Types of

steel tubes

Outer diameter

Wall thickness

Cold-rolled tubes

Tube sizes(mm)

Tolerances(mm)

Tolerances(mm)

<114.3

±0.79

-12.5%

≥114.3

-0.5%, +1%

Standard

Models of steel tubes

Tensile strength (MPa)

Yield strength (MPa)

Elongation (%)

Hardness

API SPEC 5CT

J55

≥517

379~552

check the table

≤241HB

K55

≥517

≥655

N80

≥689

552~758

L80(13Cr)

≥655

552~655

P110

≥862

758~965

Standard

Models of steel tubes

Chemical compositions (%)

C

Si

Mn

P

S

Cr

Ni

Cu

Mo

V

Als

API SPEC 5CT

J55K55 (37Mn5)

0.34~ 0.39

0.2~ 0.35

1.25~ 1.5

≤0.02

≤0.015

≤0.15

≤0.20

≤0.20

≤0.02

N80 (36 Mn2V)

0.34~ 0.38

0.2~ 0.35

1.45~ 1.7

≤0.02

≤0.015

≤0.15

0.11~ 0.16

≤0.02

L80 (13Cr)

0.15~ 0.22

≤1.0

0.25~ 1.0

≤0.02

≤0.010

12.0~ 14.0

≤0.20

≤0.20

≤0.02

P110 (30CrMo)

0.26~ 0.35

0.17~ 0.37

0.40~ 0.7

≤0.02

≤0.010

0.8~1.1

≤0.20

≤0.20

0.15~ 0.25

≤0.08

≤0.02