Steel Chimneys

[neilmark]

Does anybody have any guidance or documents on how do design an opening in a chimney. We usually go through the CICIND code and provide vertical and horizontal stiffener plates etc, but these are expensive and time consuming to fabricate. We are looking to stiffen the holes with a tube of steel or elipse inserted into the hole and welded to the shell. Similar to the inlet openings which are shown on the diagrams in the BS and Eurocode...We just cant seem to find a design guide for this type of stiffening.

 

[JStephen]

Is the chimney in question built to any particular standard? If so, that would be the first place to look.
There is also an ASME standard for stacks, but I'm not familiar with the details of it.
Round and elliptical openings in tanks and vessels are usually just reinforced using area-replacement design. The details get complicated due to having limits on the extent of reinforcing and allowances for varying yield strength, but the idea is simple.