⚡ electrical engineering

Theoretical calculation and simulation analysis of contact pressure of the slave sealing surface of a new-type wedge ring gasket

This paper presents a theoretical calculation and finite element simulation to analyze the contact pressure of a new-type wedge ring gasket, identifying the slave sealing surface height as the most influential factor and demonstrating its superior sealing performance compared to traditional octagonal gaskets under medium pressure.

Original authors: Wenbin Xu, Yingying Yang, Yongjie Xu

Published 2026-08-12

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CC BY 4.0

Original authors: Wenbin Xu, Yingying Yang, Yongjie Xu

Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). ✨ This is an AI-generated explanation of the paper below. It is not written or endorsed by the authors. For technical accuracy, refer to the original paper. Read full disclaimer

Imagine the hidden world of pipes and valves that keep our modern cities running, carrying everything from water to chemicals. These pipes are often joined together by flanges—think of them as heavy-duty, bolted handshake connections. But here's the tricky part: if the seal between these metal faces isn't perfect, dangerous leaks can happen, sometimes leading to explosions. To stop this, engineers use gaskets, which are like special, squishy rings that get squeezed tight between the metal faces to block any escape routes. For decades, the industry has relied on a standard "octagonal" gasket (a ring shaped like a stop sign) because it works well. However, just like how a new smartphone might offer better features than an older model, engineers are constantly looking for gasket designs that seal even tighter, especially when the pressure inside the pipe gets high. This paper dives into a new, clever design called a "wedge ring gasket" that tries to get smarter as the pressure increases, rather than just getting squeezed harder.

The researchers in this study wanted to see if this new wedge-shaped gasket could do a better job than the traditional octagonal one. They focused on a specific part of the gasket called the "slave sealing surface," which is the side that presses against the smaller flange. Using a mix of math equations and powerful computer simulations (a method called Finite Element Analysis, or FEM), they tested how different shapes and sizes of this new gasket affected the pressure it applied to the seal. Think of it like testing different sizes of wedges in a doorstop: does a taller wedge hold the door better? Does a sharper angle work more effectively? They simulated the gasket under a pressure of 5 MPa to see how it behaved.

The team discovered that the height of the sealing surface (labeled as $h_f$ ) was the most important factor. When they made this part taller, increasing it from 12mm to 24mm, the contact pressure dropped significantly, from 111.38 MPa down to 47.23 MPa. It turns out that a taller surface spreads the force out over a larger area, reducing the stress at any single point. They also found that the ratio of the angles on the top and bottom of the wedge ( $\theta_m/\theta_f$ ) mattered, but less so than the height. Interestingly, changing the inner diameter ( $d_1$ ) or the thickness of the small end ( $T$ ) didn't have much of an effect on the pressure, provided the inner diameter stayed above a certain critical point of 110.5mm.

The most exciting finding, however, was how the new gasket behaved under pressure compared to the old octagonal one. In a traditional octagonal gasket, the internal pressure actually weakens the seal, causing the contact stress to drop. It's like a door that gets harder to keep closed the more wind pushes against it. But the new wedge ring gasket does the opposite: the internal pressure pushes the wedge tighter into place, increasing the contact stress and creating a "self-sealing" effect. In their simulations, the new gasket maintained a much stronger seal under operating conditions than the traditional octagonal gasket. The authors suggest that this new design could offer a more reliable way to prevent leaks in high-pressure systems, proving that sometimes, a little bit of geometry can make a huge difference in safety.

Technical Summary: Theoretical Calculation and Simulation Analysis of Contact Pressure of the Slave Sealing Surface of a New-Type Wedge Ring Gasket

Problem Statement
Flange gasket joints in piping systems are critical components in chemical plants and other industries, where failure often leads to severe accidents such as leakage and explosions. While various studies have addressed creep relaxation, bolt distribution, and stress relaxation in traditional gasket designs (e.g., metal C-rings, corrugated gaskets, and octagonal gaskets), there is a need to optimize the sealing performance of new structural designs under working conditions. Specifically, this paper addresses the contact stress behavior of the "slave sealing surface" (the surface contacting the slave flange) of a new-type wedge ring gasket, a component of a self-tightening flange joint system.

Methodology
The study employed a dual approach combining theoretical derivation and finite element analysis (FEM):

Theoretical Calculation: The authors derived mechanical equilibrium equations to calculate the average contact stress of the slave sealing surface. This involved analyzing forces acting on the ring gasket, including bolt preload, internal pressure, and friction angles. Formulas were established to determine contact areas and stress distributions based on structural parameters: master-slave surface cone angles ( $\theta_m/\theta_f$ ), slave sealing surface height ( $h_f$ ), small-end thickness ( $T$ ), and small-end inner diameter ( $d_1$ ).
Finite Element Analysis (FEM): Simulations were conducted using ABAQUS software on NPS 80mm Class 5MPa butt-welding flanges. The model utilized ideal elastic materials (SA105 for flanges/gaskets and SA193-B7 for bolts) with specific elastic moduli and Poisson's ratios. The analysis followed a five-step loading sequence: partial bolt force, total bolt force, fixing bolt length, applying internal pressure (5 MPa), and applying equivalent cylinder end face pressure (15.7 MPa). A node path from top to bottom on the slave sealing surface was selected to monitor contact pressure distribution.

Key Contributions and Results
The paper presents a theoretical framework for calculating slave sealing surface stress and validates it through simulation. The primary findings regarding the influence of structural parameters on contact stress are:

Parameter Sensitivity: Among the variables tested ( $h_f$ , $\theta_m/\theta_f$ , $T$ , and $d_1$ ), the slave sealing surface height ( $h_f$ ) exerted the greatest influence on contact stress. As $h_f$ increased from 12mm to 24mm, the maximum contact stress decreased significantly (from 111.38 MPa to 47.23 MPa) due to an increased contact area.
Cone Angle ( $\theta_m/\theta_f$ ): Increasing the cone angle ratio slightly decreased maximum contact stress and effective sealing width. However, larger angles resulted in a noticeable increase in non-sealing areas, leading to inefficient use of the gasket surface.
Inner Diameter ( $d_1$ ) and Thickness ( $T$ ): The small-end inner diameter ( $d_1$ ) showed a critical threshold at 110.5mm; beyond this value, it had no effect on contact stress. The small-end thickness ( $T$ ) had minimal influence on the stress distribution.
Validation: Theoretical calculations and simulation results were found to be basically consistent. The theoretical values were slightly higher than simulation values, attributed to the theoretical assumption of a rigid flange versus the elastic deformation modeled in the simulation.

Comparative Performance
A direct comparison was made between the new-type wedge ring gasket and a traditional octagonal gasket under operating conditions (medium pressure):

New-Type Wedge Ring Gasket: Under internal pressure, the contact stress on the slave sealing surface increased, and the sealing band expanded compared to the pre-tightening condition. This demonstrates a self-tightening effect where medium pressure enhances the seal.
Traditional Octagonal Gasket: Conversely, under the same operating conditions, the contact stress on the slave sealing surface decreased, and the sealing band narrowed compared to the pre-tightening condition.

Significance and Claims
The paper concludes that the new-type wedge ring gasket offers superior sealing performance compared to the traditional octagonal gasket. The study claims that the wedge structure effectively utilizes internal medium pressure to promote sealing (self-tightening), whereas the octagonal gasket's performance degrades under similar pressure. The research provides a theoretical basis for optimizing the structural parameters of this new gasket type, specifically highlighting the critical role of the slave sealing surface height ( $h_f$ ) in determining contact stress and sealing efficacy. The findings suggest that the new design is better suited for maintaining seal integrity in flange joints subjected to internal pressure.

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