Temporaily support a horizontal boiler steam drum

[refined sweat]

So we have a boiler (steam and mud drum). It is at ground level, 48inch ID and about 30' in length are the vessels. We will need to temporarily support the steam drum to remove some tubes.

So far, they seem to propose installing 2 I beams evenly spaced in between the drums, cope and weld to the steam and mud drums. For now, I will assume they will use a 4'' carbon steel I beam (will confirm). Once we know their placement we can run a simple statics equilibrium formulas. Sum of the forces and moments in Y direction are zero to find the support forces. Then make sure these individual forces do not exceed the allowable stress of the beam (yield). Then check for buckling with Eulers column equation as well.

Some assumptions: The drums are of sound and original thickness, we know the boiler casing is probably taking care of ~25% of the load of the steam drum but will not assume this, lastly I plan to add 20-30% to the empty weight of the vessel for safety.

How does this sound? Any other checks we should do? And what if they use 3 beams, how would you find the 3rd unknown force with only (2) equilibrium equations?

I realize this is basic statics but its been a few years for me and this is also a critical job.

Thank you

 

[refined sweat]

Can someone move this to the structural sub forum

 

[racookpe1978]

How do "they" propose supporting the reinforced long Pressure vessel after the longitudinal ribs are welded on?

At just points - like a horizontal tank? Or continuously down the whole vessel directly to the working surface (concrete?) With multiple different jackstands or hardpoints?

 

[LittleInch]

Needs a drawing to understand what you're planning to do.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[saplanti]

Your description is confusing, however I understand you have bottom supported boiler from my previous experience on boilers. The support on one side is under the mud drum which also supports the steam drum through evoporation sectional tubes.

I guess the roof ceiling ( which probably includes the wall tubes as well ) is also supported by the steam drum.

You want to replace some of the evaporator tubes between drums.

Do you have any calculation from the original design?

Steam drum has internals which their weights might upset you.

You need to sketch up tthe drums, wall tubes and intended supports in mind. Otherwise you will not get adequate contribution. Even experienced person can give you wrong direction if your sketch does not describe what your intension is.