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Quotes - Engineering - Sales| BONNETS | TUBESHEETS | VARIES BY | IDENTIFIED BY |
| Cast Iron, Brass, Steel | Steel, Brass, Naval Brass | Series | Part number |
Bonnets, Tubesheets and Hardware
Where the Ranges Differ Most
Beyond the shell and the tubes, an exchanger is made up of bonnets, tubesheets, baffles, tie rods and hardware. These components vary considerably across the catalogued ranges, and they are where identification by part number matters most.
Bonnets. Cast iron is standard across most of the range. Cast brass appears on the WU, SU and tank heater ranges as an alternative, and some SU units carry steel bonnets. The bonnet also houses the pass partitions, which makes it specific to the pass arrangement as well as the size.
Tubesheets. Steel or brass on the single-wall ranges depending on series and vintage, and naval brass on the double-wall DSU and DWU. That naval brass is one of the more reliable indicators of genuine double-wall construction.
Why the part number matters here. Two units of identical shell dimensions can carry different bonnet materials, different tubesheet materials and different pass arrangements. Measuring establishes the size and tells you nothing about the rest.
Hardware and gasket faces. Compression bolts, tie rods and the machined gasket faces on the bonnet and tubesheet all wear. Where a joint keeps weeping despite correct gaskets and torque sequence, the gasket face is worth measuring rather than fitting a third gasket.
Component Materials by Series
The part number establishes the material and arrangement for every component.
Bonnets
- Standard: Cast Iron
- Alternative: Cast Brass
- Some SU units: Steel
- Houses: Pass partitions
Tubesheets
- Steel on some ranges
- Brass on others
- Steel or brass depending on vintage
- Naval brass on DSU and DWU
- Established by part number
Also Varies
- Baffle arrangement
- Tie rod and spacer detail
- Compression hardware
- Gasket face machining
- Connection size and type
Related
The Part Number Beats the Tape Measure
Identical Dimensions, Different Parts
Two exchangers of the same shell diameter and length can carry different bonnet materials, different tubesheet materials and different pass arrangements. All three affect which spare parts fit.
A photograph of the nameplate takes a minute and establishes all of it from the record. Field measurement establishes the size and leaves everything else to be guessed.
Naval Brass Is a Useful Clue
On the shell and tube ranges, naval brass tubesheets indicate double-wall construction. If you are trying to establish whether an old unit is a DSU or an SU and the nameplate is illegible, that is a good place to look.
It is a clue rather than proof. The catalogue number range is the definitive answer: 5-262 and 5-267 for double-wall against 5-260 and 5-265 for single.
