Oxygen Piping

Our factory has oxygen pipes (running infact into kms from our o2 plant to the individual shop floors) - carbon steel - and though welded - but again at valves etc you have the moving components and/ or threads. I don't think any problem are there in it.

The threads are usually sealed with - not oil but either teflon or any suitable non-oxidisable sealant, where the oil comes in from ?

What kind of pressures?

It is not unusual to have a Ca Fe system for O2 service.

If your concern is cleanliness - Is it their concern too? Is there filtration designed into the system? Is it a burn O2?

An RFI is certainly within reason - but just the point of O2 in Ca Fe itself should not be.

cr3

Pressure? Less then a 100# through the distribution

We are going to use oxygen rated dope and or teflon tape.

Burn O2? Yes.

Our concern was possible oils left over reacting with oxygen.

Filtration disigned into system? No

We are going to use oxygen rated dope and or teflon tape.

I have been out of industry for afew years. We commonly had burn O2 in Ca Fe in the chip plants. The specs for installation of this (and all) services clearly stated what was acceptable and not.

Your RFI shows awareness on your part. I would think you to have specs available to you. If your specs indicate these are permissible then you have done your part.

As a former QA/QC rep to the largest chip plants in the world for super/ultra clean construction projects I say good job on the query. Too many people (contractors) just blow and go.

Why should be the oils left over in the piping ? and any way if a few drops are left over, the ignition temperature may not be reached. For the burning O2, in industrial application, I dion't think i will bother much.

And I don't consider it to be a safety hazard (in fact a lot of times I have to burn off the oil with the flame before welding (don't tell my ohsas auditor) but some times in pin holes it is easier to burn off the oil and grind before welding.

of course these are hyd oil and non combustible - like what will be left out in you lines.

The friction of O2 at high pressure can make it combustible.

Hi,

Please note the details below:

Fittings and lengths of pipe shall be examined internally before assembly and, if necessary freed from scale or dirt. Oxygen piping and fittings shall be washed out with a suitable solution which will effectively remove grease and dirt but will not react with oxygen. Hot water solutions of caustic soda or trisodium phosphate are effective cleaning agents for this purpose.

1910.253(d)(3)(viii)

Piping shall be thoroughly blown out after assembly to remove foreign materials. For oxygen piping, oil-free air, oil-free nitrogen, or oil-free carbon dioxide shall be used. For other piping, air or inert gas may be used.

Comments: Oxygen can be explosice when in contact with oil. So care must be taken to have the pipes thoroughly rinsed and cleaned.

Agree with previous comment.

O2 above about 30% will spontaneously react with most oils. This reaction can be explosive.

At Mt Isa we had a labourer lose most of the fingers on one hand because a ball valve on the oxy line had had the ball greased. It was only a thin film, but when the O2 hit it it exploded and tore through a triple wire reinforced hose, taking the mans fingers with it.

Thoroughly remove all traces of oil from threading the pipe or you have a potential disaster.

I have previously installed carbon steel ox lines in a ship yard. You must use seamless pipe, a106b cleaned and caped. Make sure you keep all lab records of pipe cleaning. Valves must be bought oxy-cleaned from manufactuer. The system i installed was socket weld. Threads that were needed were sent out and cleaned. All tools used to install and cut pipe were cleaned for oxy service. Use exteme care in install. The consequences aren't takeing a chance. I hope this was some help.

Thanks for the feed back, much appreciated, I will let you know the outcome.

PI

I have frequently been asked for cleanign programs for oxygen service. The lines shoudl be thoroughly degreased first using an alkaline water based solution. Any residual iron oxides should then be removed using a citrosolv type treatment. The pipe should be passivated followign the standard citrosolv method and then the line should be dried to a -20 or so dew point.

The reasons for this are four fold.

1) residual hydrocarbons as oils or varnishes will be degraded by the the pressurized oxygen.

2) The presence of iron oxides will increase the reaction rates catalytically.

3) a non iron oxide free and thoroughly dry surface will result in particulate tranmission with the oxygen.

4) systems that have not been passivated will suffer accelerated corrosion.