The selection of compressed air pipeline materials shall comprehensively consider the compressed air quality, pressure level, environmental corrosion and other factors, and follow the relevant national standards. The following are specific selection specifications and basis:
1. material types and applicable scenarios
| Material Type | features | applicable Scenarios |
|---|
| carbon steel pipe | strong and durable, easy to shape, low cost; but easy to rust, need regular maintenance | industrial scenarios with low quality requirements for compressed air (such as air supply for general pneumatic tools) |
| galvanized pipe | corrosion resistance, rust prevention and beautiful appearance; However, it is easy to rust after the galvanized layer is damaged. | Building or industrial applications with limited budgets and low air quality requirements |
| aluminum alloy pipe | light weight, easy processing; but the surface oxide layer is easy to corrode after damage | lightweight or specific corrosive environment (such as salt water environment) |
| stainless steel pipe | excellent anti-rust, corrosion resistance, high temperature resistance; high cost | high-standard industries (e. g., pharmaceuticals, electronics, precision manufacturing) |
| plastic pipes (PVC, etc.) | easy to install, low cost; but poor corrosion resistance, easy to aging | temporary or low demand scenarios (need to be replaced regularly) |
2. Selection Core Specification
- compressed air quality priority
- solid particles and humidity levels:
- ≥ Level 5: Carbon steel pipe can be used (after cooler and dryer need to be installed).
- Level 3-5: Hot-dip galvanized steel pipe or stainless steel pipe is preferred.
- ≤ Level 3: Stainless steel pipe or copper pipe (such as instrument air supply pipe) must be used.
- oil pollution control: If the compressed air contains oil, oil-resistant materials (e. g. nitrile rubber seals) should be used.
- Pressure and temperature match
- low pressure system (≤ 1.6MPa): Carbon steel or aluminum alloy pipe can be selected.
- Medium and high pressure system (>1.6MPa): Seamless steel pipe or thickened stainless steel pipe must be used.
- High temperature environment (>60 ℃): Need to use high temperature resistant materials (such as 316L stainless steel).
- Environmental Adaptability
- coastal area aluminum alloy or 316L stainless steel (resistant to chloride ion corrosion) is preferred.
- chemical corrosion environment: Select lined PTFE or FRP pipe.
3. Key National Standards
- code for Design of Compressed Air Station (GB50029-2014)
- clarify the relationship between the selection of piping materials and the level of compressed air purification (see above specifications).
- Compulsory requirement: Pressure pipeline shall comply with TSG D0001, Safety and Technical Supervision Regulation for Pressure Pipeline-Industrial Pipeline.
- Code for Design of Industrial Metallic Piping GB50316
- it specifies the technical standards for welding and flanged connection of metal pipes.
- Requirements: Stainless steel pipe welds shall be pickled and passivated.
- Compressed air-Part 1: Pollutant purification classes GB/T13277.1-2008
- defines the grade standard of solid particles, humidity and oil content in compressed air.
4. installation and maintenance recommendations
- connection mode:
- threaded connection: Suitable for small pipe diameter (DN≤ 50mm), need to use PTFE sealing tape.
- Welded connection: Suitable for large diameter or high pressure pipelines, argon arc welding process is recommended.
- Flange connection: Easy to disassemble, but ensure the parallelism of flange surface (deviation ≤ 1.5 ‰).
- Pressure test:
- required after installation hydrostatic test(The test pressure is 1.5 times the working pressure) and tightness test.
- Regular inspection:
- ultrasonic testing of pipe wall thickness every 2 years to prevent corrosion and thinning.
Industry case: A pharmaceutical factory adopts 304L stainless steel pipe and oil-free air compressor to stabilize the dew point of compressed air at -40 ℃, reduce the microbial contamination rate by 92%, and reduce the equipment maintenance cost by 45%.
