Introduction:

With the development of hydraulic technology, correctly selecting, processing, and arranging hydraulic steel pipes to make hydraulic systems more energy-efficient, reliable, and long-lasting has become a research topic for hydraulic system designers. This article discusses the selection, processing, and installation of hydraulic steel pipes.

  1. Material Selection:

Pipe materials should be chosen based on system pressure, flow rate, and application. Key considerations include:

  • Sufficient pipe strength
  • Appropriate diameter and wall thickness
  • Smooth inner walls without rust, oxidation, or defects

Unacceptable conditions include:

  • Severe corrosion on inner or outer walls
  • Scratches deeper than 10% of wall thickness
  • Surface dents exceeding 20% of pipe diameter
  • Uneven wall thickness or noticeable ovality

Medium and high-pressure systems typically use seamless steel pipes due to their high strength, low cost, and leak-free connections. Common choices include:

  • Cold-drawn low-carbon steel (grades 10, 15, 20) for general hydraulic systems
  • Stainless steel pipes for hydraulic servo systems (corrosion-resistant, smooth surfaces, precise dimensions, but more expensive)
  1. Pipe Processing:

Main processing steps include cutting, bending, and welding. Proper processing methods are crucial for system reliability.

a) Cutting:

  • Use grinding wheel cutting machines for pipes under 50mm diameter
  • Use mechanical methods for pipes over 50mm diameter
  • Avoid manual electric welding or oxygen cutting
  • Ensure cut surfaces are perpendicular, smooth, and free of burrs or scale

b) Bending:

  • Use mechanical or hydraulic pipe benders
  • Cold bend pipes 38mm and under to avoid oxidation
  • Avoid hot bending; use pressed elbows instead
  • Minimum bend radius should be 3 times the pipe diameter
  • Ovality after bending should not exceed 8%
  • Bending angle deviation should not exceed ±1.5mm/m

c) Welding:
Step 1: Prepare pipe ends with appropriate bevels
Step 2: Choose suitable welding method (argon arc welding preferred)
Step 3: Inspect weld quality (check for cracks, inclusions, porosity, etc.)

  1. Pipe Installation:

Install pipes after connecting equipment and hydraulic components are in place. Key principles include:

a) Bracket installation:

  • Weld bracket pads directly or through angle iron supports
  • Use expansion bolts for concrete walls
  • Space brackets appropriately to prevent vibration

b) Pipe layout:

  • Arrange pipes horizontally or vertically
  • Avoid crossing pipes and maintain proper spacing
  • Prioritize large diameter pipes and those close to supports
  • Use straight pipe sections for connections to fittings or flanges
  • Maintain minimum clearances between pipes and components
  • Use 90° and 45° bends for pipe groups
  • Keep pipe runs short with smooth transitions
  • Ensure accessibility for maintenance and repair
  • Seal pipe ends during installation breaks to prevent contamination

Conclusion:

The selection, processing, and installation of hydraulic steel pipes are crucial aspects of hydraulic system design and modification. Proper methods ensure stable system operation, prevent leaks, and maintain system functionality and safety.