Production precautions of stainless steel flanges

The production of stainless steel flange has 3 matters needing attention:

The pretightening force of the screw:

1. It is suitable to increase the pre-tightening force and the sealing tightness of the gasket. (Reducing the capillary phenomenon of the permeable gasket material);
2. The pre-tightening force is evenly applied to the gasket — the method of reducing the screw diameter and increasing the number of screws can be adopted.
3. The pre-tightening force cannot be too large, nor can it be too small. (The gasket will be crushed or extruded if the force is excessively large, while will the initial tight sealing condition cannot be achieved if the force is too small.)

Stainless steel SS316 weld neck flanges and slip on flanges

Stainless steel SS316 weld neck flanges and slip on flanges

Rust removal process:

1. Remove all visible dirt on the surface before removing the rust, then remove the oil with a solvent or detergent.
2. Use a tungsten steel blade to shovel the rusty part on the surface that can be easily removed.
3. Use a scraper and wire brush to remove the rust from the corners.
4. Remove the protrusions and various burrs like welding slag.
5. Thoroughly clean up with emery cloth and wire brush.
6. Use a clean cloth, or a cloth dipped with solvent to clean and paint the surface.
7. Note that the tough coating film can be preserved, and the surface of the original painting is polished with emery cloth, the defect of the coating film is polished into an axe shape. Directly paint it after cleaning.
8. Stainless steel flange is treated with specialized bleach. If there is no bleach, soak the workpiece into 10-20% nitric acid and 5% phosphoric acid for 4 hours.

Flange sealing principle:

The sealing principle of flanges is that the two sealing surfaces press each other to form a tight seal. In order to maintain a tight seal, it is necessary to maintain a large screwing force. For this reason, large screws and the matching screw caps are used. However, the larger the diameter of the screw, the higher the tendency that the flange is bent, so the only way is to increase the wall thickness of the flange. The entire device will require a great size and weight, which becomes a special problem because the weight is the main problem that many people must pay attention to in production.

Haihao Group manufacture & supply all types stainless steel flanges such as weld neck flanges,slip on flanges,blind flanges,threaded flanges,socket weld flanges,plate flanges,long weld neck flanges,spectacle blind flanges,orifice flanges,reducing flanges,flange olet and so on.The materials contain ASTM A182 F304,F316,F321,F347,etc.If you want to know more about our forged flanges,please email to


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