8 replies to this topic

[sheiko]

Hello people,

I am confused between FAT (Factory Acceptance Test) and SAT (Site Acceptance Test) activities relative to precom/com. I know what each term means but i would like to know their respective objectives, scope and sequence with one another? Also, is it possible to perform FAT during precom/com on site instead of factory? Is SAT part of precom/com? In a nutshell what are the limits between each above mentionned activities?
Any documentation to share?

Thanks

Edited by sheiko, 28 November 2010 - 11:42 AM.

[Zauberberg]

Sheiko,

What particular pieces of equipment, standalone packages, or process units you have in mind? These may differ.

[sheiko]

Sheiko,

What particular pieces of equipment, standalone packages, or process units you have in mind? These may differ.

The system is an air (screw) compressor package, with dryers, filters and cooling system inside.

Edited by sheiko, 28 November 2010 - 08:39 AM.

[Zauberberg]

We've had such package installed at the post-commissioning stage (i.e. one year after the plant was handed over to the Operator) in Equatorial Guinea. The complete procedure consisted of:

- FAT
- SAT/Commissioning

FAT has provided us with performance charts (pressures, temperatures, air flow delivered by the compressor, dew point of dry air/cycle timings, Nitrogen purity and flow from the Membrane etc.) simulated at plant operating conditions. This was done in the US at the manufacturer site, and some of our guys were present there as well.

SAT/commissioning consisted of connecting the equipment to the existing tie-ins, and running it first in the LAG mode, then switched to LEAD mode. That was the way to confirm if the package can meet plant demands as requested in the specification data, i.e. whether it can deliver Air/Nitrogen flows and purities at the actual/specified conditions. A successful performance test 24hrs long has been set as the criteria for signing off the SAT.

Not sure if this was what you were asking for, but it may provide some help.

[sheiko]

Thank you.

I have to say that i am not very familiar with LEAD/LAG modes, do you mean checking the high/low pressure switches that stop/start compressors in function of plant air demand?

Regarding documentation, could you share a typical Standard Operating Procedure of your property, for this type of package? What should be included, especially in the Process Control area?

I am wondering this because when i was reviewing the procedure and check-list provided by the packagist, i have identified a number of things that i believe are missing. I have not found some tests specific to the package like:
- compressor units individual trips (for each compressor)
- compressor units PSH interlock (for each compressor)
- general trip of the compressors
- ...

So i made these comments to the package representative who immediately included them in its procedure...Now i´m confused as there well may be other tests missing (oil temp, pressures, ...). Shall i trust the packagist? To put things in a nutshell and in perspective, when you buy a car (which is a kind of "package"), do you check absolutely everything before driving it?

Edited by sheiko, 06 December 2010 - 02:18 AM.

[Zauberberg]

The elements you mentioned must be there, even if they are not included in the original checklist - all the switches, interlocks, and instruments must be visible in the vendor P&ID including detailed description in the Operating & Maintenance Manual.

Simulating safety interlocks is a common thing prior/during dynamic commissioning, and it is your right to request such activity to be included in the SAT/commissioning procedure. It is up to you - as a Commissioning Lead - or up to the Operator company (package owner) to define what prerequisites are mandatory for complete sign off and handover. This differs from place to place.

[sheiko]

And could you please explain what are LAG and LEAD modes?

[Zauberberg]

Exactly as you described in your e-mail. Each compressor kicks-in and kicks-out at a certain, predefined pressure setting. For example:

LEAD machine: continuously running e.g. at 9barg
LAG machine: kick-in at e.g 8.5barg, kick-out at 9.0barg

That way a continuous supply of plant/instrument air is ensured, with maximum pressure range between 8.5-9.0 barg.

[sheiko]

Thanks a lot! And...congratulations for the Davis Cup

Edited by sheiko, 06 December 2010 - 02:24 AM.