installation of platforms on exising stacks 2

[hhmh2003]

In our refinery we have to install new platforms and ladders to existing stacks of boilers, furnaces and heaters. This is for the monitoring of emissions from the stack.

The platforms shall be installed at a minium of eight stack diameters from stack bottom.

What sort of calculations should i perform to check the stability of existing stacks for new loads.

 

[metengr]

Hire a qualified structural engineer.

 

[hhmh2003]

Thanks for the reply..

Actually there is a debate going on who should do the job of analysis of stack. A structure engineer or a mechanical engineer with experience in design for stacks. The platform is going to be welded to the stack and structure engineer says he will design the platform but will not analyze the stack because its an equipment and an experienced equipment engineer should analyze the stack.

I want to subcontract this job and want to know what sort of calculations should I ask from the subcontractor. Actually the stacks are existing and should I ask for wind analysis of the stacks again for new platforms or should I ask for only the dead/live load analysis of the stack due to the new platform..

regards,

 

[metengr]

I want to subcontract this job and want to know what sort of calculations should I ask from the subcontractor. Actually the stacks are existing and should I ask for wind analysis of the stacks again for new platforms or should I ask for only the dead/live load analysis of the stack due to the new platform..

Wind load calculations in addition to static load analysis of the stack as a result of the addition of a platform. Make sure the structural engineer is licensed.

 

[fegenbush]

Where is this job located? Some jurisdictions require a SE license separate from a PE license.

Lots of structural guys out there. Structural AND Mechanical, the pickings start getting slim.

 

[chicopee]

I would look at having a self supporting platform with ladder instead of using the stack as either the full or partial spport system.

 

[StoneCold]

I am with Chicopee on this one. I don't know how high 8 stack diameter is but I am thinking that it would be much simpler to have the platform be self supporting, maybe some small lugs to keep the platform and the stack moving together in the wind but that is it.
Retrofitting is always difficult.

Regards
Stonecold

 

[JStephen]

It would be advantageous to have someone familiar with stack design specifically to check the stacks themselves, and that could be considered either structural or mechanical (note that the stack construction standard is an ASME standard.) It would also much simplify the work if the original design documents for the stacks were available.

 

[MJCronin]

Aged steel stacks are subject to accelerated corrosion and have a well earned reputation for sudden failure.

I would seriously consider a self-supporting structure, as mentioned above.

Some exploratory UT readings of your existing stack could be money well spent.

A justification for a well designed self-supporting structure would be: if the stack is replaced, the platform structure need not be....

My opinion only

 

[bhushan76]

If any of these stacks are refractory lined internally, you will have to be careful so as not to damage existing refractory lining due to welding and/or vibration during retrofitting.

 

[PersonalProfile]

Generally an advocate of permanent infrastructure, though there may be case to consider an EWP (hire as required, long term lease or own etc) in this application?

Regards,
Lyle