Elliptical gaskets and octagonal gaskets are two types of sealing gaskets. They differ a lot in sealing characteristics and usage limits. They are totally different.
Let’s start with their sealing principles. The octagonal gasket makes face contact. Specifically, it has 8 inclined surfaces. When it touches the flange, the whole surface fits together. The elliptical gasket is different. It makes line contact, using two arcs to touch the flange.
For pre-tightening requirements, the octagonal gasket is easier. Tighten the bolts once, and it seals. The elliptical gasket needs one more step. It requires secondary tightening.
Look at stress distribution. The octagonal gasket’s stress spreads evenly. So it resists pressure fluctuations better. The elliptical gasket’s stress is concentrated locally. But it seals better initially.
Now, let’s talk about their usage limits and possible risks.
First, reusability. The octagonal gasket can be reused. Even if there are slight scratches on the surface, sand them with metallographic sandpaper. It will be fixed and can be used again. The elliptical gasket is different. It can’t be reused. Its line contact causes local plastic deformation. Once removed and reinstalled, the risk of seal failure is very high. It’s basically unusable.
Then, adaptability to working conditions. In high-pressure scenarios with frequent pressure fluctuations, the octagonal gasket is better. Its face contact makes stress distribute evenly. So it suits pipelines with frequent pressure changes. The elliptical gasket’s line contact provides higher initial sealing specific pressure. So it’s more suitable for ultra-high-pressure static sealing scenarios, like hydrogenation reactors.
To sum up, if the pipeline needs frequent disassembly and has frequent pressure fluctuations, the octagonal gasket is the first choice. For one-time installation and ultra-high-pressure static sealing scenarios, the elliptical gasket is better!
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Wenzhou Huahai Sealing Co., Ltd., a veteran firm, focuses on R-type metal ring gaskets. It holds ISO9001, API-6A, API17D certifications, and special equipment licenses — proof of quality and standards.
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