Heat Exchanger Tube Thickness enhancement for HTRI Desgn
Heat Exchanger Tube Thickness enhancement for HTRI Desgn
(OP)
When designing Shell & Tube Heat Exchangers as per HTRI Xist, is it required to enhance the Tube thickness at input to ensure pressure drop limitation when Tubes are procured with
a) Minimum wall tolerance of +20% -0
b) Average wall tolerance of + - 1o%
What input thickness is to be used.
a) Minimum wall tolerance of +20% -0
b) Average wall tolerance of + - 1o%
What input thickness is to be used.
RE: Heat Exchanger Tube Thickness enhancement for HTRI Desgn
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P.E. Metallurgy, consulting work welcomed
RE: Heat Exchanger Tube Thickness enhancement for HTRI Desgn
Both Average wall and Min wall are used.
1. For CS & LAS Tubes Min wall Tubes are used.
2. For SS Tubes Average or Min Wall Tubes are used as per Customer requirement.
Please advise HTRI Input for both the cases.
RE: Heat Exchanger Tube Thickness enhancement for HTRI Desgn
For Minimum Wall tubes the average measured wall thickness is typically around 10% thicker than the nominal thickness, so the tube ID will be smaller and you need to account for this in your HTRI input. Typically this is accomplished by increasing the tube wall thickness by 1 BWG (e.g. specify 13 BWG in HTRI for 14 BWG Minimum Wall tubes. Remember that the pressure drop through a tube is inversely proportional to the tube ID to the 5th power, so a 10% difference in the ID can have a substantial impact on the pressure drop.
Keep in mind that everything I've written above is for welded tubes (since seamless tubes are drawn over a mandrel I don't think the wall thickness tolerance actually effects the measured ID?) and assumes that there won't ever be any fouling deposits on the tube ID.
-Christine