The metal ring pad is made of metal material by forging and heat treatment and mechanical processing into a solid metal gasket with a cross-sectional shape of elliptical shape. It has a radial self-tightening seal and is a standard R-type metal ring pad. Its principle of action is The gasket is in contact with the inner and outer surfaces (mainly the outer side surface) of the flanged trap groove, and is pressed to form a sealing action.
The elliptical gasket -shaped metal ring pad is installed in the ladder ring groove on the flange surface. When the connecting bolt is tightened, it is axially compressed and the upper and lower ladder grooves are tightly pressed to produce plastic deformation, forming an annular sealing band and establishing an initial. seal. After boosting, the ring pad is radially expanded by the pressure of the medium. The shims of the gasket and the trapezoidal groove are more tight and self-tightening. However, an increase in the pressure of the medium also causes the flange and the connecting bolt to deform, resulting in a relative separation between the sealing faces, and the gasket sealing ratio is relatively lowered. Therefore, the ring pad can be considered as a semi-self-tightening seal.
The elliptical ring pad and the flange groove are in line contact, the sealing performance is good, but the processing precision is high, so the manufacturing cost is high. At the same time, the hardness of the elliptical metal ring pad material should be lower than the flange surface 15~20HB, and it is recommended not to reuse.
Oval metal ring pad performance characteristics:
1. High temperature resistance and high pressure resistance, suitable for high pressure flanges;
2, the seal is durable and reliable;
3. Adapt to the working conditions of pressure and temperature fluctuations;
Applications: It is commonly used in high temperature and high pressure steam, gas, solvent pipe flanges, tower tanks, pressure vessels, high speed joints, high temperature and high pressure valves, and covers. Wellhead device and seal on the tree in the oil and gas industry
The metal ring pad was originally from the United States. It was first used in the boiler field in the 1920s. Later it was used for manhole cover and sealing of other windows of the autoclave. It was particularly valued in the petroleum production and refining industry. As the temperature and pressure of steam power plants increase, the use of metal ring mats is becoming more widespread.
The main structural form of the metal ring pad:
Oval metal ring pad technical standards:
Available in any standard and non-standard sizes, including API 6A, ASME B16.20, DIN 2693-67, JPI-7S-23-72, and other standards.
Domestic relevant standards:
GB/T 9130-1988|Technical conditions for metal ring gaskets for steel pipe flange connection
GB/T 9128-2003|Metal ring gasket size for steel pipe flange
GB/T 9128.2-1988|Oval metal ring gasket for steel pipe flange connection
GB/T 9130-2007|Technical conditions for metal ring gaskets for steel pipe flanges
JB/T 89-1994|Metal ring pad for pipe flange
HG 20612-1997|Metal ring gasket for steel pipe flanges (European system)
HG 20633-1997|Metal ring mat for steel pipe flanges (American system)
SH 3403-1996|Metal ring pad for pipe flange