Fracture Mechanics and Swagelok Fitting for Hydro Testing

[CADTeach2]

Looking for fracture mechanics predictions and calculations with regard to hydrotesting.
I'm trying to prove how thick a test plate has to be and what material with the proper tensile stress.
I've looked at ASME B1.20 for requirements. Any comments.
Much appreciated.

BLW

 

[axlechaos]

When I was 'on the tools' many years ago, I worked in controls as applied to the oil and gas industry. Swaglok and Parker were the main suppliers of SS tube compression fittings. The fittings suppliers also provided SS seamless tube in varying diameters and wall thicknesses to ASTM A269. The material had a yield stress of 75,000 psi, and we used a safety factor of 4:1 at the time. This gave us an allowable stress value of 17,500 psi, and when used in conjunction with manufacturers recommendations, operated at pre-determined pressures. Working pressure and burst pressures were obviously different, and every now and again we would burst a tube with fitting attached. The tube always burst, usually 3-4 inches back from the fitting, and usually around predicted values as per theory, and tube tolerances.

I can talk about this all day, and you can also get information from Parker or Swagelok. Also note that a company called Fine Tubes produce top quality tubing - but it does cost more!

 

[rb1957]

are you testing a plumbing set up (implied by Swagelok in the header) ? or some plates ?

not sure how to apply damage tolerance to swagelok fttgs ... maybe ask swagelok ?? ... you can surely apply fatigue and crack growth, but do you really need residual strength ??