Tubes for hydraulic cylinders

Tubes for mechanical machining – type HPZ are precision seamless tubes for the production of hydraulic cylinders or seals of piston rods. The inner working surface is obtained by mechanical machining, by honing or peeling and subsequent rolling.

Tubes intended for direct use in the cylinders – type HP are seamless tubes with a precisely machined inner surface, which are primarily intended for the manufacture of hydraulic cylinders. The inner working surface is achieved by peeling and subsequent rolling of the inner surface of the tubes.

Tubes intended for piston rods and telescopic cylinders – type HPK are cold drawn seamless tubes for piston rods, telescopic cylinders and cylinder liners. Use of tube piston rods and pistons is often preferable than the use of solid materials. Use of the tube material, which exhibits the same resistance to load stress, bending and in torsion, means a significant reduction in the weight of the cylinder.

Dimensions of hydraulic cylinder tubes

Precision tubes for mechanical machining – HPZ type

INNER DIAMETER (ID) 40,0 – 115,0 mm

WALL THICKNESS (WT) 5,0 – 10,0 mm

Precision tubes machined to “ready to use” – type HP

INNER DIAMETER (ID) 40,0 – 110,0 mm

WALL THICKNESS (WT) 4,0 – 10,0 mm

Precision tubes destined for piston rods – type HPK

OUTER DIAMETER (OD) 40,0 – 120,0 mm

WALL THICKNESS (WT) 5,0 – 10,0 mm

Steel grades for hydraulic cylinders

EN 10305-1 E355

EN 10 294-1 20MnV6

STN/ČSN 42 0260 11 523

DIN 2391-2 St52

DIN 17100 St52-3

Tolerances for hydraulic cylinders

for mechanical machining – HPZ type

Tolerances of the outside diameter (OD) HPZ tubes meet the appropriate dimensional table standards. Tolerances values of the inside diameter (ID) are presented in the table .

Tolerance of the wall thickness is -/+ 7.5% of the wall thickness.

HPZ tubes eccentricity is included in the wall thickness tolerance

for HP tubes

Tolerances of the outside diameter (OD) HP tubes meet the appropriate dimensional table standards DIN 2391-1, EN 10305-1. Tolerances values of the inside diameter (d) H8 a H9 are presented in the table.

Tolerance of the wall thickness is -/+ 7.5% or 10% of the wall thickness.

HP tubes eccentricity is included in the wall thickness tolerance.

Length of tubes for hydraulic cylinders

(a), manufactured length of precision tubes in the range of 3 to 6 meters

(b), maximum precise length 6 meters

Tube testing

Selection of the tests is either according to standards or upon agreement with customer:

• cast / chemical analysis,
• tensile test,
• dimensional inspecti,
• visual inspection,
• NDT to find longitudinal defects.

Other tests are possible upon agreement.

Certified test reports

According to EN 10 204 – 3.1.

Straightness of tubes

Straightness of the tubes is 0,001 multiple of the tube length maximum, allowed straightness for one meter length is 1.0 milimeters.

Delivery condition of tubes

The tubes are delivered as cold drawn and annealed to relieve the stress BKS (+SR).

Other delivery conditions are possible upon agreement.