Premium Octagonal Steel Tube JIS G3472 for Global Markets

Product Description

Special-shaped tube

A special-shaped tube (or special-section tube) refers to any steel or metal tubing with a cross-section other than the standard round, such as square, rectangle, oval, hexagonal, D-shape, or even custom profiles, used for enhanced structural strength, specific design aesthetics, space-saving, or unique engineering functions in construction, machinery, and architecture. They offer benefits like greater bending resistance, lighter structures, and better torsional stability than round tubes, saving material while improving performance. 

Common Shapes 
Polygonal: Square, rectangular, triangular, hexagonal, octagonal.
Curved/Deformed: Oval, flat oval, D-shaped, semi-circular, fan-shaped.
Complex: Trapezoidal, lemon shaped, with splines, with fins

Benefits
Structural: Larger moment of inertia and section modulus provide greater resistance to bending and torsion, allowing for lighter structures.
Functional: Can create integrated pathways for wiring or components, as seen in furniture or railings.
Aesthetic: Offers unique visual appeal for architectural and decorative elements.
Material Saving: Reduces overall structural weight, saving on material costs. 

Applications
Construction: Handrails, balustrades, door/window frames, decorative supports.
Machinery: Conveyor systems, agricultural equipment, machine tool components.
Automotive: Chassis, body structures, specialized vehicle parts.
Aerospace & Marine: High-strength, lightweight components. 

Production
These tubes are made by drawing or rolling round tubes through custom-designed dies or tooling to achieve the specific profile. Blue Sky Factory delivers the most satisfactory custom-shaped tubes for you.

Polygonal

Curved/Deformed

Complex

Their multi-faceted design provides better torsional stiffness and load distribution, making them excellent steel replacements. 

Increased Rigidity: The flat sides and vertices provide significantly higher torsional stiffness and bending resistance compared to round tubes.
Structural Efficiency: Better load distribution and buckling resistance, especially in thin-walled designs.
Unique Functionality: Enables specialized designs for better grip, specific mounting, or internal/external features not possible with round tubes. 

These shaped tubes can be used in heat exchangers,they can enhance heat transfer and reduce flow resistance, and have the advantages of compact structure and high efficiency

Enhanced Heat Transfer: Corners and non-circular shapes promote secondary flows and vortices, increasing turbulence and heat transfer coefficients.
Reduced Pressure Drop (Δp): Some elliptical designs can significantly lower pressure drop, allowing for higher fluid velocities and further heat transfer gains.
Compactness: Improved heat exchange performance allows for smaller, lighter, and more efficient heat exchangers.

These are typically used as drive shafts, designed in specific shapes to achieve characteristic strength, stiffness, and damping effects.

Improved Stiffness: Special shapes offer greater rigidity and better resistance to deflection (bending) compared to a circular tube.
Vibration Damping: The geometry helps reduce vibrations and noise (like "Wu, Wu" sounds) that can plague standard driveshafts, especially under changing loads.
Fatigue Resistance: Careful design of these shapes, with smooth transitions (blending radii), prevents stress points that lead to cracks and fatigue. 

Specification

Type	Seamless/Welded	Technique	Cold drawn/rolled
Section Shape	Special Shaped	Length	under 5.5m  or Customized
Dimensional Deviation	Shaped:±0.2mm  Round:±0.05mm	Curvature	≤3mm/m;≤0.3%L
Allow Twist value	H=Sinα(A-2R)	A≤30mm,H≤1.5mm/m;               A>30~75mm,H≤2.0mm/m
Material	Carbon or Alloy	Steel tube derivative process	Cutting, chamfering, punching, CNC turning/milling, grinding
Common shapes
D-shaped tube	Round grooved tube	Square groove tube	Knife shaped tube
Steamed bun tube	Flat oval tube	Oval tube	Horseshoe armrest tube
Hexagonal tube	Semicircular tube	Fan tube	Triangle tube
Gable shaped tube	Hexagonal plum blossom tube	Arched armrest tube	Double-sided arched tube

The shape above is the irregular tube we often make

D-shaped tube,  Round grooved tube,  Square groove tube,  Knife shaped tube,  Steamed bun tube,  Flat oval tube,  Oval tube,  Horseshoe armrest tube,  Hexagonal tube,  Semicircular tube,  Fan tube,  Triangle tube, Gable shaped tube,  Hexagonal plum blossom tube,  Arched armrest tube,  Double-sided arched tube

Cold work steel tube do not undergo mechanical property testing; The mechanical properties of steel tubes delivered in heat-treated state are as follows
Item NO.	Steel Grade	Tensile Strength     Rm  /Mpa	Yield Strength          Rel  /Mpa	Elongation           A   /  %	Impact Test
					Temperature  /℃	Absorb Energy  /J
		≥				≥
1	10	335	205	24	——	——
2	20	410	245	20	——	——
3	35	510	305	17	——	——
4	45	590	335	14	——	——
5	Q195	315~430	195	33	——	——
6	Q215B	335~450	215	30	+20	27
7	Q235B	370~500	235	25	+20	27
8	Q345B	470~630	345	20	+20	34
9	Q390B	490~650	390	18	+20	34

Equivalent Material referance:
GB	TOCT	ASTM	BS	JIS	NF	DIN
10	10	1010,1012	045M10	S10C	XC10	C10,CK10
20	20	1020	050A20	S20C	XC18	C22,CK22
35	35	1035	060A35	S35C	XC35,C35	C35,CK35
45	45	1045	060A42\060A47	S45C	XC45	C45,CK45
15CrMo	15XM	A387 GR.B	BS1653	SCM415	15CD4	15CrMo5
20CrMo	20XM	4118	CDS110	SCM420	18CD4	20CrMo5
30CrMo	30XM	4130	1717COS110	SCM430	30CD4	25CrMo4
42CrMo	38XM	4140	708A42	SCM440	42CD4	42CrMo4
35CrMo	35XM	4135	708A37	SCM435	35CD4	34CrMo4
25Mn	25T	1025,1026	080A25,080A27			26Mn5
16Mn	14T2	SA414Gr.G	1633Gr.L	SPV32	A52C1	17Mn4/19Mn5
20Cr	20X	5120	527A19	SCr420	18C3	20Cr4
40Cr	40X	5140	530A40	SCr440	42C4	38Cr4/41Cr4
37Mn5		J55	EN46	NC-55E	38MS5	1.5122
40Mn2	40Γ2‌	1340		SMn438	40N5	42Mn6

 Fujian Blue sky pipe Manufactury Co, Ltd., formerly known as Zhejiang Blue sky Steel pipe Manufacturiy Co, Ltd., moved to Wendu Industrial Zone, Fuding in 2013.The company covers an area of 26600 m²,construction area of 11800 m²,specializing in the production of steel tubes/pipes for more than 30 years.

Our company specializes in producing all kinds of steel tubes , product specifications include: Seamless steel pipe with wall thickness 1-14mm and outer diameter 15-75mm,cold drawn pipe, cold rolled pipe , precision welded pipe, alloy pipe , pressure vessel pipe and special shaped pipe.

 

FAQ

Q: Are you trading company or manufacturer?
A: We are professional manufacturer for steel pipes,and our company also is a very professional and technical foreign trade company for steel products. We have more export experience with competitive price and best after-sales service. Apart from this,we can provide a wide range of steel products to meet the requirement of customer.
Q:Will you delivery the goods on time?
A: Yes,we promise to provide best quality products and delivery on time no matter if the price change lot or not. Honesty is our company's tenet.
Q: Do you provide samples ? is it free or extra?
A: The sample could can provide for customer with free,but the freight will be covered by customer account. The sample freight will be returned to customer account after we cooperate.
Q: How can I get your quotation as soon as possible?
A: The email and fax will be checked within 24 hours,meanwhile,Wechat and WhatsApp will be online in 24 hours. Please send us your requirement and order information,specification(Steel grade,size,quantity,destination port),we will work out a best price soon.
Q: Do you have any certifications?
A: Yes,that's what we guarantee to our clients. we have IS09000,IATF16949 certinicate,ISO 14001 certificates etc.Our products are of high quality and we have professional engineers and development team.
Q: What is your terms of payment?
A:Payment<=1000USD, 100% in advance. Payment>=1000USD, 30% T/T in advance ,balance before shipmenit or paid against copy of B/L within 5 working days. 100% Irrevocable L/C at sight is favorable payment term as well.
Q: Do you accept the third party inspection?
A: Yes absolutely we accept.

Company Profile