Requirements for Pipes Used for Hydraulic System

Design, placement, welding and cleaning
2．1Desgin 
2．11 Radius of blend pipe, assembly and spanner space must be considered for pipes arrangement 
2．12 The pipe should be solid and anti-shaking. Supporting frame or pipe clip should be set according to related standard. 
2．13 Dia. and thickness of pipe must meet the flowing speed and pressure of the system.
2．14  Material of pipe should be chose according to the drawing. There must be no oxidation and other defects on the surface of the pipe. Straightness of the pipe should be less than 2‰.
2.15 15# cool pulling seamless steel pipe is recommended. Dia. 50/dia.40, thickness 4~5mm. Dia.34/dia.28, thickness 4~5mm. Dia.22/dia.18, thickness 2.5~3mm. Dia.14/dia.10,thickness 2~2.5mm.
 
2．2 Blend pipe and pipe arrangement 
2．21 Cold-formed method is adopted: ≤φ48, machine blend is adopted, ＞φ50, forgings blend will be adopted. 
2．21 Blend pipe radius: R≥3d.
2．23 One complete pipeline comprises of several pipes. These pipes should be arranged one by one, one after another.
2．24 Sizes should be taken when the blend pipe is formed. Length, chamfering and groove should be fixed according to different pipes. 
2．25 Moulds should be used when blending is on process. Ovality of the pipe a:b＜10%, wave steepness 5% 
2．3 Pipe installment, cleaning and handling 
2．31 After the first pipe installment, marks should be made in case there will be 2nd assembly in the future.
2．32 Thickness of the welding pipe≤3.5mm, gas shielded welding. 
2．33 Thickness of the welding pipe≥5mm, gas shieded welding first and then electrical welding on the surface.
2．34 Butwelding should be adopted to weld pipe with flange, conjunction, groove, chamfer welding according to TB/ZQ-4000.4-86. Sleeve joint welding should be avoided.
2．35 Pipe cutting should be done by machineries. Fire cutting is not allowed in case there will be oxidation on the surface.
2．36 Residual, burr and casting fin should be removed after pipe welding. 
2．37 Pipe pre-assembly: no forced conjunction. All the pipes should be connected naturally and in fine condition. If not, please make the conjunction part well. 
2．38 Acid pickling and Ni-P plating of pipes should be processed. 
2．39 Clean the processed pipes with compressed air and then assembly them according to the marks.