Conflict in heat exchanger datasheet

[HOUARI YAHIAOUI]

Hello experts;
I want to clarify this case, if it is a discrepancy or not.In data sheet of a shell and tube heat exchanger I found that the designer mention this in notes :
Note : TUBE SIDE CS+3mm, SHELL SIDE CS+6mm, TUBESHEET Superduplex 2507, TUBES Superduplex 2507.

I want to know what is the difference between the tube side and tubes mentionned in the note,as i know that the tube side is the same as tubes,but the materials choosen in this note disturbs me.

cordially

 

[EdStainless]

More info would be nice. The full data sheet might help explain what is going on here.
If I saw that note I would presume that the tubes and tubesheet are 2507 (poor notation, should use UNS).
Are the first notes related to corrosion allowance? What is this note attached to in the sheet? CS on the tube side has +3mm and CS on the shell side has +6mm?

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

 

[georgeverghese]

Though I would agree this is poor engineering language, would guess this CS+3mm refers to the tubeside channels and head.

 

[HOUARI YAHIAOUI]

Hello experts;
Thank you all for your response at my question, the occupation now is clarified where :

1)the shell side : means all elements of the heat exchanger where the shell side fluid passes.

2)the tube side: means all elements of the heat exchanger where the tube side fluid passes therefore the tubes, tubesheet,channel and the head are considered to be elements of tube side part.

Whene we have exceptions llike the preoccupation I publied above where the tubside material is CS+3mm and tubes and tubesheet are maded by superduplex 2507 means that only tubes and tubesheet material is superduplex but the other elements of the tubeside part will be constructed by CS+3mm like (channels and head).

 

[Christine74]

The material description most likely means that the tubes and the tubesheets are solid Superduplex 2507, the shell is carbon steel with 6 mm of clad/weld overlay on the ID, and the channel(s) is carbon steel with 3 mm of cladding.


-Christine

 

[HOUARI YAHIAOUI]

^ I agree with you that the tubesheets and tubes are solid Superduplex 2507, but for the shell and channels the +3 or +6 mm is the corrosion allowances and not a cladding.

 

[SJmetallurgist]

+3,+6 are clearly notations for corrosion allowance. based on relative corrosion on both sides. Though I am highly surprised - As such,if tubesheet and tubes are supposed to be superduplex 2507 (generic alloy nomenclature), why not channel side is either solid superduplex OR CS +3mm superduplex cladding? something is wrong in the understanding of your Engineer. Copy pasted datasheets can cost lives in operation. when superduplex 2507 is being used, I envisage a high chloride service, such as seawater service. Channel side should not be compromised with.

Another scenario could be that the fouling coefficient of the fluid might be high, that might be the reason to have superduplex SS 2507 material only for tubesheet and tubes AND NOT channel side material. even after fouling, superduplex SS wont corrode, and chemical cleaning will be easier to perform without corrosion concerns.

 

[MJCronin]

All

It is standard practice for the HX purchaser/specifier to NOT give a corrosion allowance on the tubes themselves.

It is also standard practice in cases where there is a less corrosion resistant material (CS) and a more corrosion resistant material (2507) to have the tubes made of the more corrosion resistant material.

Typically, with a 2507/CS combination, the HX will be configured with the corrosive flow on the tubeside.

This enables the HX to have a cost saving 2507 clad tubesheet and complete 2507 protection on the tubeside.

Tubes should be of seal welded configuration in that case.

The newbie confusion you stated above illustrates the reason why a full TEMA datasheet should be used for HX specification.

http://www.doyleroth.com/tema.html

MJCronin
Sr. Process Engineer