The structure and common failure of high pressure hose

Considering technology maturity and controllability, the vast majority of factory equipment or construction machinery still uses hydraulic pressure as a drive source. Because a lot of basic infrastructure is inseparable from hydraulic pressure, hydraulic pressure is called "the source of all power" in the industry.

Factory equipment steel pipe hose and realize the connection

Excavator steel pipe hose together play a role

Pipes can be divided into hard pipes and hoses.

Hard pipe mainly refers to steel pipe, iron pipe and other metal pipes;

Hose mainly refers to rubber pipe, PTFE (polytetrafluoroethylene) pipe, corrugated pipe and other flexible pipes.

This main body is "high pressure oil pipe", we initially understand the use and weakness of high pressure oil pipe from the structure of high pressure oil hose (protection points).

High pressure hose, also known as hydraulic hose, rubber hose, is the blood vessel of the hydraulic system, which realizes the transfer of pressure while transporting fluid. In a broad sense, high-pressure hoses also include hoses that transport water, steam, chemical liquids, etc.

General hydraulic oil fluid with high pressure hose, water glycol fluid with hydraulic hose.

High pressure oil hose internal structure:

① Wire braided rubber hose (low pressure/small diameter)

It is the most popular structure for oil pressure hose.

The reinforced layer is a structure with steel wire woven in each layer.

Prevent the steel wire layer from rubbing with each other design the middle rubber layer.

The outer rubber is a high-wear resistant material used to protect the outer pipe from injury and prevent the reinforcement layer from rusting.

The inner rubber is made of materials that can withstand fluid corrosion.

② Wire spiral rubber hose (medium high pressure/medium diameter)

Compared with wire braided hose, the structure is mainly used in high pressure areas.

The inner rubber layer and the reinforced layer add fiber braid layer between the layers.

 It can be seen that the key points of tubing quality or technology are:

① Outer rubber gum (corrosion resistance, wear resistance, etc.)

② Steel wire quality/braiding tightness (withstand + toughness)

③ Inner rubber (resistance to hydraulic oil and water corrosion)

These 3 points are also the confirmation points for judging the quality of hose!

Common failure of high pressure hose

① Tube explosion: Pressure exceeding the pressure specification is applied

The tube explodes after the pressure range is exceeded

As a channel for conveying pressure, the high-pressure hose must withstand the pressure of the internal liquid. Because it is the basic raw material of rubber that determines it is the short board on the transmission system (although not as durable as the steel pipe, it can be bent and moved), and it is a consumable. Pressure is an important element of pipe selection, the peak pressure of the equipment and the working pressure of the high pressure tubing do not match the risk of tube explosion, resulting in equipment shutdown and even lead to safety hazards! And some brands of tubing nominal pressure or quality instability also greatly increase the probability of tube explosion.

② Tube explosion: the use of mismatched fluid (erosion)

The inner rubber is corroded, corroded and cracked

There are many types of fluids used according to the actual situation. There are general mineral oil, water glycol mineral oil, water, chemical fluid and so on for fire prevention purposes. Hose inner rubber different formulations, required to be able to resist the erosion of the corresponding fluid. The oil pipe that is not resistant to the fluid meets the fluid, which is easy to cause the inner rubber to crack (as shown in the figure above), and the fluid (especially the water in it) penetrates into the steel wire layer, accelerating the deterioration of the steel wire layer for cladding, and in serious cases, the weak local part of the pipe burst.

③ Crack/burst pipe: excessive bending beyond the specification value of the tubing

Overbending causes bending

Most hoses move repeatedly with the operation of the equipment, which requires the hose to have good toughness. At the same time, the narrow installation space of the equipment also puts forward higher requirements for the bending radius of the hose. And this is closely related to rubber formulation and steel wire flexibility. Be sure to confirm the parameters of the tubing manufacturer and the bending data report issued by the relevant manufacturers, and do not rely on the feel to choose the moving part of the tubing. The mismatched tubing selection and regular spot inspection are not in place, and the bending stress concentration part is prone to the outer rubber cracking and steel wire fracture, and the tube explosion occurs.

④ Wear/burst tube: acceleration of deterioration under adverse environment

Excessive wear causes the outer rubber to fall off and must be replaced immediately

Rubber products are generally afraid of ultraviolet light, ozone, water, high temperature, friction, which accelerate their aging affect the service life. The equipment is inevitably in a high temperature and high humidity environment, and the open storage of construction machinery has higher requirements for the hose rubber formula. Therefore, avoiding friction, excessive bending, reducing bending frequency, avoiding high temperature and humidity, and being trampled are positive solutions.