I have a steel cylinder with flash rust from the last hydro. Has two gallons of evapo-rust in it.

[divad]

Because the last hydro tester was incompetent.

That's reassuring...

 

[Rusty Shackleford]

Because the last hydro tester was incompetent.

 

[Rusty Shackleford]

That's reassuring...

Different guy is doing this one.

And again, it’s flash rust. I want to kill the corrosion cells. And it will be hydroded next week.

 

[Rusty Shackleford]

I just want to know how to remove the residue the best way.

 

[divad]

Was not blaming you. An "incompetent" hydro guy Is a scary concept.


Maybe they should tumble the hydro guy.

 

[Rusty Shackleford]

The previous hydro was done by a large company, AirGas, at one of their locations.

I have a new hydro place and have already taken steel cylinders to this guy, he is good and he listens.

 

[Rusty Shackleford]

AirGas rusted three of my 95s because the technician was too lazy to properly dry them before plugging them.

 

[Rusty Shackleford]

The dive shop did whisk them afterwards. This one picked-up a bit of flash rust since then. I want to kill the corrosion cells in the steel.

The Evapo-Rust should do that. Whisking won’t. Not good for what’s left of the phosphate coating either.

 

[W W Meixner]

The dive shop did whisk them afterwards. This one picked-up a bit of flash rust since then. I want to kill the corrosion cells in the steel.

The Evapo-Rust should do that. Whisking won’t. Not good for what’s left of the phosphate coating either.

Rusty...

Also being re-hydro/cylinder inspection certified...flash rusting during re-hydro process is caused when the shop fills steel cylinders with cold water and lets them sit over-night to allow the cold water to come up to room temperature before the cylinder is placed into the water jacket and the re-hydro process is begun...the corrosion usually begins in the threads as they are not coated...the rust droplets then flow down the cylinder walls...streaking the cylinder walls brown...the brown droplets then pond in the cylinder base...

Ideally...all temperatures within the test room should be the same...as some ''off room temps'' may give a false re-hydro reading...

If the cylinder was filled with temperate water and the re-hydro/O2 clean...if required/cylinder drying was performed immediately...flash rusting will not occur...

I never allowed a steel cylinder sit over-night once it was filled...and I've never had a flash rusting problem...

If a cylinder came to me with flash rusting...I always tumbled the cylinder first...

I have never heard of the chemical Evapo-Rust and can provide no help other than to advise...chemicals...especially corrosives should not be used on scuba cylinders for any purpose...

W...

 

[Rusty Shackleford]

It’s pH neutral and a chelating agent, completely non-corrosive. I am not concerned it will structurally compromise the cylinder in any way, I am wanting to sure I have a good post-treatment process to decon the cylinder.


I believe a rinse with dawn detergent and fresh water before flushing with corrosion inhibitor will suffice.