Application environment requirements of metal hose

We are no strangers to metal hoses, but we must have a good understanding of their application environment. If they are not properly used, it will constitute a waste of information. When they are severe, there will be risks. Next, we will elaborate on the following five elements for the application environment of metal hoses:
The metal hose manufacturer shall guide the application of metal hose to the environment:
1. Temperature
For metal hoses used at high temperatures, the rated operating pressure must be lowered according to the modification factor of operating pressure and temperature of metal hoses at high temperatures to ensure that they are stopped under safe conditions.
2. Corrosion
The raw material of metal hose is usually stainless steel, and the active anions (such as chloride ion and sulfur ion) in the medium are easy to damage the stainless steel passive film, showing small corrosion holes on the bottom metal, which is the active center generated by pitting corrosion. The external potential of the metal inside the etch hole is relatively negative, while the external potential of the metal outside the etch hole is relatively positive. Therefore, an active passive micro galvanic corrosion cell is formed inside and outside the etch hole. The cell has a structure of large cathode and small anode area ratio. The anode current density is large, and the etch hole deepens quickly. The strength of the corroded metal hose decreases, and it is easy to become invalid when receiving internal pressure and tensile load. Therefore, for metal hoses used in corrosive environments, relevant information should be selected, protection methods should be added, and corrosion resistance should be improved.
3. Fatigue failure
Under dynamic operation, metal hoses are usually damaged by fatigue cracks when subjected to cyclic load effects. Such damage is normal failure. In order to extend the service life, it is necessary to ensure that the hose is designed and selected correctly, the device is accurate, and no additional stress such as hose distortion occurs.
4. Water hammer phenomenon
Water hammer is a pressure transient process caused by sudden change of medium activity and sudden change of fluid momentum in the pipe. It is a special oscillation phenomenon caused by unstable activities in the pipe. When the pressure wave with sharp rise and fall is transmitted through the pipeline, it will produce a noise like that announced when the pipeline is hit with a hammer. Therefore, it is also known as "water hammer with two edges and one edge". When the water hammer attacks, the impact on the elbow section of the pipe becomes more severe. Therefore, the user should follow the requirements of the operating procedures, such as slowly heating, steadily pressurizing, and falling instantaneous flow and pressure changes, to avoid the occurrence of water hammer.
5. Transport media
If the delivery medium in the metal hose has chemical characteristics (acidic or alkaline) and is prone to electrochemical reaction, the raw materials of each part of the hose shall be selected reasonably according to the corrosion resistance function parameter table of the hose raw materials.
In addition to the above, the life of metal hoses will also be affected by thermal shrinkage, external oscillation and impact, alternating operating conditions, short and regular monitoring and maintenance, and inadequate handling.