GB/T18984 Low-temperature heat exchanger tubes

GB/T18984 Low-temperature heat exchanger tubes seamless steel pipe

GB/T18984-2003 standard suitable for -49 to -148 degrees F cryogenic pressure vessel piping, and low-temperature heat exchanger tubes seamless steel pipe.

Out diameter and Wall thickness

(Not more than 25 mm) outside diameter and wall thickness of the steel pipe shall conform to GB/T 17395-1998 Table 1 provisions. According to the requirements of the demand side, the supply and demand sides consultation, produce the provisions specifications steel pipe.
The pipe diameter (D) and wall thickness (S) tolerances shall comply with the requirements in Table 1.

Process Size(mm) Tolerance
Hot-rolled O.D. <351  +/-1.0% D(+/-0.50min)
>=351  +/-1.25% D
W.T. <=25  +/-12.5% S(+/-0.40 min)
Cold drawn O.D. <=30  +/-0.20
30-50  +/-0.30
>50  +/-0.75% D
W.T. <=3  +12.5% S, -10% S
>3  +/-10% S

Note: 
Outside diameter greater than or equal to 351 thermal Flaring wall thickness allowable deviation: Guests 15 write S

Chemical Compositions(%)
Grade C Si Mn P(max) S Ni Mo V
16MnDG 0.12-0.20 0.20-0.55 1.20-1.60 0.025 0.025  -  -  -
10MnDG <=0.13 0.17-0.37 <=1.35 0.025 0.025  -  - <=0.07
09DG <=0.12 0.17-0.37 <=0.95 0.025 0.025  -  - <=0.07
09Mn2VDG <=0.12 0.17-0.37 <=1.85 0.025 0.025  -  - <=0.12
06Ni3MoDG <=0.08 0.17-0.37 <=0.85 0.025 0.025 2.5-3.7 0.15-0.30 <=0.05
Longitudinal mechanical properties of the steel pipes
Grade Tensile strength Lower yield strength(Rcl/Mpa) Elongation
Rm/Mpa W.T.<=16mm W.T.>16mm A/%
16MnDG 490-665 >=325 >=315 >=30
10MnDG >=400 >=240 >=35
09DG >=385 >=210 >=35
09Mn2VDG >=450 >=300 >=30
06Ni3MoDG >=455 >=250 >=30


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