What is knurled low finned tube?

A knurled low finned tube refers to a type of heat exchanger tube that features knurling on the surface and low fins. Knurling is a manufacturing process where a pattern of small ridges or grooves is added to a surface to provide better grip or enhance heat transfer.

Knurled low finned tube manufacturing process:

The fins are rolled out of outer wall of the plain tubes by a pass roller. Tubes and fins are in same piece tube. We call it “N” type fin tube.

In the case of knurled low finned tubes, the knurling process is applied to the outer surface of the tube. The purpose of the knurling is to increase the surface area of the tube, which enhances heat transfer efficiency. The knurled pattern creates turbulence in the fluid flowing through the tube, improving the heat exchange between the fluid and the tube surface.

The term "low finned" refers to the type of fins used on the tube. Low fins are typically smaller and have a lower fin density compared to high fins. The lower fin density allows for better fluid flow and reduces the pressure drop in the heat exchanger.

Knurled low finned tube material:

Carbon steel , low-alloy steels , stainless steel ,Copper-nickel alloys tube ASTM B111:  Copper and Copper-Alloy Seamless Condenser Tubes and Ferrule Stock C70600 / C71500 / C12200 / C12100 / C68700 C70600 equals to BFe10-1-1 ;  C71500 equals to BFe30-1-1, aluminum bronze, nickel alloys , titanium etc

Knurled low finned tubes applications

Knurled low finned tubes are commonly used in various heat transfer applications, such as air conditioning, refrigeration, and heat recovery systems, heating systems; Ventilation systems; Refrigeration and climate control systems; mechanical engineering; Automotive manufacturing; Chemicals and pertrochemical and power plant technology.They are particularly useful in applications where compact heat exchangers are required, as they provide a larger surface area for heat transfer within a limited space.

Knurled low finned tubes typical scope:

Specifications of Low Fin Tubes(N Fins)

Finning Facility: 10 finning machines;

Daily capacity up to 3000 meters; Tube OD: 12.7 mm~25.4mm

Tube Length: 18 meters max.

Fin Height: 1.2 mm ~2.77mm

Fin Thickness: appr. 0.3mm

Fin Pitch: 30 FPI /28 FPI/ 26 FPI/ 36 FPI /43 FPI

We can provide the integral low fin tubes with un-finned section gaps( 5mm Min.) in the middle of core tube OR bent with designed Bend Radius.

Knurled low finned tube acceptance critic:  WOLVERINE  /  HPT  / GEWA-K & GEWA-KS

Knurled low finned tube delivery condition:

The integral low fin tube quality is assured by hydrostatic or pneumatic tests, eddy current tests & MARCO tests in order to verify design specifications.

Tube ends are square cut, free burrs, internally dried and air blown clean, externally coated with varnish.

The desiccants are put into the each package for continental transportation.

Overall, the combination of knurling and low fins in these tubes helps to improve the heat transfer efficiency and performance of heat exchangers, making them more effective in transferring heat between fluids.

Knurled low finned tube