In the process of high-frequency welding of steel pipe, the welding process and the control of process parameters, the location of the induction coil and the location of the resistance of the weld pipe weld quality have a great influence. 1) Control of the gap of the steel pipe，the steel strip enters the welded pipe unit and is formed by the forming roll. After the guide roller is oriented, the circular steel pipe tube with the opening gap is formed, and the extrusion amount of the squeeze roller is adjusted so that the gap gap is controlled at 1 ~ 3mm, and make both ends of the welding flush. Weld gap control too large, will weld poor welding and produce no fusing or cracking; weld gap control is too small, due to heat is too large, resulting in weld burning, melting metal splash, affecting the weld quality of welding. 2) The induction of high-frequency induction coil should be placed in the same center line with the steel pipe, the front end of the induction coil from the squeeze roller centerline distance, without burning the squeeze roller under the premise of steel pipe specifications should be As close as possible. If the induction circle is far from the squeeze roller, the effective heating time is longer, the heat affected area is wide, so that the strength of the steel pipe weld is not broken or not penetrated; otherwise the induction circle is easy to burn the squeeze roller.  3) The resistance of the position of the regulator is a tube or a group of special pipe, the cross-sectional area of the resistor should not be less than 70% of the cross-sectional area of the pipe diameter, the role is to make the induction coil, rods form an electromagnetic induction loop, resulting in proximity effects, eddy current heat concentrated in the vicinity of the edge of the pipe weld, so that the edge of the tube heated to the welding temperature. The resistor should be placed in the V-zone heating section and the front end is at the center of the squeeze roller so that the centerline coincides with the centerline of the tube. Such as the location of the resistance device is not good, affecting the welding speed and welding quality, so that steel pipe cracks. 4) High-frequency welding process parameters - the input heat control high-frequency power input to the steel pipe weld part of the heat is called the input heat.

Deformation characteristics of spiral steel pipe have three points: 1. The full cross-section of the spiral steel pipe evenly distributed as a foundation, the choice of pairs or pairs of rollers to form a complete shape of the hole because of the larger roll section roller diameter. 2. The combination of the spiral steel pipe is the distribution of the force in the whole section of the curve, the wear of the plastic and the quality of the material and the quality of the analysis of the original deformation of the roll is divided into several pairs of smaller rolls to apply twists and turns, between the small roller from the non-binding twists and turns. This skill can significantly reduce the roll weight and improve the quality of the tortuous appearance, especially for large standard cross-section of the goods, the role of significant. 3. The spiral steel pipe common roller twists and turns in the tortuous deformation. Only the set of units of the hole planning guidelines remain unchanged. The lattice in the same frame deformation has the following three characteristics: 1) Straightness: the standard in the arc similar to the point, and the point can form a straight line I standard change spiral pipe can be b similar to the point of the line to move the end; 2) Parallelism: tangents and lines of similar points are always parallel; 3) Share: similar to the point of the interval and its twist radius of the amount of the amount.

The three steps of large-diameter thick-walled steel pipe production of  are as follows: The first production methods: from thick-walled steel pipe (plate, belt) directly into the welding pipe, the main process for the strip forming, welding, sizing. Features: less production processes, the project process is simple, the product production cycle is short, the product accuracy is slightly lower. The second production method: from the thick-walled steel pipe (plate, belt) first direct welding into a certain size pipe, and then after cold drawn or cold rolled into a finished product tube, known as DOM welded steel pipe. The main process for the forming, welding, sizing, cold rolling or cold drawing (with mandrel or no mandrel), or continuous cold drawing (ie welding - cold drawn joint production line). Features: the production process dispersion, process and production cycle is long, covers an area of large, product size and accuracy, both inside and outside the surface smooth, mechanical properties and microstructure state. The third mode of production: by the thick-walled steel pipe (plate, with) the first direct welding into a certain size pipe, into the continuous reducer to reduce the diameter into a finished product tube. The main process for the forming, welding, continuous cold reduction. Features: compact production process, simple process, the unit production efficiency, specifications range change fast, suitable for the production of small diameter and thin-walled welded steel pipe.

The nominal diameter of seamless steel pipe is the size of all piping accessories in the piping system. The nominal diameter is a convenient rounded element for reference and is not strictly related to the machining dimension. Nominal diameter with the letter "DN" followed by a digital sign. Seamless steel pipe Nominal diameter, also known as the average outside diameter (mean outside diameter). This is the tube from the metal tube is thin, tube diameter and tube diameter is almost the same, so the outer diameter of the tube and the tube diameter of the average as the diameter of the call. DN is the nominal diameter, nominal diameter (or nominal diameter), is a variety of pipe and pipe accessories common caliber. The same nominal diameter of the pipe and pipe accessories can be interconnected, with interchangeability.It is not the actual sense of the pipe diameter or diameter, although its value and pipe diameter is closer or equal. In order to make the pipe, pipe connection size uniform, using the nominal diameter (also known as nominal diameter, nominal diameter). For example, welded steel pipe can be divided into thin-walled steel pipe, ordinary steel pipe and thickened steel pipe. Seamless steel pipe. Its nominal diameter is not the outer diameter, nor is the inner diameter, but similar to the ordinary pipe diameter of a nominal size. Each nominal diameter corresponds to an outer diameter whose inner diameter varies with thickness. Nominal diameter can be expressed in metric mm, also available in English.

One. Punching pipe penetration 1) Before the construction, the control of the pile should be designed according to the original map, and the axis as the base of the pile by the root of the review, make measurement records, check the correct pile before the construction. Spiral pipe for piling to the scene, the lifting of the use of a little bandage lifting, to be hung to the pile position for the pile, the pile will be placed in advance pile pile pile, to ensure accurate and vertical penetration. Before piling, it is necessary to place a special pile cap on the pile head, put the pile with a hardwood cushion, piling the spiral pipe pile to the pile position, because the pile and pile cap total weight and pile hammer Placed in the pile top will sink, a lot of penetration into the soil, to be sunk to stability and then hammer; 2) Began piling, the piling machine due to penetrate into the large and empty, start hammering operations should be slowly intermittent test, until the pile into the formation of a certain depth, not continuous hit. Pile drilling process, you must always correct the pile driver bar and the vertical pile, and to maintain the pile hammer, pile cap and pile in the same longitudinal axis;   3) Piling spiral pipe into the 1 ~ 2m, should be re-corrected vertical degree, when playing to a certain depth and check the pile of good quality, and then continue to hit, until the water 60cm ~ 80cm stop hammering, Then repeat the above steps until the design elevation is reached. If the construction process found that pile tilt, should be timely adjustment or pull out the steel pipe pile re-construction; 4) Piling spiral pipe pile depth: through the river bed 10m, and a minute percussion within the number of sinking no more than 5mm. Two. Pile Pile connection with pile up and down butt welding. Before welding, the lower part of the pile pipe must be damaged and damaged part of the repair, the top of the pile at the end of the rust / water or oil sludge removal, polished good welding port, so that the upper and lower pile gap is 2 ~ 4mm, while multi- After each layer of weld, the timely removal of welding slag, and for the appearance of inspection, each layer of welds should be staggered, while the pile weeks with welding stopper to strengthen the upper and lower pile connection. After welding must be cooled more than 5min, and then hammer piling. Three. Welding pile cover After the construction of the pile pipe pile to be completed, the artificial pile into the pile to the pile top, and in the upper part of the steel pipe pile with welding pile, while welding in the outer wall 8 ~ 12 20mm anchor steel.