Good Morning every one.

My questions:

1)Should the springs be locked during compressor nozzle alignment with connected piping
OR.
2)1)Should the springs be unlocked during compressor nozzle alignment with connected piping

Thanks.

Awaiting your rply...........soon.

any body help me.............

Hi...

Your question may have different answers as different EPCs have different philosophies as well as the compressor vendors!!

But from my experience with Siemens , the vendor checks the alignment both in spring locked condition as well as unlocked condition to ensure that there are no unnecessary strains on the nozzle due to pulling or pushing of flanges during alignment!!!!

Keep Smiling,

SJ

Why would you check with springs locked ? It is an unreal situation so far as nozzle loads are concerned. You might as well say all supports are anchors ... equally rubbish.

The logic may be as follows:

Consider a case where the alignment may be proper in spring unlocked condition. But remember there is temperature & fluid in addition to the dead weight & lets assume that the degree of misalignemt in locked condition is unacceptable. During event of shut down, temperature goes away as well as the fuid, thus, reaching a no-load condition. If the flanges are unbolted, the pipe will misalign & realignment will result in building forces on the shaft!!

You're right that supports are not anchors!!!!Even I've seen support on steel structure close to nozzle (not properly braced producing Y-displacemet) causing bigger misalignment in pipe !!

Keep Smiling,

SJ

Nozzle alignment during installation should be checked under spring locked condition

Rubbish. Springs should be active. An experienced installer will use the adjustable supprtrs and restraints which you thoughtfully provided to align the nozzle connection in every plane. This requires freedom to move in the vertical plane ans well as the horizontal planes.

In this case the Caesar calculation is useless.

Yes I can confirm that site will modify the original calculation in order to suit their philosophy.

Regards,

Yes Moverz is right, the alignment check is perform by measuring clearence between nozzle and flange at ambient temperature with free end (flange bolts are removed) and with operation support condition.
Allowable displacement is less than 1.00 mm for all directions.
Using CAESAR II set case WNC, if calculated displ. larger than allowable, use adjustable guide support near the nozzle to reduce displacement.

Regards

Nalibsyah

I think the most correct method :

1. If temperature is high, especially in the creep range temperature, then
you must lock the spring, so it will be balanced during operation.
This will reduced creep damaged. Its called "Hot Balanced Method"
For this method you will need to calculate and select the proper size
of spring for cold load and hot load, and lock the spring in the cold load
position.
2. But if you have temperature is low or far beyond creep range temperature
then it is ok to unlock the spring, that will give no force to the nozzle
during installation condition. This method ussualy called "Cold Balanced
Method".

Regards

Dee

Dee,

I think you are confused. The reason for having springs active when aligning pipe to a compressor is that the pipe system is usually three dimensional and will need to move in all three planes to allow proper alignment, particularly the rotational alignment which is the most difficult to achieve and potentially most damaging to the machine.

Piping can be +/- 12.5% on wall thickness and conseqently mass. Thus predicted weight loads will not be accurate and should not be relied upon, so far as spring balance local to machinery is concerned.

Furthermore ... how many compressors actually operate at a temperature in the creep range of piping ?

Thanks Moverz,

I generally speaking about what technique usually being used when you get spring near your "Equipment". Speaking for compressor as it is only operate from low to moderate temperature it usually use the cold balance method.
And the reason for using this method, beside as you describe above also that actual weight of system is ussualy higher than as pipe stress calculated that might make the cold set not exactly as the value it is required in field, and will impact also to the hot load. Some of our Mechanical field engineer and operator in the field mostly choose these method.