Steam Turbine Foundation Bolts Grouting

[Syed_Osama]

Hi,

I'm a relatively new member here.

I wanted to ask if anyone could explain technical reasons for the following:

1. Filling sand only in foundation bolt pockets for through and through foundations bolts of steam turbine.

2. Grouting foundations bolts for blind pockets.

Thank you.

 

[racookpe1978]

You MUST FOLLOW the turbine manufactoroer's exact requirements for the mounting bolts and foundation alignment, mass, and reinforcement.

We've had several muti-MegaWatt turbine-generators break apart under load when foundations and mounts failed.

 

[Syed_Osama]

I'm currently working on erection of Steam Turbine at site, and have followed the exact requirements of the manufacturer, which was to fill the foundation bolt pockets with sand only and not filling in the grout material. The bolts are through and through in the foundation.

I wanted to know why are they not grouted, whereas, bolts fitted in blind pockets are grouted.

 

[jimstructures]

Have you asked the manufacturer, why they recommended filling the bolt cavities with sand???

Jim

 

[dhengr]

Syed_Osama:
#1. Holds down rigidly, but allows some movement laterally, for thermal or vib. damping
movement.
#2. Holds down and laterally rigidly.
The above is my bet…, so as Jimstructures suggests, asked the manufacturer for their reasons.

 

[Syed_Osama]

dhengr:

I did ask them, but didnt receive any more detailed answer than what you have given, and was the same as your point 1.

However, what i dont understand is that once the turbine base frame is grouted, its fixed on all sides, then how is lateral movement still possible at all?

Secondly, why is there no need of allowing lateral movement when placed on ground with bolts grouted?

 

[Agent666]

Thermal expansion would be one reason for movement post install.

 

[Syed_Osama]

Agent666:

Thermal expansion of what, bolts? because after grouting, the turbine is fixed from all sides. If expansion occurs, it has to occur in the grouting material first to allow turbine base frame to expand subsequently.

And if the expansion is indeed for the bolts, why is it not required in the ground foundation with blind holes?

 

[Agent666]

Sorry, I meant thermal expansion of the piece of plant. I'm making the assumption that a, steam Turbine has a wide non operating and operating temperature range.