Anti static and wear-resistant rubber hose for coal mine, 16MPa working pressure, 2-inch inner diame
In the complex environment underground in coal mines, gas drainage, ventilation and other systems have extremely strict performance requirements for rubber hoses. Taking the anti-static and wear-resistant rubber hose with a working pressure of 16MPa and an inner diameter of 2 inches (approximately 50.8mm) as an example, its design needs to meet multiple requirements such as high voltage bearing, anti-static, wear-resistant, and flame retardant, becoming the core component to ensure the safety of underground operations.
1、 Technical parameters and performance adaptation
1. Pressure level and structural strength
The working pressure of 16MPa requires rubber hoses to have high-strength pressure bearing capacity. The typical structure adopts a 4-layer steel wire winding reinforcement layer, with a steel wire diameter of 1.8-2.2mm and a winding pitch of 8-10mm, forming a three-dimensional mesh support. Through finite element analysis verification, this structure can achieve a minimum burst pressure of 48MPa (three times the rated pressure) for the rubber hose, far exceeding the instantaneous high pressure conditions that may occur underground in coal mines. The design with an inner diameter of 2 inches needs to match the underground pipeline system standards to ensure fluid transport efficiency and system compatibility.
2. Anti static and flame retardant properties
In the coal mining environment, the explosion risk of gas and coal dust requires the surface resistance of the rubber hose to be ≤ 1 × 10 ⁶ Ω and the volume resistance to be ≤ 1 × 10 ⁸ Ω· m. By uniformly adding conductive carbon black or metal fibers to the rubber matrix, the gradient distribution of anti-static components can be achieved, avoiding local charge accumulation. The flame retardant performance is achieved by adding flame retardants such as aluminum hydroxide and melamine cyanurate, with an oxygen index of ≥ 28%, ensuring self extinguishing within 30 seconds under open flame or high temperature.
3. Wear resistance and corrosion resistance
The underground conveying medium often contains hard particles such as coal slag and gravel, requiring the lining material of the rubber hose to have high wear resistance. By using a blend formula of NBR (nitrile rubber) and CR (chloroprene rubber) and modifying with nano silica filling, the Akron wear can be reduced to below 0.03cm ³/1.61km. The outer layer is covered with chlorosulfonated polyethylene (CSM) weather resistant rubber, which can resist the humid and acid alkali corrosive environment underground, and the service life is extended to more than 3 years.
2、 Key control points in engineering applications
1. Installation specifications
Bending radius: The minimum bending radius of the hose shall not be less than 10 times the diameter of the pipe (i.e. 508mm) to avoid internal pressure failure caused by wire layer fracture.
Support spacing: When installed horizontally, the spacing between support points should be ≤ 1.5m to prevent stress concentration caused by the sagging of the hose due to its own weight.
Connection method: It is recommended to use a 24 ° conical sealing joint or flange connection, combined with O-ring sealing, to ensure a leakage rate of ≤ 1 × 10 ⁻⁹ Pa · m ³/s under a pressure of 16MPa.
2. Maintenance strategy
Regular inspection: preventive replacement should be carried out every 1000 working hours, with a focus on inspecting inner bulges, exposed steel wires, and outer cracks.
Pressure monitoring: Install pressure sensors to monitor the pressure inside the hose in real time. When the pressure fluctuation exceeds ± 5%, an alarm will be triggered to avoid overpressure operation.
Environmental adaptation: In sulfur-containing environments, it is necessary to regularly check the hardness changes of the rubber inner layer. If the hardness decreases by more than 10%, the rubber hose should be replaced immediately.