On the Concrete Mobile Pump , there is not only normal elbow bend , also have 1#,2#flap elbow on it. We have Putzmeister 1# flap elbow, 2#elbow, zoomline concrete pump hinge flat elbow, Sany concrete pump flap elbow and so on. This kind of concrete pump hinge flat elbow material is same with normal elbow material, which is made by 45Mn2 and high manganese steel, but this flap elbow usually service life is longer, and more thicker , especially the concrete pump end elbow, service life is 50000cbm-80000cbm , the