GB/T18984 Low-temperature heat exchanger tubes

GB/T18984-2003 standard suitable for -49 to -148 degrees F cryogenic pressure vessel piping, and low-temperature heat exchanger tubes seamless steel pipe. Seamless steel tubes for low-temperature service Hardness testing methods of high-pressure pressure boiler tubes

• Seamless steel tubes for low-temperature service
• Hardness testing methods of high-pressure pressure boiler tubes
• Boiler pipe forming: ① fin tube ② serpentine tube ③ reaming welding
• Characteristics of boiler pipe
• Heat boiler seamless extrusion technology
• Low and medium pressure boiler pipe

Out diameter and Wall thickness

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

(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.