Fastener spacing and sealing with o-rings


by greentlc
Tags: fastener, orings, sealing, spacing
greentlc
greentlc is online now
#1
Mar22-12, 07:20 PM
P: 29
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
Phys.Org News Partner Science news on Phys.org
Internet co-creator Cerf debunks 'myth' that US runs it
Astronomical forensics uncover planetary disks in Hubble archive
Solar-powered two-seat Sunseeker airplane has progress report
huntoon
huntoon is offline
#2
Mar22-12, 09:16 PM
P: 145
How much pressure do you anticipate? What is the area of your flange surface?
huntoon
huntoon is offline
#3
Mar22-12, 09:26 PM
P: 145
try this:
http://www.krrao.com/images/ASME_Ch4...6_11-14-08.pdf

greentlc
greentlc is online now
#4
Mar22-12, 09:38 PM
P: 29

Fastener spacing and sealing with o-rings


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.
huntoon
huntoon is offline
#5
Mar22-12, 10:40 PM
P: 145
just curious, why do you need the minimum amount of bolts?

for theory?
for cost?
for weight?
greentlc
greentlc is online now
#6
Mar27-12, 08:52 PM
P: 29
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
peterlonz
peterlonz is offline
#7
Mar31-12, 12:28 AM
P: 6
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 accomodate the bolt heads.


Register to reply

Related Discussions
sigma-rings are closed under countable intersections (sigma-rings are delta-rings) Calculus & Beyond Homework 2
Grade 660 Class A,B,C Fastener Rusted. Mechanical Engineering 0
Polynomial Rings/Fields/Division Rings Calculus & Beyond Homework 9
relationship interatomic spacing or interplanar spacing and grain size Atomic, Solid State, Comp. Physics 5
Need a fastener locking mechanism for #8-32 NC screw. Mechanical Engineering 21