Compression of Compressed Fibre Gaskets: Is it Linear?

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In summary: However, it is also possible to have gaskets with a "torque to yield" design, in which the bolt maintains proper compression even when it is removed. Additionally, many gaskets are composed of multiple layers, and depending on the layer composition, may require different bolt torque values in order to achieve a proper seal.
  • #1
James3849
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Hi All,

I am currently researching required bolting torques for flanges on a large water pipeline, but my question relates to compression of compressed fibre gaskets.

I know that catalogues and vendors typically specify the percent compression under a specfic test stress, and also percent recovery. What I would like to understand though is, is the amount of compression directly porportional to applied stress (i.e. linear) or can we assume this is so, or a is it slightly more complex?

I need to know this to ensure a proper seal in the flange, espcially under full pipeline operation.


Cheers
 
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  • #2
i do not know and it varies...typical gasket material is uniform. but..in any gasket application involving bolt patterns there is a specific torque sequence. on a cylinder head it is a cork screw pattern starting with the bolt located in the center of the head and spiraling outward. i recommend you measure the gasket thickness and tork down the gasket to actual specs. unbolt the assembly and measure the gasket for crush.
 
  • #3
some gasket assemblies use "torque to yield" bolts. they maintain the proper compression on the gasket by being in "stretch mode". these kind of seals require the replacement of the bolts if disassembled. additionally, many gaskets are not a single material, but a sandwich of multiple layers. the layers composition determine its compression requirements.

dr
 
  • #4
being in the design phase of the project, we don't really have the luxury of testing gaskets for compression at different bolt torques. We are currently undertaking an investigation into selecting the most appropriate gasket for the job and need to model effect of gasket compression and recovery during full operating conditions.

what would be extremely useful would be stress/strain(compression) curves for different gasket materials.

although from what I've found from vendors, they don't have this information readily available as they tend to deem it proprietry knowledge.

Does anyone know where I could find any characteristic curves for gaskets, particularly for compressed fibre gaskets?
 
  • #6
Flexitallic has a lot of information. I design high temperature equipment and use a lot of their thermiculite gaskets and the spiral wound gaskets.

Here is some information on the compressed fiber gaskets.

http://www.flexitallic.com/pdf/broCompFiber.pdf

Also, regarding bolt torque see the ASME (American Society of Mechanical Engineers) section VIII division 1 or 2 for their method of flange design.

Thanks
Matt
 
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FAQ: Compression of Compressed Fibre Gaskets: Is it Linear?

1. What is compression of compressed fibre gaskets and why is it important?

Compression of compressed fibre gaskets refers to the amount of force applied to the gasket in order to seal a joint. This force causes the gasket to compress, filling any gaps and creating a tight seal. It is important because a proper amount of compression is necessary for the gasket to effectively seal the joint and prevent leakage.

2. Is the compression of compressed fibre gaskets linear?

The compression of compressed fibre gaskets is typically linear, meaning that as the compressive force increases, the amount of compression also increases in a predictable manner. However, this may not always be the case due to factors such as gasket material and design, as well as the surface conditions of the joint.

3. How do I determine the appropriate amount of compression for a compressed fibre gasket?

The appropriate amount of compression for a compressed fibre gasket can be determined through testing and calculation. The gasket manufacturer should provide guidelines for the recommended compression range for their specific gasket material. It is important to also consider the specific application and any potential joint surface irregularities when determining the appropriate compression.

4. What factors can affect the compression of compressed fibre gaskets?

The compression of compressed fibre gaskets can be affected by several factors, including the gasket material and design, the amount of compressive force applied, and the surface conditions of the joint. Any variations in these factors can impact the amount of compression achieved and ultimately, the effectiveness of the gasket in sealing the joint.

5. How does compression impact the performance of compressed fibre gaskets?

The amount of compression applied to a compressed fibre gasket can greatly impact its performance. Too little compression may result in an inadequate seal, while too much compression can cause the gasket to deform or fail prematurely. It is important to follow the manufacturer's guidelines and properly measure and control the compression to ensure optimal performance of the gasket.

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