Ed Graves wrote:

> Question for the group. A chain of dive shops here in the Puget Sound
region has
> made the decision not to fill any aluminum scuba 'tanks' manufactured
before 1989.
> Is this an extreme reaction?

I don't own a single 6351-T6 alloy tank.  I've always had Catalina tanks and
they never used this alloy.  Woe be unto a shop that declines to fill my
tanks even after they have been eddie tested.  I have and can again tell the
world what I think of anyone who tries this.

The problem with 6351-T6 alloy is not just that it's more prone to failure,
which it seems to be.  The bigger problem is how it fails.  Tanks made of
other alloys normally fail by splitting.  It's bad enough to have 80 cubic
feet or more of compressed air released suddenly, but not nearly as bad as
what happens when a 6351-T6 tank fails.  They tend to fragment, exploding
rather than splitting.  It's the explosive fragmentation that is most
responsible for the seriousness of injuries to dive shop personnel.  This is
the source of the fear and, in my opinion, it's a very valid fear.

This came up in Florida not long ago.  In fact, I believe a Florida incident
was what finally made 6351-T6 alloy a popular cause.  A tank explosion that
severely injured a teenager in Palm Beach County lit the fire and several
additional instances in Dade (Miami) and Monroe (Keys) Counties fanned the
flames.  A S. Florida dive assocation, not surprisingly made up entirely of
dive shop representatives, announced that their new policy was going to be
no fills of 6351-T6 tanks that had not been Visual Plus tested in the last 6
months and no fills of any tank over 10 years old.  All hell immediately
broke loose.  You may assume that I was quite active in the discussion since
all 4 of the tanks I owned at the time were just over 10 years old.  The end
result was that the policy died a very quick death.  There were a number of
factors which were pivotal:
1. If the Visual Plus eddie test was good enough to determine which 6351-T6
tanks were to be replaced and which were to be left in service, then it was
good enough for tanks over 10 years that passed it, hydro and visual tests.
All data supporting the test was on tanks that had failed the test.  There
was none on tanks that passed it and subsequently failed.  While age
obviously contributes to the potential for micro cracks in the neck area of
tanks, there was no evidence that, lacking such cracks, age was a factor.
2. The shops were going to charge a hefty fee for the Visual Plus test.
They had absolutely nothing to say about why it would be required semi
annually.  There simply was no support for such a rule.

The end result of all of this was a change in procedures for most shops, but
nothing like what was originally proposed.  As of now, shops fill tanks that
are current for visual and hydro, just like they always did.  Most, but not
all shops, use the Visual Plus or similar test on aluminum tanks, at an
increased price, but only annually.  There may be some shops that decline to
fill aluminum tanks without the Visual Plus test and, to be honest, there
should be.  Nobody wants another run of in-shop explosions.  As far as I
know, none of the local shops even tried to enforce a 10 year age limit on
tanks that they fill.  I know nobody has ever hesitated to fill one of mine.

Your area is not the first to follow S. Florida's attempted lead.  The
information that led to the idea in the first place was widely circulated,
as was Florida's proposed policy.  The death of the policy, as usually
happens, was not nearly as well publicized.  If I were you, here's what I'd
do.  This is my opinion and not necessarily what everyone will decide:
1. If you have tanks made of 6351-T6, destroy them and get new ones.  While
there is no evidence that tanks that pass the Visual Plus are unsafe, that
may be only because the Visual Plus has not been around long enough to
develop teh evidence.  I won't own one and if I won't own it, I won't sell
or even give it to someone else.  The cost of a few tanks is not worth the
potential risk to me.
2. Make a point of talking to specific shops that employ the policy.  Take
your tanks to them and if they decline to fill them, leave, stating your
reason for leaving clearly and loud enough for other customers to hear.  Do
it during at times when other customers are likely to be present.  The shops
need to know that their policy is sending their business to shops who are
more reasonable.
3. Make use of Rec.Scuba forums and any other public forum you can to state
your opinions on the policy and be persistent in demanding support for any
policies you think are founded only in a shop's desire for profit.  The
diving public is a powerful economic force in the industry, but only when a
large proportion of us are involved.
4. Be watchful for false relationships in supporting data.  On of the most
common is "All (or a majority) of the tanks that failed the Visual Plus were
over 10 years old." and "All (or a majority) of the 6351-T6 tanks that
failed were over 10 years old."  Both may be true, but neither says anything
about tanks that passed the Visual Plus.  Another is "We don't know how
quickly cracks develop, so we need semi annual tests."  This also may be
partly true, but not knowing is not a reason to subject customers to high
cost tests.  If they don't know, they need to find out.  If not knowing were
the critereon, then tests every time a tank is filled is just as supportable
as once every 6 months, or any other arbitrary frequency.
5. You're going to run into shops that simply do not know what to do and are
following practices of others on no basis other than "if others are doing
it, it must be OK."  Be kind to those who are honest enough to admit this,
encouraging them to seek information of their own so that they can make a
more informed decision on the basis of fact rather than following the lead
of others.  These are the shops most likely to realize how much the proposed
policy is based on fear rather than logic and are most likely to decide in
favor of rational analysis rather than panic.
6. If you have tanks that are not made of the 6351-T6 alloy, take them to
shops that include the Visual Plus or similar test and pay a fair price to
help them offset the cost of the machine and employee time.  The test is for
cracks in the neck area of tanks and 6351-T6 tanks are not the only ones
that share this risk.  The test gives you better information on how safe
your tanks are and your willingness to support the test makes your position
regarding filling of older tanks that passed it more solid.  FWIW, all of my
tanks have been Visual Plus tested more than once and none of them have
failed yet.  If one ever does, I'll have the test repeated and then destroy
the tank.
7. My final suggestion is not as applicable to everyone, but it's a choice I
made.  I don't like the way Luxfer handled the alloy issue.  They developed
the Visual Plus test for tanks they produced out of the inferior alloy and
then charged shops for it.  That charge got passed on to us.  At the very
least, I think they should have provided the equipent free of charge to
shops that continued to sell their tanks.  While I don't think Luxfer
intentionally used a dangerous alloy, they still did so.  Catalina didn't.
I chose to make my decision on which tanks to recommend and which to
recommend against on the basis of performance.  Catalina gets my vote,
Luxfer doesn't.  I do not own and prefer not to own a Luxfer product.

Lee