Attention to the installation of ASME B16.20 spiral wound gasket
The ASME B16.20 spiral wound gasket is a kind of sealing gasket widely used at present. It is the best gasket for the semi metal sealing gasket, which is intertwined alternately with V or W thin steel strip and various filling materials. It can withstand high temperature, high pressure and adapt to the conditions under ultra-low temperature or vacuum. The chemical corrosion of the medium to the gasket, its structure density can be made according to the requirements of different locking force. In order to strengthen the main body and accurate positioning, the winding gasket is equipped with a metal inner ring and an external positioning ring, and the internal and external steel ring is used to control its maximum compactness. The surface precision of the flange sealing surface of the gasket contact is not high.
The ASME B16.20 spiral wound gasket is widely used in oil, chemical, metallurgical, power generation, ships and other industries. It is the key component of the static seal of pressure pipes, valves, pumps and heat exchangers in our country. Therefore, the selection and use of high quality spiral wound gasket is of great significance for reducing and eliminating running, risking, dropping, leakage, ensuring the safety of the mainframe equipment and the normal operation of pressure pipes.
The ASME B16.20 spiral wound gasket location seal gasket should ensure that it is installed in the middle. If the eccentricity is installed, the size of the bolt pretightening force along the flange circumference will be different, which leads to the uneven compression of the metal wound gasket and the leakage easily. Correct and reliable installation of spiral wound gasket is the key to ensure good sealing effect. Cleaning flange surface before installing metal winding gasket, need to use brush or cloth carefully clean flange surface, ensure that there is no foreign body on flange surface. If the surface quality of the flange seal surface (mainly surface roughness) cannot meet the requirements, even if the pretightening force of the bolts is increased, it is easy to produce leakage. Different forms of metal wound gaskets have different requirements for the surface quality of the flange sealing surfaces. The metal winding pad requires the surface roughness of the sealing surface R. It should reach 3.2Pm, while some spiral wound gaskets require R to reach 1.6Km or even higher.
Points for attention when installing metal wound gaskets in ASME B16.20:
1, check the quality of flanges, bolts, nuts and gaskets carefully before installation, check the installation of flange or interface carefully, and have defects such as unbiased, wrong, open, and wrong holes.
2, the surface of the flange or seal must be cleaned, and the surface of the gasket and bolts and threads shall not be adhered to mechanical impurities.
3, the gasket cannot be partial, should ensure that the pressure is uniform.
4. When tightening the nut, the force should be uniform. The bolts should be evenly and evenly divided into 2~3 times to tighten the gaskets evenly.