Reserch On The Bending Techniques Of Heating Bending The UOE Pipe Made Of Controlled And Rolled Steel

Bend is one of the important pipe fittings in pipeline construction. Itsmain function on the pipeline is to change the direction of the pipeline asrequired. Also it is to buffer the stratum transference of the region wherepipeline is located, the action of the structural mechanics of the tensileand compressive stress and torque moment which earthquakes and thechange of the ambient temperature etc. exerts on the straight pipes. Agreat quantity of UOE hot bends made of controlled and rolled steel havebeen used in large-scale pipeline construction like the West-East GasPipeline Project and Zhong-Wu Pipeline Project.Therefore, thecomprehensive quality of the bends is one of the important factors whichrestrict the safe and stable operation of the pipelines.Because the properties of the controlled and rolled steel may changeafter reheating, its strength will lose more than one half if the heatingprocess is not controlled properly during fire bending, and it will breakopen under serious situation.This article especially discusses the bending techniques of the UOEhot bend made of controlled and rolled steel. Its mechanical propertiesand quality are also discussed and analyzed here. The influence factorsand the controlling methods on the entire quality of the UOE hot bendmade of controlled and rolled steel are found out. These influence factorsare heating temperature, heating speed, cooling speed, the width of theheating zone, tempering temperature, the heat preserving time and thepropelling speed.Through theoretical analysis and actual site bending test, sitebending test on UOE heating bending pipe of the controlled and rolledsteel, with Grade X60, φ610×11.1mm has been made. On the other hand,the certification test on UOE pipe made of controlled and rolled steel,with Grade X70, φ1016×17.5mm which was produced by the NewJapanese Iron Works for the Chinese West-East Gas Pipeline Project hasalso been made and its mechanical properties and quality have beenanalyzed.This article , through bending technological test, mechanicalproperties test, degree of hardness test and metallographic test, hasanalyzed and studied UOE hot bends made of controlled and rolled steelthe bending techniques, and proposed the optimizing parameter range asfollows: the heating temperature is 950℃~1050℃;the cooling speed is20℃~40℃/s;the width of the heating zone is 30~40mm;the temperingtemperature is 500℃;the heat preserving time is 1.0~1.2h, and thepropelling speed is 0.5mm/s, actual site bending express that the heatingbending pipe,which has adopted This article has proposed the optimizingparameter range, has been made . It has been fitted to the technicalstandard requirement of the Chinese West-East Gas Pipeline Project(Q/SYXQ 16-2002) ,which has ensured the entire quality of the bends.