High Precision Steel Pipe for Gas spring Cylinder Type:Seamless and Welded Steel Tube Roughness 0.1-0.8ra Material E195-E235,Q195-Q235,#10,#20,#45,SAE1010,SAE1020 Surface:Black/bright Standard:DIN, GB, JIS, DIN 17175, DIN 2391, GB 5310-1995, GB/T 13793-1992, GB/T 3094-2000, GB/T 8163-1999, JIS G3101 Size :OD 3mm-140mm Thickness 0.5-20mm Processing :Cold rolled /cold drawn 1. BK (+C) No heat treatment after last cold forming process. 2. BKW (+LC) After last heat treatment there is a light finishing pass (cold drawing) 3. BKS (+SR) After the final cold forming process the tubes are stress relieve annealed. 4. GBK (+A) After the final cold forming process the tubes are annealed in a controlled atmosphere. 5. NBK (+N) After the final cold forming process the tubes are annealed above the upper Woven bag / wooden or crate carton/ Bundle Packing/ Plain end or vanished as per customer's request. Usage: Gas Spring Cylinder