Delivery with steel pipes have been more and more widely used in various industries, and steel pipe multi-buried in damp underground, which has strict requirements for the use of performance of the steel pipe. Existing heat transmission with welded pipe leak in use, check the steel pipe partial serious penetrating cracks.
The pipe rupture process does not actually generate significant plastic deformation, penetrating crack all of the vertical surface of the positive crack origin, which is a completely non-plastic low stress brittle fracture, the steel pipe rupture is not subjected to stress overloads impact. Artificially interrupted fracture dimple fracture description the pipe matrix did not happen in the course of embrittlement.
EDS method fouling and corrosion products from the surface of the steel pipe outer analysis of the high content of calcium, silicon, sulfur, sodium, chloride and the like. Development of cracks from the outer surface of the expansion process, a lot of bifurcation, intergranular toward large steel pipe inside and outside surface decarburization stress, in order to determine the materials belong to intergranular stress corrosion cracking. Therefore the pipeline to the presence of an external stress corrosion environment is the root cause of the location of steel pipe rupture.
Low carbon steel containing nitrate, ammonium nitrate, mixed acid, sodium hydroxide, hydroxide, calcium hydroxide, ammonium and alkali prone to intergranular stress corrosion cracking in an aqueous solution of salts. Steel surface decarburization stress increase so that the surface layer, cracks in the corrosive action, and result in the nitrate cracking, and is, when the presence of residual stress or applied stress (welding, etc.), the channel along the intergranular lot of intergranular corrosion occurs stress corrosion cracking, while this rupture the steel pipe pipeline temperature range, it is sensitive to temperature stress corrosion.
Summary:
(1) steel pipe leaks in use due to stress corrosion caused by intergranular stress corrosion cracking.
(2) pipeline in the presence of an external stress corrosion environment is the root cause of the low stress brittle fracture in steel pipes of the location.
Post time: Sep-19-2019