Thick-walled steel pipes require daily maintenance and economical introduction during use

First, thick-walled steel pipes require daily maintenance during use: Thick-walled steel pipes are widely used steel varieties. It directly affects economic benefits and personnel lives. Countries around the world attach great importance to the inspection of thick-walled steel pipes and use various non-destructive testing (NDT) methods to conduct strict inspections on thick-walled steel pipes. To a certain extent, thick-walled steel pipes should pay attention to corresponding maintenance during use. In general, a dedicated person should be assigned to conduct daily inspections of thick-walled steel pipes, check whether the uprights and pads have sunk or loosened, whether all fasteners of the frame have slipped or loosened, and whether all components of the frame are complete; make good drainage of the thick-walled steel pipe foundation, and conduct a comprehensive inspection of the thick-walled steel pipe frame foundation after rain, and it is strictly forbidden to allow the thick-walled steel pipe base to sink; the construction load of the operating layer shall not exceed 270KG/square meter, and the crossbar support, cable wind rope, etc. shall not be fixed on the thick-walled steel pipe, and it is strictly forbidden to hang heavy objects on the thick-walled steel pipe; it is strictly forbidden for anyone to arbitrarily remove any parts of the thick-walled steel pipe; in case of strong winds above level 6, heavy fog, heavy rain and heavy snow, the operation of thick-walled steel pipes should be suspended, and the operation can be continued only after checking that there are no problems before resuming work.

Second, the performance and economy of thick-walled steel pipes: In addition to the above-mentioned structural types of pipe fittings used in actual piping projects, there are also many other structural forms of pipe fittings to meet the requirements of various working conditions, especially special working conditions. When designing or selecting a project, the higher the strength grade of the pipe fittings, the higher the performance, but the greater the cost of the project, which will cause waste. From the perspective of economic benefits, while meeting the requirements of the project design, the cost should be reduced as much as possible, but it is often easy to form a result of a small number of selected pipe fittings with many varieties, which is not conducive to the management and regulation of on-site construction materials and the substitution of materials required by design changes. Therefore, the selection of pipe fittings should be comprehensive and economical, and the variety of pipe fittings should be reduced as much as possible. In addition, factors such as on-site construction conditions, construction level, and procurement cycle of pipe fittings should also be taken seriously in the selection of pipe fittings. In specific cases, the possibility of using reinforced pipe joints, bevel elbows, and on-site bending processing of small-diameter pipes should also be considered. At the same time, it is also necessary to understand the production capacity and products of pipe fitting manufacturers and the market supply situation.

Third, the causes and adjustments of uneven wall thickness of steel pipes:
1. The causes of spiral wall thickness unevenness are: uneven wall thickness caused by the non-correct rolling center line of the punching machine, unequal inclination angles of the two rollers, or too small pressure on the head, which is generally distributed in a spiral shape along the entire length of the steel pipe. Uneven wall thickness caused by the premature opening of the centering roller, improper adjustment of the centering roller, and shaking of the top rod during the rolling process is generally distributed in a spiral shape along the entire length of the steel pipe.
Measures: Adjust the rolling center line of the punching machine to make the inclination angles of the two rollers equal, and adjust the tube rolling mill according to the parameters given in the rolling table. For this situation, adjust the opening time of the centering roller according to the outlet speed of the rough pipe. Do not open the centering roller too early during the rolling process to prevent the top rod from shaking and causing uneven wall thickness. The opening degree of the centering roller needs to be appropriately adjusted according to the change in the rough pipe diameter, and the size of the rough pipe runout should be considered.
2. Causes of linear wall thickness unevenness: The height of the mandrel pre-penetration saddle is not adjusted properly. The mandrel contacts the rough tube on one side during pre-penetration, causing the rough tube to cool too fast on the contact surface, resulting in uneven wall thickness or even concave defects. The gap between the continuous rolling rollers is too small or too large. Deviation of the center line of the tube mill. Uneven pressure reduction of single and double stands will cause linear symmetrical deviations of the steel pipe in the single stand direction (extra thick) and double stand direction (extra thick). Mortar fracture and large differences in the gap between the inner and outer rollers will cause linear asymmetrical deviations in the steel pipe. Improper continuous rolling adjustment, stacking, and drawing steel rolling will cause linear wall thickness unevenness.
Measures: Adjust the height of the mandrel pre-penetration saddle and ensure that the mandrel is aligned with the rough tube. When changing the hole type and rolling specifications, the roller gap should be measured to keep the actual roller gap consistent with the rolling table. Use an optical centering device to adjust the rolling center line, and calibrate the center line of the tube mill during the annual overhaul. Replace the broken frame in time, measure the inner and outer roll gaps of the continuous rolling rollers, and replace them in time if there are any problems. During continuous rolling, avoid pulling and piling steel.
3. Causes of uneven wall thickness at the head and tail: The cutting inclination and curvature of the front end of the tube billet are too large, and the centering hole of the tube billet is not straight, which can easily cause uneven wall thickness at the head of the steel pipe. The elongation coefficient is too large during perforation, the roller speed is too high, and the rolling is unstable. The unstable steel throwing of the punching machine can easily cause uneven wall thickness at the tail of the rough pipe.
Measures: Check the tube billet to prevent the cutting inclination and large pressure reduction at the front end of the tube billet. The centering hole should be corrected when changing the hole type or overhauling. Use a lower perforation speed to ensure the stability of rolling and the uniformity of the rough pipe wall thickness. When the roller speed is adjusted, the matching guide plate is also adjusted accordingly. Pay attention to the use status of the guide plate and increase the inspection of the guide plate bolts to reduce the movement of the guide plate during steel rolling to ensure stable steel throwing.