This fitting can be anywhere in a house, all it does is connect two pipes together. I haven't been able to crack or yield these fittings from over torqueing or thermal cycling. The only way is to induce SCC by loading the fitting and basically dipping it in ammonia repeatedly. It'll cause SCC...
Thanks for all your help Rich. At least now I have an idea what the stress is in the fitting. As far as the design, I'll have to take a break for a while.
Your point is well taken Rich, I under stand that if I change it, it won't be standard. I was hoping to find a way to change where the pressure is applied. What I was thinking was if the same pressure were applied to a thicker section, it would induce less strain, and therefore have less...
I understand your persistence and appreciate it. I know that I still have to keep it in spec, and I have to make sure that it still works with the male threads of competitors. However, I'm not concerned about failure under pressure because these are for residential plumbing and carry a...
It's not me that is tightening these fittings, so I can't assume that a contractor is going to know how much torque to apply. Also, I stated some thing wrong. When I said I was going to change the pitch, I meant change the pitch diameter or in other words change the angle of the taper between...
I've tested similar competitor fittings and found most of them cracked. There was one brass fitting that didn't crack, but it was cast and much thicker than mine. The other ones that didn't crack were bronze-brass, but that costs three times as much. One design that preformed well was...
I know about SCC (stress corrosion cracking), and I've looked into different materials, but the problem is the cost. My employer wants me to keep using 360 brass if possible. I'm testing some fittings that are chrome plated that should protect against SCC. The chrome seems more like a...
I know that there is some portion of the stress in the axial direction, but that isn't my main concern. I'm more interested in the hoop stress because the the part is failing due to stress corrosion cracking, not blowing out. My hope is to find where most of the hoop stress is located and...
I'm redesigning a Female NPT fitting and was wondering if anyone had any info on how to figure out internal stress or how it might be distributed throughout the fitting. Is it all hoop stress, or is there a lot of axial stress from the threads pushing against each other? What is a reasonable...
