submerged arc steel pipe, submerged arc steel pipe production, submerged arc steel pipe selection

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Selection and production process of submerged arc steel pipe

Date:2025-01-06
First, the selection of submerged arc steel pipe:
1. For pipelines with high peak-shaving requirements, due to the uneven gas consumption of users and frequent fluctuations in pipeline pressure, the steel pipe is subjected to great alternating stress. Existing defects in the pipe will expand under alternating stress. If spiral welded steel pipes with many welds and high defect probability are selected, the operation of the pipeline will not be guaranteed.
2. The pipeline passes through the earthquake fault zone or passes through the local high-intensity earthquake area. Due to the frequent geological activities in these areas, longitudinal or axial alternating stress will be generated on the pipeline. There are many spiral welds and the defect probability is higher than that of submerged arc steel pipes. Under long-term stress, the probability of accidents in spiral welded steel pipes is much higher than that of submerged arc steel pipes. Therefore, submerged arc steel pipes should be used in such areas.
3. Submerged arc steel pipes should be used for pipelines with high requirements for internal and external anti-corrosion layers. Spiral submerged arc welded steel pipes have more welds, and the weld excess height is generally higher than that of submerged arc steel pipes. When the steel pipes are subjected to internal and external corrosion protection, the degree of bonding between the anti-corrosion material and the bare pipe is not as tight as that of submerged arc steel pipes, and the anti-corrosion effect is not as good as that of submerged arc steel pipes.
4. Submerged arc steel pipes should be used for important crossing and spanning projects. Since future maintenance and management are more difficult than general line sections, it is particularly important to use submerged arc steel pipes with high performance.
5. Submerged arc steel pipes should be used for weak links in pipelines, such as hot-bending elbow pipes. Due to the change in direction, the internal and external forces borne by hot-bending elbows are greater than those of general line straight pipe sections. Due to the influence of various factors during the simmering process, its stress is not easy to eliminate. It is a relatively weak link in long-distance pipelines. The use of submerged arc steel pipes with good comprehensive performance can make up for these shortcomings.

Second, the production process of submerged arc steel pipes:
Straight seam steel pipes are steel pipes with welds parallel to the longitudinal direction of the steel pipe. They are usually divided into metric electric welded steel pipes, electric welded thin-walled pipes, transformer cooling oil pipes, etc. The production process of straight seam steel pipe is simple, with high production efficiency, low cost and rapid development. The strength of spiral welded pipe is generally higher than that of straight seam welded pipe. It can produce welded pipes with larger diameters with narrow billets, and can also produce welded pipes with different diameters with billets of the same width. However, compared with straight seam pipes of the same length, the weld length increases by 30~100%, and the production speed is lower. Plate inspection: After the steel plates used to manufacture large-diameter submerged arc steel pipes enter the production line, the whole plate wave inspection is carried out; Edge milling: The two edges of the steel plate are double-sided milled by the edge milling machine to achieve the required plate width, plate edge parallelism and groove shape; Pre-bending: The plate edge is pre-bent by the pre-bending machine to make the plate edge have the required curvature; Forming: On the JCO forming machine, half of the pre-bent steel plate is first pressed into a J shape by multiple step punching, and then the other half of the steel plate is bent in the same way to form a C shape, and then an open O shape is formed; Pre-welding: The formed straight seam welded steel pipe is joined and continuously welded by gas shielded welding (MAG); Internal welding: The inner side of the straight seam steel pipe is welded by longitudinal multi-wire submerged arc welding (mostly four wires); External welding: The outer side of the submerged arc steel pipe is welded by longitudinal multi-wire submerged arc welding; Wave inspection I: 100% inspection of the inner and outer welds of the straight seam welded steel pipe and the parent materials on both sides of the welds; X-ray inspection I: 100% X-ray industrial television inspection of internal and external welds, using image processing system to ensure the sensitivity of flaw detection; full-length expansion to improve the dimensional accuracy of the steel pipe, and the distribution of stress in the 50# steel plate; water pressure test: the expanded steel pipes are inspected one by one on the water pressure testing machine to ensure that the steel pipes meet the test pressure required by the standard. The machine has automatic recording and storage functions; chamfering: the steel pipes that have passed the inspection are processed at the pipe end to achieve the required pipe end groove size; wave inspection II: wave inspection is carried out again one by one to check for possible defects of straight seam welded steel pipes after expansion and water pressure; X-ray inspection II: X-ray industrial television inspection and filming of pipe end welds are carried out on the steel pipes after expansion and water pressure test; magnetic particle inspection of pipe ends: this inspection is carried out to find defects at the pipe ends; anti-corrosion and coating: the qualified steel pipes are anti-corrosion and coated according to user requirements.
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submerged arc steel pipe, submerged arc steel pipe production, submerged arc steel pipe selection
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