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Product Detail

Large-diameter seamless steel pipe

Process: Hot rolling tube expansion, precision annealing
Surface: flat without peeling or burrs
Ra：≤6.3‑12.5μm
Material: Common 20 #, 45 # Q355B
Specification: Outer diameter 220-630mm, wall thickness 6-80mm customizable

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OD*WT（mm）

219*6 219*12 245*8 299*10 325*10 325*20 426*12 450*16 480*16 Custom Specs

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Product Detail

Product Overview：

Large-diameter seamless steel pipes can be categorized into hot-rolled large-diameter seamless steel pipes and hot-expanded large-diameter seamless steel pipes. Hot-expanded seamless steel pipes, also known as hot-expanded tubes, typically range in size from 325mm to 1220mm and can be up to 120mm thick. They are steel pipes with low density but strong contractility, produced through a manufacturing process that utilizes the cross-rolling or drawing method to expand the diameter of the raw tube. Hot-rolled seamless steel pipes undergo no specialized heat treatment after hot rolling and are directly delivered after cooling, known as the hot-rolled condition. The termination temperature for this condition is generally between 800-900℃, followed by natural cooling in air, making the hot-rolled condition equivalent to normalizing treatment.

Product List
Product Name:	Hot-rolled large-diameter seamless steel pipe \| Seamless pipe
Product Name:	Hot expanded seamless steel pipe \| Seamless pipe
Product Name:	10# large-diameter seamless steel pipe \| seamless pipe
Product Name:	20# large-diameter seamless steel pipe \| seamless pipe
Product Name:	45# large-diameter seamless steel pipe \| seamless pipe
Product Name:	Q235 large-diameter seamless steel pipe \| seamless pipe
Product Name:	Q345 large-diameter seamless steel pipe \| seamless pipe
Product Name:	16Mn large-diameter seamless steel pipe \| seamless pipe
Product Name:	40Cr large-diameter seamless steel pipe \| seamless pipe
Product Name:	27SiMn large-diameter seamless steel pipe \| seamless pipe
Product Name:	12Cr1MoV large-diameter seamless steel pipe \| seamless pipe
Product Name:	15CrMo large-diameter seamless steel pipe \| seamless pipe

Parameter range
Outer diameter	Φ220mm-Φ630mm
Wall thickness	6mm-80mm
Standard length	1-12m, customizable length available
Outer diameter accuracy	Maximum ±0.05mm
Executive Standards	ASTM A106, API 5L, DIN 17175, GB/T 8163
Non-standard customization	Support for special wall thickness, inner hole honing, and irregular size processing

High frequency specifications in stock (outer diameter x commonly used wall thickness mm)
Outer diameter (mm)	219	245	273	299	325	351	377	402
Standing wall thickness (mm)	6、7、8、10、12、14	6、8、10、12、14、16	7、8,、10、 12、14、16、18	8、10、12、14、16、 20	8、10、12、14、16、18、20	8、10、12、14、16、 20	9、10、12、14、 16、18、20、25	10、12、14、16、20、25
Corresponding nominal diameter DN	DN200	-	DN250	-	DN300	-	DN350	-

Outer diameter (mm)	426	450	480	508	530	560	610	630
Standing wall thickness (mm)	10、12、14、16、18、20、22、25、30	10、12、14、16、 20、25	10、12、14、16、 20、25、30	12、14、16、20、25、30	12、14、16、18、20、25、30	12、14、16、20、25、30	12、14、16、20、25、 30	12、14、16、18、20、 25、30、35
Corresponding nominal diameter DN	DN400	-	-	DN450	DNS00	-	DN600	-
Industry standard: Outer diameter ≥ 219mm is considered as large-diameter seamless pipe; Dimensional standard national standard: GB/T17395

Optional tolerance range
Tolerance control	Optional manufacturing process
Tolerance ≤ 0.05 mm	Cold rolling
Tolerance ≤ 0.10 mm	Cold rolling
Tolerance ≤ 0.30 mm	Cold drawing \| Cold rolling
Tolerance ≤ 0.50 mm	Cold drawing \| Hot rolling
Tolerance ≤ 1.00 mm	Hot rolling \| Hot expanding

Allowable deviation of outer diameter
Accuracy class	Normal level (default)	Higher level (specified in the contract)
Allowable deviation	± 1% D or ± 0.5mm, whichever is greater	± 0.75% D or ± 0.3mm, whichever is greater
Applicable process	Hot rolling and expansion	Hot rolling and expansion

Common outer diameter actual tolerance
Outer diameter (mm)	219	273	325	377	426	530	630
Ordinary level tolerance (mm)	±2.19	±2.73	±3.25	±3.77	±4.26	±5.30	±6.30
Qualified range (mm)	216.81~221.19	270.27~275.73	321.75~328.25	373.23~ 380.77	421.74~430.26	524.70~535.30	623.70~636.30

Allowable deviation of wall thickness for hot-rolled large-diameter steel pipes (D>102mm)
S/D (wall thickness/outer diameter)	≤0.05	0.05～0.10	＞0.10
Allowable deviation	± 15% S or ± 0.4mm, whichever is greater	± 12.5% S or ± 0.4mm, whichever is greater	+12.5%S/-10%S

Allowable deviation of wall thickness for hot expanded diameter steel pipes (219-630mm mainstream)
Project				Wall thickness
Allowable deviation				+17.5%S / −12.5%S
Actual tolerance of commonly used wall thickness
Wall thickness S (mm)	8	10	12	14	16	20	25	30
Upper deviation (mm)	+1.40	+1.75	+2.10	+2.45	+2.80	+3.50	+4.38	+5.25
Lower deviation (mm)	-1.00	-1.25	-1.50	-1.75	-2.00	-2.00	-3.13	-3.75
Qualified range (mm)	7.00~9.40	8.75~11.75	10.50~14.10	12.25 ~ 16.45	14.00 ~18.80	17.50~23.50	21.87~29.38	26.25 ~ 35.25

Curvature (straightness)
Wall thickness conditions	S ≤ 15mm	S ＞ 15mm
Bending degree per meter	≤1.5 mm/m	≤2.0 mm/m
Full length curvature	≤ Total length × 0.15%	≤ Total length × 0.15%

Optional delivery status
Oil removal from oil pipes	Annealing and straightening	Steel pipe corrosion prevention
Steel pipe threading	Length cut-to-length	Steel pipe coating
Steel pipe cap	Exquisite bundling	Beveling

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Product Detail

Product Overview：

Product List
Product Name:	Hot-rolled large-diameter seamless steel pipe \| Seamless pipe
Product Name:	Hot expanded seamless steel pipe \| Seamless pipe
Product Name:	10# large-diameter seamless steel pipe \| seamless pipe
Product Name:	20# large-diameter seamless steel pipe \| seamless pipe
Product Name:	45# large-diameter seamless steel pipe \| seamless pipe
Product Name:	Q235 large-diameter seamless steel pipe \| seamless pipe
Product Name:	Q345 large-diameter seamless steel pipe \| seamless pipe
Product Name:	16Mn large-diameter seamless steel pipe \| seamless pipe
Product Name:	40Cr large-diameter seamless steel pipe \| seamless pipe
Product Name:	27SiMn large-diameter seamless steel pipe \| seamless pipe
Product Name:	12Cr1MoV large-diameter seamless steel pipe \| seamless pipe
Product Name:	15CrMo large-diameter seamless steel pipe \| seamless pipe

Parameter range
Outer diameter	Φ220mm-Φ630mm
Wall thickness	6mm-80mm
Standard length	1-12m, customizable length available
Outer diameter accuracy	Maximum ±0.05mm
Executive Standards	ASTM A106, API 5L, DIN 17175, GB/T 8163
Non-standard customization	Support for special wall thickness, inner hole honing, and irregular size processing

High frequency specifications in stock (outer diameter x commonly used wall thickness mm)
Outer diameter (mm)	219	245	273	299	325	351	377	402
Standing wall thickness (mm)	6、7、8、10、12、14	6、8、10、12、14、16	7、8,、10、 12、14、16、18	8、10、12、14、16、 20	8、10、12、14、16、18、20	8、10、12、14、16、 20	9、10、12、14、 16、18、20、25	10、12、14、16、20、25
Corresponding nominal diameter DN	DN200	-	DN250	-	DN300	-	DN350	-

Outer diameter (mm)	426	450	480	508	530	560	610	630
Standing wall thickness (mm)	10、12、14、16、18、20、22、25、30	10、12、14、16、 20、25	10、12、14、16、 20、25、30	12、14、16、20、25、30	12、14、16、18、20、25、30	12、14、16、20、25、30	12、14、16、20、25、 30	12、14、16、18、20、 25、30、35
Corresponding nominal diameter DN	DN400	-	-	DN450	DNS00	-	DN600	-
Industry standard: Outer diameter ≥ 219mm is considered as large-diameter seamless pipe; Dimensional standard national standard: GB/T17395

Optional tolerance range
Tolerance control	Optional manufacturing process
Tolerance ≤ 0.05 mm	Cold rolling
Tolerance ≤ 0.10 mm	Cold rolling
Tolerance ≤ 0.30 mm	Cold drawing \| Cold rolling
Tolerance ≤ 0.50 mm	Cold drawing \| Hot rolling
Tolerance ≤ 1.00 mm	Hot rolling \| Hot expanding

Allowable deviation of outer diameter
Accuracy class	Normal level (default)	Higher level (specified in the contract)
Allowable deviation	± 1% D or ± 0.5mm, whichever is greater	± 0.75% D or ± 0.3mm, whichever is greater
Applicable process	Hot rolling and expansion	Hot rolling and expansion

Common outer diameter actual tolerance
Outer diameter (mm)	219	273	325	377	426	530	630
Ordinary level tolerance (mm)	±2.19	±2.73	±3.25	±3.77	±4.26	±5.30	±6.30
Qualified range (mm)	216.81~221.19	270.27~275.73	321.75~328.25	373.23~ 380.77	421.74~430.26	524.70~535.30	623.70~636.30

Allowable deviation of wall thickness for hot-rolled large-diameter steel pipes (D>102mm)
S/D (wall thickness/outer diameter)	≤0.05	0.05～0.10	＞0.10
Allowable deviation	± 15% S or ± 0.4mm, whichever is greater	± 12.5% S or ± 0.4mm, whichever is greater	+12.5%S/-10%S

Allowable deviation of wall thickness for hot expanded diameter steel pipes (219-630mm mainstream)
Project				Wall thickness
Allowable deviation				+17.5%S / −12.5%S
Actual tolerance of commonly used wall thickness
Wall thickness S (mm)	8	10	12	14	16	20	25	30
Upper deviation (mm)	+1.40	+1.75	+2.10	+2.45	+2.80	+3.50	+4.38	+5.25
Lower deviation (mm)	-1.00	-1.25	-1.50	-1.75	-2.00	-2.00	-3.13	-3.75
Qualified range (mm)	7.00~9.40	8.75~11.75	10.50~14.10	12.25 ~ 16.45	14.00 ~18.80	17.50~23.50	21.87~29.38	26.25 ~ 35.25

Curvature (straightness)
Wall thickness conditions	S ≤ 15mm	S ＞ 15mm
Bending degree per meter	≤1.5 mm/m	≤2.0 mm/m
Full length curvature	≤ Total length × 0.15%	≤ Total length × 0.15%

Optional delivery status
Oil removal from oil pipes	Annealing and straightening	Steel pipe corrosion prevention
Steel pipe threading	Length cut-to-length	Steel pipe coating
Steel pipe cap	Exquisite bundling	Beveling