Differences Between SMLS Pipes, ERW Pipes, LSAW Pipes, SSAW Pipes, and DSAW Pipes

Introduction

SMLS pipes, ERW pipes, LSAW pipes, SSAW pipes, and DSAW pipes are several critically important types of tubing in industrial production, widely used across sectors such as energy transportation, petroleum refining, and construction engineering. While these pipes share many similarities, they exhibit significant differences in application domains, specification ranges, mechanical strength, and manufacturing processes. This article provides a detailed analysis of their characteristics, advantages, and suitable usage scenarios to serve as an effective procurement guide.

SMLS Pipe

What is SMLS Pipe

Seamless steel pipes (SMLS pipes) are manufactured through hot-rolling or cold-drawing processes. The absence of welding significantly reduces residual stresses, resulting in uniform wall thickness and relatively high overall strength.

Classification of SMLS pipes:

Hot-Rolled SMLS pipes:

Manufactured by heating steel billets, piercing, and rolling. Compared to cold-drawn SMLS pipes, hot-rolled SMLS pipes feature a relatively rough surface, lower dimensional accuracy, and larger tolerances for both inner and outer diameters. They are commonly used in petroleum, natural gas, boilers, bridge pile foundations, and other fields for transporting liquids, gases, and solids. The manufacturing process for hot-rolled SMLS pipes are relatively simple, resulting in lower production costs and higher manufacturing efficiency.

Cold-drawn SMLS pipe:

These are manufactured by subjecting steel billets to multiple cold-drawing processes at ambient temperatures. Cold-drawn SMLS pipes feature smoother surfaces, tighter dimensional tolerances, exceptional precision, and uniform wall thickness. They are commonly used in precision instruments, hydraulic equipment, automotive components, and similar applications. The production of cold-drawn SMLS pipes involves high costs and low production efficiency.

Dimension Range of SMLS pipes

The outer diameter of SMLS pipes typically ranges from as small as 1/8 inch (approximately 3.175 mm) to 48 inches (approximately 1219 mm). Wall thicknesses are available in multiple grades, with common specifications including SCH40, SCH80, and STD. Different wall thickness grades correspond to distinct application scenarios. Standard lengths generally fall between 6 meters and 12 meters, with maximum lengths reaching up to 24 meters.

Advantages of SMLS Pipes

High Strength:

SMLS pipes offers superior strength and durability, capable of withstanding high-temperature, high-pressure, and highly corrosive environments. It is ideal for demanding applications in industries such as oil and gas.

Seamless Construction:

The absence of welded seams eliminates potential weak points, making SMLS pipes more corrosion-resistant and capable of withstanding higher pressures than welded pipes.

High Precision:

Compared to welded steel pipes, SMLS pipes exhibit superior dimensional accuracy with tighter tolerances, meeting stringent precision machining requirements and finding widespread use in high-precision applications.

Low Cost:

SMLS pipes feature relatively low production costs, extended service life, and minimal operational and maintenance expenses.

Excellent Flow Characteristics:

The smooth surface of SMLS pipes facilitates superior fluid flow, minimizing friction during liquid and gas transportation to enhance delivery efficiency.

ERW Pipes

What is ERW Pipes

Electric Resistance Welded pipes (ERW pipes) are steel pipes manufactured through the resistance welding process. Steel plates are rolled into a tubular shape, and electrical current is applied to the seam, generating resistance heat that melts the steel and fuses it together to form ERW pipes.

Types of ERW Pipe

ERW pipes can be categorized into high-frequency ERW pipes and low-frequency ERW pipes based on the current frequency used during the welding process. High-frequency ERW pipes are suitable for producing steel pipes with thinner walls. Low-frequency ERW pipes are widely used for fluid transportation. However, due to inferior welding quality and efficiency compared to high-frequency resistance welding, low-frequency resistance welding is gradually being replaced by high-frequency resistance welding.

Dimension Range of ERW Pipes

The outer diameter of ERW pipes typically range from 1/8 inch (approximately 3.175 mm) to 24 inches (approximately 609.6 mm), with wall thicknesses generally varying from 2 mm to 25 mm.

Advantages of ERW Pipes

High Production Efficiency:

The resistance welding process enables efficient, continuous welding at high speeds, facilitating large-scale production.

Uniform Wall Thickness:

ERW pipes feature consistent wall thickness, ensuring smooth flow of fluids like oil and natural gas. Uniform wall thickness enhances the pipe’s pressure resistance and corrosion resistance.

Low Energy Consumption:

Compared to SMLS pipes, welded pipes utilize electrical current for welding, eliminating the need to heat the entire steel billet to extremely high temperatures, resulting in lower energy consumption.

High Material Utilization:

Unlike SMLS pipes, welded pipes do not require piercing or rolling processes, leading to higher material utilization of steel.

Applications of ERW Pipes

ERW pipes have a wide range of applications and are suitable for use in low-to-medium pressure environments. They are commonly employed in construction, automotive, and water supply systems.

SAW Pipes

What is SAW Pipes

SAW pipes are manufactured by fusing steel plates using the submerged arc welding process.

Types of SAW Pipes

SAW pipes are categorized into LSAW pipes, SSAW pipes and DSAW pipes. LSAW pipes are welded along a straight line, SSAW pipes are welded along a spiral path, while DSAW pipes feature simultaneous internal and external welding—either longitudinally or spirally.

SAW Pipes Size Range

LSAW pipes typically have outer diameters ranging from 0.8 inches (approximately 20 mm) to 56 inches (approximately 1422 mm), with wall thicknesses generally between 6 mm and 80 mm. SSAW pipes typically have outer diameters ranging from 0.8 inches (approximately 20 mm) to 98 inches (approximately 2489 mm), with wall thicknesses generally between 5 mm and 25 mm.

Advantages of SAW Pipes

Larger Dimensions:

Compared to SMLS pipes and ERW pipes, SAW pipes can be manufactured in larger sizes. Pipes of varying dimensions serve different applications, with large-diameter SAW pipes commonly used for transporting oil, natural gas, and other fluids.

High-Pressure Resistance:

SAW pipes feature stable weld composition and superior weld quality, enhancing the strength and toughness of the steel. Additionally, the SAW process enables the fabrication of thick-walled pipes, making them widely applicable in high-pressure environments.

Applications of SAW Pipes

SAW pipes offer low operating costs, large diameters, and thick walls. They are commonly used in sectors requiring large-diameter pipelines and long-distance transportation, such as oil and gas, water supply, power transmission, and construction piling.

LSAW Pipes

What is LSAW Pipes

Longitudinal Submerged Arc Welded pipes (LSAW pipes) are steel pipes manufactured by rolling steel plates into a tubular shape and then welding them longitudinally using the submerged arc welding process.

Advantages of LSAW Pipes

Superior Weld Quality:

Compared to spiral welds, longitudinal welds are shorter and more uniform, effectively reducing stress concentration at welded joints. This enables LSAW pipes to operate safely under high-stress, harsh conditions while significantly lowering the risk of pipeline leaks or ruptures.

Dimensional Accuracy:

LSAW pipes offer higher dimensional precision in outer diameter and wall thickness than SSAW pipes, facilitating easier on-site installation.

Thicker Wall Thickness:

LSAW pipes can be manufactured with greater wall thickness, delivering superior strength.

Enhanced Corrosion Coating Performance:

During anti-corrosion coating application, LSAW welds minimally impact coating integrity, extending coating lifespan by decades. This prolongs pipeline service life and reduces maintenance expenses.

Large Diameter Capability:

LSAW pipes can be produced in large diameters, meeting high-volume liquid or gas transportation demands.

SSAW Pipes

What is SSAW Pipes

Spiral Submerged Arc Welded pipes (SSAW pipes) are manufactured by coiling steel plate into a tubular shape at a spiral angle and welding along the spiral seam using submerged arc welding technology.

Advantages of SSAW Pipes

High Pressure Resistance:

The spiral weld seam of SSAW pipes evenly distributes pressure, making it suitable for transporting oil and natural gas.

Large Diameter:

The spiral welding process enables SSAW pipes to be manufactured in larger diameters, effectively increasing pipeline capacity for large-scale transportation.

Low Cost:

Compared to LSAW pipes, SSAW pipes have relatively lower production costs, reducing purchase expenses. Additionally, SSAW pipes are easy to install, lowering installation costs.

Longer lengths:

Unlike LSAW pipes, the spiral welding process for SSAW pipes allows production of longer lengths, making them suitable for projects with specific length requirements.

DSAW Pipes

What is DSAW Pipes

Double-sided Submerged Arc Welded pipes (DSAW pipes) are manufactured using the submerged arc welding process to weld along the longitudinal seam or spiral direction on both the inner and outer sides of the pipe.

Advantages of DSAW Pipes

High Strength:

Compared to LSAW and SSAW pipes, the double-sided welding process of DSAW pipes delivers superior mechanical properties, enabling them to withstand high pressure and operate in extreme environments.

Cost-Effectiveness:

Although the initial purchase cost of DSAW pipes is higher, the double-sided welding enhances corrosion resistance and high-pressure tolerance, resulting in lower long-term maintenance costs.

High Production Efficiency:

DSAW pipes utilize a double-sided submerged arc welding process, achieving high welding efficiency and rapid production speeds.

Important Considerations When Ordering Steel Pipes

When considering the purchase of steel pipes, conduct a comprehensive evaluation based on factors such as usage costs, application fields, processing techniques, and dimensional ranges. Consult your supplier in detail to understand the specific differences between various pipe types, ensuring you select the most suitable option. This approach enhances project safety while reducing procurement and maintenance costs. As a trusted Chinese steel pipe supplier with years of industry expertise, we offer high-quality pipes and reliable services to ensure your project runs smoothly. For any related needs, please contact us. Our team will do our utmost to find the most suitable solution for you.

Summary

By comparing SMLS pipes, ERW pipes, LSAW pipes, SSAW pipes, and DSAW pipes, we gain a clearer understanding of their distinctions. When selecting steel pipes, this knowledge helps identify the appropriate application scenarios and advantages of each type, enabling the selection of the most suitable steel pipes for construction projects.