.

Too bad. Lynne's position makes perfect sense from a beam strength point of view. A thicker sheet is like a thicker beam. For the same dimensional flex, the thicker beam will have more dimensional stress and tear at its outer dimensions than the thinner beam. Also, the forces are more traumatic leading to permanent deformation (corrugation) of the material. That is why a glass fiber is flexible, and a glass window is not. It seems the failure of some engineers to see the firebox sheet as a moving, flexing object is the source of the debate.

Trivia: anyone ever heard the term "panting" applied to boilers? It dates back to our dead forefathers. Back in the day, "panting" described the visible flexing of boiler shells in time with the stroke of river paddle wheel engines.

That is some really important information for the miniature boiler makers and scale steam locomotive builders.

They nearly always use thicker courses and seemingly always have.

Two boilers have recently been in the news - the Tornado and 3801. How do those bolier designs conform to, or differ from, these Master Boiler recomendations?

If there are differences, are they relevant to the issues thay are having with these boilers?