LL Type Finned Tube for Heat Exchanger

Introduction of LL Type Finned Tube for Heat Exchanger
 

Type LL finned tube is a finned tube in which the fin feet are preformed into an LL shape (overlapping LLs) and a strip of aluminum fins or copper fins is applied to the base tube under tension. However, the feet are pre-formed so that one foot overlaps the other, increasing the base tube protection and thermal contact area of ​​the finned tube. LL Type Finned Tube is usually used in steam coils, air pre-heaters., the maximum operating temperature can reach 180 °C.

The"LL"shaped fin design features interlocking fins that are twisted together to prevent movement and separation. The fins protect the entire tube, the smooth flat fins with"LL"shaped fins perpendicular to the surface of the seamless steel tube tube provide very low resistance to air/gas flow and ensure that fouling is kept to a minimum. The bottom of the fin is in contact with the base tube and provides a complete jacket over the length of the fin. Hence the name applies to applications where corrosion is a factor. This LL Type Finned Tube is often used as a replacement for more expensive extruded fins in corrosive environments. 

LL Type Finned Tube for Heat Exchanger Quick Details

Core tube material:
1. Carbon steel: A179, A192, SA210 Gr A1/C, A106 Gr B
2. Stainless steel: TP304/304L, TP316/TP316L
3. Copper: UNS12200/UNS14200/UNS70600, CuNi70/30, CuNi 90/10
4. Titanium: B338 Gr 2

Fin material:
1. Aluminum (Alu.1100, Alu.1060)
2. Copper.
3. Steel

Fin type: Solid plain
Fin Tube Type:LL Type
Outer diameter (OD): 16mm Min~50.8mm max.
Tube length: up to 18,000 mm.
Fin height: 16.5mm max.
Fin thickness: generally 0.4mm~0.6mm
Fin pitch: 2.1mm minimum (12FPI)
Surface Protection: Both bare ends shall be zinc or aluminum metallized by electrospray arc system coating.
Accessories: Tube support boxes, clamps or spacer boxes (materials: aluminium, zinc and stainless steel).

Common Specifications of LL Type Finned Tube for Heat Exchanger

Manufacturing Process
 

Type LL finned tubes are preformed into LL shape (overlapping LLs) with fin feet and aluminum fin tape or copper fin tape is applied to the base tube under tension. The feet are pre-formed to allow one foot to overlap the other, increasing base tube protection and finned tube thermal contact area.

LL Finned Tube is combined with two different materials
 

Core tube material: carbon steel, low alloy steel, stainless steel, brass, copper, copper-nickel alloy, aluminum bronze, nickel alloy.