Recessed tube hole in Steam Drum.

[GemmellG]

Has any one any information regarding recessed tube holes in Boiler Steam drum recess is inside of the drum. Typical tube holes are not recessed. I have a boiler that have recessed tube hole with he generating bank tube flared inside hole. Client has asked me why?. My thought has to be the thickness of the drum.

 

[metengr]

GemmellG
Can you supply a picture of this recessed tube hole arrangement?

 

[chicopee]

If I remember correctly and I'll verify that when I get back in a few days, recessed tube holes have grooves. I'll also will give you an answer to the reason for having recessed tube holes but you hit on the point about the drum being too thick.

 

[GenB]

I seen them and its acceptable in which shells. A lot more work since machining of the shell from the inside is required. I also seen reassessed tubes welded from the outside on high pressure boilers.

 

[chicopee]

This is an excerpts from my notes taken during a lecture back in'84. The lecture was given by John Longhorn mechanical specialist for travelers Insurance Co.. JL stated that "the optimum thickness of tubesheets is 1-1/4" to 1-1/2". In excess of this optimum thickness, tube ends that are to be rolled will undergo too much extrusion." Based on that information, the vessel manufacturer will need to counterbore the tube seats.