High pressure rubber hose
In the 21st century, China National Offshore Oil Corporation's development strategy proposes to focus on developing offshore and shallow oil fields. Therefore, the petroleum industry requires the use of shallow oil pipelines in addition to drilling and vibrating pipelines. Shallow sea subsea oil pipelines have been produced domestically, but floating or semi floating oil pipelines and deep-sea subsea oil pipelines still rely on imports. With the implementation of China National Offshore Oil Corporation's development strategy, the requirements of offshore oil exploitation on tubing performance will continue to improve.
Production process
1. Use a mixer to mix the inner layer adhesive, middle layer adhesive, and outer layer adhesive according to the formula; Use an extruder to extrude the inner layer of oil pipe and wrap it on a soft or hard core coated with a release agent (liquid nitrogen freezing method can also be used without the pipe core).
2. The calender presses the middle layer of adhesive into thin sheets, adds isolation agent to roll and cuts them into the specified width according to the process requirements.
3. Wind or weave the inner layer oil pipe containing the pipe core onto a winding machine or weaving machine with copper plated steel wire or copper plated steel wire rope. At the same time, synchronously wind the middle layer of adhesive film between every two layers of copper plated steel wire or copper plated steel wire rope in the winding machine or weaving machine, and tie the beginning and end of the winding steel wire (some early winding machines require pre stressing and shaping of the copper plated steel wire).
4. Wrap the outer layer of adhesive on the extruder again, and then wrap it with a lead or cloth vulcanization protective layer.
5. Sulfurize through a vulcanization tank or salt bath.
6. Finally, remove the vulcanization protection layer, extract the pipe core, press the upper pipe joint, and conduct sampling and pressure inspection.
In short, the manufacturing of high-pressure oil pipes involves a wide range of equipment, various types of raw materials, and complex production processes. However, in recent years, the production process of hydraulic oil pipes mainly made of plastic or thermoplastic elastomers can be appropriately simplified, but the raw material price is high and rubber is still the main raw material.
fault analysis
1. Failure of the outer adhesive layer:
(1) Cracks appear on the surface of the hose
The main reason for the appearance of cracks on the hose is that the hose is bent in a cold environment.
(2) Bubbles appear on the outer surface of the hose
The reason for blistering on the outer surface of the hose is due to poor production quality or improper use during operation.
(3) The hose is not broken but there is a large amount of oil leakage
A large amount of oil leakage was found in the hose, but no rupture was found. The reason is that when the high-pressure liquid flow passed through the hose, the inner rubber was eroded and scratched, until a large area of steel wire layer leaked out, resulting in a large amount of oil leakage.
(4) The outer adhesive layer of the hose severely deteriorates, with micro cracks appearing on the surface, which is a manifestation of natural aging of the hose. Due to aging and deterioration, the outer layer continuously oxidizes, covering its surface with a layer of ozone, which thickens over time. As long as the hose is slightly bent during use, small cracks will occur. In this case, the hose should be replaced.
2. Failure of inner adhesive layer:
(1) The rubber layer inside the hose is hard and has cracks: the main reason is that the addition of plasticizers in rubber products makes the hose flexible and plastic. But if the hose overheats, it can cause the plasticizer to overflow.
(2) The rubber layer inside the hose is severely deteriorated and significantly swollen: The rubber layer inside the hose is severely deteriorated and significantly swollen due to the incompatibility between the rubber material inside the hose and the oil used in the hydraulic system, and the hose deteriorates due to chemical action.
3. Faults manifested in the reinforcement layer:
(1) The hose was ruptured, and the braided steel wire near the break was rusted. After peeling off the outer adhesive layer for inspection, it was found that the braided steel wire near the break was rusted. This is mainly due to the effect of moisture or Corrosive substance on this layer, which weakens the strength of the hose and causes the hose to break under high pressure.
(2) The reinforcing layer of the hose is not rusted, but there is irregular wire breakage in the reinforcing layer.
The hose broke and no rust was found on the reinforcement layer after peeling off the outer adhesive layer. However, irregular wire breakage occurred along the length direction of the reinforcement layer, mainly due to the high-frequency impact force on the hose.
4. Faults manifested at the rupture opening:
(1) One or more parts of the hose are broken, with neat cracks, and other parts are kept in good condition.
The main reason for this phenomenon is that the system pressure is too high, exceeding the pressure resistance of the hose.
(2) Torsion occurs at the point of hose rupture
The reason for this phenomenon is that the hose is subjected to excessive torsion during installation or use.
5. In summary, based on the above analysis, the following precautions should be taken when using hydraulic hoses in the future:
(1) The hose arrangement should avoid heat sources as much as possible and be away from the engine exhaust pipe. If necessary, devices such as sleeves or protective screens can be used to prevent the hose from deteriorating due to heat.
(2) In areas where hoses must cross or may rub against mechanical surfaces during operation, protective devices such as hose clamps or springs should be used to prevent damage to the outer layer of the hose.
(3) When the hose must be bent, the bending radius should not be too small and should be greater than 9 times the outer diameter. There should be a straight section greater than twice the outer diameter of the pipe at the connection between the rubber hose and the joint.
(4) When installing the hose, it should be avoided to be in a tight state. Even if there is no relative movement between the two ends of the hose, it should be kept loose. The tensioned hose will expand under pressure and reduce its strength.
(5) Do not twist the hoses during installation. Slight twisting of the hose may reduce its strength and loosen the joint. During assembly, the joint should be tightened on the hose instead of the joint.
(6) If the hose is installed on key components, it is recommended to conduct regular inspections or replacements.
High pressure hose is mainly used for mine hydraulic support and oilfield exploitation, and is suitable for transporting petroleum based (such as mineral oil, soluble oil, hydraulic oil, fuel oil, lubricating oil) liquids, water-based liquids (such as emulsion, oil-water Emulsion, water) Gas and liquid transmission.
