Wire wrapping and pressure rating?

[eskimo3883]

Hi Pescador775,

Does stripping off the wire wrapping do anything to the pressure rating? Can I assume a bare tank still has a chance of passing a hydro?

[luis]

If you are referring to a WWII surplus tanks, the wire rapping is for shatter protection only. It is not intended to take any of the hoop stresses (cylinder wall stresses due to pressure).

As a matter of fact for that type of tank, the wire wrapping has to be removed before hydro testing.

Don’t confuse this cylinder with the SCBA type cylinder that is hoped wrapped with (I believe) fiber glass.

[SDAquamaster]

It is my understanding that Luxfer's hooped wrapped scuba tanks are just AL80's with a composite wrap applied over the top to allow a higher service pressure.

The bad news is that if the resin covering the wrap is damaged it will absorb water and the tank is essentially toast. And I don't think removing the wrap with the intent of going back to an AL80 is an option as any hydro testing would need to be done based on the service pressure of the original wrapped tank.

The SCBA tanks used by fire fighters on the other hand use an aluminum tank with much thinner walls (about 1/8") over which the composite wrap is applied. They are also prone to being condemned if the wrap is damaged and, depending on the tank, they have either a 10 or 15 year service life after which they cannot be recertified.

Most of the fire departments in this area that went with hoop wrapped tanks 15 years ago are moving back to aluminum tanks given the cost differences and the limited service life and durability of hoop wrapped tanks.

[21]

I have not unwrapped a surplus tank in years. I do recall that the wire was very durable and difficult to cut with pliers or even wire cutters -but my cuttters may have been dull.

When finished there was one huge stack of wire.

I unwrapped 38s, 60s and 90s. The later took what seemed like forever to unwind!

A word of caution wear gloves!!!

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