Simple question: What is the principle of flange sealing?
Thread Content
This post was last edited by security on 2011-6-3 at 10:29. Sealing in flange connections is achieved by using gaskets that are softer (compared to the flanges themselves); these gaskets deform under pressure and fill in the uneven gaps between the two sealing surfaces, thereby preventing fluid leakage and ensuring a secure seal. Thus, sealing in flange connections relies on the sealing surfaces, the gaskets, and the compressive force that causes the gaskets to deform, with this compressive force being generated by tightening the bolts.
The pressure generated by bolt deformation compresses the gasket.
Could the original poster please explain the sealing principle of that type of gland? There are many different types of glands, and their sealing principles vary as well
It seems that the function of a flange is mainly for connection. If you are referring to the sealing principle between flanges, it is due to the slight protrusion on the flange itself; when the two flanges are fastened together with bolts, the gasket is compressed, thereby achieving sealing between them.
The sealing between the flange and the pipe is achieved through methods such as welding, while the sealing between flanges is primarily achieved through plastic surface contact sealing.
The sealing of the flange is achieved by compressing the gasket after tightening the bolts; the gasket deforms, thereby creating friction or a seal against the flange’s sealing surface. Achieve a sealed effect
During pre-tightening, the specific pressure on the flange sealing surface shall not be lower than the pre-tightening sealing specific pressure—initial sealing condition. During operation, the specific pressure on the flange sealing surface must be no lower than the operating sealing specific pressure, that is, m times the calculated medium pressure under operating sealing conditions.
It’s the force generated between the gaskets that causes them to deform, thereby reducing the gap between them; this achieves a sealing effect. Even if you hold two palms together tightly, they can still hold water. . . . Hehe
Reply to 1# j16119: The flange connection structure is a assembly consisting of a pair of flanges, several bolts and nuts, and a gasket. In practical applications, flange seal failure caused by the failure of the connecting elements or the components being connected is rare; leaks are more often due to poor sealing. Therefore, the main issue to be addressed in the design of flange connections is preventing medium leakage. The principle of flange sealing is that, under the preload from the bolts, the flanges compress the gasket located between the sealing surfaces. The pressure applied per unit area (compressive stress) must reach a certain value in order to deform the gasket and compress it, thereby filling the micro-gaps formed by machining on the sealing surfaces and creating the initial sealing conditions. The required compressive stress is called the gasket sealing specific pressure, denoted by y, with units of MPa. The sealing specific pressure is mainly determined by the gasket material. Obviously, once the material of the gasket is determined, the wider the gasket, the greater the pre-tightening force required to achieve the desired specific pressure; this in turn requires larger sizes for the bolts and flanges. Therefore, in flange connections, the gaskets should not be too wide, nor should the entire flange surface be covered with gaskets. When the equipment or pipeline is in operation, the axial force generated by the pressure of the medium causes the bolts to be stretched, and the flange sealing surfaces move apart from each other, thereby reducing the compressive stress between the sealing surfaces and the gaskets. If the gasket has sufficient resilience such that the recovery from compression deformation can compensate for the deformation of the bolts and sealing surfaces, thereby reducing the pre-sealing specific pressure to at least a certain value (this specific pressure is known as the operating sealing specific pressure), then a good sealing condition can be maintained between the flange sealing surfaces. Conversely, if the resilience of the gasket is insufficient, the pre-sealing specific pressure drops below the operating sealing specific pressure, and even gaps reappear at the seal, then the seal fails. Therefore, in order to achieve sealing at the flange joint, it is necessary to adjust the deformation of each component of the sealing assembly to match the sealing conditions under operating conditions, so that the sealing element maintains a certain residual clamping force even under operating pressure. To this end, both the bolts and flanges must possess sufficient strength and stiffness to prevent excessive deformation of the bolts under the axial force generated by internal pressure.
7th floor is correct! When discussing flange sealing, specific pressure must be mentioned!