Finned Tubes and U-Bend Tubes for Heat Exchangers and Air Coolers: A Buyer’s Guide

In refineries, petrochemical plants and power plants, a large share of heat exchanger maintenance comes down to tubes: replacing a bundle, re-tubing an exchanger, or supplying finned tubes for an air cooler. The exchanger design is usually fixed; what the buyer has to get right is the tube specification. This guide explains the main tube types and what to include in an enquiry.

Where the tubes go

Shell-and-tube exchangers carry one fluid inside the tubes and the other around them in the shell. Tubes are straight or U-bent, and are often supplied as replacement bundles or loose tubes for re-tubing.

Air-cooled exchangers cool process fluid with ambient air blown across finned tubes. They are widely used where cooling water is scarce or expensive, and the fins are what make the air side work.

We also supply complete units; see our air heat exchangers and shell-and-tube heat exchangers.

Common tube types

Serrated fin tubes and laser-welded finned tubes — welded fins for higher temperatures, such as heat recovery and fired heater convection sections.
LL and KL (knurled L) fin tubes — wrapped fins typical of air coolers.
Low-fin tubes and U-bent low-fin tubes — integral fins that increase surface area inside a shell-and-tube exchanger.
U-bend tubes — plain tubes bent to the radii of a U-tube bundle.
Inner ribbed tubes — internal ribs for steam and boiler applications.

What to put in a tube enquiry

Base tube material standard and grade (for example ASTM A179 for low-carbon steel heat exchanger tubes, or ASTM A213 for alloy and stainless tubes), outside diameter, wall thickness (minimum or average) and length.
For finned tubes: fin type, fin material, fin height, thickness and pitch, and the unfinned lengths at each end.
For U-bend tubes: the bend radii and quantity per radius, and any heat treatment of the bends your specification requires.
Testing: hydrostatic or eddy-current testing as required by the material standard or your specification.
End finish and packing — tubes and fins are easily damaged in transit, so agree crating before production.

If you are replacing tubes in an existing exchanger, send the exchanger data sheet or the tube sheet layout. It is the most reliable way to make sure the new tubes fit.

Documents to ask for

Ask for mill test certificates for the base tubes with traceable heat numbers, together with the test records required by the standard. For critical exchangers, third-party inspection by a body such as SGS or BV is common practice; where you request it through us, the fee is paid by the buyer.

How we work

YuxingCorp coordinates supply from manufacturers we have visited and qualified, together with supplier coordination and shipping and freight logistics coordination. Each shipment comes with a complete export document pack — commercial invoice, packing list, certificate of origin and bill of lading. Import customs clearance, duties, taxes and local registration are the buyer’s responsibility. Our standard payment terms are T/T: 30% deposit and 70% before shipment.