Stay Plates in Header Box

[yl0525]

Hi, I am new to this forum and would like to look for useful guide/ info on how to determine hole/holes size on stay plates which to be welded to a header box. I manage to use CodeCalc to determine the required thickness of stay plate but have no idea on how the hole/holes to be. Could anyone here please help on this???

 

[speco]

yl0525,

Since nobody else has responded I will give it a shot. First, your problem is greatly simplified if the stayplate is also a pass partition. Then you don't need any holes for fluid flow. However, that's not always practical.

The real answer comes down to a combination of Code requirements, manufacturing capabilities, and fluid flow requirements. Normally, I would make the total area of the holes in the stayplate at least as much as the tube area in the pass downstream of the stayplate. The diameter or shape is pretty much a matter of how you make them. That is, whether they are drilled or burned (or otherwise elongated) holes. Of course you have to account for the holes in the plate efficiency calculations. I am assuming that you are making this header box per ASME Sect. VIII and Appendix 13.

Regards,

Speco

 

[yl0525]

Hi Speco, thanks for your reply.

You are right, I am making a header per ASME VIII App 13 as CodeCalc designs non-circular section based on App 13. Exactly, i will have no problem if the stay plate is a partition plate which there is no holes inside.

But now my case is to have hole/holes inside since it is a single pass. It is true that the cross-sectional area of each pass through stay plate shall be at least the same flow area of the corresponding tube pass, as per required in API 661. And now I am more intereted on the plate efficiency calculation mentioned in your earlier reply. Are you refering to plate ligaments efficiency?

Thank you,
YL

 

[speco]

ylo525,

Yes, I am referring to the ligament efficiency. Obviously, if you remove some of the metal in the stayplate, you have to account for it in the stress calculation. I'm not really an expert on ASME Code calculations, but it should be detailed in Appendix 13.

Regards,

Speco (

http://www.stoneprocess.com)

 

[yl0525]

Speco,

Well I have gone through the App13 and managed to figure out how the ligament efficiency is calculated. Will further study on this particular section.

Thanks for your useful hint and guidance=)

Best Rgds,
yl0525