1. Corrosion The metal hose is generally made of stainl […]
The metal hose is generally made of stainless steel. The active anions in the medium (such as chloride and sulfide ions) can easily damage the passive film of stainless steel, and small corrosion holes appear on the base metal, which is the activity generated by pitting corrosion. The metal surface potential inside the etch hole is relatively negative, and the metal surface potential outside the etch hole is relatively positive, so the inside and outside of the hole constitute a live-passive micro-galvanic corrosion cell. The cell has an area ratio structure of large cathode and small anode. The current density is very large, and the corrosion hole deepens quickly.
For metal hoses used at high temperatures, the rated working pressure must be reduced according to the temperature correction coefficient of the working pressure of the metal hose at high temperatures to ensure safe use.
3. Fatigue failure
Under dynamic working conditions, metal hoses tend to suffer fatigue crack damage under the action of cyclic loads. Such damage is a normal failure. In order to prolong the service life, it is necessary to ensure that the hose is designed and selected correctly, and the installation is accurate, and does not cause additional stress such as twisting of the hose.
4. Water hammer phenomenon
The water hammer phenomenon is a pressure transient process caused by the sudden change of the medium flow state and the change of the fluid momentum in the tube. It is a special oscillation phenomenon caused by the unstable flow in the tube. When the rapidly rising and falling pressure wave is transmitted through the pipeline, it will produce a kind of noise as if hitting the pipeline with a hammer, so it is also called water hammer two blade one. When water hammer occurs, the impact force on the elbow section of the pipeline becomes stronger. Therefore, the user should follow the requirements of the operating regulations, such as slow heating, steady pressure, reducing the amount of instantaneous flow and pressure changes, and avoiding water hammer.
5. Transport medium
If the conveying medium in the hose has chemical properties (acidic or alkaline) and is prone to electrochemical reactions, the material of each part of the hose should be reasonably selected according to the corrosion resistance parameter table of the hose material.