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  1. valvit

    API 6A Ball Valve - Bore Requirement

    For 10K no. For other pressure ratings yes. See Tables 67-72, as well as Table 4 for tolerances. Valvit
  2. valvit

    MAST (Maximum Allowable Shaft Torque)

    TOV, All valves must open or close with pressure in the pipeline. With the valve in the closed position, and full pressure (MAOP) on one side of the valve, and low to zero pressure on the other side, this is known as full differential pressure (aka delta-P). Most valves, when opening against...
  3. valvit

    Valve testing in high temperature

    API 6A PR2 test specifies 20 cycles at both minimum and maximum rated temperature. Valvit
  4. valvit

    MAST (Maximum Allowable Shaft Torque)

    Most manufacturers will report MAST at Maximum Allowable Operating Pressure (MAOP). At maximum temperature rating, the MAOP is lower. If the valve MAST is lowest at maximum temperature and the coincident pressure, that is the value you should report. Valvit
  5. valvit

    Renewable seat ring threaded only or threaded seal welding

    Per API, if you seal weld the ring, it is not a renewable seat. To be a renewable seat, it must be threaded or pressed in. Valvit
  6. valvit

    The use of 17-4PH Stainless Steel in Ball Valves

    You've answered the question for yourself. 17-4 has higher SMYS and UTS than anything in the austenitic family, so parts of the same size will be stronger and will have higher allowable stress values. If you have high sulfur content, you need to be concerned with H2S content. 17-4 is highly...
  7. valvit

    Weld Overlay of Sealing Areas

    I would agree. Since the spring is jacketed by the PTFE, you should not experience galvanic corrosion. Valvit
  8. valvit

    Weld Overlay of Sealing Areas

    Lip seals need a very smooth surface finish to provide an effective seal. Any corrosion in the seal area will allow the lip seal to leak, thus the need for the corrosion protection. The lip seal itself, should use a spring made from a corrosion resistant material. Valvit
  9. valvit

    Maximum allowable stem torque calculation

    I use Roarks 6th Ed. This formula is just for the portion of the stem that is in the double-D (opposing flat sides) shape. The section below the double D is (probably) circular in section and needs to be evaluated separately. The below is the formula for non-circular section under pure...
  10. valvit

    Operating Range of RTFE seats in a Butterfly valves

    @CKchi... RPTFE may have a maximum temperature range of 200C, and it may also be suitable for Class 600 pressure....but not at the same time. Many manufacturers will answer each question independent of the other...and ignore the fact that because of creep, RPTFE cannot handle higher pressures...
  11. valvit

    Valve markings

    I agree with reverman, both the body marking in 4.2 and the nameplate marking in 4.3 are mandatory (as well as all of section 4). Valvit
  12. valvit

    API 6A-Annex M Qualification of Heat Treating- No.of thermocouples for Calibration

    The number of thermocouples required is not additive. You are correct, 16 thermocouples are required. Valvit
  13. valvit

    FMC pneumatic valve actuator help

    My advice is to be sure you understand how to disassemble anything when it could have a compressed spring. Stop work, and get a maintenance manual from the manufacturer. Valvit
  14. valvit

    what end type is this

    Best guess is that stands for Extended Buttweld end. Very common for a small diameter forged ball valve like that, to have "integrated" pipe nipples, forged directly with the valve ends. This moves the heat source from field welding away from the body and seat seals, and prevents damage during...
  15. valvit

    DIB-1 ball valve pressure relief device

    LittleInch, Yes, it is a spring relief valve. Commonly 1/2" NPT or ISO 228 parallel thread. Valvit
  16. valvit

    i m confused on how to start design valves on material selection

    If you are designing for a specific project, a good rule of thumb is to check to see what material the associated piping is made from. If the piping is carbon steel, then your valve can likely be carbon steel as well. If the piping is stainless steel...then your valve may have to be stainless...
  17. valvit

    DIB-1 ball valve pressure relief device

    I presume you are building a valve to API 6D, since you are referring to DIB-1. For now, B31.3 makes no reference to API 6D as an approved valve standard, but ASME committee are including it for B31.3-2015 revision, so thats good news. Also note the title of 24th Edition of 6D now includes...
  18. valvit

    Ball Diameter calculation for ball valve

    There is no standard to refer to when determining the bore to sphere ratio. I agree it is true that the rest of the valve design is performed after the bore/seat design is complete...and in that manner, it can be said that the rest of the design is dependent on the bore...but to Mike's point...
  19. valvit

    Angle pattern globe valve

    An angle valve is suitable for 2-phase flow because if you fill the pipe halfway with water, the other half is filled with air, and you have 2-phase flow. If you connect 220V-3 phase electric to the pipe, then you are allowed to multiply the 3-phase electric to the 2-phase fluid to get 6-phase...
  20. valvit

    Is Backseat test required for new valve?

    API 598 and API 6D both state that if a valve is equipped with a backseat, it must be tested. ASME B16.34 does not address the topic. Backseat test is a test on the valve stem...and has nothing to do with the seat test. If you ordered the valve to be tested in accordance with API 598, and it...

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