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  1. CADCAMTech

    Non uniform wall thickness.

    JStephen, The attachment is a Autodesk Inventor cad file so you should be able to open it in most cad packages, but i will upload a 3D pdf or just a regular PDF later. This is for a piece of down hole oilfield equipment so the ASME code does not apply as far as I am aware. As for FEA, I have...
  2. CADCAMTech

    Is 24" Sch 40 wall 0.687" or 0.688"?

    JStephen, It is my understanding that those piping standards Schedule 40, 80, etc were defined using the imperial system, so it is likely that many if not all of the sizes and wall thicknesses work out to some fraction of an inch (1/2, 1/4, 1/8, 1/16, 1/32, 1/64).
  3. CADCAMTech

    Non uniform wall thickness.

    When calculating the approximate hydrostatic burst pressure of a part that has a non uniform wall thickness what is the proper way to go about doing the calculation? Can I just take the wall thickness at the thinnest section and apply the formulas for thin walled pressure vessels, or is this...
  4. CADCAMTech

    Is 24" Sch 40 wall 0.687" or 0.688"?

    This is just a guess but it may just be a difference in how it was rounded, 11/16 of an inch is 0.6875. So one source may have rounded up and the other rounded down. Either way 0.001 inches is pretty small and I would assume that both 0.688 and 0.687 inches fall within the manufacturer/mill...
  5. CADCAMTech

    Pressure required to shear screws.

    R6155, My initial question was a pressure vessel related question, but it has evolved into this now. I will move some of this over to the forum you suggest. As for AISC I have no doubt that it has good resources for mechanical design calculations but I was more interested in your reasoning for...
  6. CADCAMTech

    Pressure required to shear screws.

    r6155, You will have to explain why I should use the AISC specification, I will certainly have a look at it but I like to know why a certain formula or method is applicable. I have found several textbooks, documents, websites, and forums that discuss designing for shear stress. Ive listed a few...
  7. CADCAMTech

    Pressure required to shear screws.

    BJI, The first image below is the actual setup, the darker outside sleeve moves left to right when the pressure is applied. The second image is the test setup the lighter plunger on the right side of the image moves right to left shearing the screw in the same direction it would shear under...
  8. CADCAMTech

    Pressure required to shear screws.

    racookpe1978 The area calculation is good. Both your syntax and mine mean the exact same thing. I also double checked it in my CAD software so I know it is right.
  9. CADCAMTech

    Pressure required to shear screws.

    jgKRI, There is no significant pre-load on the screws, they are just slightly more than hand tight in some cases the customer may add loctite to ensure the screws don't back out. The screws have no purpose other than to shear at the right pressure. And the fit and tolerance is exactly the same...
  10. CADCAMTech

    Pressure required to shear screws.

    jgKRI, You will have to further explain how that setup is different than say a bolt in single shear? You are right it is not the exact setup but I think it is the best way to approximate what happens when the assembly is pressured up. I am open for other suggestions if you have one. ironic...
  11. CADCAMTech

    Reaction force on shear coupling.

    Yeah I am going through some autodesk training tutorials right now. I was trying to work off my memory and it obviously was not good enough. Hopefully I can start to use this program more to make some of the information stick.
  12. CADCAMTech

    Reaction force on shear coupling.

    I think I may have found the issue. After I completed the simulation there was a drop down menu to view something called Reaction Forces, which had the options to view: SPC Force Total SPC Force Along X SPC Force Along Y SPC Force Along Z I did not understand that SPC Force indicates "Single...
  13. CADCAMTech

    Reaction force on shear coupling.

    The projected area normal to the y-z plane is 2.65 in^2.
  14. CADCAMTech

    Reaction force on shear coupling.

    rb1957, When in use, the pressure applied to those ID faces cause the fitting to slide horizontally in the picture. There are shear screws in the holes you can see in the pictures that resist this horizontal motion until they break. At this point the sleeve slides all the way down and relieves...
  15. CADCAMTech

    Pressure required to shear screws.

    See the images below for how I have the shear tests setup. We have used this process many times for other projects where we have needed to know the force required to press/pull something and have had good success with it. The pressure gauge is set to record the maximum value reached during each...
  16. CADCAMTech

    Reaction force on shear coupling.

    rb1957, Correct, the two pictures are from the same screen, one is from the setup view and the second picture is after the simulation is ran.
  17. CADCAMTech

    Pressure required to shear screws.

    No, I used (PI*Dia^2)/4.
  18. CADCAMTech

    Reaction force on shear coupling.

    Yep I think so, the coordinate system in the lower left of the image below shows x in the direction I would expect it.
  19. CADCAMTech

    Pressure required to shear screws.

    Ok so I have done some testing of just the shear screws themselves by using a press instrumented with a pressure gauge, and then using the known piston diameter to calculate the force required to shear the screws. I got an average value of 3379 lbf to shear 3 screws. When we pressure the system...

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