S and T exchanger seal rods and sliding strips, sliding shoes 1

[vessexst]

Hi,


Well I have never been at site and I am new to designing S and T exchangers. I wanted to know the difference between the arrangement of sliding plate (sliding shoes, rods etc) and seal strips. I know the difference between the purpose they both serve but I dont know how are they placed. As per what I have come across, seal strips are welded inside the shell since they are to prevent by pass leakage of shell side fluid. However, the sliding plate (shoes, rods etc) are welded with the tubesheet and baffles. They slide in and out with the tube bundle. However, this is not the case with seal rods that are welded inside with the shell.

I want to know the exact arrangement from fabrication point of view.

 

[SnTMan]

vessexst, most often, all these parts are placed within the tube bundle. Sliding plates (or skid bars) are placed at the bottom of the bundle, 15 or 20 deg off bottom CL. Their purpose is to, as the name implies, is to provide a means for the bundle to slide into and out of the shell without damaging the baffles, tubes, etc. Common for them to extend past the baffle OD slightly.

Seal bars are placed within the bundle as needed to prevent bypass of the shellside fluid due to clearances from pass lanes, floating heads, etc. Normally placed at the outside of the tubefield, but may be within it as well. Skid bars can double as seal strips as well. Seal rods or dummy tubes may be placed within the tubefield to seal passlane clearances. I personally don't recall sealing elements fastened to the shell, but I suppose it could be done.

Typical arrangements are well illustrated and sealing requirements are well defined in API 660. One of the most important early tasks in S & T design is confirm the tubecount, taking into consideration the need and location of these elements.

Regards,

Mike



The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[vessexst]

@sntman: Thanks for the info!!!

So, the seal strips are also welded to tubesheet and baffle plates just like the sliding plates are??

 

[SnTMan]

Yes, usually so, although they may not always extend to the tubesheet(s).

The problem with sloppy work is that the supply FAR EXCEEDS the demand