Spiral steel pipe welds such as the gap is too large, the composition of the vicinity of the effect of reduction, the lack of eddy current heat, weld intergranular junction failure occurs or not cracking; such as the gap is too small to form a nearby effect increases, welding heat is too large, constitute welding And the weld is kneaded and rolled to form a deep pit, which affects the surface quality of the weld. After the two margins of the tube are heated to the welding temperature, after the kneading of the kneading roll, the metal crystal grain mutual penetration, crystallization, the end of the formation of a solid weld. Spiral steel pipe if the kneading force is too small, constitute a small number of crystals together, the weld metal strength decreases, after the force will crack; if kneading force is too large , will make the molten state of the metal is squeezed out of the weld, not only reduces the weld strength, and will occur a lot of surface glitches, and even constitute a shortcomings such as welding joints.

The loss of the inner coating will reduce the corrosion resistance of the steel pipe, steel pipe production need to strictly control the quality of the problem. The coating is mainly small diameter steel pipe, oil, embroidery, graphite, etc. are not clean, the density of the anchor pattern can not meet the requirements of the paint is not enough to cause the bond. ,  The main forms are: 1. Drum is formed because the coating is not completely dry, the pipe under the sunlight insolates folded under the coating after water is heated rapidly expanding volume, bolstered internal coating. 2, The vertical fall off along the longitudinal direction of the tube is mainly uncoated light pipe in the open piled up when the rain poured into the accumulation of pipe at the bottom of the formation of the more serious rust, rust when the four steel pipe at the same time, the more serious parts of the rust is not complete, it formed along the longitudinal delamination of the body. 3, The ring drum package inside the drum package is mainly in the tube of sand blowing ash in the compressed air in the water, soot the wind straight forward, the steel pipe in the rotation, the formation of a ring of water marks,the coating also forms a ring. 4, The beginning of the end of the coating inside the end of the coating are basically in the end of the coating, because the end of the inside of the fan to the tube inside the hair, blowing the end of the tube of water, but also to prevent the air into the moisture end of steel pipe. The drum is only produced at the beginning of the coating, and not at the end of the steel pipe. The measures to prevent falling off are: 1, The coating environment control, when the ambient humidity ≥ 90%, or body temperature below the dew point temperature below 3 ℃, should not be produced. 2, After the coating must be poured into the tube of the cooling water to clean, to ensure that the inner surface of the tube before drying. 3, Before the coating with a tube drying dehumidification device, to prevent moisture affect the quality of the coating. 4, Shot peening rust in a timely manner to clear the nozzle to prevent the nozzle blockage, while ensuring the depth of the anchor line at the same time have a certain density in order to increase the adhesion of the coating. 5, The speed of anti-corrosion can not be too fast, the process of conversion between the pipe to have a certain time interval, so that the moisture inside the tube has a natural air-drying process.

In the field of precision seamless carbon steel pipe inspection technology, precision seamless carbon steel pipe refers to the outer diameter of less than φ100mm carbon steel precision seamless steel pipe. Precision seamless carbon steel pipe is auto parts, chemical, heat, boiler, mechanical hydraulic Industry important timber. Through the coil eddy current detection is a precision seamless carbon steel pipe surface of a circumferential surface. In the use of through the coil of the eddy current testing, the precision of the seamless steel pipe is detected, the greater the area of the coil detection, the lower the signal to noise ratio. It is for this reason, the carbon seamless steel pipe eddy current testing standards, the use of through the coil eddy current testing, the external size of not more than 140mm. In addition, large diameter steel pipe through the flaw detection, precision seamless carbon steel tube magnetization and demagnetization and so there is a certain degree of difficulty. Sink ultrasonic inspection is the use of steel spiral forward, ultrasonic probe fixed. Through the sink and the bottom of the pipe was fully water coupling characteristics, to ensure that the thickness of the coupling layer unchanged. However, because the main ultrasonic detection of internal defects on the surface and sub-surface defects in the blind area, resulting in can not be detected, coupled with the use of spiral forward, for 12m long precision seamless carbon steel pipe space occupies 30m space and other deficiencies, has been affecting the steel pipe selection and promotion of detection methods. Therefore, at home and abroad for the detection of precision seamless carbon steel pipe, the general use of magnetic leakage or water pressure experiments.

Small diameter thick-walled steel pipe is a circular cross-section, surrounded by no circular circular encouragement policy, square, rectangular steel. Small diameter thick-walled steel pipe is made of steel ingot or solid made of capillary, and then made by hot rolling, cold or cold. Small diameter thick-walled steel pipe with hollow cross-section, a large number of pipes used for conveying fluid, steel and round steel and other solid steel compared to the same bending, the lighter weight rescue initiatives, is an economic section of steel, widely used in manufacturing structural parts and mechanical parts, such as oil drill pipe, car drive shaft, bicycle frame and steel used in construction. According to the production methods can be divided into different, cold-rolled pipe, extrusion pipe and other growth over the same period, generally in the automatic rolling mill production.  The solid tube is inspected and removed to cut the desired length of the small diameter thick-walled steel pipe, centered on the end face of the perforation of the tube, and then sent to the heating furnace for perforation, perforation at the piercing machine while rotating and advancing, and the role of the head, the tube gradually formed within the cavity called the capillary was significantly lagging, and then sent to the automatic rolling mill to continue rolling the final by the whole machine are thick wall thickness, by the sizing (reducing) machine sizing, to meet the specifications strong combination, the use of continuous rolling mill production is a more advanced method, if you want to get smaller and better quality seamless pipe, cold rolling must be used or a combination of the two methods of cold rolling is usually on the steel pipe rolling a small-diameter thick-walled steel pipe in a circular hole consisting of a variable-section circular hole and a non-moving tapered head. Cold drawing is usually carried out on a single-chain or double-chain extrusion method. Placed in a closed extruded cylinder with a perforated rod and moving together to continuously ferment a small diameter thick-walled steel pipe, extruding the extruder from a smaller die hole, which produces a smaller diameter steel pipe.

The first, wall unevenness of steel pipe (180 degrees eccentric) 1. The tube is cut and cut 2. Billet heating uneven or centering bias 3. The perforation roller does not coincide with the roll or the roll center and the perforation center are inconsistent 4. The mandrel is bent or the center of the roller is offset from the rolling center or the roller frame is in poor condition 5. Personnel operation problems (open open roller frame in advance) The second. rough inside and outside of the capillary 1. Check whether the surface of the tube cracks, folding, pits, inclusions, tube according to the process requirements of uniform heating. 2. Check the wear of the three rolls and adjust the reduction (head position). Control roll cooling water. 3. Replace the wear of the head (nose, perforation part of the cone) to ensure that the pressure of cooling water.