Pump Complete Unit Test 1

[Tilas]

Hi ,

Im new here and i'd like to ask experts opinion for my case.I am working for an epc contractor and our Client has a requirement for a BB5 pump with L.O. system. Client wants to have a complete unit test for this items (meaning both pumps A&B). Since API 610 10th para 7.3.4.3 for "Complete Unit Test" is bulleted thus we Client/ Contractor can specifically request for this test. My question would be:

1. What exactly is the definition of complete unit test? How will it be done and for what reasons are we requiring this test?
2. Does a complete unit test for both machine adds any advantage or just on one machine for 2 items is enough.

Need your enlightenment guys.

Thanks a lot.

Tilas

 

[LittleInch]

Tilas,

Not sure what a L.O. system is (always best not to use abbreviations if you can avoid it), but a complete unit test is basically what it says, i.e. a test of the complete unit which is actually going to be delivered as a package of pump and motor. Companies sometimes like to do this as it demonstrates that the as delivered unit has been tested as a single item. However this normally increases your schedule as the other common option is that the pump is tested using a "slave" motor in the pump manufacturers premises and the motor (I assume it's electrical but you don't say) is tested at the same time or before the pump at the motor manufacturers location and in both cases appropriate test documentation produced. Then the two are brought toghether, bolted up and shipped. If the complete unit then needs testing again this can add several weeks and more costs for not much additional benefit in most peoples view. Pumps alway need to be aligned after instalation on site after piping hook-up any way.

If you're going to do a complete unit test then you would need to do it on both pump sets, even if they are identical units on a 2 x 100% basis.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[Tilas]

Thanks LittleInch,

Actually my pump is "yes" an Electrical Motor Driven one and L.O. stands for Lube Oil System (API 614).

So as per my case,does complete unit test mean including the lube oil system , job seal & seal system , job motor etc.

Thanks,
Tilas

 

[LittleInch]

Complete unit test means as much of the complete unit as can be tested in the works. The lub oil system may be a separate supply, but if it's part of the pump supply package then yes, it's lube oil system, job seal, job motor the whole as delivered package. There may be some temporary interconnecting pipework e.g for the lub oil, but otherwise it should be the whiole system. As said, this is real pain for the pump suppliers and they don't like doing it, so it will add time and costs and then it's up to your client as to decide if it's worth it or not. If they've had a recent problem or failure with a new unit, then they may decide it is, but most of the time the benefit is pretty marginal.

Having looked up a BB5 pump, I'm not too surprised they've called for a complete system test on this one. If it's a very big unit, they may have issues with the amount of power required and / or fluid handling, but that's up to the pump package supplier... Without giving too much away, for info, what's the duty and power? The bigger and more complex you get, the more likely they want complete confidence that the supplied package is going to work first time.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[DubMac]

There is nothing odd at all about string testing entire unit; especially the size/complexity that includes a lube oil system. The end-user just wants to ensure the entire unit can be aligned, and operate in sync without "issues" before it gets to the field. Could be there are vibration/harmonic issues, L.O. piping issues, etc. Lube Oil units are famous for having a valve turned the wrong way or piped backwards. The unit may well be headed to another part of the world. Then again, EPC's have been known to put all kind of requirements in to cover their *sses!

Whatever the reason, there will be one helluva adder for a complete string test with job motor and L.O. system.

 

[LittleInch]

Dub Mac, I agree. What Tilas needs to recognise is that in my experience it will add between 4 to 8 weeks to his delivery as they will need to wait for everything to arrive beofre they can test and as you say, add a fair bit to the price. However depending on where in the world this is going you would save that if you had to fly out a pump tech to sort out your commissioning issues as you probably wouldn't be able to run it up before pressing the button in anger.... It's all about costs to mitigate against a risk. Also depends on how good your inspector is in the pump suppliers and sending someone good to do the SAT and check what you have had built before they package it all away and cover it in plastic and wood.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[Artisi]

You very first question is really the crux of the matter " .......and for what reasons are we requiring this test?"
Good question, have you resolved it as yet? If you have then what are the reasons - if not - why not?

When manufacturing high tech. equipment (guess we can just about include this pump unit in this category)it is far better to have ongoing critical point inspections, especially the pump unit throughout the manufacturing stage, i.e, raw castings (pump cases and impellers), completed machined castings, pre-assembly and final assembly inspections. It is reasonable to ask for a shop test on the assembled pump using a shop motor, however what do you want from this, does the pump meet hydraulic requirements or does it run without any mechanical problems or both?

Unless there is something special about the drive motor, then a final witnessed test run should be sufficient, likewise for the oil lube system, are they to spec. and do they operate as required etc etc.

If the pump unit, motor and lube system are being assembled in the shop and shipped as a complete unit, you need to ask yourself, what advantage is there for a fully assembled test run - because once on site the complete must be partially dismantled to recheck the pump / motor alignment etc etc.

I have been involved with some high tech. high powered pumps ranging upward of 2000 kW - the last project was far to big to pre-assemble as a unit and test run before shipping, however they were subject to vigorous manufacturing inspections and the first time run was after installation - happy to say no pump design, manufacturing or assembly problems.

Of course consultant love to include all and sundry into their specifications - the more inspections, testing etc they can involve themselves in the better - results in a far fatter invoice at the end of the project but certainly doesn't necessarily ensure a smooth and successful outcome.





It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[Pumpsonly]

Most end user would like to have a complete unit test or string test ( Pump +job driver + job seal system + accessories)done in the vendor factory when ever possible to avoid surprises at the site. It is much easier to get errors fixed at the factory than at the site. You do not what to face with the situation where the errors are only discovered during pre-commissioning and you are only 2 week to full start up of the plant.
However, it is not always possible to use job motor for string test,if the pumped liquid SG is much lower than water which is used for the factory test. Some application may also not be possible to performance a full speed test with water.

 

[LittleInch]

Tilas,

Pumpsonly makes a very good point in that if your SG of your product is less than water, your job motor would be undersized and unable to run at full flow or pressure, thus limiting your test to flow of 75% or less.

I can understand why clients like to have a full unit test as it gives them a nice warm feeling, but you should point out that like artisi says, good inspection of the components is far better and note the impact on delivery time.

The unit test might show up some critical fault, but running times are often quite short so won't show up any long term running issues.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[Tilas]

Thanks Guys,

As additional information, my pump has a "Performance Test & Mechanical Run Test" with shop motor and shop lube oil system.
SG of the liquid is around 0.90 and both test can be done at rated speed as confirmed by the manufacturer. After the P.O. , my Client is thinking about including the said "String/Complete Unit Test". And he's thinking to do it for both A&B pumps.

The L.O. unit will be separate from the pump skid and it will be connected at site with interconnecting piping under our "Contractor" scope. I guess this is the reason why they want to test it all together at the shop prior to sending to site.

By the way, how long does a complete unit test take? My Mechanical Run is 4 hours , is it also possible to do the complete unit test by 4 hours? At which point in curve will it be done? rated?

Thanks again guys.

 

[LittleInch]

The actual test can take as long as you want it to take. The long time period is bolting it all together, filling the LO system, testing it for leaks, aligning the pump and motor, attaching the pump to the floor, getting all the water and flow connections sorted, plugging in your power cable, calibrating all the test instruments...... The actual test itself is realtively short.

Minimum tests are detailed in section 8.3.3. of API 610, but normally client specs want more (e.g. 0,20,40,60,80,100,110% of rated flow). Depends also if your client wants a soak test (say 24 hours at rated duty). You can find the water in the test loop heats up too much when you do this, but I'll leave that to the pump vendor to tell you if its a problem or not. At normal SG of 0.9, your motor will be 10% over on power at rated duty so make sure it's good enough for the job (probably is if he says it's ok).

Of course if anything goes wrong such as excess vibration etc then you could be there for a lot longer while they sort it out.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way