Testing air tubes to failure with 30,000 psi capability

[lloyd-ss]

We've already got a technical discussion going on this topic in the R&D gate
http://www.gatewaytoairguns.org/GTA/index.php?topic=117738.new#new
but I did want to mention here that I will be posting info in that thread about the test equipment and procedure and strength of materials, etc., of the air tubes that will be tested.  I don't intend for this to be a double post, but more of just a link to the other discussion.  I think it's important to have some idea about the safety, or lack of safety, in the equipment we are using. Accidents usually happen because we either don't understand that what we are doing might not be safe, or because we got careless and forgot the safety rules.
So this is just some info about the safety of steel air tubes.  It is only one example, but it makes me a feel a little more confident (but not casual) about the safety of the tube.
Here is a video of the first test, but the actual tech discussion will be in the other post in the R&D gate.
Lloyd

[Geoff]

 very neat test their Lloyd thanks I enjoyed watching the video.

[lloyd-ss]

Thanks Geoffrey.  I shot the video of the test outside of garden shed because I knew it was going to be messy, and it was.    
When it blew, it sprayed a fine mist of hydraulic oil all over the floor of the shed.   Oh well, it will hold down the dust.

[Sfttailrdr46]

Thanks Geoffrey.  I shot the video of the test outside of garden shed because I knew it was going to be messy, and it was.    
When it blew, it sprayed a fine mist of hydraulic oil all over the floor of the shed.   Oh well, it will hold down the dust.

go to the local lumber yard I'm sure they will be happy to give you a 5 gallon pail of sawdust which if you spray some Fantastic on the floor first will pick up most of the mess without needing to mop first just sweep and all done

[nervoustrigger]

Wow, that's fantastic!  Expertly done in both execution and explanation.  Spotting the readout of the thread root was a nice touch.  Thank you for sharing it with us.

[lloyd-ss]

Wow, that's fantastic!  Expertly done in both execution and explanation.  Spotting the readout of the thread root was a nice touch.  Thank you for sharing it with us.

Jason, thank you, and glad you noticed the stretching in the region of the threads that basically didn't have anything threaded into them. This is a 7/8 O.D. tube with a 13/16-28 thread, so there is only about .030 wall thickness in tension in that region.  It sees no radial pressure because it is outside the o-ring seal.  The end plugs threaded in and out easily after the test, and I was just about ready to write that the only damage was the split on the side, but I started looking some more and spotted the stretched threads.  Unfortunately, both end plugs were steel, and if I do this again, I will try one end with an aluminum end plug.  Calcs show that the aluminum plug might have been on the verge of stripping its threads at 16,000 psi.
Lloyd

[amb5500c]

The intent of this post is to lead you to the discussion in the R&D gate.
Richard