With the development of modern industry, especially modern oil, chemical industry, nuclear power industry and large power plants, pressure vessels are developing towards high temperature, high pressure, high vacuum, cryogenic, large scale, and multi-series. There are constantly new requirements, various new materials and new structures, and their sealing characteristics also vary greatly. In addition, pressure fluctuations, temperature changes, weakening of bolt preload force, flange inclination and misalignment, sealing surface defects, and media corrosion will greatly affect the sealing effect. Therefore, how to choose the right seal according to the working conditions and how to install it correctly are the keys to ensure the sealing effect. Today, the editorial focuses on how to properly install the gasket.
What tools are required for installation?
The following equipment needs to be prepared before installation:
1. calibrated torque wrench, hydraulic wrench or other tightening tool;
2. Steel wire brush, brass brush is better;
6. Other factory tools, etc.
Special tools are required to clean and tighten fasteners, always use standard mounting hardware and follow safety guidelines.
1. Check and clean up:
① Remove all foreign contaminants and debris from the pressure surface of the gasket, various fasteners (bolts, studs), nuts and gaskets;
②Check fasteners, nuts and gaskets for burrs, cracks and other defects;
③ Check the flange surface for deformation deformation, radial scratches, deep tool abrasions or other defects that affect the correct fit of the gasket; if defective originals are found, replace them in time, for example, if you have doubts about replacing it, you can contact the seal manufacturer in time.
2. Alignment flange:
Align the flange face with the bolt holes and report any failure to get a positive face.
3. Install gasket:
①Make sure the gasket fits the specified size and material;
② Check the gasket to make sure there are no defects;
③ Carefully insert the gasket between the two flanges;
④Make sure the gasket is centered between the flanges;
⑤ If the instructions for installing the gasket do not require the use of adhesives or release agents, otherwise their use without permission is prohibited;
⑥ Level the surface of the flange to ensure that the gasket will not be punctured or scratched.
4. Lubricate the loaded surface:
②Apply a sufficient amount of lubricant to the working surfaces of all threads, nuts and gaskets;
③ Make sure the grease does not contaminate the flange surface or the gasket surface.
5. Install and tighten bolts:
①Always use the right tools;
②Use a calibrated torque wrench or other tightening tools that can control the function;
③Consult the seal manufacturer's technical department for torque requirements and regulations;
④Follow the "transverse symmetry principle" when tightening the nut;
Follow the following 5 steps to tighten the nut:
Step 1. All nuts should be hand tightened first, larger nuts can be tightened with a small hand wrench.
Second step: Tighten each nut approximately 30% of the required full torque;
Step 3. Tighten each nut to approximately 60% of the required full torque.
Step 4. Retighten each nut using the "lateral symmetry principle" to 100% of the required full torque
Note. The above steps can be repeated multiple times for large diameter flanges.
Step 5: Tighten all nuts one by one clockwise at least once to reach the required full torque.
6. Tighten the bolt again:
① Consult the seal manufacturer's technical department for guidance and suggestions on bolt retightening;
②Asbestos-free gaskets and gaskets containing rubber components that have been used at high temperatures should not be retightened (unless otherwise noted);
③ Fasteners subjected to a corrosive heat cycle must be re-tightened;
④Retorque operation must be performed at ambient temperature and atmospheric pressure.