Tek-Tips is the largest IT community on the Internet today!

Members share and learn making Tek-Tips Forums the best source of peer-reviewed technical information on the Internet!

Register Log in
  • Congratulations MintJulep on being selected by the Eng-Tips community for having the most helpful posts in the forums last week. Way to Go!

Recent content by Piyush582

  1. Piyush582

    Boss Oring failure

    The boss O-ring gland is pretty much standard and Parker refers to the same spec for O-ring cavity dimensions. The backup rings are not required in this case as it is backed up by metal. The O-ring gland is created by metals (fitting and manifold) on all side. As long as the metals stay in...
  2. Piyush582

    Boss Oring failure

    I think as long as the torque force does not damage the manifold, it should be fine as during pressure load the stress levels in the manifold will go down. Regarding the fitting, if I go with the worst case scenario of 5523 lbf torque force (1150 in-lb) and 5523 lbf pressure force, then the...
  3. Piyush582

    Boss Oring failure

    I don't see the attachment in my previous post. Let me try it again through this post. if you don't see it attached, try this link. http://files.engineering.com/getfile.aspx?folder=67be0d58-1da4-414e-a210-9f66bfcdc8f1&file=Bolt_torque-_preload.jpg...
  4. Piyush582

    Boss Oring failure

    Israelkk I agree with most of your theory and am on the same page with you, except for the "you "can not" split the force between the manifold and the fitting. Both feel same load. The stiffness ratio only dictates how much the fitting will be stretched when the pressure is applied as long as...
  5. Piyush582

    Boss Oring failure

    Let me share with you all the calculation data and then you can point where exactly I misunderstood. The torque of 900 in-lb is applied to the fitting which created a preload force of 4235 lbf (tensile in fitting, compression in manifold). The force here will be the same for both manifold and...
  6. Piyush582

    Boss Oring failure

    We have checked that O-ring for compatibility and the results came out good. The O-ring is per NAS1612, material controlled by NAS1613 with allowed temperature range upto 250F. I read the Machine design section again, and I confirm that the portion of the total load which is taken by the...
  7. Piyush582

    Boss Oring failure

    ISraleK, it seems like you are making a lot of sense. To my understanding, we are applying a preload force of 4235 lbf with 900 in-lb torque and assuming k factor of 0.2. If the pressure load is less than the torque preload, then the force will distribute between the fitting and manifold in the...
  8. Piyush582

    Boss Oring failure

    IsraelK, thanks for the quick response. The recommended torque values we get are from the AS18280 procurement spec for that fitting. For the -12 size, the recommended torque is 855-945 lb-in or 78ft-lb max. I agree the force on the fitting under 4500 psi is 5523 lbf but when the pressure is...
  9. Piyush582

    Boss Oring failure

    The manifold material is 7075-T73 Aluminum alloy and the fitting is 304 CRES. We did follow the recommended torque for the 304 CRES fitting. The yield for the 7075 Aluminum is more than 304 CRES so I assume the recommended torque for the fitting should be sufficient to avoid any loosening under...
  10. Piyush582

    Boss Oring failure

    We recently conducted a high pressure impulse cycle (50 to 4500 to 50 psig) test on a manifold assembly with boss fittings on it. The port is per AS5202-12 with MS21902J12 fitting and boss O-ring (NAS1612-12) installed in it. After about 9000 cycles at 140F, the O-ring extruded and broke down...
See more

Part and Inventory Search

Back
Top