tank inspections & fill pre 1989 AL tanks

[divemaster_jim]

I just heard a rumor about a "VE" stamp on pre-90 tanks, To be applied when the tank is hydro'd. Anyone else heard anything close?

 

[james croft]

That is what I heard. Tanks passing hydro/eddy get stamped with a VE. Have not seen this in print but was told this. I guess it can be found on a DOT site.

 

[Leadking]

That is what I heard. Tanks passing hydro/eddy get stamped with a VE. Have not seen this in print but was told this. I guess it can be found on a DOT site.

from the DOT website http://hazmat.dot.gov/regs/rules/final/71fr/71fr-51122.htm

Therefore, in this final rule, we are removing the
proposal expanding the scope of the rulemaking to include cylinders
manufactured of aluminum alloy 6351-T6 and used in carbon dioxide
service. We agree with the commenter's [CGA] statement that cylinders
used in carbon dioxide service generally operate at lower pressures
and, thus, have a reduced likelihood of developing SLC. Commenters are
correct there have been no reported

[[Page 51124]]

cylinder ruptures involving DOT 3AL cylinders manufactured of aluminum
alloy 6351-T6 and used in carbon dioxide, fire extinguisher, or other
industrial gas services. However, we will continue to monitor these
cylinders for evidence of SLC and, if the situation warrants, we may
revisit this issue in a future rulemaking.

B. 40-Year Service Life

Currently, cylinders manufactured of aluminum alloy 6351-T6 may be
used indefinitely so long as they conform to the requalification test
and inspection criteria established in the HMR. The SNPRM proposed a
40-year service life from the date of manufacture for DOT 3AL cylinders
manufactured of aluminum alloy 6351-T6 and used in SCUBA, SCBA, oxygen,
and carbon dioxide services. Several commenters [CGA; Air Liquide;
Barlen] to the SNPRM oppose the 40-year service life proposed for DOT
3AL cylinders manufactured of aluminum alloy 6351-T6. These commenters
suggest there is no evidence these cylinders are more likely to be
susceptible to SLC as they age and state the proposed amendment lacks
the appropriate test data, analysis, or statistical data to support the
implication that older cylinders are more likely to develop SLC. These
commenters further suggest requalification is the most appropriate
method to identify and condemn DOT specification cylinders regardless
of their age.
After consideration of these comments, we agree our proposed 40-
year service life for cylinders manufactured of aluminum alloy 6451-T6
and used in SCUBA, SCBA, carbon dioxide, and oxygen services is not
warranted at this time. We also agree with the commenters' [CGA; Air
Liquide; Barlen] statements that the requalification process is an
effective method of condemning deteriorated or damaged DOT
specification cylinders. Further, there is evidence these cylinders are
being voluntarily removed from service as defects are identified
through inspections and testing. Therefore, we are not adopting the 40-
year service life in this final rule. We will continue to monitor
cylinders manufactured of aluminum alloy 6351-T6 for evidence of SLC.
If the situation warrants, we may revisit this issue in a future
rulemaking.

C. Requalification Schedule for Eddy Current Examinations

Currently, the HMR specify periodic requalification requirements
for DOT 3AL cylinders. Periodic requalification includes a volumetric
expansion test and visual examination at least once every five years.
In the SNPRM, we proposed to require an initial eddy current
examination to be performed within three years of the effective date of
this final rule, and every 5 years thereafter. Commenters generally
support the proposed eddy current examination for cylinders used in
SCUBA, SCBA, oxygen and carbon dioxide services. However, several
commenters [CGA; Barlen; Matheson; Engineered Inspection; Western
Sales; Bruecks] assert the requirement to perform the initial eddy
current examination within three years of the effective date of this
final rule is unnecessary and may be difficult to comply with. These
commenters point out requiring the eddy current examination within
three years of the effective date may result in a large number of
cylinders pulled from service for requalification twice within a five
year period; once for the eddy current examination and once for the
scheduled periodic requalification. Several commenters [Engineered
Inspection; Western Sales; Bruecks] also assert the eddy current
marking could cause confusion because it is required to be marked in
association with the test date of the last volumetric expansion test,
which could be different from the date of the eddy current examination.
Additionally, one commenter [Matheson] is concerned the few companies
currently equipped to conduct eddy current examinations may become
overloaded with additional test work, resulting in backlogs and test
delays. To alleviate confusion and reduce the overall burden, these
commenters suggest revising the amendment to require eddy current
examinations at the time of a cylinder's next scheduled periodic
requalification, which is required every five years.
We agree. In this final rule, we are removing the proposal to
perform an eddy current examination within three years of the effective
date of this rule, and we are requiring an eddy current examination to
be conducted at the cylinder's next required periodic requalification
after January 1, 2007, the effective date of this final rule. As a
result, the date stamp on each cylinder will accurately reflect the
date of the last periodic requalification, including the eddy current
and visual examination.

 

[Scared Silly]

What about all the tanks that were failed VIP with visible cracks? Those should be added to the 10 that you are counting for more accurate numbers. I have seen dozens of the tanks with cracks in the neck during and after my inspector class. These tanks were just a time bomb waiting to go off.

By this logic you would need to add in all of the other cylinders that failed their VIP as well. Then we would need to add in all that failed hydro.

There are lies, damn lies, then there are statistics.



One part of Lee's posting of the DOT rule bears repeating:

"Therefore, we are NOT adopting the 40-year service life in this final rule."

No worries, many LDS stores are adopting their own rules :-(

 

[in_cavediver]

By this logic you would need to add in all of the other cylinders that failed their VIP as well. Then we would need to add in all that failed hydro.

There are lies, damn lies, then there are statistics.



One part of Lee's posting of the DOT rule bears repeating:

"Therefore, we are NOT adopting the 40-year service life in this final rule."

No worries, many LDS stores are adopting their own rules :-(

If you read carefully, there is this line:

"Further, there is evidence these cylinders are
being voluntarily removed from service as defects are identified
through inspections and testing."

This seems to indicate that the actions of the scuba industry annual VIP's and basically blacklisting these tanks was taken into account.

That said, I don't worry about old 6061 tanks. I am glad to see the 6351 tanks go. And for the record, yes, there are many 'safe' ones out there and I don't really care. I've been offered two of them and I turned them both down. Told the owners to drain them and get the $20-$30 bucks each at the recycling center. (of course now, I'd tank one just to cut it in half and look at it)

 

[Gil57usa]

As long as the visual and hydro is good there is no reason not to fill them. There are some older tanks that can be identified by the code SP or E preceding a number. These tanks should be over stamped 3AL by the Hydro tester. If it says 3AL it is made from 6061 alloy that is the current safe material.

 

[DiveSite]

As long as the visual and hydro is good there is no reason not to fill them. There are some older tanks that can be identified by the code SP or E preceding a number. These tanks should be over stamped 3AL by the Hydro tester. If it says 3AL it is made from 6061 alloy that is the current safe material.

The comment in RED is another example of mis-information being taken as fact because it was "on the internet" or "someone on ScubaBoard said it was true".

Here is a link to a picture of a tank that disproves what the above post states as fact.
The tank in the picture is a LUXFER with the 3AL stamped from the factory and the original hydro date is 08/1982 which is the 6351-T6 alloy.

http://www.divesitescuba.com/3AL_TANK.jpg

 

[Scared Silly]

The above is certainly true, I was down at my hydro facility last fall and saw a 3AL cylinder with two SLC in it. At first it threw me until I look at the mfg. date. Some 1980's date on it.

 

[oxyhacker]

The DOT 3AL specification was created in '82 or so, and the 6351 alloy continued to be used until '89, so there are a lot of 6351 tanks around which were factory stamped 3AL.

 

[DiveSite]

The DOT 3AL specification was created in '82 or so, and the 6351 alloy continued to be used until '89, so there are a lot of 6351 tanks around which were factory stamped 3AL.

That was one of the points I was trying to make. The other being, just because somebody on ScubaBoard says something is true doesn't make it true.