Importance of using a steel wire reinforced rubber hose

Rubber hose is a hose made of rubber. It is widely used in industry, agriculture, military industry, medical treatment and people’s livelihood. Rubber hoses are divided into pure rubber hoses and reinforced hoses. Reinforced rubber hoses refer to hoses with one or more layers of reinforcing material between the inner rubber layer and the outer rubber layer. The reinforcement layer structure is diverse. And the reinforcing materials are basically divided into two categories: fiber and metal (metal reinforcement material is generally steel wire).

Hose pressure level

The working pressure of reinforced rubber hoses is roughly divided into 5 levels according to SAEJ 517 standard. They are low pressure, medium pressure, high pressure and ultra-high pressure. Within the same level, 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. Low-pressure hoses are reinforced with fiber materials. Medium-pressure hoses can be reinforced with fiber materials or steel wires. High-pressure and ultra-high-pressure hoses are generally reinforced with steel wires. Only hoses for special purposes are reinforced with aramid fiber materials that have a smaller volume mass than steel wire and a higher tensile strength than steel wire.

The reinforcement layer of steel wire reinforced rubber hoses has a braided structure and a winding structure. But sometimes a mixed structure of the two is also used. Under the same conditions, the winding structure hose has higher pulse pressure resistance than the braided structure hose. Because there are no interweaving points between the winding steel wires like the braided structure. Therefore, there will be no local friction between the steel wires.

Steel wire braided structure

The braided structure is made up of two strands of steel wires running in the positive and negative directions interwoven in the form of “two up and two down”, presenting a mat pattern structure. According to the pressure requirements of the hose, it can be single-layer or double-layer. The steel wire specifications also vary in thickness.

Steel wire winding structure

The winding structure is made up of two groups of adjacent layers of steel wires wound in reverse spirals, and the steel wires are not interwoven with each other. The steel wire winding layer is an even number of layers. According to the pressure requirements of the hose, there are generally 2 layers, 4 layers and 6 layers. The steel wire also varies in thickness.

The larger the diameter of the steel wire, the stronger the pressure resistance of the hose. Conversely, the smaller the diameter of the steel wire, the weaker the pressure resistance of the hose. At the same time, the more layers of reinforcement, the better the pressure resistance. The fewer layers, the worse the pressure resistance.

Special large-diameter rubber hose

Wire braided and wound rubber hose, the inner diameter is generally below 51 mm. Hoses with an inner diameter greater than 51mm are called large-diameter hoses. Such as oil drilling rubber hoses, offshore oil transportation rubber hoses, dock suction rubber hoses, dredging rubber hoses, and solid material transportation rubber hoses such as ore sand. Agricultural irrigation and drainage rubber hoses and other suction hoses are also large-diameter rubber hoses. But its reinforcement layer is mainly dipped textile (called cloth layer). At the same time, it is supplemented by armored steel wire spiral wire to maintain the annular shape of the hose and withstand positive and negative pressures.

Marine Oil Hose

The offshore oil transportation rubber hose is a moored crude oil transportation hose with an inner diameter of 150 to 600 mm. There are two types: underwater and floating. Due to the harsh use conditions of this hose, its structure is relatively complex. In addition to the fabric buffer layer, the reinforcement layer is mainly composed of multiple layers of steel cord winding layers and steel wire spirals. The cord winding steel wire can be a single steel wire or a thin stranded steel wire rope.

Drilling Hose

Oil drilling rubber hose, the inner diameter is 64~102 mm, the working pressure is 27~52MPa. It is a large-diameter ultra-high pressure rubber hose. This hose is reinforced by winding a single thick steel wire or a stranded thin steel wire rope, generally 4 layers.

Oil drilling hose is a hose specially used in oil field exploitation and drilling industry. It can withstand the transmission of liquid and gas under high pressure and high temperature environment. The hose is usually composed of inner rubber layer, reinforcement layer and outer rubber layer. It can meet the special needs in oil drilling.

First, the reinforcement layer of oil drilling hose usually adopts multi-strand synthetic fiber wire or steel wire to ensure its pressure resistance. Secondly, the inner rubber layer usually adopts oil-resistant materials such as PU or NBR to ensure its durability and chemical resistance. In addition, the outer rubber layer usually adopts weather-resistant materials such as PVC or PE to protect the inside of the hose and enhance its durability.

Oil drilling hose has strong pressure resistance and high temperature resistance. In oil well drilling, the hose needs to withstand the transportation of high-pressure liquid and gas. Therefore, it must have high pressure resistance. In addition, the temperature at the drilling site is usually high. Therefore, the hose must also have high temperature resistance.

In addition, oil drilling hose also needs to have anti-corrosion and anti-wear properties. In the process of oil field exploitation, there will be various corrosive substances such as acids, alkalis, and salts. Therefore, the hose must be corrosion-resistant. In addition, the hose is easily worn when it comes into contact with the drill bit, rock, mud and other materials, so it also needs to be wear-resistant.

Dock Hose

Dock oil hose, the inner diameter is 102~304 mm, the working pressure is 1.55MPa. It is mainly used for suction and discharge of oil and petroleum products between docks and tankers. It is actually a soft connection between the dock and the tanker oil pipeline to adapt to the up and down and horizontal floating of the tanker in the water. This type of hose is generally reinforced with steel cords and supplemented with thick steel wire spirals. The cord layer is generally 4 layers. This type of suction and discharge rubber hose can also be used to discharge and absorb other chemicals.

The role of steel wire in rubber hoses

Reinforced rubber hoses are flexible conduits. They are used to transport liquids, gases, and granular or powdered solid materials, and to transmit hydraulic and pneumatic power. Whether it is transporting materials or transmitting power, the hose must withstand internal or external pressures of varying sizes. Therefore, the main function of the steel wire reinforcement layer is to strengthen the rubber hose. Make it resistant to positive and negative pressures. During the use of rubber hoses, especially hydraulic hoses, the pressure they are subjected to is not constant. It must withstand periodic pulse pressures from 0 pressure to 125% of the working pressure. Sometimes it must withstand higher instantaneous impact pressures.

Rubber hose safety factor

In the design of rubber hoses, a safety factor needs to be added to the required working pressure. That is, the ratio of the smaller burst pressure to the larger working pressure. The safety factor ranges from 2 to 5, and is generally 4. Rubber hoses, especially hydraulic hoses, must withstand periodic changes in the inner diameter due to pressure during operation, such as increase and decrease, and length extension and shortening. They must also withstand periodic flexion changes caused by bending and deformation during installation. In addition, there are also deterioration effects on the inner and outer rubber layers caused by the transported materials, the medium for transmitting power, and the climate temperature. All these factors not only directly affect the performance of the rubber hose, but also affect the service life of the hose.

In the design of rubber hoses, the considerations for steel wires are mainly tensile strength, toughness and specifications. At the same time, appropriate steel wires are selected according to the pressure level of the hose. Generally speaking, the lower the tensile strength of the steel wire, the better the flexibility. 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 steel wires with high strength and good flexibility. This will play an important role in improving the performance and service life of rubber hoses. The bonding between steel wire and rubber is very important for the flexural resistance and pulse performance of rubber hoses, especially hydraulic hoses. After the rubber hose is formed and vulcanized, the components of the hose body are well bonded, making the hose body an indivisible whole. This is one of the issues that must be considered in hose design.

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