this kind of concrete pump welding pipe is popular in middle east countires and Asia countries, welded pipe is usually used on the stationary pump, because there is a welding line on it, fitting the stationary pump, service life is about 10000-15000cbm, hardness is about 60-62HRC. Usually the material is 20# and 16Mn, but it is the welding tube. The most important is that welding pipe price is lowest , purchase cost is lowest.    
thickness: 4.5mm/5.0mm/5.5mm/7.0mm. Also this welding pipe usually fitted the usual SK148mm flange , also SK 148mm metric, HD, PM ZX 175mm, Schwing MF 166mm,Sany 157mm, Zoomlion ZX etc flange collar.    
we are not only the welded pipe , also have st52 seamless pipe , 20# seamless pipe, harden pipe, double wall layer pipe. 

concrete pump spare parts welded pipe picture show: other concrete pump main parts my company can also supply for you : about other concrete pump spare parts which are used on the mobile pump and stationary pump , including concrete pump elbow, concrete pump clamp coupling, concrete pump reducer pipe, concrete pump rubber hose, concrete pump rubber piston, concrete pump delicery cylinder , concrete pump wear plate and cutting ring, and so on parts at stock !