Clean Room Nitrogen Piping Requirements

Cleanrooms are totally different than medical services. Don't know much about it, but stainless is very common in cleanrooms. Even welders must ware white suits and plastic hair caps and nobody enters the area with anything like a pencil still in their pocket. I hope it wasn't 24".

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"The problem isn't working out the equation,
its finding the answer to the real question." BigInch

I would fall in line with the client on this. I would require 316ss cleaned for oxygen service to remove any residual oils. Buttwelding would be good but if it is small I might also consider swagelock fittings.

Copper can't be used because it will put copper in the N2 which is damaging to some of the oxide layers.

Regards
StoneCold

We are moving clean room operations to an existing building so there won't be any "suiting up" involved.

For me, it is just a word edit in the spec.

For the installing contractor - it is $$$$. He bid copper, the client comes back with wanting SS.

We (engineer and contractor) agree that SS is more applicable, given what we know now about what they want to do with it.

The issue is what was required when the RFP was issued. This is just one of several issues involved with this particular project - the client just seems to be sticking to his guns on this one.

Is there any standard or document I can reference?

The project is on a military base and even the standard they have for clean rooms does not mention pipe materials.

you might try to get some info over here,

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"The problem isn't working out the equation,
its finding the answer to the real question." BigInch

You need to clarify "Clean Room". If this is a class 100,000 room or workstation then you want no hydrocarbons to enter the room through the airlock (if there is one) or through the N2 piping. Is the N2 required to be water pumped and oil free? If so then you are probably dealing with an Oxygen clean room. Ever seen the movie "The LOX Monster"?

In addition to what level "cleanroom" you're talking about, what is the intended usage for the nitrogen? Is it used as a purging gas for diffusion furnaces, or for blow-offs of semiconductor wafers? At the very minimum, what business your client is in can give you clues about what they might have in the level of cleanliness. What other equipment/facilities are involved:

>> HEPA filtered air?
>> workbench types?
>> other equipment in the cleanroom?
>> changing room with air shower?
>> where the nitrogen goes in the existing cleanroom?

For process gases, we used to clean/degrease with LOX, but that was done by the facilities guys, so I don't know the details.

TTFN

FAQ731-376

Per the client, they are class 100 clean rooms.

The nitrogen is coming from a bulk liquid nitrogen tank.

The clean room will be used for high end electronics. There is an air shower, HEPA filters, etc.

We know "now" that stainless steel is what is desired and needs to be installed. The client (lab users) have told us that if copper is installed, they will just tear it out and install the stainless.

The real issue is what direction was given - which was very vague/misleading - initially.

That is why I am looking for some type of documentation that gives guidelines/direction for piping materials in clean rooms.

There is a lot of undocumented "this is the way it is done" - but I cannot find any documents that states, "this is the way it will be done".

Here's a couple of links, hope they give you a little more ammunition:


Cleanroom Standards  

We call those "derived requirements. No specification is fully encompassing; there are always inferred requirements. These are coupled with customer "expectations" and customary industry practice.

You apparently bid a job that required a certain level of knowledge and expertise that your company didn't have, to wit, my previous background was semiconductor, so I instinctively think of nitrogen piping as 316SS with Swagelok fittings, and I've only seen copper piping in low end applications.

It sounds like you're trying to lay the cost back on the customer; good luck with that. 316 is customary for this industry; your company's lack of experience in this industry is now paid for.

TTFN

FAQ731-376

Is this a TMDE facility?

The project was a design/build where the client supplied us with the requirements of the design. It encompasses many different types of labs - class 100 clean rooms just being one lab area. If this was not design/build, we would be responsible for determining the level of purity - but with the design/build - the owner is responsible for providing the proper requirements.

The documents we received to bid the design were "poor" at best - something the owner acknowledges. This issue is just one of many such issues for this project.

Nowhere did the owner state the purity of the nitrogen - just that it was coming from a bulk tank. We design nitrogen systems for hospitals using bulk nitrogen - so, in the absence of clear guidance, that is the direction we took.

We are designing the HVAC systems in the clean rooms per the appropriate documented standards for air cleanliness. We have HVAC engineers who have experience with clean rooms - they state they have seen copper piping used a lot.

But there is nothing I can find as to the type of piping to be used in the clean room for the gases being used.

If copper is a problem (on the exterior of the pipe) - then there will be other problems where lab vacuum and compressed air are being run in copper (oxy cleaned)

There is also an issue that not all the labs are clean rooms - where stainless is likely overkill.

I am looking for a document that says we made a mistake in specifying copper or a document that states we are ok.

I don't think one exists.

Lets look at it from a certification point of view. When the project is complete there will probably be a team come in with documents for those lab areas. Probably called Lab Certification Manuals which will state the Gas (N2)Purity, Cleanliness requirements, lighting requirements at bench level and many others. Will the team be turning out the lights and checking for hydrocarbon contamination? Does the area/lab/room require positive ventilation at all times and at what cfm.
I would find out if this type of documented information is available.

TTFN

FAQ731-376