2 replies to this topic

[WilliamN]

Dear friends,

 

Aspen EDR software gives the following results:

 

Mean shell metal temperature = 307F

 

Mean tube metal temperature = 290F

Minimum tube metal temperature = 200F

Maximum tube metal temperature = 300F

 

One source claimed expansion joint is required if the metal temperature difference is greater than 90F. However, this source did not elaborate if the difference refers to the mean temperature or max/min temperature.

 

Appreciate your comments if expansion joint is needed for the above conditions.

[Art Montemayor]

Just about every experienced process design engineer and every plant operations engineer will tell you that expansion joints on TEMA fixed heat exchanger shells are to be avoided at all costs.  Field results have shown nothing but troubles and hazards with these type of expansion joints and it is a simple matter to use other types of TEMA shells or configurations.  In 53 years, I have come across only two instances where I "inherited" exchangers with shell expansion joints - and I eliminated them.  One of them was a shell-side condenser - which was an accident waiting to happen.

 

In my experience, this isn't only my opinion and I would welcome any experienced field comments on this subject from Forum members.  I have found that there are other TEMA shells that can be used instead.

[srfish]

An expansion joint is not required for those metal temperatures. Average metal temperatures are used to evaluate the requirement for an expansion joint and what type. For rules of thumb on maximum metal temperature differences refer to a tip on www.gulleyassociates.com titled "Is an expansion joint required in the shell?".

 

As Art mentioned, there are problems with expansion joints. The bellows type expansion joints are easily damaged. The flanged and flued head type are more sturdy but not as flexible. For more information on expansion joints refer to "Working Guide to Shell-and-Tube Heat Exchangers" by Stanley Yokell. The guide has criteria for determining the best type of expansion joint.