Carbon Steel Fin Tubes High Frequency Welding

A.       HF WELDED HELICAL FINNED TUBES SEGMENT Industrial is proud to supply a wide range of high frequency helical high finned tubes - great for the petrochemical and power generation industry. A continuous helical fin is attached to the base of the tube by high frequency electric resistance welding. The helical fins produce a homogeneous, clean, continuous bond for efficient heat flow and resistance to corrosion.   B.       High frequency welded finned tubes features High frequency welded finned tube is a kind of efficient heat dissipation element. It improves the shortcomings of other finned tube radiators. The finned tube itself is a strip steel with a thickness of 0.8-1mm wrapped around the finned tube. At the same time, high frequency welding process is used to weld the fins firmly on the tube, ensuring the bonding strength between the tube and fins. Its metal thermal strength has reached 1.10~1.20w/kg ℃, The finned tube is widely used in the manufacture of economizer of boiler, air preheater and energy-saving radiator of workshop and residence, and is the first choice for later winding of heat pipe. The spiral finned tube is a high efficient heat transfer element. Its heat transfer area is several dozens of times than the bare tube, which can enhance heat transfer, reduce flow resistance, and reduce metal consumption, thus improving the economy and operation reliability of the heat exchange equipment. At present, spiral finned tubes have been widely used in various boilers. C.       High frequency welded Principle Finned tube is a steel strip wound on the outer circle of the seamless steel tube with a certain thread pitch (the steel strip is perpendicular to the surface of the outer circle of the steel tube). High frequency current is used as the welding heat source. The skin effect and electric heating effect of high frequency current are used to locally heat the contact surface between the steel tube and the steel strip and the area to be welded, so that the contact surface can reach a plastic weldable state. At the same time, an upset forging force is applied on the outside of the fin to make the metal oxide Extrusion of local melt and excess plastic metal makes the combination of solid atoms between steel pipe and fin material, thus realizing plastic welding of contact surface. D.       High frequency welded finned tubes Manufacturing process The welding of high-frequency welding spiral finned tubes can be generally divided into the following processes: (1) Procurement and re-inspection of steel pipes. Steel pipes shall be purchased according to the standards and technical terms required by the drawings; After arriving to the factory, re-inspection shall be carried out carefully. The re-inspection contents shall include: quantity, specification, various inspection reports, appearance, dimension, spot check on chemical composition etc. (2) Preparation before welding. The steel pipe surface must be in a state conducive to winding. The pipe surface should be free of pits, dents, overlaps and grooves. Before welding, the oxides, grease, impurities and coatings affecting the welding quality on the external surface of the base pipe must be removed, usually by polishing or sandblasting. Fin shall be made of thin steel plate, and the whole roll of thin steel plate shall be cut to the required width according to the required fin height. (3) Fin winding and welding. The steel pipe is installed on the fin winding machine, and the fins are according to the qualified winding and welding process. The fin tubes are welding while winding on the fixed guide rail until the length is reached. (4) Inspection and test. The appearance inspection, scraping and peeling inspection are carried out for the wrapped fin tubes one by one, and the inspection results should conform to the drawings and technical requirements. Then carry out the hydrostatic test one by one. The test pressure shall be 1.5 times of required spec., and the pressure holding time shall not be less than 5mins. (5) Fin protection. The finned tube shall be purged with compressed air after manufacturing. Good finned tubes outer surface will be sprayed with anti-corrosion oil. The two ends of the finned tube are protected with caps to prevent water and debris entering the tube.   E.        HFW Finned tubes process control The welding rate and quality will directly affect the strength and heat transfer performance of fins. If the welding rate is low, the weld strength will decrease, the thermal resistance of the finned tube will increase too. Then the heat transfer coefficient will decrease. The welding strength is an indicator to measure the welding quality of fins. If the weld strength is low, the fins will fall off when working due to the thermal stress, fluctuation and bending stress. After the fins fall off, they will gather together to affect the heat transfer, causing the fin tube to be burned. F.        HF WELDED TUBE SIZES AND MATERIALS Usually a combination of carbon steel, low alloy steel, and stainless steel, we supply the helical finned tube, which can either be serrated (segregated) or solid. Tube thickness depends on the fin thickness and tube OD. The minimum thickness for tubes with a solid fin is 2.13mm and 1.99mm for tubes with a serrated fin. Fin height is dependent on the type of fin, tube OD, fin thickness and material. If it’s a solid fin it’s usually between 6.3mm and 31.8mm, whilst serrated fins are 12.7mm-38.1mm. Fin thickness varies depending on the fin type, as well as the height of the fin and tube OD. The helical finned tube is usually between 1 fin/inch and 7 fins/inch.   G.       We supply the helical finned tube in a wide range of sizes, including: Tube OD: 25.4 / 31.8 / 38.1 / 50.8 / 63.5 and 76.0 mm Pipe OD: 26.7 / 33.4 / 42.2 / 48.3 / 60.3 / 73.0 / 88.9 / 101.6 / 114.3 / 141.3 / 168.3 and 219.1 mm   l  SERRATED FIN Fin Height: 0.5–1.5” (12.7–38.1mm) (higher on application) Fin Thickness: 0.036–0.05” (0.9–1.27mm) Fin Spacing: 1–7 per inch (39–276 per metre)  Tube Outside Diameter: 0.75–8” (19.05–219.1mm) Segment Width: 5/32, 5/16” (4.5, 8.0mm)   l  PLAIN FIN (SOLID FIN) Fin Height: 0.25–1.0” (6.4–25.4mm) (higher on application) Fin Thickness: 0.036–0.098” (0.9–2.5mm) Fin Spacing: 1–7 per inch (39–276 per metre)  Tube Outside Diameter: 0.75–8” (19.05–219.1mm)