We Super Steel Manufacturing Co.,Ltd(SMC) are amongst the top manufacturers and suppliers for the seamless steel pipe, welded steel pipe, OCTG products and fittings from China. We have been manufacturing and supplying these products to the industry since 1993, and received repeat orders and appreciation from our valued customers.
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Always up to date. In this column you can find the steel pipe related articles, including industry trends, product standards and materials, and some technical guidelines.
Seamless steel tubes for hydraulic props are specialized steel tubes designed for hydraulic supports in coal mine longwall systems, as well as cylinders and hydraulic systems in construction and heavy equipment.
Manufactured primarily from 27SiMn alloy structural steel, these tubes undergo salt bath quenching at 920°C ±10°C and tempering at 550–600°C, providing exceptional strength, wear resistance, and corrosion resistance required for harsh mining and engineering environments.
Unlike ordinary seamless pipes, these belong to the category of high-precision cold-drawn seamless steel tubes, requiring strict control over raw materials, dimensional accuracy, and mechanical performance.
Technical Requirements of Seamless Steel Tubes for Hydraulic Props
Because these tubes directly impact mining safety, they must meet extremely demanding performance standards:
1. Mechanical Properties
High strength: Required to withstand high internal pressures and external loads.
High toughness: Prevents brittle fracture under impact or shock loading.
2. Dimensional Accuracy
Precise inner diameter: Ensures tight fit with pistons and seals to avoid leakage.
Uniform wall thickness: Prevents eccentricity, uneven stress distribution, and premature failure.
3. Surface Quality
Ultra-smooth internal surface: Inner wall roughness typically Ra ≤ 0.4 μm, reducing seal wear and frictional resistance while ensuring long-term sealing performance.
4. Processing Performance
Excellent deep-hole machinability for honing to final dimensions and surface finish.
Materials & Standards of Seamless Steel Tubes for Hydraulic Props
Common Materials
27SiMn – High-strength alloy steel developed specifically for mining hydraulic props; excellent toughness and hardenability.
30CrMnSi, 35CrMo – Higher-strength alternatives for more demanding conditions.
Hydraulic prop tubes are alloy steels enhanced with elements that improve strength, hardenability, and toughness. They typically require heat treatments such as quenching + tempering, surface quenching, or chemical heat treatment to achieve optimal performance.
Although not stainless steel, they offer superior wear resistance and machinability compared with stainless grades.
Standards
GB/T 33160-2016 – Seamless Steel Tubes for Hydraulic Supports (China industry standard)
DIN 2391 – High-precision seamless tube standard commonly applied in advanced hydraulic systems
Application Areas of Seamless Steel Tubes for Hydraulic Props
Primary applications include:
Hydraulic supports, cylinders, and columns for coal mines
Hydraulic cylinders for construction machinery and heavy equipment
Other industries:
Plastics machinery, injection molding, forging and die-casting equipment, automotive manufacturing, shipbuilding, metal processing, military equipment, diesel engines, agricultural machinery, automation, petrochemicals, aerospace, HVAC, and more.
Manufacturing Process of Seamless Steel Tubes for Hydraulic Props
The production of hydraulic prop tubes involves strict precision control:
High-quality round billet
Hot rolling
Cold drawing / cold rolling
Heat treatment (quenching + high-temperature tempering)
Straightening
Internal honing
Non-destructive testing
Final inspection and warehousing
Advantages and Disadvantages of Seamless Steel Tubes for Hydraulic Props
Advantages
Flexible component layout
Lightweight, compact, low inertia, quick response
Easy operation with wide stepless speed adjustment (up to 2000:1)
Automatic overload protection
Mineral oil provides natural lubrication and long service life
Simple linear motion
Easy to automate; electro-hydraulic control enables advanced automation and remote operation
Disadvantages
Lower efficiency due to flow resistance and leakage; risk of leakage contamination and fire hazards
Performance sensitive to temperature changes
High precision manufacturing leads to higher cost
Liquid compressibility prevents precise transmission ratio
Fault diagnosis is difficult; requires skilled maintenance
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