1. Temperature: Select the gasket based on the maximum and minimum temperatures of the working environment, as well as the allowed continuous working temperature. The temperature range that different gasket materials can withstand varies greatly. For example, some non-metallic gaskets may be suitable for lower temperatures, while metal gaskets typically can withstand higher temperatures. At the same time, the gasket material should have creep resistance to reduce stress relaxation and ensure sealing under working conditions. Reference can be made to the maximum working temperature chart of commonly used non-metallic materials and the comparison data of creep testing of gaskets at a certain temperature.
2. Application scenario: Specific information about the connection system where the gasket is located needs to be considered, such as the material of the flange, the type and roughness of the sealing surface, and the relevant situation of the bolts. For non-metallic flanges, it is necessary to choose gaskets with lower pre tightening force requirements to prevent the flange from being crushed during the fastening process; Different types of flange sealing surfaces correspond to different types of wound gaskets; And different gaskets also have different requirements for flange roughness.
3. Medium characteristics: The gasket should not be affected by the sealing medium under the entire working conditions, including high temperature oxidation resistance, chemical corrosion resistance, solvent resistance, permeability resistance, etc. The chemical corrosion resistance of the gasket material to the medium is the primary consideration. For non-metallic materials in non-metallic gaskets or composite gaskets, reference can be made to the non-metallic material chemical resistance performance table provided by the gasket manufacturer. If there is a metal material in direct contact with the medium in the gasket, its corrosion resistance should not be lower or higher than that of the flange material.
4. Pressure: The gasket must be able to withstand the maximum pressure in the system, which may be 1.25-1.5 times the normal working pressure. For non-metallic gaskets, it is also necessary to consider whether the product of their maximum operating temperature and maximum pressure (PxT value) is within the limit range, as different types of gaskets can withstand different pressures. In addition, it is necessary to check the flange pressure rating diagram applicable to various types of gaskets.
5. Size: On the premise of meeting the roughness and unevenness of the flange, try to choose thinner gaskets. The thickness of the gasket is related to factors such as its type, material, diameter, processing condition of the sealing surface, and sealing medium. Generally speaking, thin gaskets have a stronger ability to resist stress relaxation, a smaller area in contact with the medium, reduced leakage along the gasket body, and a smaller blowing force, making them less likely to be blown out. Suitable gasket thickness and other dimensions can also be selected based on relevant gasket standards.
In addition, factors such as the physical and mechanical properties, compression rebound performance, stress relaxation rate, and leakage rate of the gasket need to be considered. At the same time, follow relevant industry standards and specifications to ensure that the selection of gaskets meets the requirements of specific applications. If the application has special requirements or there are no standard connection sizes, specialized design may be required. Common types of gaskets include non-metallic gaskets, semi metallic gaskets, and metallic gaskets. Different types of gaskets have different characteristics and applicable ranges. For example, non-metallic gaskets (such as asbestos rubber sheet gaskets, PTFE coated gaskets, etc.) are commonly used in low-pressure applications; Half metal gaskets (such as spiral wound gaskets and metal coated gaskets) have good sealing and pressure resistance performance; Metal gaskets are suitable for high-pressure situations, and their materials are selected based on the corrosive properties and temperature of the medium.
Post time: Jul-19-2024