Oxygen Cleaning a Long Length of Stainless Steel Tube

[Tassi Devil Diver]

Hello, I need to oxygen clean 6 lengths of 6m (20') 1/4" stainless steel tube for a gas mixing station we are building.

What process/ method would you use to clean these long lengths of stainless steel tube?

Any assistance would be greatly appreciated.

 

[Got2Go]

Use a small water pump and fill a bucket with a simple green crystal and water solution(or your cleaner of choice for O2 prep).
Dump pump in bucket with hose clamped to end of SS tube...and a hose on the other end of SS tube returning the liquid back to the bucket.
Run pump for 10-15 minutes...use hot water.

Rinse SS tube with distilled water...blast with OCA from a cylinder/compressor.

Obviously, properly clean all the materials used for this.

 

[iain/hsm]

Hello, I need to oxygen clean 6 lengths of 6m (20') 1/4" stainless steel tube for a gas mixing station we are building.
What process/ method would you use to clean these long lengths of stainless steel tube?
Any assistance would be greatly appreciated.

36 metres of stainless tube for high pressure oxygen service?
First question before you even begin and consider cleaning stainless tube for oxygen service would be is this for yourself, for your own project or are you doing it or selling it to a customer for money.

Second question would be of the tube itself is it 316 or 304 stainless material and what is the proposed wall or bore thickness your proposing for this project also who are your proposed suppliers. Reason I ask is I’m first looking to find out if it’s a “clean bore” tube designed for a gas service use or the cheaper hydraulic tube you are proposing using. Your proposed wall thickness or bore size would also be critical.

Third question is the maximum working pressure P1 of the oxygen. From that you can calculate out the gas velocity, the gas pressure drop and from that the adabatic shock load at the end of this 36 meter long pipe run when you turn it on and the reason why I asked question one.

Rule of thumb with stainless tube in oxygen is use seamless tube at short lengths with a suitable wall thickness/OD to result in the lowest gas velocities with any additional angle or bend made with a slow bend radius and avoid creating sharp angle such as branch tee’s or other such tube elbows for the main velocity gas run.

36 metres of 1/4” bore pipe is long enough to create enough energy with enough particulate to create a spark let alone using 1/4” OD tube. For such a long run, first consideration would be to ditch using stainless tube and use an inert tube material such as an alpha brass seamless tube and/or increase the bore and re think using a 3/8 OD x 16 AWG tube and see the difference in velocity risk reduction.

Frankly for a 36 metre oxygen run I’m surprised an alpha brass tube is not your first material of choice.

 

[Tassi Devil Diver]

Thanks Got2go.

Iain/hsm, this is all for private use to connect 5 bank tanks to a fill panel, they will contain gases ranging from air to Nx50 maybe 1 will contain oxygen, the max distance of travel will be around 6m. The tubing is seamless rated to 400bar for gas service, I would expect the maximum pressure would be 200bar.

 

[iain/hsm]

That’s good. then you don’t have to worry about the written risk assessment and “Work Safe” rules and regulations. Also as a written risk assessment and cleaning procedure is now not required for a private job you can be a tad easier on the procedures.

For us each type of component has its own cleaning procedure and another just a concise inspection procedure. Ours just for tube is a seven page 2000 word document a little too big for the forum but one thing to add.

After cleaning long tube you should also consider inspection and protection from recontamination.

Further cutting this long tube with a hacksaw after you have cleaned it then assembling into your system is a classic point of failure.

To my mind clean the long tube lengths by all means but re flush and clean after you have re worked and manipulated each of the component parts made from the original tube length.

If you also filter the flushed solution after cleaning you will be amazed the amount of particulate, metal flakes and general bits that remain after working the tube. All of these particles go towards the ”kindling effect” like using kindling to create a good fire.

Re used end fitting also store an amazing amount of crud and silver flakes even with small components the amount of particles left behind never ceases to amaze me. Even after cleaning each part three times, and each time doing what is called a “partial count” to equate the carry over left in the tube from the debris flushed out.

Each time diminishing the risk by lowering the contamination. Iain

 

[Wookie]

What Iain said, except after it's all completed, flush it in the direction and against the direction of flow with your cleaner and rinser of choice. Make sure your final regulator doesn't participate in the rinse session. Jumper across the regulator if necessary.

 

[iain/hsm]

What Iain said, except after it's all completed, flush it in the direction and against the direction of flow with your cleaner and rinser of choice. Make sure your final regulator doesn't participate in the rinse session. Jumper across the regulator if necessary.

I can see you being popular on a big site or vessel having to drag all the gear to the other end of the job and start all over again with that idea. Thankfully we now have pumps that do that all for us, reverse flushing push pull units.

The original reason for this was from the old navy technique of using 3000 and 6000 lb class socket welded fittings that were either welded together or brazed with silver wire and the contamination and flux used would weep out of the socket and or collect in the gap where the pipe end met the socket base. Hopefully the OP isn’t going down that over the top route of connection and may prefer using the simpler Swagelok double ferrule tube end connections.

But it does begger the question why having pushed the junk down to the end of the tube in the first place, why pull it all back again to where it started…………. I suppose.

 

[CraigAClark]

Monel 400 is what I use on installations where liability is a concern. Which basically means every installation. You say "personal use" only, but if you fill a friends bottles, that is not personal use anymore. I've said this before, friends will sue you just as fast as a customer would.

 

[RayfromTX]

Your friend's wife's insurance company's lawyer is more likely to be the plaintiff.