Ss corrugated flexible hoses are widely used in the petrochemical industry, but there are also some problems in application, mainly due to the selection and improper installation of hose lengths. If the hose length is too long, it will cause instability of the system, increase fluid resistance, increase mechanical damage and vibration, etc.; if the hose length is too short, the purpose of compensation, vibration reduction, and noise reduction will not be achieved. Therefore, determining the length of the stainless steel corrugated flexible hose is the primary task. In addition, the following factors should also be comprehensively considered: the nature of the medium, the operating temperature, the operating pressure, the nominal diameter of the connecting pipeline, the site category, the connection method, the displacement method, etc.
SS Corrugated Flexible Hose Installation Type
Correct installation of the stainless steel corrugated flexible hose is an important part of ensuring their full performance. The stainless steel corrugated flexible hose is usually installed after the root valve of the tank inlet and outlet pipes, and there is also a valve behind the stainless steel corrugated flexible hose so that the storage tank and the pipeline directly form a soft connection, which is convenient for the maintenance and replacement of the metal hose. The stainless steel corrugated flexible hose has limited ability to compensate for axial displacement in the natural state. When the installation length is equal to the natural length, it must not be able to withstand strong axial tension and cause breakage, resulting in pipeline leakage. Therefore, the installation length of the stainless steel corrugated flexible hose should be less than the natural length to ensure a certain degree of freedom.
Since the flexible hose ss mainly absorbs the lateral and axial displacement generated by the system, in addition to ensuring the freedom of the flexible hose ss during installation, it can also be absorbed by the arrangement of the pipeline. There are two common piping methods, L-type, and Z-type installation. L-shaped installation is more common, and the overall layout is neat and beautiful, which reduces the length of the pipeline and reduces the fluid resistance, but the axial stress generated by the pipeline will act on the flexible hose ss and the nozzle of the storage tank, which shortens the use of hoses and valves. At the same time, it will also damage the nozzle and cause oil leakage. Although the Z-type installation increases the length of the pipe and the number of elbows, the axial displacement of the pipe system can be absorbed by itself, reducing the axial stress on the flexible hose ss and nozzle, prolonging the service life, and also conducive to the stability of the pipe system.
From the point of view of safety and service life, the Z-type installation is better than the L-type, so the Z-type installation is preferred when the plane position allows.
Precautions for installation of ss corrugated flexible hose
(1) The flexible hose ss must be checked before installation, and the problem should be eliminated in time;
(2) During the hoisting process, there must be measures to prevent damage to the flexible hose ss;
(3) A short pipe should be installed after the metal hose to compensate for the deviation of the neutral size of the hose;
(4) Flexible hose ss made of steel belt mesh sleeves should be selected as far as possible. Because of its high natural vibration frequency, generally between 20 and 30 Hz, far greater than 7 Hz, the possibility of resonance between the hose and the storage tank is extremely small;
(5) During installation, it is not allowed to forcibly pull, press and twist, or knock the flexible hose ss, and the method of tightening the flange bolts should not be used to eliminate the installation deviation;
(6) No brackets or supports shall be set on the flexible hose ss;
(7) The height of the flexible hose ss from the ground or platform should be greater than its lateral displacement compensation;
(8) For pipelines with thermal insulation and cold insulation requirements, the normal operation of flexible hose ss shall not be affected.