What are the differences between equipment heat exchangers, wave-patterned gaskets, and graphite wound gaskets?

Currently, some gaskets used in bolted flanges (such as wound gaskets, rubber sheet gaskets, and covered gaskets) suffer from problems such as easy crushing, easy disassembly, and high pre-tension. The wave-tooth composite gasket combines the advantages of both metallic and non-metallic seals, offering excellent sealing performance, good compressive resilience, strong resistance to high and low temperatures as well as corrosion, a long service life, and cost-effectiveness. It has been applied to industries such as petrochemicals to a certain extent, achieving good results. The corrugated composite gasket is composed of a corrugated metal framework with specific structural parameters and flexible graphite material, as shown in the figure below. Concentric arc-shaped grooves are formed on the upper and lower surfaces of the metal frame, and a layer of flexible graphite material of appropriate thickness is then applied to those surfaces, thereby creating a gasket with a unified structure.

When the corrugated composite gasket is in use, under the compressive force exerted by the flanges, the flexible graphite is compressed and fills in the defects on the flange sealing surface; the ring-shaped tooth peaks on the corrugated metal framework create a linear seal with the flange sealing surface. The wave-shaped metal frame is in the elastic stage, which maintains sufficient pressure on the sealing surface. The annular seal formed by the flexible graphite, together with the linear seals created by the peaks of the metal frame, ensures that the gasket seal remains in good condition at all times. As the pressure in the device increases, there is a tendency for the flange surfaces and gaskets to separate; however, the elastic properties of the wave-shaped metal framework of the corrugated gasket ensure that the sealing surfaces remain in close contact. In this way, whether under normal operation or during start-up and shutdown, sufficient pressure can always be maintained on the sealing surfaces of the flange and gasket, ensuring effective sealing.

In fact, GB/T 150.3-2011 lists wave-patterned gaskets in \"Table 7-2 Characteristic Parameters of Common Gaskets\" in Chapter 7 (Flanges); as shown in the figure below, its values for m and y are 3 and 50 respectively, which are lower than those of wound gaskets, which are 3 and 69. However, the research and application history of composite flexible graphite wave-shaped gaskets is not long. 1. By using “wave-shaped tooth pad” as the search terms for title, keywords, and abstract on CNKI, only 38 Chinese articles were found, with the earliest one dating back to 2002. 2. The GB/T 19066 series of standards for \"flexible graphite metal corrugated composite gaskets\" was first published in 2003; no earlier versions could be found on the Industrial Standards Network. 3. SH/T 3430, \"Flexible graphite corrugated composite gaskets for petrochemical shell-and-tube heat exchangers\", developed by SEI and LPEC, the two research institutes under Sinopec, was published in 2018 – no earlier version exists.