Welcome to Hardhatengineer.com. I am Varun Patel. In this video, you will learn about the most common questions regarding gasket that you may face during the interview.
You will learn about these questions;
- Can you explain some properties of gasket material?
- What is centering ring in spiral wound gasket?
- What are the most common materials used for winding in Spiral Wound metallic Gasket?
- How to identify the type of winding material in a spiral wound gasket?
- On which type of flanges, use of spiral wound gasket are restricted by code?
- What type of gasket is used in Heat Exchanger?
So please watch this video till the end. And don’t forget to subscribe to my channel because that way you will get regular updates on a new video. You can subscribe right now by just clicking subscribe button on your screen. So let’s start with the first question.
Can you explain some properties of gasket material?
Gaskets must maintain a seal for an acceptable period against all the operational forces involved. To achieve this, there are eight important properties which any gasket material must possess these properties.
The gasket should not be porous to the fluid being sealed.
The gasket should compress into the imperfections on the flange sealing faces to create the initial seal.
- Stress relaxation (creep resistance)
The gasket should not show significant flow (creep) under the influence of load and temperature. Such flow will allow the bolts to relax, reduce gasket surface stress and cause leakage.
Although normally stable, flanges do move slightly relative to one another under the influence of cycling temperature and pressure. The gasket should be capable of compensating for such movements.
- Chemical resistance
The gasket should withstand chemical attack from the process medium being handled. Likewise, the gasket material itself must not contaminate the process medium.
- Temperature resistance
The gasket should be able to withstand the effects of the maximum and minimum temperatures within the process and the external atmospheric temperatures.
The gasket has to be easily removable after use.
The gasket must not cause corrosion of the flange faces.
What is centering ring in spiral wound gasket?
To answer this question, you should know the components of the spiral wound gasket. There are three components in spiral wound gasket.
- Outer Ring
- Winding Material (Filler & Metal Strip)
- Inner Ring/Centering Ring
You can see in the image spiral wound gasket. Many spiral wound gaskets for critical applications include an inner guide ring which also known as a centering ring, which gives the gasket a greater resistance to thermal shock and in the case of vacuum service prevent the filler material being sucked in. Inner rings should be used with spiral wound gaskets on male-and-female flanges, such as those found in heat-exchanger, shell, channel, and cover-flange joints.
What are the most common materials used for winding and filler in Spiral Wound metallic Gasket?
Winding material is a thin metal strip that used to hold the filler material. Stainless steel grade 304, 316 and 321 are a popular material grade for the winding. Selection of the filler material is made based on the fluid service. Graphite, PTFE and ceramic material are well-known filler material that used with spiral wound gasket.
How to identify the type of winding material in a spiral wound gasket?
- For easy identification, Spiral Wound Gaskets are painted in accordance with ASME B16.20.
- The solid color on the EDGE of the outer ring indicates the metallic winding material
- The striped color on edge indicates the non-metallic filler used between the metal winding.
- The color on the surface of the Outer ring indicates material of the Outer Ring
In this image, you can see the sample marking of 6” 300 Class Spiral wound gaskets, manufactured in accordance with ASME B16.20. Here, the outer ring is of SS304, the winding material is SS316L metal strip, and filler material is flexible graphite.
On which type of flanges, use of spiral wound gasket are restricted by code?
ASME B 16.5 does not recommend the use of spiral wound gaskets on 150# rating flanges other than welding neck and lapped joint type.
What type of gasket is used in Heat Exchanger?
Metal jacketed gaskets are commonly used in heat exchangers. In Metal Jacketed Gasket Soft filler material is enclosed in a thin sheet of metal jacket. You can see the image of the channel cover gasket.
This is the end of the video. I hope that you have learned from this video. In the next video, I will explain to you about a few more important questions related to piping components. So keep on checking my youtube channel for new video.
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