Despite all of the above, many shops fixate on #5 and refuse to fill 6351-T6 alloy tanks.
8) Many shops refuse to fill any tank made before 1990, even though Catalina tanks have always used 6061-T6 alloy and that most tanks switched to 6061-T6 alloy by mid 1988, meaning they refuse to fill a lot of 6061-T6 alloy tanks as well.
9) Some shops refuse to fill any tanks made more than 20 years ago. I don't normally do business with those shops as I find that kind of ignorance often pervades the entire operation and I have a low tolerance for ignorance and stupidity. On the other hand, you have to be realistic - it is their shop and if they feel it is a risk to fill 6351-T6 tanks, you are not going to be able to talk them out of it as it is an emotional or in some cases authoriitarian argument rather than a rational or scientific one.
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jbrians
Contributor
I am the proud owner of 4 SPXXX tanks and have no problem getting them filled when current at 4 of the 5 LDS.
The 5th one doesn't get much trade from me as their ignorance has caused doubt in my mind and I question every opinion they have now.
The 5th one doesn't get much trade from me as their ignorance has caused doubt in my mind and I question every opinion they have now.
Rick Christ
Contributor
http://www.scubaboard.com/forums/tanks-valves-bands/269221-tanks-ones-cant-re-hydroed-4.html
Check my post, it may answer your question
Check my post, it may answer your question
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