dummy or spacer tubes use?

[GGNTR1981]

I am repairing a tube leak and ended up having some of the dummy or spacer tubes removed in our reheat section. I was woundering why are they there is it to support the bundle or to reduce convection. Any help would be of benifit.
Thanks

 

[davefitz]

sometimes there is installed a squashed tube to maintain spacing between elements and also to reduce vibration potential.

Also, if there is found to be a lot of steam in the fluegas after you restart, it probably was not a dummy tube that you removed.

 

[rjoaks]

Dummy tube and I assume these are not connected to the reheat tube circuit are in place to maintain tube spacing to keep a uniform flue gas flow over the tube bank. Removal may cause a problem with poor performance of the boiler if the reheat tubes become miss aligned.

rjoaks