LL-footed finned tube

The‍‌‍‍‌ production process of this fin type is very similar to that of L-type fin, however, the design of the fin foot is up-graded. Once the base tube is covered with the fin strip, the foot of the fin is lengthened and overlapped so that it completely encircles and encloses the outer surface of the tube.

The overlapped fin foot, by more completely enclosing the tube, forms an additional protective layer between the base tube and the external environment. This feature markedly enhances the corrosion resistance of the tube against atmospheric corrosion, thus it is ideal for environmental protection applications.

As a result of its enhanced corrosion resistance and its comparatively lower price, this type of fin is usually chosen as a cost-effective alternative to the more expensive extrusion fin tubes in moderately corrosive environments.

The highest operating temperature allowed for this fin type is ‍‌‍‍‌180°C.

The‍‌‍‍‌ most notable trait of the LL-type finned tube is its overlapping "double-L" protection and that is also where its name comes from.

Overlapping Winding: The LL-type tube, unlike the L-type one, is manufactured such that the "feet" (the L-shaped base) of the fin strip purposely overlap during winding.

Full Coverage Design: Thanks to the overlapping setup, the fin strip not only fully covers but also wraps the base tube surface like tiled roofs. This makes sure that the base tube is not exposed directly to air or corrosive media, hence, it is well protected against corrosion from atmosphere.

When it comes to corrosion resistance, integrally finned (extruded) tubes are usually the first choice and the most expensive ones. The LL-type tube, however, is a cheaper way of providing corrosion protection without the use of extruded tubes.

While L-type tubes can handle temperatures up to 150°C, LL-type tubes can tolerate slightly higher temperatures resistance, with a maximum operating temperature typically at 170°C-180°C. Even though it is better than L-type in this regard, it still falls in the mechanically wound category. So, at very high temperatures (>200°C) or under severe thermal shock conditions, its bonding strength will be weaker in comparison to KL-type or G-type (embedded) finned ‍‌‍‍‌tubes.

FAQ：

1. Are you manufacturer or trader?

We are titanium tube manufacturer producing from melting titanium sponge, extruding hollow billet, rolling to finished tubes and destructive test mechanical test, chemical analysis, non-destructive tests like Ultrasonic test, Eddy current test, Pneumatic test and hydrostatic test are available in house.

Beside titanium tube production line, we also have finning lines. Our factory is still expanding and will invest more on finning facilities.

2. How many workers are there in your factory?

Till 2026, we have 210 staffs.

3. How fast can you deliver the materials?

It depends on the size and quantity, the standard time is 45 days.

4. What is the payment term you can offer?

Standard term is 30% T/T in advance, balance before shipment. L/C is also acceptable. It can be discussed based on different project.

5. Can you provide third party inspection service?

Yes, we can arrange BV/TUV/SGS/LR etc inspection. EN10204 3.2 certificate can be provided.

6. What is your annum turnover?

For 2025, we have had 100 million US dollars turnover for our whole group including factory and the export company.

7. What is the percentage of your export and domestic market share?

Approximately 30% of orders are for export and 70% are for domestic market. However we are aiming to increase more investment on export and hopefully the percentage can be 50-50 in the near future.

8. What country are your clients from?

We are working with overseas clients from Europe like Netherland, France, Italy, Spain etc, USA, Korea, Japan, Indonesia, Vietnam, Singapore, Chile, Argentina, Brasil, Russia, Belarus, Uzbekstan. Basically we work with clients from all over the world. We welcome every client to approach us for inquiry, and we will be ready to serve our clients. We also welcome our clients to visit our factory for onsite audit.