High Frequency Induction Welded Pipe, HFI pipe

In High Frequency Induction (HFI) Welded Pipe production process, hot rolled steel coils are fed with a high capacity accumulator in order to achieve continuous welding.

 High frequency welding, HFI pipe
 High frequency welding, HFI pipe

HIGH-FREQUENCY WELDING is a welding process in which the heat source used to melt the joining surfaces is obtained from high-frequency (HF) alternating current (ac) resistance heating.

The high-frequency induction (HFI) resistance pressure welding technique for longitudinal welding. The endless strip passes through rolling stands where it is shaped to an open pipe, which runs through a high-frequency inductor consisting of a metal coil with single or multiple windings. As a result, high-frequency ring current is induced into the pipe that closes preferably at the strip edges which converge in the welding point. The temperature required for welding is generated by resistance heating of a narrow zone along the strip edges.

The heated strip edges are squeezed together by pressure rollers, resulting in a homogeneous longitudinal weld without any filler metals. The flash generated on the inside and outside surfaces during welding is scraped off to the level of the pipe surface with special tools.

Immediately afterwards, the HFI weld is subjected to a multi-step inductive annealing treatment to ensure that the properties in the weld area match those of the base material. Then the continuous pipe string is straightened, size rolled and finally cut to length by a flying saw.

Coil edges are milled using carbide cutters in order to assure a high quality weld. Coils are then formed by cold forming method using a set of cage rolls and fin passes, and then joined using high frequency currents using induction or alternatively conduction methods.

The process begins with the cutting of the strip of the required size on slitting line and then fed through the Tube Mill for formation of line pipe. Once the formation of pipe is done, it is passed through the high frequency welder where the edges are welded together.

During the process of welding, because of immense generation of heat, there is formation of beads on both the edges, inside and outside the pipes. These beads are then cut in order to have unrestricted flow of fluid/gas inside the pipe.

Thereafter, pipes are cut into the required length and are transferred to finishing sections for further processing and testing of the line pipes like straightening, End Chamfering/Facing, Hydro-testing, Non-destructive Testing, Threading, Galvanizing etc., depending on the requirement of the customer.

Expertise

Using its specialist expertise in high frequency welding, TWI has supported industry with a range of project and consultancy work which has included:

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Application Areas

HFW welded steel pipes are widely preferred in Oil, Natural Gas, Water and other liquids transportation and distribution lines, heating, cooling, ventilation piping and steel structures for construction and other general purposes by means of precise production tolerances and high capacity manufacturing method.

Welded pipes by manufacturing process

Sunny Steel produce an extensive selection of welded steel pipe including ERW, HFI, EFW, LSAW, DSAW and UOE type carbon steel pipe along with their respective flanges and fittings.

Electric Resistance Welded Pipe
ERW
ERW (Electrical Resistance Welding) pipes are manufactured by cold forming of steel coil into a round cylindrical shape are used in various engineering purposes..
High Frequency Induction (HFI) Welded Pipe
HFI
In High Frequency Induction (HFI) Welded Pipe production process, hot rolled steel coils are fed with a high capacity accumulator in order to achieve continuous welding.
Spiral submerged-arc welding pipes
SSAW
Spiral submerged arc welding is its forward direction and forming tube centerline hose reel molding angle side molding edge welding and weld them into a spiral.
Electric Fusion Welded Pipes
EFW Pipes
The EFW pipe divison consists of a JCO forming press, helical / spiral mill, inside and outside welding system, heat treatment furnace and testing facilities.
Longitudinally Submerged Arc Welded Steel pipes
LSAW
LSAW (Longitudinally Submerged Arc Welded Steel pipes) in leaflets plate as raw material, the steel plate in the mold or molding machine pressure (volume)...
Double Submerged Arc Welded (DSAW) steel pipe
DSAW
Double Submerged Arc Welded (DSAW) steel pipe is available in straight and spiral welded formats and used in a variety of applications.
UOE (Uing and Oing forming) Pipes
UOE
UOE(Uing and Oing forming) is a method used for production of longitudinally welded large diameter pipes.
J-ing, C-ing and O-ing pipes
JCOE
J-ing, C-ing and O-ing process with characteristics of high forming accuracy and efficiency as well as balanced...
SAW
SAWPIPE commonly refer to large diameter weld pipe, it can be classified into LSAW and SSAW .

Weled steel pipe specification, Standard and identification

Welded steel pipe (steel pipe manufactured with a weld) is a tubular product made out of flat plates, known as skelp, that are formed, bent and prepared for welding.

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Hot dip galvanizing

Galvanized pipe process characteristics

What is Galvanized Steel Pipe? Galvanized steel can be made into a strong plumbing or tubing material -- one that resists corrosion from exposure to water or the elements. It has been used used for water-supply pipes or as a strong tubing for outdoor applications.



SUNNY STEEL

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