Got some numbers (temperatures) for this one? Without digging out the data,
my impression is that baking the paint happens at a few hundred degrees F
and heat treating at much higher temperatures.

Were the tanks pressurized when baked, or did they blow up later?

Roger

http://home.insightbb.com/~derbyrm

"Capt John" wrote in message
oups.com...

The only thing you have to look out for with powder coating is if the
metal is heat treated. If the metal was heat treated the baking part of
the powder coating process can cause big problems with the integrity of
the metal. This happened on several occasions to people who had scuba
tanks powder coated, they blew up. If their's no heat treating involved
it's probably not a problem.

'High Temperatures'? You must be thinking of iron, copper, etc.

Not aluminum. In fact there are many alloys which are room-temperature
heat treated.

bob
(refugee of both ALCOA and Kaiser Aluminum)


derbyrm wrote:
Got some numbers (temperatures) for this one? Without digging out the data,
my impression is that baking the paint happens at a few hundred degrees F
and heat treating at much higher temperatures.

Were the tanks pressurized when baked, or did they blow up later?

Roger

http://home.insightbb.com/~derbyrm

"Capt John" wrote in message
oups.com...

The only thing you have to look out for with powder coating is if the
metal is heat treated. If the metal was heat treated the baking part of
the powder coating process can cause big problems with the integrity of
the metal. This happened on several occasions to people who had scuba
tanks powder coated, they blew up. If their's no heat treating involved
it's probably not a problem.

Sure, I know about "ice box rivets," but do dive tanks come in that kind of
aluminum?

Roger (who does associate heat treatment with iron and copper)

http://home.insightbb.com/~derbyrm

"RW Salnick" wrote in message
...
'High Temperatures'? You must be thinking of iron, copper, etc.

Not aluminum. In fact there are many alloys which are room-temperature
heat treated.

bob
(refugee of both ALCOA and Kaiser Aluminum)


derbyrm wrote:
Got some numbers (temperatures) for this one? Without digging out the
data, my impression is that baking the paint happens at a few hundred
degrees F and heat treating at much higher temperatures.

Were the tanks pressurized when baked, or did they blow up later?

Roger

http://home.insightbb.com/~derbyrm

"Capt John" wrote in message
oups.com...

The only thing you have to look out for with powder coating is if the
metal is heat treated. If the metal was heat treated the baking part of
the powder coating process can cause big problems with the integrity of
the metal. This happened on several occasions to people who had scuba
tanks powder coated, they blew up. If their's no heat treating involved
it's probably not a problem.

From what I remember reading of it the combination of temperature and
baking time weakened the tanks. They were not pressurized at the time,
the valves were removed. They ruptured during their first refill after
coating, SCUBA tanks are placed in water during filling, so if they go
their not like a bomb. Supposedly makes a hell of a noise and lots of
water thrown all over the place. But the energy is disapated in the
water.

Capt John wrote:

From what I remember reading of it the combination of temperature and
baking time weakened the tanks. They were not pressurized at the time,
the valves were removed. They ruptured during their first refill after
coating, SCUBA tanks are placed in water during filling, so if they go
their not like a bomb. Supposedly makes a hell of a noise and lots of
water thrown all over the place. But the energy is disapated in the
water.


Not necessarily. The water helps contain any fragments but is actually
there to cool the tank during filling.

There is a LOT of energy in a tank that has 3000 psi in it.

One example:

http://www.napsd.com/cscuba.htm

Note the bottom photo of the water tank that the scuba cylinder was in
at the time.

--

The Universe is utterly indifferent to the fact that you do not realize
the consequences of your actions
__________________________________________________ ______________________________
"A prudent man foresees the difficulties ahead and prepares for them;
the simpleton goes blindly on and suffers the consequences." - Proverbs 22:3

Most scuba tanks are 6061 aluminum and is precipitation hardened at around
200F for several days. Most powder coat needs 250 to 300F for about 20
minutes. Powder coating will weaken a tank some but a reasonable safety
margin for high pressure tanks is at least 3 to 1 so if it exploded the
powder coat may have contributed but there was another fault that was the
primary reason.

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

"derbyrm" wrote in message
news:1ytDf.521748$084.451397@attbi_s22...
Got some numbers (temperatures) for this one? Without digging out the
data, my impression is that baking the paint happens at a few hundred
degrees F and heat treating at much higher temperatures.

Were the tanks pressurized when baked, or did they blow up later?

Roger

http://home.insightbb.com/~derbyrm

"Capt John" wrote in message
oups.com...

The only thing you have to look out for with powder coating is if the
metal is heat treated. If the metal was heat treated the baking part of
the powder coating process can cause big problems with the integrity of
the metal. This happened on several occasions to people who had scuba
tanks powder coated, they blew up. If their's no heat treating involved
it's probably not a problem.