ALTA cold drawn welded tubes with H8 +SR finish

ALTA Cold drawn welded tubes with H8 + SR finish have the distinctive properties of electro-welded tubes, with precise dimensional tolerances and high concentricity: only ALTA knows how to add to this by guaranteeing a unique internal finish in H8 tolerance with material in +SR condition.


These special features are made possible by manufacturing in which coil thickness is obtained through a rolling process and is strictly controlled. The coil ends are prepared in a particular way to achieve optimum contact during the welding operation, and cold deformation of the coil begins until the desired circular section is achieved.

After deformation, the high quality of the welding operation creates a specific temperature, melting the edges of the coil without added materials. This forms a continuous tube with no change in chemical composition in the weld area, offering a safety factor of V = 1. The result is a tube that has a clean, defect-free surface with optimal thickness and concentricity tolerances, ideal for the following cold drawing operation.

The cold drawing process follows the deformation and welding of the tube and ensures excellent product surface finish, achieving precise dimensional tolerances.
Therefore, the optimal quality of the raw tube, together with heat treatment, gives the drawn tube remarkable mechanical properties and resilience.

Finally, the high quality of cold drawn electro welded tubes is also ensured by regular destructive and non-destructive laboratory testing, including dimensional inspection and surface finish measuring.

Today, cold drawn electro welded tubes are the best product for producing high-quality hydraulic cylinders at lower costs.

General technical data sheet for cold drawn welded tubes with H8 +SR finish


OD 30 mm to OD 230 mm | Thickness 2.5 mm to 15 mm
LENGTHUp to 12 m
(fixed lengths or custom cuts on request)
CHARACTERISTICS+SR, elongation >10%
with >27J resilience at -20 C°
H8 | H9 |
UNIQUE CHARACTERISTICSresilient, concentric 3%, elongation =∖>10%.
EN 10204:2004/3.1