# Fastener spacing and sealing with o-rings

• greentlc
In summary, a spherical container with two hemispheres joined together with a bolted flanged connection will require a minimum number of bolts to compress the o-ring and seal the joint.
greentlc
I have to seal a spherical container comprised of 2 hemispheres joined together with a bolted flanged connection. I plan on using o-rings to seal the liquid (water) in. The problem I am having is finding the minimum number of bolts required to compress the o-ring and seal the joint. Can anyone point me in the right direction? Any help is appreciated.

Thanks

Last edited:
How much pressure do you anticipate? What is the area of your flange surface?

I'll check that link out. To answer your question, the internal pressure is about 125 kPa and the flange area is 0.061 m2.

just curious, why do you need the minimum amount of bolts?

for theory?
for cost?
for weight?

huntoon,

I am mostly going through the through the calculations for theory as it is for a school project. I was just trying to factor in the force required to keep the o-ring in compression with the internal pressure working to un-seal the joint. Using this I was going to calculate the number of bolts around the bolt circle. Is this not usually done, or is it done by different means? Thanks again for the help

greentlc

A conventional & quite normal engineering approach to this question, would be to select one of the many Standards documents which deal with sealing flanges at various pressures, with appropriately chosen safety factors.
Be aware that your O ring should be only ever subject to minimum compression within it's elastic deformation range. Any O ring supplier can provide charts advising on this. Remember that O rings will almost always be seated in O ring grooves which are also subject to close specification by the O ring suppliers.
Your bolt spacing will probably be commanded by the flange thickness & available surface area to accommodate the bolt heads.

## What is the purpose of fastener spacing when using o-rings?

The spacing between fasteners is important because it helps to distribute the load evenly across the o-ring, preventing it from being damaged or deformed. It also helps to ensure a proper seal is maintained.

## How do I determine the correct fastener spacing for my o-ring application?

The correct fastener spacing will depend on factors such as the size and material of the o-ring, the pressure and temperature of the application, and the type of fasteners being used. It is best to consult with a design engineer or refer to industry standards to determine the appropriate spacing.

## What is the recommended distance between fasteners for o-ring applications?

The recommended distance between fasteners can vary, but a general rule of thumb is to have the spacing be at least 1.5 times the diameter of the o-ring. This allows for proper compression and sealing of the o-ring.

## How important is proper sealing when using o-rings?

Proper sealing is crucial when using o-rings, as they are often used in applications where leaks can have serious consequences. The correct fastener spacing and a good seal will help to prevent leaks and ensure the o-ring functions properly.

## What are the consequences of incorrect fastener spacing with o-rings?

Incorrect fastener spacing can lead to uneven distribution of load on the o-ring, causing it to fail or deform. This can result in leaks, loss of pressure, and potential damage to the equipment or system the o-ring is used in. It is important to follow proper fastener spacing guidelines to avoid these consequences.

• Mechanical Engineering
Replies
9
Views
2K
• Mechanical Engineering
Replies
5
Views
3K
• Mechanical Engineering
Replies
2
Views
927
• Mechanical Engineering
Replies
3
Views
2K
• Mechanical Engineering
Replies
1
Views
2K
• Aerospace Engineering
Replies
7
Views
2K
• Mechanical Engineering
Replies
1
Views
1K
• Mechanical Engineering
Replies
15
Views
5K
• Aerospace Engineering
Replies
2
Views
2K
• Mechanical Engineering
Replies
3
Views
8K