Views: 5 Author: Site Editor Publish Time: 2020-04-06 Origin: Site
Why corrugated expansion joints are made of stainless steel
The main performance of the compensator includes: compensation amount, elastic stiffness, compressive strength, stability, fatigue strength, etc. The general design of thermal pipe network requirement is to meet the strength, stability, and fatigue life, the greater the compensation amount, the better the stiffness value, the smaller the better. The rotation compensator can be combined with corrugated tube elements through additional attachments such as tie rods, hinges and other components to form various types of rotation compensators. Through different combinations of rotation compensators, various forms of compensation piping systems can be formed to complete the heat pipe. Network compensation needed.
(1) The amount of stainless steel corrosion is small, so the thickness of the expansion joint can be designed thinner, and the single wave compensation amount is large;
(2) The plasticity of stainless steel is about double that of carbon steel, which is conducive to cold forming;
(3) Under the same service life, the allowable stress amplitude of stainless steel is higher than that of carbon steel, which is about 1.5 times.
What is the selection principle of expansion joints
(1) Carbon steel and low alloy wave expansion joints are only suitable for t≤375 ℃; Austenitic stainless steel wave expansion joints are suitable for t≤500 ℃.
(2) Corrugated expansion joints are made of carbon steel or low-alloy steel should not exceed 1mm in corrosion margin, otherwise austenitic stainless steel should be used.
(3) For mediums prone to corrosion such as chloride, sulfide, acid, and alkali, or when the working temperature is high (over 550 ° C), corrosion-resistant alloys or high-temperature alloys should be selected to make expansion joints, such as domestic materials FN-2, NS111 and B-315 or Incoloy800, 825, etc.
(1) Select the appropriate material, select the corrosion-resistant material according to the working environment of the compensator, the chemical properties of the flowing medium in the pipeline, and whether it is corrosive; According to the working temperature of the pipeline, the high and low temperature resistance in combination with the high and low pressure resistance of the working environment of the pipeline, the compensator material with the appropriate thickness is selected based on the above.
(2) Select the appropriate wave number, and consider the fatigue times of the compensator under stress according to the use of the bellows, the amount of compensation, and other factors. Select the appropriate wave number that is suitable for small deformation stress and fatigue resistance.
(3) Whether it is necessary to add a guide device. Depending on the long working time of some compensators, column instability may occur. Some guide devices should be added.
(4) Whether to strengthen the ring, according to some compensators to adapt to higher working pressure, appropriately increase the strengthening ring or multi-layer architecture. The reinforcement ring is locally reinforced and the multilayer structure is integrally reinforced.
(5) Connection method: flange connection, clamp connection and welding connection can be selected according to the port condition of the compensator and pipeline or corresponding equipment. When selecting a flange connection, you must choose the appropriate flange according to the figure. The flange technology must meet the corresponding standards as a norm. In actual operation, the wrong flange is often selected. This must be paid attention to. Affect the use of the entire pipeline, resulting in the loss of the compensator pipeline.