Refrigeration plant Hydro test

[psrao]

Dear all,

I have a silly question. Does any Refrigeration plant, which runs in satisfactory condition requires pressure test periodically. If it is required and it can be done with Nitrogen then it is ok. But entire refrigeration system or presuure vessel like liquid receivers in large capacity plants can be done with Hydraulic test (Water). Is it advisable? Is there any EHS regulatory requirement any where to do Hydro test of Refrigeration plant periodically, which normally done in other vessels like Boiler.

With regards,
P S Rao.

[Toosh]

Hi PS, Most systems only require a pressure test (a ) if you have a leak or if they are shut down for annual maintenance, though this only usual on large plant

Regards Norm

[hendry]

psrao
1] periodic test in any plant subject to authority requirement.
2] once your plant in up running, no external water/moisture should enter incidentally.
3] dry nitrogen is good choice!
4] test pressure depends on the aging of equipment; possibly to 1.5 times ops pressure.
5] vacuum test also deem necessary.

[Josip]

Hi, P S Rao

Dear all,

I have a silly question. Does any Refrigeration plant, which runs in satisfactory condition requires pressure test periodically. If it is required and it can be done with Nitrogen then it is ok. But entire refrigeration system or presuure vessel like liquid receivers in large capacity plants can be done with Hydraulic test (Water). Is it advisable? Is there any EHS regulatory requirement any where to do Hydro test of Refrigeration plant periodically, which normally done in other vessels like Boiler.

With regards,
P S Rao.

It is not a silly question, at all...,but all depending on the rules and laws in certain area/country.

....it is obligatory to do the pressure test of vessels after every 3-5 years with nitrogen (maybe some x-ray too), but authorities can request a hydraulic test (with water or oil) and then you need to isolate complete vessel and perform it....those rules you must know before making a design the plant (to make flange connections on pipes where you need, drains, additional valves to isolate vessels without to stop the plant during pressure test (maybe for short time), etc) it is expensive but maybe less then to buy a new vessel and especially when change of vessel is almost impossible....)

...when we come to this point then we can see how good/bad is design of our refrigeration plant

Best regards, Josip

[Saturated]

To answer your question fully, the worst thing that can happen to your system is to get moisture in it. Moisture reacts with most refrigerants to create acid (which destroy the laquer on electrical windings and create sludge) and cause annoying blockages at the LRCD.

[US Iceman]

Never hydro test a refrigeration that has been in operation. (especially with water, which is what a hydro test usually consists of unless otherwise specified)

We expend considerable time and energy to ensure the refrigeration system is completely dry before charging refrigerant into the system.

If you need to do a pressure test, this can easily be done with dry nitrogen before the system is started. I can't imagine why anyone would want (or be forced to) pressure test an existing system.

If there are leaks then fix the leaks.

[Josip]

Hi, Mike

Never hydro test a refrigeration that has been in operation. (especially with water, which is what a hydro test usually consists of unless otherwise specified)

Yes, but 23 years before I had to repeat hydro test on each vessel we installed, brand new plant... (in spite what we had for each vessel factory hydro test attest) ....explanation given by inspector was: vessels have been transported to the site and who knows what was during transportation, simple....he was my Freddy Kruger, because we have to install couple of ammonia plants in his area of inspections...

We expend considerable time and energy to ensure the refrigeration system is completely dry before charging refrigerant into the system.

Right, I was trying many times to explain him about problems if some water remains in system....his answer was....that is not his problem

If you need to do a pressure test, this can easily be done with dry nitrogen before the system is started. I can't imagine why anyone would want (or be forced to) pressure test an existing system.

....hard to imagine...how you will call execution of those works....we were forced to hydro tests, drying, etc....we did them all...plant is still running

What I want to point out....for some old plants, inspector can request hydro test, complete x-ray or to reduce head pressure or to replace all vessels with new i.e. revamping plant...all that for safety what is correct.

Best regards, Josip

[US Iceman]

HI Josip,

No, I understand what you are saying. However, it does not mean the inspector is correct.

I am aware of several projects where this happened to several large screw compressor packages. The pipe fitters (who normally did steam & boiler systems) thought they woud hydro the compressor packages.

Very big mess!!!!!

Is it possible to do this?.... yes.

But it is sure a difficult way to operate a start-up!

[Grizzly]

Hi PS, Most systems only require a pressure test (a ) if you have a leak or if they are shut down for annual maintenance, though this only usual on large plant

Regards Norm

May I just point out that a existing system requiring a Hydrolic Pressure test is extremely rare although not unkown.
A Pressure test using Nitrogen is more common but only normally where a physical problem has occured, To make the Pressure Vessels Inspector concerned about strength and integraty? IE. where a weld has failed or pipe has split entering the pressure vessel.
A Pressure Test is not to be confused with a leak test, both use nitrogen but the pressures required are hugely differant.
Also extreme caution should be observed when adding any Nitrogen to Part of a system because if your isolation valve / valves pass.
You are then adding non condensables to your refrigerant side of your system. Personnaly I tend to avoid were possible part pressurising any system.
I appologise to most of the guys here as I am probably teaching to suck eggs.
But the number of time I here people say pressure test rather than leak test. I felt it would not harm to point out there is a huge differance.
Thanks Grizzly

[rkmoorthy]

hai guys can you give me full details about container chiller the brand of carrier.

[Josip]

Hi, rkmoorthy

Welcome to RE forums....

hai guys can you give me full details about container chiller the brand of carrier.

Can you be more specific with your request (size, capacity, colour), please

Best regards, Josip

[TXiceman]

Water is the worst thing you can put in a refrigeration system. Most codes allow for a pneumatic test on the vessels and piping systems as well as hydro test.

One manufacturer I worked for NEVER tested a refrigeration vessel with water. They used a light oil which was compatible with most oils and refrigerants on all vessels and heat exchangers which they built. They also required the same of vessels they purchased from outside sources. If they could not test with oil, they had to perform a pneumatic test or provide a through drying procedure on the vessel.

I had a chemical customer "Hydro" test a remote evaporator system and piping after will told them in writing of the potential problems. When we got on site to commission the system, water could be blown from the low point drains. They had to blow hot dry nitrogen through the system for two weeks to get it dry enough to use a vacuum pump. Even with the vacuum pump we still ran a "cold trap" for about 5 days. Then it took another week on the vacuum pump to get it dry enough to charge with R-22 (about 9000# of R-22).

Now they raised old Billy heck about taking too long to start the system. The flooded evaporators had lo-fin tubes and we figure the fins were holding water.

So when any one wants a refrigeration system hydro tested on water, I have them sign a disclaimer about the problems of water.

Ken

[mctavara]

Hi PSRAO,

Just note and very simple. It's a big NO to introduced H2O to pressure test a refrigeration side for plant installation including the vessels in the circuit is prohibited. Yet for load side you may like water/glycol evaporators etc. As the guys advise, Dry Nitrogen is the best element to be used in testing.

BR,
mctavara

[massfd]

I like the oil idea better, using nitrogen or any other compressed gas for high pressure testing can be like a bomb going off if the vessel ruptures.

Useing water or oil just results in a big leak as there is no stored energy as there would be when using any compressed gas.

We have to test our 4500psi air cylinders at 7500psi, they are first filled with water to the top. A rupture during testing just releaves the pressure, I would hate to see what would happen if it contained 7500psi of compressed air

[nike123]

I like the oil idea better, using nitrogen or any other compressed gas for high pressure testing can be like a bomb going off if the vessel ruptures.

Useing water or oil just results in a big leak as there is no stored energy as there would be when using any compressed gas.

We have to test our 4500psi air cylinders at 7500psi, they are first filled with water to the top. A rupture during testing just releaves the pressure, I would hate to see what would happen if it contained 7500psi of compressed air

Did you read any post above or you just want to impress us with your pressures 10 times greater then what we dealing with?

[massfd]

Did you read any post above or you just want to impress us with your pressures 10 times greater then what we dealing with?

Yes I did read the post and it bothers me that the title is Hydro Test but some are talking about using nitrogen.

My point was Hydro Testing and pressure testing are not the same thing. Hydro testing results in very little stored energy being released in a failure where a compressed gas failure will release large amounts of energy.

I have made my point, nike123 whats yours???

[abet_meneses]

in my 20 plus experience in refrigeration this is my first time i heard of hydro test on refrigeration system.system operating satisfactorily doesnt require leak test,much less a water test.fyi.

[nike123]

Yes I did read the post and it bothers me that the title is Hydro Test but some are talking about using nitrogen.

My point was Hydro Testing and pressure testing are not the same thing. Hydro testing results in very little stored energy being released in a failure where a compressed gas failure will release large amounts of energy.

I have made my point, nike123 whats yours???

Both hydro or gas test are pressure tests and pressure resistant testing is purpose of these tests. My point is all arguments against hydro (water) test elaborated in most of previous posts!
When you got lot reasons to not use hydro test and only one for use of such test in refrigeration system, then it is wise to consider and judge that arguments on balance against each other.