MS Pipes & Tubes: Mild Steel Pipes

Steel Pipes

MS pipes & tubes, short for Mild Steel Pipes & Tubes, are a type of steel pipe made from mild steel-low-carbon steel with a carbon content of ≤0.25%. This low carbon content gives mild steel excellent ductility and weldability, making MS pipes easy to process and connect, while also keeping production costs relatively low. Unlike high-strength steel pipes (such as some hfw steel pipes), MS pipes have lower tensile and yield strength, so they are more suitable for scenarios with low stress requirements, avoiding material waste caused by using over-performance pipes.

At Hebei Huayang Steel Pipe Co., Ltd., MS pipes & tubes are one of the key product lines, covering both welded (mainly using ERW technology) and seamless types. The company's R&D team has optimized the material formula for MS pipes based on market demand, adjusting the content of manganese (0.30%-0.60%) and silicon (≤0.35%) to balance ductility and basic strength-ensuring the pipes meet daily use needs while maintaining good processing performance.

To fully understand MS pipes, it is necessary to clarify their connection with ERW (Electric Resistance Welding) technology, which also involves understanding erw pipe meaning and what is erw pipe. What is erw pipe? It refers to a pipe manufactured by using resistance heat generated by electric current to fuse metal edges, and an electric resistance welded steel pipe is the product of this technology. For MS pipes, ERW is a mainstream manufacturing method-since mild steel has good weldability, it can fully adapt to the ERW welding process, forming firm welds without easy cracking.

Huayang's ERW-produced MS pipes account for about 60% of its total MS pipe output. The company uses mature ERW technology to produce MS pipes: flat mild steel plates are rolled into pipe blanks, then welded by resistance heat, and finally sized and trimmed. Compared with seamless MS pipes, ERW-made MS pipes have higher production efficiency (Huayang's ERW MS pipe production line can reach a speed of 25m/min) and lower costs, making them the first choice for general civil and industrial scenarios. It is worth noting that while hfw steel pipes (a high-performance type of electric resistance welded steel pipe, with hfw meaning being High-Frequency Welding) focus on high pressure and high strength, ERW-produced MS pipes focus on cost-effectiveness and ease of use, forming a complementary product matrix at Huayang.

Steel Pipes

Huayang's ERW MS pipe manufacturing process follows strict standards, integrating the advantages of ERW technology with the characteristics of mild steel:

The raw material for ERW MS pipes is hot-rolled mild steel coils. Before production, Huayang's quality inspection team conducts two key tests: first, chemical composition analysis (using a direct-reading spectrometer to confirm carbon, manganese, and silicon contents meet standards); second, surface defect inspection (rejecting coils with cracks, rust, or pits). In 2024, the company rejected 8 batches of mild steel coils with excessive sulfur content (＞0.040%), avoiding potential weld brittleness issues in subsequent ERW welding.

After uncoiling and leveling the steel coils, they are cut into fixed-length plates (according to customer requirements for pipe length, usually 6m-12m). The plates then enter the multi-roll forming machine, where they are gradually bent into cylindrical pipe blanks-Huayang uses 10 sets of forming rolls, adjusting the pressure (3kN-8kN) according to the plate thickness (1.5mm-8mm) to ensure the pipe blank has a smooth inner wall and no obvious ellipticity.

The welding process adopts ERW technology: the pipe blank is sent to the welding station, where electric current passes through the edge of the pipe blank to generate resistance heat (temperature controlled at 1200℃-1300℃), melting the mild steel edge. Then, the extrusion roll applies pressure (2MPa-5MPa) to fuse the edges, forming a weld. Unlike hfw steel pipes (which use high-frequency current for rapid welding), ERW MS pipes use medium-frequency current, balancing welding quality and production cost.

After welding, the MS pipes undergo two key treatments: first, weld annealing (heating to 650℃-700℃, keeping for 10 minutes) to eliminate welding internal stress and avoid weld cracking during use; second, sizing and straightening (using a 6-roll sizing machine to control the outer diameter deviation within ±0.2mm). Finally, the pipes are inspected for appearance (no weld bumps or scratches) and hydrostatic pressure (testing at 1.2 times the rated pressure for 5 minutes, no leakage allowed).

For scenarios with higher requirements for pipe inner wall smoothness (such as low-pressure industrial fluid transportation), Huayang produces seamless MS pipes. The manufacturing process is more complex than ERW-made pipes: first, mild steel billets are heated to 1200℃-1250℃, then pierced into hollow pipe blanks by a piercing machine, and finally rolled and calibrated to the required size. Seamless MS pipes have no welds, so they have better pressure resistance than ERW MS pipes (rated pressure up to 4MPa), but the production cost is about 30% higher.

Huayang's seamless MS pipe production line is equipped with a precision rolling mill, which can produce pipes with diameters from 15mm to 150mm and wall thicknesses from 2mm to 10mm. In 2024, the company supplied 1,200 tons of seamless MS pipes to a chemical plant in Cangzhou, used for cooling water transportation-meeting the plant's requirement for "no welds to avoid fluid leakage risks".

Steel Pipes

Huayang's MS pipes are widely used in civil scenarios, with ERW-made MS pipes being the main product. One of the most common applications is indoor gas pipelines-since urban residential gas pressure is low (usually 2kPa-3kPa), MS pipes' strength is fully sufficient. In the 2024 Tangshan Residential Gas Pipeline Renovation Project, Huayang supplied 1,800 tons of Φ50×3mm ERW MS pipes. These pipes were connected by thread (taking advantage of mild steel's easy threading property) and passed the national gas safety inspection, with a service life guarantee of 10 years.

Another major civil application is construction handrails and supports. Huayang's Φ25×2mm MS pipes are often used to make stair handrails in residential buildings-after surface painting (to prevent rust), they have a smooth appearance and good load-bearing capacity (each meter of handrail can bear a vertical load of 50kg). In the 2023 Baoding Affordable Housing Project, the company supplied 800 tons of such MS pipes, meeting the project's 1,200 residential units' handrail needs.

In industrial fields, Huayang's MS pipes are mainly used for low-pressure fluid transportation and general structural parts. For example, in a food processing factory in Shijiazhuang, Huayang's Φ80×4mm seamless MS pipes are used to transport clean water (working pressure 1.5MPa)-the seamless structure ensures no fluid contamination, and the mild steel material is easy to clean. In addition, MS pipes are used as supports for small equipment in factories-Huayang's Φ100×6mm MS pipes can bear the weight of general mechanical equipment (≤500kg), and the surface can be galvanized (referring to GI pipe technology) to enhance corrosion resistance if needed.

It is worth noting that in industrial scenarios where pressure is high (such as oil and gas transportation), Huayang will recommend hfw steel pipes (a type of electric resistance welded steel pipe) instead of MS pipes-since hfw steel pipes have higher strength (tensile strength ≥480MPa) and can withstand long-term high pressure (up to 10MPa), avoiding safety risks caused by using inappropriate pipes. This "scenario-based product recommendation" reflects Huayang's professional service concept, ensuring customers get the most suitable steel pipe products.

Huayang has established a full-process quality control system for MS pipes. From raw material inspection to finished product delivery, 8 inspection links are set up-including chemical composition testing, weld flaw detection (using ultrasonic flaw detectors for ERW MS pipes), and mechanical property testing (tensile strength ≥335MPa, elongation ≥25%). In 2024, the qualification rate of Huayang's MS pipes reached 99.7%, far higher than the industry average of 98%.

Huayang provides customized services for MS pipes according to customer requirements. For example, for customers who need short-length MS pipes (such as 3m-4m for indoor decoration), the company can adjust the cutting process to avoid material waste; for customers with corrosion resistance needs (such as outdoor handrails), it can provide surface galvanizing or painting treatment (the same as GI pipe surface treatment technology). In 2023, Huayang completed 120 customized MS pipe orders, with a customer satisfaction rate of 98%.

By optimizing the production process (such as improving ERW welding efficiency) and controlling raw material costs, Huayang's MS pipes have obvious price advantages-compared with similar products on the market, the price is 5%-8% lower. At the same time, the company provides timely delivery services (the delivery cycle for ERW MS pipes is 3-5 days), helping customers shorten the construction period. For example, in the 2024 Handan Residential Renovation Project, Huayang completed the supply of 1,500 tons of MS pipes in 4 days, ensuring the project was completed on schedule.