new chiller down after 10 days

[GTE]

Hi,
we have just bought a brand new air cooled chiller.
within a few days and on the hottest day of summer, the discharge pressure relief valve failed.

The manufacturer stated that vibration caused the valve to fail...it has been out for the past 30 days now.
My questions are:
could it be a manufacturer defect?
What should we do?
The project is outside the UK. The manufacturer is a well known supply, one of the leaders in the market.
What would you do?
Can I ask to have a new chiller?
Thank you,
Yves.

[Rob White]

.

Vibration is down to the design and manufacture of the system??

Design issues after such a short period of time is not good.
In all my years I have never heard of a PRV venting because of vibration so if it has it's new to me and I would suggest again that it is a design fault so it goes back to my first sentence.

If it failed on a hot day after just a few days of running that to me is a design fault because the thing should be capable of withstanding ambient temps and if it can't then maybe it was designed to the wrong temp?

So not knowing specifics and individual circumstances on the evidence you state I would say they should put right the fault and leave you with a system that is capable of doing the job you want.


But and there is always a but.......

But if they designed it to your specifications and it failed it is then down to you, if they designed it to their specifications with the information you supplied, it is down to you but if they designed it to their specifications with their information, it is down to them to sort out.

Rob

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[Grizzly]

Hi GTE.
An even simpler question.
Was It commissioned by the manufacturer or their Agent.
Does this chiller have an Alarm History?
Most modern Manufacturers have such within their control software program.
By vibration do you mean a resonance?
Something is not right but given the little you have told us.
Its almost impossible to state further.
Grizzly

[Grizzly]

Hi GTE.
Just to add further.
On the hottest day of the Year.
I was called to a chiller system which was not cooling correctly, as it would normally!
I ended up walking away telling the customer I could do nothing for him.
As this was a system with a Water Cooled Condensers.
However because of how production had turned on all the production lines at once, or at least with little lag in between.
I was watching a chiller trying to cool down to -3.0c with the Water on the Condensers at 34.0c
and they wanted to put more lines on!

Game over.
A new chiller rarely gets brought online smoothly and usually is flogged until a compromise is reached between those using and those maintaining.
Throw what the salesman has said you can do with the chiller out of the window!
Talk to each other and work out what needs to be done to achieve what you need.
so far I have 49+ years as an engineer and I have yet to see a plant or chiller that works perfectly first time.

I repeat. One which cools a medium but does not have control of how that is used.
Is never going to work straight out of the box.
People need to talk!

Grizzly

[redroge]

Why didn't the hp switch operate !

[Grizzly]

Good point redroge!

How are the PRV's piped away from the chiller?
stress a PRV or its manifold and they have been known to fail!
Out of Interest GTE what make are the PRV's?
Grizzly

[Glenn Moore]

First point that came into my mind ,as redroge asked “why didn’t the HP switch function and stop the plant before the PRV blew.
Which manufacturer claimed it failed due to vibration. 1) the chiller manufacturer or the PRV manufacturer ?.
2) The Safety HP switch should have stopped the plant at least 1 Bar or more before the PRV setting
3) The question is who commissioned the plant and where is the commissioning sheet from site.
4) Was the chiller, factory commissioned or on site commissioned .
5) PRV’s do not fail due to vibration ,but can fail if the system discharge pulsations are close to the PRV,s set point
6) The HP safety switch function should be tested and it’s trip point measured as against the relief set point of the PRV re its calibration certificate
7) It would be interesting to see the report on the PRV as to what the vibration failure actually was . Did the PRV body fracture?, Did the PRV spring or seat seal fail? or did the PRV simply blow due to excessive over pressure.
8) Did the site engineer raise the HP safety switch setting to prevent the plant tripping on HP ?
9) what was the HP safety switch setting ? What was the PRV blow setting ?

A thorough investigation needs to be carried out to investigate some of the above questions , as may be the PRV actually did its function correctly whereas the HP safety switch did not.

These questions need to be answered as the PRV is your ultimate safety ,and for it to “fail” in such a short time could leave other personnel working in the area of the chiller in danger of serious injury or worse.
I’ve investigated a number of issues where parts of valves ,valve caps ,drier shells, pipes etc become projectiles in plant rooms due to trapped liquid ,trapped sub cooled liquid, heavy pressure pulsations etc . If it’s happened once it can happen again unless a solution is found
More system information and some photos of the failed parts and plant may give us a clue as to what the problem may be ,with a bit more info the chances are one of us on here may have seen or experienced a similar situation

[Grizzly]

Sound words Glenn.
My Guess is we are not going to be told more!
Grizzly

[Steve186]

Hi GTE
As i was reading this thread redroge asked the key question why did the chiller not shutdown on high pressure the hp cut-out is normally set 3.0 barg below the prv rated pressure
also i dont know what chiller you have but most chillers these days will load limit to prevent hp trips
so the first thing to do is look at the commissioning data and see what the hp cut out was when the chiller was commissioned as for vibration the only chiller that ive seen frature the prv' is the early york YCIV and was common.
Did no one from your company witness the chiller on the test bed to insure correct operation

[GTE]

Thank you for all the answers which I have read very carefully.
I have now more information.

The salesman told me it was vibration but I believe I was mislead. So you guys were right!!
What, I believe, has happened.
They have not mounted the PRV on the discharge of the compressor and somehow put the chiller in operation.

The refrigerant circuit has built up pressure during the hottest day and it appears that the refrigerant has found it way out and spread on the condenser. This is a 500kW air cooled liquid chiller with scroll compressors. Brand new.
So you guys sensed it right it seems. They have not commissioned the chiller correctly.
I will ask for have the commissioning report and the alarm report.
The only thing is that it is very difficult to get information from the salesman. They keep their card very close to their chest obviously.
My question now is : has this damage the overall long term operation of the chiller?
And why it would take over 1 month to fixe?
Thank you
Regards
GTE

[redroge]

A couple of questions!
Was he a salesman or a sales engineer?
Make and model of chiller ?
are you an engineer or the customer?

[al]

"The refrigerant circuit has built up pressure during the hottest day and it appears that the refrigerant has found it way out and spread on the condenser"

Has the gas leaked out of the condenser? Can you post a pic?

Not only has it not been commissioned properly, the high pressure safeties have failed to stop the chiller.

[passandscore]

Have you confirmed that the relief valve setting is correct? With the system running, if the high pressure control is operational and a relief lifted, it is either a undersized relief or a faulty relief valve. I have never heard of vibration causing a relief valve to fail.

[GTE]

the guy is supposed to have some engineering knowledge.
I am an engineer and the customer. We have just bought it. I am a mechanical engineer, I studied thermodynamics engineering a long long time ago.

[GTE]

from the latest info. it was not vibration. they have not mounted the PRV on the chiller before putting it in operation.

[Glenn Moore]

GTE that doesn’t explain why the HP safety control didn’t stop the machine . The PRV should only operate if the HP safety switch fails which should be a double bellows type so why is there no mention of the safety switch ????

[redroge]

Still no make and model of chiller !

[Grizzly]

Guys,
Are we are all reading PRV failure as if it is lifting!
GTE's first language is not English I would suggest.

I have been dealing recently where a running system had one of its dual discharge PRV's fail.
Resulting in total loss of 125kg of 134a (Ouch!).
There was no high pressure in fact the system was fully commissioned and running as it should.
The PRV concerned failed because of Lateral stress.
see photo.

15428

The PRV's were changed (after 5yrs usage) but the vent line to outside was left to the customer to reconnect.
It transpires that the reconnected vent pipe had been realigned incorrectly causing high misalignment stresses.
This one when disconnected at the Union, had about 10 mm vertical spring the lateral pressure pulling on the PRV.
Which eventually caused a hairline fracture on the PRV to Manifold /Female valve seat.

Lots of discussion as to who is at fault, but ultimately any good Engineer knows!
That misaligned stresses are a huge source of Mechanical Failure.
Especially with the Running Resonances you get with a hard working screw Comp.

Therefore. Misaligned pipework, under stress!
Can cause a catastrophic failure without the system ever being anywhere near it's High pressure limits.

Never ever seen it before this year?
Grizzly

[GTE]

YLAA517 is the model

[GTE]

Well, I am Italian. Project is in poland. So Not english. not first language.
Tell me. Has the chiller underwent a long term reduction of its economic life? that is all I am trying to know.

I will read more about "misaligned stress"?? (never heard of that but will investigate)
Thank you,
Regards,

[redroge]

Have you had a York engineer out to check the chiller ?

[Glenn Moore]

GTE
Any decent refrigeration engineer should be able to sort out the problem with this chiller. The fact that you think the PRV was never fitted to the system does not answer the question as to why the HP safety controls failed to stop the plant from over pressurising and create leaking from the condenser!!!!!
Your question as to the possibility of long term damage to the plant cannot be answered until what the actual fault that occurred has been answered.
But if the plant has been over pressurised due to lack of control to the plants discharge pressure and consequential leakage from the condenser, then the following possibilities may be relevant.
The condenser may have over pressure damage to its tubing ,return bends and its brazed joints ,which would need re pressure and strength testing.
Also there could possibly be damage to the scroll compressors. The dome of most scroll compressors “its discharge pressure area” is shrunk onto the scroll set component to produce a gas tight seal between the scroll discharge dome to the suction intake shell area .
Over pressurising the compressor discharge area , can in extreme cases cause the dome to expand causing internal leakages between the discharge dome, around the scroll set and down to the suction of the compressor causing the compressors to run hot due to re compressed hot gas .
Obviously excessive discharge temperatures and pressureses could potentially leave many parts In the systems discharge subseptable to early failures unless a complete strength is carried out .
This whole saga sounds like the blind leading the blind, and your being given the mushroom treatment ie kept in the dark and fed bulls—t.
Someone in this installation should have been paid to install and commission it and to be responsible for any warranty failures of this plant . So when you bought the system the quotation of what you were buying and services you were paying for must be in the contract, or was this installed by someone other than a qualified engineer.?.

[GTE]

Hi, the chiller was commissioned and put in operation by the supplier of the chiller. They are installing these chillers left right and center, so why they omitted to the PRV ? I don't know. it is clearly a silly mistake. I just don't want to pay the price of this mistake.


Anyway mistake has been done. What should I request from the supplier to unsure the chiller has not been damaged and make sure I protect the interest of my client?
Thanks
GTE
PS: Thanks Glenn for the insight .

[redroge]

Get them back under warranty !