|
Standard
|
Grade
|
Mechanical Properties（NBK)
|
|
Tensile
Strength (Mpa)
|
Yield
Strength (Mpa)
|
Elonga-tion
(%)
|
|
DIN2391
|
ST35
|
340-470
|
≥235
|
≥25
|
Annealing
After the goods are cold drawn to sizes, the tubes are put on annealing furnace for heat treatment and normalising.
Straightening
Post annealing, the goods are passed through a seven roller straightening machine to achieve proper straightening of the tubes.
Eddy current
Post straightening, each tube is passed through eddy current machine to detect for surface cracks and other defects . Only the tubes that pass eddy current are fit for delivery to customers.
Finishing
Each tube is either oiled with corrosion resistant oil or varnished for surface protection and corrosion resistant as per customers requirement, each tube end is covered by plastic end caps to avoid damage in transit, the marking and specs are put and the goods are ready for dispatch.
