The inert gas can blow away and if fuel is still sitting around, then it's
still creating fumes and can ignite itself too. Unless it can't be done,
I'd take the tank out and put it in a shop to weld. But where there's a
will, there's a way. Once the tank is empty and purging, the boat can be
purged also. We used to purge aircraft tanks for up to a week before
working on them, and even then we'd enter the tank with a fumes tester that
checked the air to see if there was jet fuel or gas fumes floating around.

Brian


--
http://www.advantagecomposites.com/tongass -- My 22' Tolman Skiff project
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Resins products


..
"dazed and confuzed" wrote in message
...
Steve wrote:
"Brian D" wrote in message
news:9Qmfc.39212$wP1.153766@attbi_s54...

It just takes care. If you can, you wash out the tank. Regardless, you
purge it with air for many hours to guarantee it is dry. You fill the

tank

with inert gas such as argon, then weld. Same process if you weld tanks

of

unknown condition or which had unknown contents. Welders do it all the
time.


Once the tank is inerted, I would still be concerned about the residual
gas
fumes in the bilges. An area where you can properly perge or inert.

If it doubt, or you can't test it before welding, then the tank should
be
removed from the boat.

Steve
s/v Good Intentions


why not inert those areas as well?

--
A significant part of courage is realizing that only you need to know
how terrified you are..