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Straight-seam Welded Pipe
High Production Efficiency
Longitudinal welded pipes are continuously produced from coiled steel plates or strips, resulting in an efficient process and significantly reduced production costs.
Flexible Specifications
We can produce very large diameter and thick-walled steel pipes, which are difficult to achieve with seamless steel pipe production.
High Precision
Modern welded pipe production lines are precisely computer-controlled, ensuring exceptionally high dimensional accuracy and consistent, reliable weld quality.
Short Delivery Cycle
Due to continuous production, production and delivery speeds for large-volume, standard-specification orders are significantly faster than for seamless steel pipes.
Core production technology
1. High-Frequency Longitudinal Welded Pipe (HFW/ERW)
HFW pipe utilizes the "skin effect" and "proximity effect" of high-frequency current to instantly heat the edges of the steel strip to a molten state, achieving intergranular bonding under the action of squeeze rollers. Its characteristics are:
Narrow heat-affected zone: Minimal impact on base material properties.
Smooth weld seam: Internal burr removal technology allows for extremely low weld height, resulting in minimal fluid resistance.
No welding wire or flux required: Lower production costs and environmental friendliness.
Main applications: Medium and low-pressure fluid transportation, structural pipes, oil and gas field casing, and machinery manufacturing.
2. Longitudinal Submerged Arc Welded (LSAW) Pipe
LSAW pipe is typically formed using processes such as JCOE or UOE. A single steel sheet is first press-bent into a J-shape, C-shape, and finally an O-shape, and then welded internally and externally using submerged arc welding.
Process Characteristics: The weld seam is extremely tough and strong, capable of withstanding extremely high pressures and harsh environments.
Main Applications: High-pressure long-distance oil and gas pipelines, offshore platform structures, large bridge piers, wind turbine towers, piling, and other critical infrastructure.
Technical standards and specifications
The production and inspection of straight seam welded pipes strictly adhere to a series of international, national, and industry standards. Familiarity with these standards is a prerequisite for selecting the right pipe.
Common standards implemented:
Chinese National Standard (GB): GB/T 3091 (welded pipe for low-pressure fluid transportation), GB/T 9711 (pipe for transportation in the petroleum and natural gas industries), GB/T 13793 (straight seam electric-welded steel pipe).
American Standard (ASTM): ASTM A53 (general purpose welded pipe), ASTM A252 (welded pipe for piling), ASTM A500 (carbon steel cold-formed welded pipe for structural use).
Petroleum API Standard: API 5L (line pipe, divided into PSL1 and PSL2 grades).
Other standards: EN 10219 (European standard structural pipe), JIS G3444 (Japanese standard structural pipe), etc.
Core Material Grades:
Common materials include Q195, Q235A/B, Q355A/B/C/D, L245/N/B, L290/N/B, L360/N/B, L415/N/B, X42, X52, X60, X65, and X70. The number represents the minimum yield strength (in ksi or MPa), while the letter indicates the delivery condition or impact energy requirement.
| Projects | HFW/ERW | LSAW |
|---|---|---|
| Outer Diameter Range (mm) | 20 - 660 | 325 - 1420+ |
| Wall thickness range (mm) | 1.0 - 25.0 | 6.0 - 40.0 |
| Common Lengths (m) | 6 - 12 (fixed length/multiple lengths) | 6 - 12.5 (or as agreed) |
Application
Low-pressure fluid transport: Welded pipes are mainly used for transporting general low-pressure fluids such as water, gas, oil and heating steam. They can be used as water supply and drainage pipes, heating pipes, low-pressure process pipes, low-pressure fire-fighting pipes, and as wire and cable protection pipes.
Structural support: Round welded pipe can also be used as structural support pipes, such as steel structure support pipes, concrete formwork support pipes, steel structure pipes for net frames, and columns for small temporary buildings.
Decorative use: LSAW pipes can also be used for decorative works, such as artistic modelling pipes, staircase railing handrails, protective railings, etc., which usually need to be painted to increase the aesthetics.
Decorative use: LSAW pipes can also be used for decorative works, such as artistic modelling pipes, staircase railing handrails, protective railings, etc., which usually need to be painted to increase the aesthetics.
Large Diameter LSAW Pipe: The uses of large diameter LSAW pipe include oil well pipe, pipeline pipe, boiler pipe, mechanical structure pipe, hydraulic strut pipe, gas cylinder pipe, geological pipe, chemical pipe and ship pipe.
In summary, straight-seam welded pipes are used for a variety of purposes, ranging from basic fluid conveyance and structural support to decorative and special applications, all of which show their important industrial value and wide range of applications.
Procurement Guide
Faced with numerous suppliers and products on the market, how can you make an informed choice?
Clarify your needs: Accurately inform suppliers of your intended use, required standards, material grade, specifications (OD x wall thickness x length), quantity, and budget. This will help you quickly obtain accurate quotes.
Investigate supplier qualifications: Choose a large-scale trading company like us with stable access to steel mills, comprehensive warehousing capabilities, and a professional team. We provide a Manufacturer's Certificate of Conformity (MTC) to ensure product provenance and traceability.
Focus on surface quality and inspection reports: High-quality welded pipes should have smooth internal and external surfaces, free of defects such as scabs, cracks, and burrs. Suppliers should be required to provide necessary inspection reports, such as those for ultrasonic testing (UT), X-ray testing (RT), hydrostatic testing, and mechanical properties testing.
Focus on surface quality and inspection reports: High-quality welded pipes should have smooth internal and external surfaces, free of defects such as scabs, cracks, and burrs. Suppliers should be required to provide necessary inspection reports, such as those for ultrasonic testing (UT), X-ray testing (RT), hydrostatic testing, and mechanical properties testing.
Evaluate costs comprehensively: Price isn't the only factor. Consider logistics costs, after-sales service, technical support, and the supplier's ability to handle urgent orders.
Why choose us as your supplier?
Resource Advantages: We have established long-term strategic partnerships with numerous major steel mills, ensuring a stable supply and competitive pricing, ensuring product quality from the source.
Processing Capabilities: We are equipped with multiple advanced steel pipe finishing lines, offering value-added services such as cut-to-length, beveling, punching, welding flanges, and pipe bending, ensuring your products are ready for immediate installation.
Technical Support: Our team of experienced engineers and sales personnel can provide comprehensive technical support, from product selection and technical standards interpretation to application solution design.
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Quotation Questions ◢
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Q.
How do I choose between straight seam welded pipe and seamless steel pipe?
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What is the "diameter expansion" process? What are its benefits?
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Can you provide corrosion protection?