Manufacturing method for X80 pipeline steel spiral welded pipe

Abstract

The invention belongs to the field of mechanical equipment manufacturing and particularly relates to a manufacturing method for a spiral submerged arc welded pipe. A manufacturing method for an X80 pipeline steel spiral welded pipe includes the following technological steps that uncoiling and flattening of an X80 pipeline steel plate coil are conducted; edge milling is conducted; pre-bending is conducted; forming is conducted; pre-welding is conducted; internal welding is conducted; external welding is conducted; pipe end expanding is conducted; and product inspection is conducted. Brand new design is conducted on a welding groove type, and therefore energy of a welding line of an inner weld bead and energy of a welding line of an outer weld bead are distributed again, the energy of the welding line of the outer weld bead is improved, and the energy of the welding line of the inner weld bead is reduced. The grain size in a critical coarse-grain area in a heat-affected area can be obviously reduced due to the reduction of the energy of the welding line of the inner weld bead, scattering of distribution of chain-shaped M-A components is facilitated, meanwhile, the size of the M-A components can be reduced, and therefore the toughness of the welding heat-affected area is obviously improved. In addition, although the filling amount of the outer weld bead is increased to some extent, a double-wire tandem sequence is changed into a three-wire tandem sequence for welding, the welding speed can be ensured, and the production efficiency cannot be reduced.

Description

technical field [0001] The invention belongs to the field of mechanical equipment manufacturing, and in particular relates to a method for manufacturing a spiral submerged arc welded pipe, which is used for oil and gas transportation and is suitable for the manufacture of X80 pipeline steel spiral welded pipes of Φ1422mm×21.4mm. Background technique [0002] With the implementation of pipeline projects such as the West-to-East Gas Pipeline Project, pipeline steel has developed rapidly in China since 2000. At present, the manufacturing level of domestic pipeline steel has been at the forefront of the world. At this stage, the gas pipelines being laid are mainly made of X80 pipeline steel. The performance indicators of the X80 pipeline steel parent material currently produced can meet the standard requirements, but there are still many problems in the welding process; moreover, in oil and gas pipelines, the weld length accounts for a large proportion, so welding The performan...

AI Technical Summary

Problems solved by technology

The critical coarse-grained zone can lead to a significant decrease in the impact toughness of the welded heat-affected zone, making the overall performance of the welded joint lower than the requirements of the relevant standards. In actual production, most of the low values ​​in the Charpy impact test are below 50J

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