Login    Register
User Information
Username:
Password:
We are a free and open
community, all are welcome.
Click here to Register
Sponsored
Who is online

In total there are 42 users online :: 4 registered, 0 hidden and 38 guests


Most users ever online was 218 on Wed Dec 07, 2016 6:58 pm

Registered users: Bing [Bot], Google [Bot], MSNbot Media, Yahoo [Bot] based on users active over the past 5 minutes

The Team
Administrators
Global Moderators
global_moderators.png CS

Hydrostatic testing

A place to ask general spud cannon related questions.
Sponsored 
  • Author
    Message

Hydrostatic testing

Unread postAuthor: daccel » Tue Dec 09, 2008 10:23 am

I'm considering doing some hydrostatic testing on copper pipe with epoxy plugs, using an airless paint sprayer (variable pressure to ~3000 psi).

Do I need to worry about containment in case something fails?
  • 0

User avatar
daccel
Donating Member
Donating Member
 
Posts: 238
Joined: Thu Oct 11, 2007 9:51 pm
Location: BC, Canada
Reputation: 0

Unread postAuthor: jackssmirkingrevenge » Tue Dec 09, 2008 10:34 am

Very interesting :) I would locate the pipe being tested in some sort of box to contain any epoxy plugs that decide to convert themselves into projectiles.
  • 0

User avatar
jackssmirkingrevenge
Donating Member
Donating Member
 
Posts: 24225
Joined: Thu Mar 15, 2007 11:28 pm
Country: Holy See (Vatican City State) (va)
Reputation: 66

Unread postAuthor: far_cry » Tue Dec 09, 2008 12:39 pm

are you nuts
copper can handle this pressure maby !!!
epoxy no way
  • 0

ImageImage
User avatar
far_cry
Donating Member
Donating Member
 
Posts: 317
Joined: Wed Aug 20, 2008 3:59 pm
Reputation: 0

Unread postAuthor: ALIHISGREAT » Tue Dec 09, 2008 12:44 pm

far_cry wrote:are you nuts
copper can handle this pressure maby !!!
epoxy no way


any evidence to back that up? thought not.
  • 0

<a href="http://www.bungie.net/stats/halo3/default.aspx?player=ALI H IS GREAT"><img src="http://www.bungie.net/card/halo3/ALI H IS GREAT.ashx"></a>
Image
User avatar
ALIHISGREAT
Major General
Major General
 
Posts: 1779
Joined: Sat Aug 25, 2007 6:47 pm
Location: UK
Reputation: 0

Unread postAuthor: SpudFarm » Tue Dec 09, 2008 12:57 pm

copper pipe may hold that pressure, it all depends on the conditions. the best thing you can do is to test from small to big pipes writing down the defects they get and the info aswell as pictures.
  • 0

"Made in France"
- A spud gun insurance.
User avatar
SpudFarm
Donating Member
Donating Member
 
Posts: 2563
Joined: Sat Nov 04, 2006 9:39 am
Location: Norway Trondheim area
Reputation: 0

Unread postAuthor: Hotwired » Tue Dec 09, 2008 1:29 pm

ALIHISGREAT wrote:
far_cry wrote:are you nuts
copper can handle this pressure maby !!!
epoxy no way


any evidence to back that up? thought not.


Top left, 3928psi working pressure

But thats the working pressure, actually having it balloon out and tear will need a lot more so quite a bit of that list should still be intact at 3kpsi.

Doesn't necessarily mean it's safe to be in a cannon as it might then get upset about physical damage in addition to the pressure inside.
  • 0

User avatar
Hotwired
Lieutenant General
Lieutenant General
 
Posts: 2599
Joined: Fri Oct 13, 2006 5:51 am
Location: UK
Reputation: 0

Unread postAuthor: jackssmirkingrevenge » Tue Dec 09, 2008 2:40 pm

Properly done plugs should hold. Epoxy is a great material but the key is actually preparing it well as I stress in the how-tos, meaning making sure your surfaces are clean and abraded, mixing the parts in the correct ratio, well and at the right temperature and allowing full drying time.

Still, I'm secretly hoping it fails and you film the result ;)
  • 0

User avatar
jackssmirkingrevenge
Donating Member
Donating Member
 
Posts: 24225
Joined: Thu Mar 15, 2007 11:28 pm
Country: Holy See (Vatican City State) (va)
Reputation: 66

Sponsored

Sponsor
 


Unread postAuthor: ALIHISGREAT » Tue Dec 09, 2008 3:58 pm

are you planning on reinforcing the epoxy in any way?

i was thinking bolts through the copper, but that would put a lot of stress on the copper, its just a question of whether the copper could handle it?
  • 0

<a href="http://www.bungie.net/stats/halo3/default.aspx?player=ALI H IS GREAT"><img src="http://www.bungie.net/card/halo3/ALI H IS GREAT.ashx"></a>
Image
User avatar
ALIHISGREAT
Major General
Major General
 
Posts: 1779
Joined: Sat Aug 25, 2007 6:47 pm
Location: UK
Reputation: 0

Unread postAuthor: psycix » Tue Dec 09, 2008 4:16 pm

Its hydrostatic testing. Though it may be very informational on the strength of epoxy plugs, it wont be very dangerous or spectacular when it fails.
Heck, the plugs may be pushed out slowly.
  • 0

Till the day I'm dieing, I'll keep them spuddies flying, 'cause I can!

Spudfiles steam group, join!
User avatar
psycix
Donating Member
Donating Member
 
Posts: 3684
Joined: Mon Jun 25, 2007 7:12 am
Location: The Netherlands
Reputation: 0

Unread postAuthor: jimmy101 » Tue Dec 09, 2008 5:18 pm

I would think you would need screws or something to help hold the plugs in place. The weakest link is the epoxy to copper interface and that interface will change as the pipe is pressurized.
  • 0

Image

jimmy101
Lieutenant General
Lieutenant General
 
Posts: 3130
Joined: Wed Mar 28, 2007 9:48 am
Location: Greenwood, Indiana
Country: United States (us)
Reputation: 7

Unread postAuthor: daccel » Tue Dec 09, 2008 9:21 pm

I don't plan on using it at 3kpsi, just making sure it's safe for co2.

I think I'll test it in a metal pail filled with water, that's easy enough.

The pipe in question is 3/4" type L. I'll probably make three versions - one with no prep besides cleaning (worst case scenario out of curiosity), one with the pipe abraded, and one with holes drilled in the pipe. Screws won't work because it needs to be flush.

Anyone know how to calculate the shear strength at, say, 1/8" diameter? Looking up JB weld it says it has a tensile lap shear of 1040 psi, but I don't know what to do with that number.
  • 0

User avatar
daccel
Donating Member
Donating Member
 
Posts: 238
Joined: Thu Oct 11, 2007 9:51 pm
Location: BC, Canada
Reputation: 0

Unread postAuthor: Gippeto » Tue Dec 09, 2008 10:54 pm

If you were to consider a lap joint where an end cap and a pipe were jb'd together, the area of the actual joint (Circumference multiplied by length), multiplied by 1040lb/in2, would be the approximate failure point of the joint measured in pounds of force.

Take the failure FORCE, and divide by the area of the actual joint (pi *r*r). You now have an approximate failure pressure.

(Assuming everything was as perfect as when it was tested in the lab.)

De-rate for safety.

Jimmy raises a good point as well. The copper pipe likely will expand with pressure, bringing adhesion strength into play. It's still in psi, just remember that means pounds per square inch, and you'll be able to calculate what you need. Follow the units. :)

Make certain you get ALL the air out before you begin your testing. The results will be fairly non-dramatic if you do. Possibly frightening if you don't.

The copper tube handbook is an excellent resource to have when working with copper. It is a rather large pdf file if you have dial up.

http://www.copper.org/publications/pub_ ... ndbook.pdf
  • 0

"It could be that the purpose of your life is to serve as a warning to others" – unknown

Liberalism is a mental disorder, reality is it's cure.
User avatar
Gippeto
Donating Member
Donating Member
 
Posts: 2394
Joined: Sat Jan 19, 2008 10:14 am
Location: The Great White North...Canada eh!
Reputation: 11

Unread postAuthor: daccel » Tue Dec 09, 2008 11:54 pm

Thanks for the handy link.

Perhaps I was referring to the wrong property. Maybe tensile strength?

What I mean is if you drilled small holes in the pipe and filled them with epoxy flush with the outside of the pipe and as part of the plug, in place of screws or bolts strengthening the plug. Then the epoxy would have to break at this point rather than just breaking the bond with the copper. So I'm trying to figure out the additional strength this would add.
  • 0

User avatar
daccel
Donating Member
Donating Member
 
Posts: 238
Joined: Thu Oct 11, 2007 9:51 pm
Location: BC, Canada
Reputation: 0

Unread postAuthor: Gippeto » Wed Dec 10, 2008 12:28 am

You are talking about shear strength. I thought you were asking about lap shear. Oh well.

You're wanting a shear strength for an 1/8" plug.

pi*r*r for 1/8" diameter is .01227in2

The tensile strength of jb weld is 3960psi. When calculating shear strength, use 60% (This figure varies, depending on who you talk to. Usually between 50 and 70%.) of the tensile strength, so that is 2376psi.

So, we have a shear strength of 2376psi, and an area of .01227in2.

Following the units, we multiply 2376 lb/in2 by .01227in2 to get 29.15 pounds of force. This is the approximate force required to shear the plug in an ideal world.

De-rate this by your comfort level, or at least 50%. (My opinion.)

I hope that helps.
  • 0

"It could be that the purpose of your life is to serve as a warning to others" – unknown

Liberalism is a mental disorder, reality is it's cure.
User avatar
Gippeto
Donating Member
Donating Member
 
Posts: 2394
Joined: Sat Jan 19, 2008 10:14 am
Location: The Great White North...Canada eh!
Reputation: 11

Unread postAuthor: daccel » Wed Dec 10, 2008 1:24 am

Sorry, I wasn't clear on the properties.

Thanks, the shear strength calculation is exactly what I was looking for. And rather simple now that I think about it.

I'm assuming lap shear is the same whether it's an epoxy plug or cap fixed with epoxy like you mentioned (one vs two surfaces)?
  • 0

User avatar
daccel
Donating Member
Donating Member
 
Posts: 238
Joined: Thu Oct 11, 2007 9:51 pm
Location: BC, Canada
Reputation: 0

Next

Return to General Spud Cannon Related

Who is online

Registered users: Bing [Bot], Google [Bot], MSNbot Media, Yahoo [Bot]

Reputation System ©'