Rubber pipes refer to pipes used for gas transmission, and are commonly used in gas welding, gas cutting, various gas shielded welding, plasma arc welding and cutting. There are two types of rubber pipes for welding.
According to the standard, the blue pipe is an oxygen pipe, and the maximum working pressure is 1.5MPa. The red pipe or black rubber pipe is an acetylene pipe, and the allowable pressure is 0.5-1.0MPa.
The characteristics of the rubber pipe are physiological inertia, UV resistance, ozone resistance, high and low temperature resistance (-80-300°C), high transparency, strong resilience, compression resistance, deformation resistance, oil resistance, stamping resistance, acid and alkali resistance, wear resistance, flame retardant, voltage resistant and conductive.
Ⅰ. Measuring dimensions of rubber air hoses
Inner diameter, outer diameter, outer diameter of reinforcement layer, wall thickness, concentricity, thickness of inner and outer rubber, inner diameter of assembly. The new national standard and ISO increase the length and measuring point marks, and stipulate the measurement method of the length of the hose without pipe joints and with various pipe joints.
Ⅱ. Hydrostatic test of rubber air hose verifies pressure test
Under the verification pressure, check the rubber tube and assembly for leakage, deformation and damage after 30s-60s.
Compression deformation test: Hold for 1 minute under the specified pressure (working pressure, test pressure or other pressure lower than the test pressure), and measure the change of hose length and outer diameter, torsion angle and bending degree.
Burst pressure test: Measure the pressure at which a rubber air hose bursts at a specified rate of pressure increase.
Leak test: Hold it at a static pressure of 70% of the smaller burst pressure for 5 minutes, then repeat and check for leaks or damage. Since water is often used in the test, the burst pressure and leakage pressure measured at room temperature may be slightly lower than the viscosity of the actual liquid used.
Ⅲ. Low temperature flexure tests rigidity of rubber pipe
The rubber pipe is clamped on a torsion wheel with diameter 12 times the inner diameter of the rubber hose, and the torque measured at 180° in 12 seconds is the ratio of the torque measured at standard temperature.
Low temperature bending: Clamp the hose on a torsion wheel with a diameter of 12 times the inner diameter of the rubber pipe. After 24 hours of low temperature parking, twist it 180° within 10 seconds to check whether the inner and outer rubber is damaged.
A simple test for measuring low temperature brittleness of a hose is to bend a sample 90 degrees at low temperature, or compress a length of hose after freezing, to see if it is brittle. Another method is to free-fall with a weight of a certain weight and hit the sample to see if it is fragile.
Ⅳ. Bending test of rubber air hose
After the rubber pipe is bent to a certain extent, measure the ratio of the smaller outer diameter of the bending part to the outer diameter before bending, the passing capacity of the steel ball and the bending force when it is pressed into the pipe.
Ⅴ. Flat suction test of rubber air pipe
Vacuum for 1 minute, then hold for 10 minutes, and then roll with a steel ball with a diameter of 0.9 times the inner diameter of the rubber air hose to check the collapse of the rubber tube. Some standards measure the degree of deformation of the hose by measuring the rate of change in the outer diameter of the hose.
Ⅵ. Adhesion strength test between layers of rubber pipes
Automotive hoses are mostly braided hoses with a diameter of less than 50mm. Strip samples with a width of 10mm or 25mm are often used in the test, and a ring with a width of 25mm is also used, peeled at 90 degrees, and the tensile speed is 25 mm/min.
Ⅶ. Liquid wall penetration test of rubber pipe
Connect the hose to a container containing a certain amount of liquid under normal pressure, seal the nozzle of the container, place the test device horizontally, and then periodically measure the mass change of the entire test device caused by the liquid permeating outward through the rubber air hose. Thereby, the permeation velocity of the liquid is calculated.
Ⅷ. Volume expansion test of rubber pipe
Rubber pipe should not produce significant volume changes under fluid transfer pressures. The method of measuring volume expansion is to connect a rubber hose to a hydraulic source, and the other end to a measuring tube that measures the volume of liquid after the expansion of the hose.
Raise the pressure in the hose to the test pressure, inflate the rubber air hose, then turn off the hydraulic source and open the valve connected to the measuring tube. At this time, the liquid in the volume-expanded portion rises into the measuring tube, and the expanded volume can be measured.
Ⅸ. Cleanliness and extraction test of rubber pipe
The fuel hose is usually filled with C liquid, which is emptied after being parked for 24 hours, and the inner wall is cleaned with C liquid. Collect the C liquid after injection and cleaning, filter out the insoluble impurities, dry and weigh to obtain the weight of the insoluble impurities, and use the number of impurities on the inner surface of the rubber pipe or the size of the impurities to indicate the cleanliness.
The filtered solution was evaporated, dried and weighed to obtain the weight of soluble material. The wax was then extracted from the filtrate obtained by evaporation drying with methanol, the methanol extract was evaporated and dried, and the wax was weighed.
Ⅹ. Salt spray test of rubber pipe
Put the rubber tube assembly in a salt spray formed by a 5% sodium chloride aqueous solution at 35°C for 24 hours, and then check whether the metal of the rubber pipe joint is corroded.
