When selecting metal spiral wound gaskets, the gasket standard is determined based on the flange standard. Generally, the gasket standard matches the flange standard. First, determine the operating pressure of the sealed medium, the flange standard and type, and specify the required standard. Select the structural type and pressure rating of the metal spiral wound gasket; then, based on the operating temperature and chemical corrosion characteristics of the sealing medium, select the appropriate metal spiral wound material and non-metallic filler material. Corrosive metals and non-metallic materials are acceptable. Finally, select the corresponding gasket based on the nominal diameter and structural dimensions of the flange, and mark your selected gasket according to the marking examples specified in the standard. If using a non-standard spiral wound gasket, you need to determine the metal and non-metal materials, and then determine the gasket's structural dimensions and thickness. Factors to consider include: sufficient gasket stress to ensure a seal and prevent excessive gasket compression; the designed installation structure (generally determined by the structural dimensions of the two mating flanges); the safety characteristics of installing large gaskets; and the impact of non-standard gasket structures on the overall equipment cost.
Installation and Use of Metal Spiral Wound Gaskets
The following precautions should be taken during installation and use:
1. The sealing gasket and flange sealing surface should be clean and free from scratches, spots, or other defects that may affect the sealing performance.
2. The outer diameter of the gasket should be smaller than the outer diameter of the flange sealing surface, and the inner diameter of the gasket should be slightly larger than the inner diameter of the pipe. The inner edge should not extend into the container or pipe to avoid obstructing the flow of fluid within the container or pipe.
3. The gasket must be placed in the center of the flange, which is especially important for flanges with shoulders.
4. The gasket installation must ensure that the connecting bolts are tightened evenly and symmetrically; however, the tightening should not reach the design value. Generally, at least 2-3 cycles should be performed to ensure uniform stress distribution on the gasket.
5. After one week of operation of the valve and pipeline system, check and recalibrate the torque of the connecting bolts.
6. To ensure the service life of the gasket, do not use liquid or metal-based anti-sticking agents or lubricants.
7. If there is a leak in the pipeline, the pressure must be released, and then the gasket should be replaced or adjusted.
