×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Are you an
Engineering professional?
Join Eng-Tips Forums!
• Talk With Other Members
• Be Notified Of Responses
• Keyword Search
Favorite Forums
• Automated Signatures
• Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

#### Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

# Calculate pressure on a gasket from screw joint3

## Calculate pressure on a gasket from screw joint

(OP)
Hello!
How do you calculate the pressure on a gasket from two flanges that is being pressed together by screws.
Say you have 5 x M10 screws and you apply 50NM torque on every screw.
The surface area of one flange that is in contact with the gasket is 225 square centimeters.

See picture explanation here: https://imgur.com/a/1d6KN47

### RE: Calculate pressure on a gasket from screw joint

Hi

Using Torque = force * K * d. d= bolt diameter, K= friction factor,

50 * 10^3 = force * 0.2 * 10 transpose to find force :- Torque/ (0.2*10)

Therefore axial bolt force in one bolt is equal to 25000N.

Multiply the force by five bolts :- 25000 * 5 = 125000N

Divide the above force of 125000N by gasket area :- 125000/(225*100)= 5.55 N/mm^2

This is a rough approximation and assumes no thread lubricant. I used formula from this site

https://roymech.org/Useful_Tables/Screws/Screw_loa...

“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein

### RE: Calculate pressure on a gasket from screw joint

2
Something that happens is that thin flanges flex, particularly when used with thin gasket materials, concentrating the force and pressure very near the screws, easily leaving some areas with little to no contact pressure at all.

### RE: Calculate pressure on a gasket from screw joint

Rule of thumb is that the line linking adjacent bolt holes should be in the middle half of the gasket, which your diagram fails. I don't know if that means you can have a funny shaped gasket that adheres to this rule.

Cheers

Greg Locock

New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?

### RE: Calculate pressure on a gasket from screw joint

Is your drawing to scale? My gut feeling is that you need more bolts and/or thicker flanges. I see the flanges bending and not much compression on the gasket halfway between the bolts.

### RE: Calculate pressure on a gasket from screw joint

Bjorn92,

Your contact force is the sum total of the tensions of your screws. Desertfox has provided the standard equation which gives you some ability to predict the screw torque needed to achieve a required screw tension.

How flat are your flange faces?

--
JHG

### RE: Calculate pressure on a gasket from screw joint

Gasket principles require a combined bolt force to apply a stress to the gasket that is equal to or (ideally) exceeds the stress required for the gasket to seat (a.k.a. seal) properly.

Challenges arise when determining the appropriate gasket area that is influenced by each bolt, especially in the instance of thin flanges and large bolt centre distances, as 3DDave has identified.

Rubber/polymeric gaskets are generally self-energising and require a seating stress > 0 MPa, but harder gaskets require specific seating stresses.

You could look at standardised flanges such as ASME B16.5 for informative guidance on suitable bolt-centre and thickness ratios to design your flange.

Some flange designs call for non-linear FEA to identify areas of zero gasket contact ie. leakage potential. This is an (expensive) option if your application requires it.

#### Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

#### Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

#### Resources

Low-Volume Rapid Injection Molding With 3D Printed Molds
Learn methods and guidelines for using stereolithography (SLA) 3D printed molds in the injection molding process to lower costs and lead time. Discover how this hybrid manufacturing process enables on-demand mold fabrication to quickly produce small batches of thermoplastic parts. Download Now
Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a partâ€™s function at the center of their design considerations. Download Now
Taking Control of Engineering Documents
This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. Download Now

Close Box

# Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

• Talk To Other Members
• Notification Of Responses To Questions
• Favorite Forums One Click Access
• Keyword Search Of All Posts, And More...

Register now while it's still free!