Bonnets / bolted covers on heat exchangers
Bonnets / bolted covers on heat exchangers
(OP)
Hi guys,
Since im relatively new to pressure vessel design im struggling with a concept which i wish to gather some opinions/knowledge on. Specifically in the case of heat exchangers where does the vessel end and where does the piping begin?
What bought this up is we have a shell and tube being designed that is fixed tubesheet with a concentric reducer cone on one tubeside and an eccentric reducing cone on the other. People here have differing views on whether these reducing sections are under the pipe code (b31.3) or part of the vessel (under div.1).
The reasoning they say is that the heat exchange process is only taking place between tubesheet to tubesheet so that the bonnets can be classed as piping. Id like to hear your thoughts on this.
Cheers,
Richard
Since im relatively new to pressure vessel design im struggling with a concept which i wish to gather some opinions/knowledge on. Specifically in the case of heat exchangers where does the vessel end and where does the piping begin?
What bought this up is we have a shell and tube being designed that is fixed tubesheet with a concentric reducer cone on one tubeside and an eccentric reducing cone on the other. People here have differing views on whether these reducing sections are under the pipe code (b31.3) or part of the vessel (under div.1).
The reasoning they say is that the heat exchange process is only taking place between tubesheet to tubesheet so that the bonnets can be classed as piping. Id like to hear your thoughts on this.
Cheers,
Richard





RE: Bonnets / bolted covers on heat exchangers
PS. I can't see any benefit in distorting the perception of pressure vessel and design per piping code.
Cheers,
gr2vessels
RE: Bonnets / bolted covers on heat exchangers
The bonnet is bolted to and exerts loads on the tubesheet. Do your piping engineers know anything about tube sheets and the fundamentals behind their design? (Just like a doubler pad welded to a pressure vessel doesn't hold pressure but remains in the pressure vessel engineers domain. Any attachments then welded to this pad is in the structual engineers domain. We don't want structual engineers welding attachments directly onto a peice of pressure equipment that they don't understand.)
At what connection do you think it is SAFEST for the equipment to go from the heat exchanger code to b31.3. At the tube sheet where a piping engineer knows little about the design of tube sheet he is bolting to or possibly doesn't understand the envronment in the bonnet? Or at the end of the reducer cone where there is a nice familiar flange for him to bolt on to?
It's all abot safety!
RE: Bonnets / bolted covers on heat exchangers
Regards,
Mike
RE: Bonnets / bolted covers on heat exchangers
It would be hard to find something more necessary than your heads for the exchanger. And, if you look, these heads are listed on the U-1. If it is documented on yopur U-1, it is an integral part of your vessel.
RE: Bonnets / bolted covers on heat exchangers
rmw
RE: Bonnets / bolted covers on heat exchangers
Yes Karloss when you take a step back and look at the stresses acting it makes sense to terminate the vessel at something familiar to the piping engineer (and im guessing easier to model in autopipe and the like)
gr2vessels, the issue is (even though i dont like it at all) B31.3 is a way for our workshop to manufacture the reducer sections (as we dont have a u-stamp but have qualified welders) and attach them to the u-stamp vessel.