Turbomachine Casing dilatation and attachements

[Fran67]

Hello everybody
I work on turbomachines attached through 4 or 8 hold down bolts to a baseplate and working with low temperatures producing casing dilatation and strains (3 to 12mm according to the project)
Do you think I need to provide free dilatation systems on the casing holz down bolts (ex: sleeves on the bolts with 0,25mm gap) to let the dilatation without stresses on the attachments? Is there any standard or documentation on this subject? What do you suggest?
Thank you for your responses
F67

 

[JJPellin]

Your question is not clear to me. I do not know what you mean by the use of the word dilatation. It sounds like you may be asking something like this:

Under what circumstances would a piece of turbomachinery require sleeved bolts with keys to guide thermal growth? Is there some standard that determines this?

If so, that is too generic and broad to answer. Are you referring to compressors, steam turbines, gearboxes? Are you working with machines built to API standards? I have worked with compressors that did not include any accommodation for casing thermal growth that absolutely needed it. I have worked with large compressor that were set up to accept and accommodate casing thermal growth that really did not need it. Free standing gearboxes (in my experience) never have mechanisms to accommodate thermal growth of the gearcase. But, the larger ones probably should.

Johnny Pellin

 

[MJCronin]

Can you post either pictures or sketches to better explain your issues ?

MJCronin
Sr. Process Engineer

 

[KevinNZ]

12mm of casing dimension change is a lot to take up within the casing. I would guess this is a large machine and you should design for controlled expansion and a fixed/keyed anchorage point. 12mm us also going to affect what is attached to the machine.

 

[JJPellin]

OK. If the casing on a machine changes diameter by 12 mm, this should probably be accommodated with key blocks and sleeved bolts. I would not be as concerned about piping connected to this machine. Well designed piping should be able to accommodate this amount of movement. I am most concerned about maintaining good coupling alignment.

Johnny Pellin

 

[Fran67]

To clarify:

This is a turbocompressor without coupling (compressor and turbine casings are bolted together, rotor is monobloc)
The length of the turbomachine is between 2 and 4m, and the operating range from -150 to 0°C.
The thermal growth, can create a displacement from 3 to 12mm between two hold down bolts (machinery fasteners)
This is a machine compliant with API 617.

- Do the API 617 require sleeves on the bolt for thermal growth? (On my interpretation, it is not described as mandatory)
- Is there a standard where I could find an equation, or a formal limit to decide if it is highy recommended in my case or not?
- What do you think according to your experience?

F67