6 replies to this topic

[karthick selvaraj]

Hi,

Can anyone please let me know is there any minimum requirements for the tubesheet thickness to be followed.Because in codes and TEMA there is no clause regarding the minimum thickness on tubesheet.

Is the tubesheet thick based only the tube diameter or any other aspects. However tube to tubbesheet joint also to be considered in providing tubesheet I guess.

Please let me know on above.

Thanks
Karthick.S

[karthick selvaraj]

Adding to the above topic, I need to know reference for considering the minimum required thickness with welded joint. As for expanded it is shown in RCB 7 of TEMA.

[Art Montemayor]

First of all, I am moving this thread to the new Process Heat Transfer Forum where it belongs.

I don’t know why you assert that “in codes and TEMA there is no clause regarding the minimum thickness on tubesheet”. I take this to mean that you have looked into the ASME code and the TEMA standards (not a code) and have not found what you are looking for. If I am correct, then you haven’t done a good job of reading.

In my 1988 copy of “Standards of the Tubular Exchanger Manufacturers Association”, 7^th Edition, I clearly see in page 38 the following specific directives:

RCB-7.13 Required Effective Tubesheet Thickness
The required effective tubesheet thickness for any type of heat exchanger shall be determined from the following paragraphs, for both tube side and shell side conditions, corroded or un-corroded, using whichever thickness is greatest. Both tubesheets of fixed tubesheet exchangers shall have the same thickness, unless the provisions of Paragraph RCB-166 are satisfied.

R-7.131 Minimum Tubesheet Thickness with expanded Tube Joints

In no case shall the total thickness minus corrosion allowance, in the areas into which tubes are to be expanded, of any tubesheet be less than the outside diameter of tubes. In no case shall the total tubesheet thickness, including corrosion allowance, be less than ¾”.

B-7.131 Minimum Tubesheet Thickness with expanded Tube Joints

In no case shall the total thickness minus corrosion allowance, in the areas into which tubes are to be expanded, of any tubesheet be less than ¾ of the tube outside diameter for tubes 1” OD and smaller, 7/8” for 1-1/4” OD, 1” for 1-1/2” OD, or 1-1/4” for 2” OD. In no case shall the total tubesheet thickness, including corrosion allowance, be less than ¾”.

(I have omitted C-7.131, which refers to the Commercial and General applications)

The above also applies to seal-welded tubes because these are also expanded into the tubesheet. It is the expansion that gives the joint the majority of its integral strength, not the fillet seal weld.

You also ask: “Is the tubesheet thick based only the tube diameter or any other aspects.” Of course there are other parameters and factors that affect the tubesheet thickness. Just to name a few obvious ones: tube spacings (pitch), tubesheet alloy, tie-rod construction, corrosion allowance, tube bundle type, etc., etc. Please make a concerted effort to read, study, and understand the TEMA Standards and the ASME code if you want to learn, discuss, and mechanically design tubular heat exchangers. This is a pre-requisite.

I hope this information responds to your query.

[Robert Montoya]

Thank Mr. Art for the for good explanation, according to the explanation above the minimum thickness for tube sheet is given by RCB-7-1341 as function tube diameter for floating and fixed tube class R, C, and B.

Robert

Attached Files

•  tubesheet thickness.pdf   143.96KB   4485 downloads

[srfish]

Be sure you don't use a TEMA edition that is older than the 7th edition. The 7th and 8th editions have more accurate equations for tubesheet thickness.

[Robert Montoya]

Thank Srfish, the equations are different.

Attached Files

•  tubesheet thickness 8th edition.pdf   52.33KB   2706 downloads

Edited by roberdani12, 20 July 2012 - 04:24 PM.

[karthick selvaraj]

Hi All,

Thanks all for your valuable reply.


Karthick.S