As a key component for transporting high-pressure fluids in the industrial field, the working pressure level of steel wire braided rubber hoses directly affects equipment safety and service life. This composite structure composed of an inner adhesive layer, a steel wire reinforcement layer, and an outer adhesive layer provides high-strength support through multi-layer steel wire weaving, and is widely used in fields such as engineering machinery, oil extraction, and hydraulic systems. The pressure rating of steel wire braided rubber hoses is not a fixed value, but a systematic standard system formed by multiple factors such as material properties, structural design, and process level.

1、 Core classification criteria for pressure levels

The internationally recognized pressure rating system is mainly divided based on the pressure bearing capacity of rubber hoses, and common standards include ISO, DIN, SAE, etc. Domestic standards mainly refer to GB/T3683-2011, which divides steel wire braided rubber hoses into three basic pressure levels:

1. Low pressure type (6.3-16MPa): adopting a single-layer steel wire weaving structure, suitable for scenarios such as forklift hydraulic systems and agricultural machinery.

2. Medium pressure type (21-31.5MPa): Enhanced by interlocking double-layer steel wires, commonly used in the main oil circuit of injection molding machines and excavators.

3. High pressure type (42-56MPa and above): using three-layer steel wire weaving and special synthetic rubber formula, used for harsh working conditions such as shield tunneling machines and offshore platforms. For ultra-high pressure products with a working pressure of 70MPa, the wire winding angle is accurately controlled at a "balance angle" of 54 ° 44 'to achieve stress distribution.

2、 Key technical elements affecting pressure performance

1. Steel wire weaving process: Modern CNC weaving machines can achieve high-density weaving of 12-16 bundles per inch, which increases the pressure bearing capacity by 20% compared to traditional processes.

2. Rubber composite material: The inner rubber layer is made of hydrogenated nitrile rubber (HNBR), which can withstand high temperatures of 150 ℃. Combined with aramid fiber reinforcement layer, the rubber hose can achieve 500000 cycles without failure in pulse pressure testing. After adding anti ozone agents to the outer layer, the outdoor service life is extended.

3. Structural optimization design: Simulate the interface stress between steel wire and rubber, and control the standard deviation of blasting pressure within ± 1.2MPa by optimizing the weaving pitch. Under dynamic usage conditions, the allowable pressure fluctuation should be controlled within ± 15% of the rated pressure.

3、 Specification for matching pressure levels with usage scenarios

There are strict limitations on pressure levels in different application scenarios. The hydraulic system of construction machinery usually requires 31.5MPa grade rubber hoses and must pass the pulse test of ISO6803 standard; Rubber hoses for oil drilling must meet the API16C standard and maintain no leakage for 2 hours under a working pressure of 56MPa. In practical use, attention should be paid to:

1. Temperature compensation: When the medium temperature exceeds 70 ℃, it is recommended to reduce the rated pressure by 10% for every 15 ℃ increase.

2. Bending radius: The minimum bending radius shall not be less than 8 times the outer diameter of the steel wire braided rubber hose, otherwise the pressure bearing capacity will decrease by 30%.

3. Safety factor: static system takes 4:1, dynamic system needs to be increased to 6:1.

4、 Stress testing and certification system

Legitimate products need to go through the following testing process:

1. Blasting pressure test: Pressurize the pipe body at a rate of 3MPa/s on a hydraulic testing machine until it ruptures, and the measured value should be ≥ 4 times the working pressure.

2. Pulse test: Perform 200000 pressure cycles at 125% working pressure, with a leakage rate of less than 5mL/min.

3. Low temperature bending test: There is no cracking after winding the core shaft in a -40 ℃ environment.

4. Certification mark: Products that have passed special certifications such as MSHA (Mine Safety) and DNV (Marine Engineering) have legal effect for their pressure rating identification.

The above is the classification of pressure levels for steel wire braided rubber hoses. Users should choose the hose level based on 1.25 times the maximum working pressure of the system. After 3 years of use, a water pressure re inspection is required. If the pressure holding value drops by more than 15%, it needs to be replaced.