I would like to may be you all have any opinion about alignment. we will have LNG shutdown in may for MHI turbine due to performance loss issue. is it really required to perform an alignment if we open the turbine cover. some of my col said it is required and some others said it is not required as the alignment figure will not distored altho if we open up the turbine cover. pls let me know if you have any further question and info. thanks

If you are not moving or replacing either the trubine or the compressor, or any bearings then I don't see any reason for an alignment. Unless, of course, it has not been previously aligned or there is a suspected misalignment.

If you have no record - check alignment and record. You should have an hour to check alignment.

If you don't know stresses; check them as well - soft foot and pipe stress. What about pipe supports - under operation are they correctly positioned?

If you have a sole plate; check for voids. Perform inspection on base, skid, sole plate, etc...

Alignment is measured in thousandths of an inch. Removing the lid involves high forces to undo bolting and to lift heavy parts.

I think it makes a lot of sense to check the alignment after, in fact I might check it before maintenance begins, and then again after in order to make sure nothing has moved... It doesnt take that long to do.

But that is just me.

Is the steam inlet connected to the top case? If yes, then I would go for alignment check.
Regards,
Syed Ibrahim.

This message has been edited. Last edited by: Syed Ibrahim,

we will remove the top turbine casing, rotor, laby (primary cause due to performance loss) and bearing. our shutdown will be for 10 days including operation release and startup. yes i agreed it only take for 1 more plus to perform alignment and thats why i revert this question as an RE engineer i want to ensure everything is in good condition and quality inspection work.
for syed, the steam inlet is at the bottom casing. this is the split case turbine. as i said earlier, we remove all the part to inspect due to performance loss. we suspect rubbing or high clearance at laby. thanks again for all your replies.

it seems you are performing major overhaul. then it is a must to do alignment. for rotating beast, even it is only bearing check, it is always good to perform alignment check. do include it in your maintenance procedure.

Valve, ive understood what you meant. normally and for the last years, we did and practiced quality inspection check for our rotating equipment. we also have a quality protocol prior for every equipment overhaul. we will open up our turbine this may due to performance for 10 days. so typical political or maintenance reasons want to skip steps inorder to fasten the work. but for us, techical autorities to ensure everything is within our quality work. but for me, definitely the alignment will distort once we open up the top turbine casing. so i need to proven my solid answer to highlight to my col and teams. pls advice.

get MHI involvement. shoot them a short email regarding your concern. i am pretty sure you'll be getting similar answer as you get in this thread. then, forward it to relevant parties.

if you are calling MHI field supervisor to supervise the work, then get all parties to discuss on the planning during the opening meeting with the MHI supervisor.

correction last msg.

but for me, definitely the alignment will (not) distort once we open up the top turbine casing. so i need to proven my solid answer to highlight to my col and teams. pls advice.

thanks again for your advice,i will involve MHI supervisor in our discussion during the next turnaround. ill come back to you and share with our experience.

aidil, is the turbine horizontally split? if yeas, how is the casing bolts being loosen and tighten?

aidil, think i better rephrase my last question. what method you use to loosen and tighten the casing bolts? by slogging or by control bolting/unbolting or etc...

Valve, our turbine is vertically split, uniflow multivalve multistage condensing turbine. ours is approx 25 mW. are you from MLNG or SMDS? if youre from MLNG, i heard your MHI turbine is slightly higher than us.

we use bolt heater as a special tool for unbolting the stud bolt on high pressure and for low pressure we use spanner with long pipe.when unbolting, loose stud bolts from low pressur end to high pressure end. hope ans your question

correction again, maybe its wednesday morning, actually horizontal split case for all our MCR1, MCR2 and Propane. Thanks

i'm neither from mlng nor MLNG.

if slogging invovled in your unbolting activity, then your turbine casing may get distorted a bit i think.

altho misalignment is not seen in your online monitoring, the alignment may change everytime its condition changes from hot to cold and vice versa. it is just how much more your coupling can absorb misalignment during in operation. until the limit is hit, then misalignment is visible in the spectrum. i would advise you to perform the standard maintenance procedure.

anyway, you can always perform hot alignment to verify the reading and compare it against the ast alignment done. afterall the machine will only be handed over by operation after minimum 1 day i guess. you do this immediately after the machine shutted down.

Aidil, If bearings are replaced, alignment check after turbine assembly may be minimum requirement. To save time, you may relax the alignment specification to certain extent (with concurance of MHI & Dresser) but recording the alignment will be good reference for future. If considerable performance loss is noticed than chances of rubbing at the rotor exists and you may end up replacing the rotor.

pls check alignement no matter what...gud as reference and best engineering practises...mlng