Seamless steel pipe used for gas cylinder (GB 18248-2008)

2018-03-30

Seamless steel pipe material used for gas cylinder is 37Mn,34Mn2V,30CrMo,35CrMo,34CrMo4 and 30CrMnSiA.

Specification

Unless otherwise stipulated in the contract. Steel pipe delivery is according to nominal outside diameter (D) and nominal wall thickness (S). Through consultation between the two parties, it also can be according to nominal outside diameter and min wall thickness (Smin).

Steel pipe outer diameter and thickness should meet the stipulation of GB/T17395.

Allowable tolerance of outer diameter and thickness

Type

Steel pipe

manufacturing

method

Range of

sizes

/mm

Outer

diameter

allowable

tolerance

Wall thickness

allowable tolerance/ %

Common

level

High

class

Use nominal outside diameter and nominal wall thickness

Hot rolling

(expanding)

D﹤339.7

±1

+12.5

-10

±10

D≥339.7

+15

-12.5

+12.5

-10

Cold rolling

(drawing)

all

±0.75

±10

±7.5

Use nominal outer diameter and minimum wall thickness

Hot rolling

(expanding)

D﹤339.7

±1

+25

+22.5

D≥339.7

+30

+25

Cold rolling

(drawing)

all

±0.75

+22.5

+15

Steel pipe wall thickness allowable tolerance usually to be delivery according to common level precision. It also can be delivery according to high class precision after negotiation.

Length and tolerance

The usual length of steel pipe is 4000~12000mm. Through negotiation, the steel pipe delivery length can be ﹥12000mm or shorter than 4000mm, but not shorter than 3000mm. But the quantity of steel tube length shorter than 4000mm should not exceed 5% of the total quantity of the steel pipe.

According to negotiation, it can also be delivered according to fixed length or double length. The fixed length of the steel pipe shall be within the usual length. The length allowable tolerance is +10mm when length ≤6000mm. When length ﹥6000mm, allowable tolerance is +20mm. Each double length should leave cut margin according to stipulation as below: Outer diameter ≤159mm, 5~10mm; Outer diameter ﹥159mm, 10~15mm.