Boiler wall thickness

Does anyone know of a formula for calculating the wall thickness of steam boilers?

You want to purchase a copy of Mark's Mechanical Engineer's Handbook. There is an extensive section on Mechanics of Materials which contains much information on cylinders and tubes containing internal pressure as on boiler drums. (and the converse, collapsing of externally pressurized cylinders such as tubes in a firetube boiler)

Mark's Handbook can be bought new for an exhorbitant price from Amazon.com or can be purchased "pre owned" for considerably less from almost any used bookseller. (I paid 50 cents for my last one bought at a yard sale.) The used versions go back to 1916 and all are similiar for what you want and have a virtually identical Mechanics of Materials section. (I prefer the earlier books as the pictures are better.)

Mark's Handbook will tell you how to calculate the "strain" portion of the equation. You also have to know the "stress" limits of the material. The ASME Code gives allowable stresses for all of the commonly used boiler materials. Mark's Handbook may cover this in considerable abbreviation also.

The ASME Boiler Code (Section 1) is available directly from the ASME for an exhorbitant fee (See www.asme.org) and more reasonably at any major city or university library. It does not get modified that much in updates and any version printed after WWII would be acceptable for what you're likely to want to do.

Besides stress and strain, you also have to make decisions (or have knowledge of) corrosion allowance, joint efficiency, joint orientation, safety factors, staying & reinforcements, and a myriad of other details of boiler construction.

It's a big subject with a lot riding on it (your life!) Read and learn more, possibly a lot more, before you begin any design or construction.

Best regards, Joe