Thickness of longitudinal baffles with lamiflex seals

[adilpervaiz]

As per TEMA R- 4.421 : "Longitudinal baffles with leaf seals shall not be less than 1/4" (6.4 mm) nominal metal thickness".

Does the above thickness apply to all pressure drop conditions?? How do we calculate the thickness of longitudinal baffle (with lamiflex seals) if the pressure drop is higher than recommended (i.e. 1.1 kg/cm2)?

Regards

 

[SnTMan]

adilpervaiz, if you do not think 1/4" is sufficient, why not use the rules for welded long baffles, R-4.422?

Regards,

Mike

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

 

[adilpervaiz]

Thankyou for your response, Mike.

We are not using welded long baffle due to maintenance requirements(ease of bundle pulling for cleaning).

To be more specific, i want to know how we can calculate the thickness of a longitudinal baffle (with lamiflex seal) for a shell side pressure drop of 1.1 kg/cm2?
Is there any formula to calculate the thickness of long baffle with leaf seals like the one given in TEMA R-4.422 for welded baffle.

Regards

Adil

 

[SnTMan]

adilpervaiz, there are no specific TEMA rules for leaf-seal long baffles other than R-4.421. You could perform the calculation of R-4.422, but likely the assumed edge conditions will not apply in the case of a non-welded long baffle. A "more accurate" calculation may be a calculation assuming all edges simply supported, such as Roark Table 26, Case 1 (6th Ed.) using appropriate characteristic dimensions. Another case may more accurately represent your exact configuration.

A couple of observations on my part:
1) You need to assure yourself that the lamiflex will hold a seal at your pressure drop, else the exchanger performance will suffer.
2) It is possible to have a removable bundle with a welded long baffle. It is messy.

Regards,

Mike

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

 

[CuMo]

Mike,
do you have an example of removable bundle with a welded longitudinal baffle?
I'm curious to see what it looks like.
Thanks!

 

[SnTMan]

CuMo, I don't have any drawings, sketches, etc, but can briefly describe the main features.

First, of course the cross baffles must be split to straddle the long baffle. Cross baffle cuts perpendicular to the long baffle are preferred, but not strictly necessary.

For floating head units, the floating head is split as well. TEMA has what appears to be a sketch of this arrangement, see Table A.131, sketch (k).

For U-tubes, the plane of the bends must be parallel to the long baffle. For more than, say, four tubeside passes this can become troublesome.

In any case, it is a messy business and a great deal of early attention must be paid to tube layouts, long baffle thickness, cross baffle arrangement, tie rods, seal bars, various clearances, etc.

Regards,

Mike



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