Rust (streaks?) in steel tanks

[wetb4igetinthewater]

So after a quick swish with the diluted phosphoric acid and then diluted blue gold (a rust inhibitor), it came out better, but not perfect.

I'm going to try the brush on the scuba tools that I showed early, then put it upside down, and use some PVC pipe and my air compressor to blow out all the crap. Hopefully tonight I'll get to that.

And yes, i realize this is more than good enough but the next experiment won't hurt.

I am trying to learn here, even if it is a lesson in futility.

 

[Boarderguy]

Careful with your air compressor. Those things are notorious for having wet or oily air blowing out the hose. Use a full tank or some other clean and dry air for an HP blast.

 

[wetb4igetinthewater]

Careful with your air compressor. Those things are notorious for having wet or oily air blowing out the hose. Use a full tank or some other clean and dry air for an HP blast.

Great point. Easy to connect a HP hose and then crack open the cylinder. Then I don't need the PVC pipe to reach the bottom and blow out the particles out of the top when the cylinder is upside down.

 

[halocline]

Great point. Easy to connect a HP hose and then crack open the cylinder. Then I don't need the PVC pipe to reach the bottom and blow out the particles out of the top when the cylinder is upside down.

Don't use a HP hose, use a LP hose. It'll blow much more air. Just find your longest regulator hose and take the 2nd stage off.

 

[wetb4igetinthewater]

Don't use a HP hose, use a LP hose. It'll blow much more air. Just find your longest regulator hose and take the 2nd stage off.

I have dry suit hoses or the LPI hose to attach an air nozzle, so I'm good there.

I've been cleaning it out, then putting the cylinders upside down and letting gravity do some of the work. Based on what is found on the floor, that works to some degree.

I fully admit I'm past the point of diminishing returns. But as I said, learning experience. Not looking for efficiency but what results I get.

 

[stretchthepenn]

Don't use a HP hose, use a LP hose. It'll blow much more air. Just find your longest regulator hose and take the 2nd stage off.

I suggest sliding a hose-saver (or whatever those plastic/rubber thingies are called, the long cones that dive shops put on your hoses when you get service done even though you wish the shops would leave the stupid things off) over the LP hose's end. That way, you won't have a metal end banging around inside the tank.

 

[wetb4igetinthewater]

I suggest sliding a hose-saver (or whatever those plastic/rubber thingies are called, the long cones that dive shops put on your hoses when you get service done even though you wish the shops would leave the stupid things off) over the LP hose's end. That way, you won't have a metal end banging around inside the tank.

I will use PVC pipe to direct the air to the bottom of the cylinder which will be upside down so that things fall out.

 

[Eric Sedletzky]

I will use PVC pipe to direct the air to the bottom of the cylinder which will be upside down so that things fall out.

You’re better off getting a male thread air chuck, the type that plug into an air line, and solder a long copper tube onto the end. I use 1/4” copper tubing. You can get an air nipple fitting for your LP inflator hose and fit the other end with a slide air chuck. Use clean tank air to blow out the tank.
I use it on a Scubapro MK20 since those flow the most air out of any reg. With the smaller diameter copper tubing the exiting air can flow out of the tank easier.
I have another copper blower with a curved end so that you can blow air down and out of the tank when it’s upside down. You just have to hook it in to get into to the tank then rotate it around so you blow the inside of the shoulder/neck area 360 degrees.
I hope you got a clear mental picture and all this makes sense.
I can post some photos if you wish?

 

[wetb4igetinthewater]

. can post some photos if you wish?

Yes please! Thanks!

 

[zider]

So after a quick swish with the diluted phosphoric acid and then diluted blue gold (a rust inhibitor), it came out better, but not perfect.
View attachment 776848
I'm going to try the brush on the scuba tools that I showed early, then put it upside down, and use some PVC pipe and my air compressor to blow out all the crap. Hopefully tonight I'll get to that.

And yes, i realize this is more than good enough but the next experiment won't hurt.

I am trying to learn here, even if it is a lesson in futility.

I’ve had good success with blue gold as an O2 cleaner but not as a rust inhibitor. For that I’ve always used the GSM rust inhibitor. A bottle will last a long time and it’s simple to use. Tumble the tank with a couple pints of diluted inhibitor and then blow dry. I’ve got a small farm of steel cylinders and I’ve never seen flash rust in any of my bottles using this inhibitor. I hope this helps!

Oxy-Safe Rust Inhibitor - Quart

Also called Compound O, it is used following the tumbling of steel tanks to prevent flash rust, a reddish film which often forms on the interior walls during drying of the cleaned cylinder. This chemical replaces Compound B, a popular anti-rust...

www.global-mfg.com