Inspection and installation of flange
1. Open the product package to check whether the main part of the list or the contract in line with the product, inventory the number of products.
2. Check whether the product surface pits, scratches, rust fragments and oil, flange surface roughness of not more than 6.3μm, if the roughness does not match, then trim the flange surface, check the flange, bolt holes, etc., and cleaning method Blue face
3. Flange sealing surface should be smooth and smooth, no burr and radial groove; thread flange part of the thread should be complete, no damage; concave and convex sealing surface of the sealing surface should be able to naturally fit, the height of the convex surface shall not be lower than the concave Groove depth.
4. Check and clean bolts, nuts, apply insulating grease to all bolts and nut threads
5. Align the flanges to keep them coaxial, parallel, and carefully install the gasket, prohibit the use of lubricants, grease, and adhesives on the gasket and flange surfaces to prevent damage to the seals on the gasket.
6. Align the bolt holes and insert them into the fixed flange (especially for large flanges) with 30 perforated nails at least 120 degrees.
7. Insert bolts, nuts and washers. Lubricants with grease should first be fitted with stainless steel washers, preloaded bolts until the flange and gasket are in contact with each other
8. Use a micrometer, flashlight and other tools to check the gap between the flange and the gasket, if the gap exists, indicating that the flange assembly is not parallel.
9. If there is a gap, unscrew the nut a little bit and then retighten until the two flanges are in contact with the gasket. This method is necessary to prevent the flange from contacting the gasket. If the method is not correct Will also cause the flange and gasket contact with the bolt when the load is too large to damage the gasket seal.
10. Tighten the loose nuts again by following the recommended bolt tightening torque (10-15% bolt torque), remove the piercing studs, apply bolts, nuts, washers, and tighten with the same torque.
11. Continue to tighten the bolt and raise the preload to 50% of the bolt torque; continue to tighten the bolt until the final torque.
12. This is an operating procedure for effective tightening of bolts, especially for large diameter piping systems.
13. All of the above operations should use a torque wrench (mechanical or hydraulic) or use a bolt pretensioner.
Source: China Flange Manufacturer – Yaang Pipe Industry Co., Limited (www.yaang.com)