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  1. cnuk

    A519 Wall Thickness Tolerance

    I have a question regarding ASTM A519 wall thickness tolerance. The wall thickness tolerance says - If OD is less than 3”, the tolerance is 12.5% when the WT < 15% of the OD and 10.0% when WT > 15% of the OD. - If OD is 3” to less than 6”, the tolerance is 10% when the WT < 15% of the OD and...
  2. cnuk

    &quot;Coeff of Friction&quot; for slips on a tube

    I have an application where I need to grip onto the OD of a tube with jaws/slips to resist an axial load that is applied to the tube. There will be three or five jaws equally spaced around the OD to clamp. In order to size the hydraulic cylinders that will provide the clamping force I need to...
  3. cnuk

    Stainless Steel for Cryogenic Application

    Excellent guys. Thank you very much for sharing your expertise.
  4. cnuk

    Stainless Steel for Cryogenic Application

    I need to select a stainless steel grade for a cryogenic application. We use liquid nitrogen to drop the temperature of a steel pipe in order to remove an lining inside the pipe (differential thermal expansion causes cracking & thus removal). We load the tank with steel tubes at room...
  5. cnuk

    Welding 50ksi Structural to Q&amp;T Plate

    Thank you for the help by sharing your knowledge. Very helpful.
  6. cnuk

    Welding 50ksi Structural to Q&amp;T Plate

    I am trying to redesign an existing piece of outdoor structural equipment and bring it in line with code. I have two options to rework a deficiency where a square HSS member joins to a plate with a fillet weld around the square HSS: 1. Replace an 1 1/4" A36 plate with a ~80 ksi plate. Likely...
  7. cnuk

    API %CT J55 to ASTM A??? Cross Reference

    This may be a simple question but it has me stumped. I am trying to find the equivalent ASTM Axxx number for API tubing/casing (eg:5CT J55). Does an equivalent ASTM number exist? I have reviewed the API specs I have and found no such cross reference. The reason I ask is that I am trying to...
  8. cnuk

    PTFE Seal Temperature

    Thanks for the reply. We don't have control over the preload with our design. As far as properties go, we ran the material on our DMTA and the modulus drops by a factor of 4 between 100C and 150C, both far lower than room temp obviously. We see what I would call creep at current operating...
  9. cnuk

    PTFE Seal Temperature

    I have a PTFE (graphite filled) seal that I am testing running on a 2" shaft @ 500 RPM, 500 Psi. Test fluid is water at 50°C. It is grease lubricated. We are measuring temperature near the seal of 150°C which seems ridiculously high to me. Are you surprised by the temperature? I would never...
  10. cnuk

    Wire Rope: spring constant

    I need to find the spring constant (or load vs. deflection curve) for a piece of wire rope (1/4" 7x19 in my case). Surprisingly this is not something that any vendors publish....only breaking strength. I suppose the published data makes sense for the typical application where you are...
  11. cnuk

    Casing/Wellhead Max Stress

    jte, Thanks for the response. I'm always impressed my the amount of knowledge shared on these forums. Greatly Appreciated.
  12. cnuk

    Is Impact test done only for Low temperature suitability?

    A related question. I thought I read somewhere (ASME BPVC?) that most plain carbon steels do not require impact testing if the operating temperature is above -29degC? The reason I ask is that I am designing a device that operated on an oilwell and is made of ASTM A36 plate and CSA G40.21 44W...
  13. cnuk

    Casing/Wellhead Max Stress

    Thanks roadapple. I started looking into API 6A but it quickly (section 4.3.3.2) refers to the ASME boiler pressure vessel code (ie: stress intensity). I don't have a copy of ASME so am still trying to figure out what exactly "stress intensity" is. It sounds like it is max principal - min...
  14. cnuk

    Casing/Wellhead Max Stress

    I have a device that is attached to the wellhead. It transmits a large bending moment, axial load, and some shear to the casing and wellhead. I would like to know what the max allowable load/stress for a given casing / wellhead flange combination is? I have looked over some of the API specs...
  15. cnuk

    Wellhead Equip: Low temp material spec ?

    Thank you for the response! I have 6A now and am reviewing it. Greatly appreciated
  16. cnuk

    Wellhead Equip: Low temp material spec ?

    Can someone tell me if there is an API spec that governs what material must be using for a structure that mounts to a producing wellhead that will operate at low temperature(-40C)? I have API 4F that covers the structure but it makes no mention of material requirements for low temperature. I...
  17. cnuk

    Concentric Housing to Shaft design question

    I think my ASCII art is confusing. There are only two bearings in the assembly, not five. The |__| I was drawing represent the contours of the housing and not the bearings. Only where the word BRG is written are there actually bearings. Certainly five bearings on one shaft would cause...
  18. cnuk

    Concentric Housing to Shaft design question

    CompositePro: I know that seals really don't like runout and that it's a much bigger problem that STBM (shaft to bore misalignment). The problem with my test fixture is not runout. The shaft bearing and sealing surfaces are ground in one operation. The shaft runs on bearings so runout is not...
  19. cnuk

    Concentric Housing to Shaft design question

    The tight tolerance are at the request of a supplier. Each of the housings carries a lip seal and the seal manufacturer wants that tolerance. Seals don't like shaft-to-bore misalignment so I need to minimize it...keep concentricity as close as possible. If I were smart enough I could attach a...
  20. cnuk

    Concentric Housing to Shaft design question

    ewh: Thank you for re-iterating what I said earlier. I think the two go hand in hand. I need to maximize concentricity in order to minimize the clearance required. I hope we can get back to discussing real design ideas to solve the problem. Thanks

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