According to the SAEJ517 standard, it is roughly divided into 5 grades: low pressure, medium pressure, high pressure, very high pressure, ultra-high pressure. Within the same rating, the pressure depends on the inner diameter of the hose. Under the same structure, the smaller the inner diameter, the higher the pressure it can withstand; the larger the inner diameter, the lower the pressure it can withstand. The low-pressure hose is reinforced with fiber material; the medium-pressure rubber hose pipe can be reinforced with fiber material or steel wire;
High-pressure, very high-pressure and ultra-high-pressure hoses are generally reinforced with steel wires, and only special-purpose hoses are reinforced with aramid fiber materials that are smaller in volume and mass than steel wires and higher in tensile strength than steel wires.
The reinforcement layer of the wire reinforced flexible hose has a braided structure and a winding structure, and sometimes a mixed structure of the two is also used. Under the same conditions, the wound structure hose has higher pulse pressure resistance performance than the braided structure hose.
This is because there are no interlacing points between the wound wires like the braided structure, and local friction does not occur between the wires.
Steel wire braided and wound rubber hose, with inner diameter generally below 51 mm. A hose with an inner diameter greater than 51mm is called a large-diameter hose. Such as oil drilling rubber hose, marine oil transportation rubber hose, wharf suction rubber hose, dredging rubber hose, ore sand and other solid material conveying rubber hose pipe.
Agricultural irrigation and drainage rubber hose pipes and other drainage and suction hoses are also large-diameter rubber hoses, but their reinforcement layers are mainly dipped fabrics (called interlayers), supplemented by armored steel wire spirals to maintain softness. The tube is annular and bears positive Π negative pressure.
Offshore oil transportation rubber hose is an offshore single-point mooring crude oil transportation hose with an inner diameter of 150-600 mm, which is divided into two types: underwater and floating. Due to the harsh use conditions of this hose, its structure is relatively complex. Except for the fabric buffer layer, the reinforcing layer is mainly composed of multiple layers of steel cord winding layers and steel wire spirals.
The cord winding wire can be a single wire or a thin stranded wire rope. The oil drilling rubber hose pipe has an inner diameter of 64-102 mm and a working pressure of 27-52 MPa. It is a large-diameter ultra-high pressure rubber hose.
This kind of hose is reinforced by winding a single thick steel wire or a pair of thin steel wire ropes, generally 4 layers, a wharf suction rubber hose pipe, the inner diameter is 102 ~ 304 mm, the working pressure is 1. 55MPa, and it is used between the wharf and the oil tanker. Suction of petroleum and petroleum products.
It is actually a soft connection between the terminal and the oil pipeline of the oil tanker to adapt to the up and down and horizontal floating of the oil tanker in the water. This kind of hose is generally reinforced with steel cord winding, supplemented by thick steel wire helix.
Reinforced rubber hose is a flexible conduit for conveying liquid, gas and granular or powdered solid materials, and transmits hydraulic and pneumatic power. Whether it is conveying materials or transmitting power, rubber hoses must withstand internal or external pressures (positive or negative pressure) of varying sizes.
Therefore, the main function of the steel wire reinforcement layer is to strengthen the rubber hose pipe and make it resistant to positive and negative pressure. The pressure on rubber hoses, especially hydraulic hoses, is not constant during use. It is subjected to periodic pulse pressures from 0 pressure to 125 % working pressure, and sometimes higher instantaneous shock pressures.
In the design of rubber hose, it is necessary to add a safety factor to the required working pressure, that is, the ratio of the smaller burst pressure to the larger working pressure. In addition, there are also the deterioration of the inner rubber layer and the outer rubber layer by the conveyed material and the medium that transmits the power, climate and environment, high temperature and low temperature, etc.
All these factors not only directly affect the performance of the rubber hose pipe, but also affect the service life of the rubber hose. In the design of rubber hoses, the main considerations for the steel wire are tensile strength, toughness (flexibility) and specifications, and the appropriate steel wire is selected according to the pressure level of the hose.
Generally speaking, the lower the tensile strength of the steel wire, the better the flexibility, and the higher the tensile strength, especially at its upper limit, the worse the flexibility and the greater the brittleness. However, it is more important to develop a steel wire with high strength and good flexibility at the same time, which will play an important role in improving the performance and service life of the rubber hose pipe.
The adhesion of steel wire to rubber is very important for the flex resistance and impulse performance of rubber hoses, especially hydraulic hoses. After the rubber hose pipe is formed and vulcanized, the components of the pipe body are well bonded, so that the pipe body becomes an inseparable whole, which is one of the issues that must be considered in the design of the hose.
