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  1. yamoffathoo

    Can IC Engine Compression Testing with/without Blanks on Inlet and Exhaust Manifolds Quantify Valve Leakage?

    I am considering refurbishing a 200,000 mile 2.4L, 4 cylinder engine sitting in my shop. Compression testing at 250 rpm yields 90 psig, which increases to 120 psig with 3 squirts of oil in the cylinders, which is below the 140 psig minimum. To determine whether inlet and exhaust valves are...
  2. yamoffathoo

    Experiments with "Constrained Layer Damping" of Small Bore Connections

    A British Firm (GL Industrial Services UK Ltd.) was experimenting with composites to dampen the dynamic response of small bore connections to compressors with the handle "Constrained Layer Damping". This investigation was completed in 2019, but the Final Summary Report is a little sparce on...
  3. yamoffathoo

    How to calculate the equivalent stiffness of concentric, composite tubes in bending?

    I would like to determine the effect on natural frequencies in bending by adding incremental layers of a composite wrap to the entire length of a stainless steel tube. For this application, the tube is simply supported at one end and anchored at the other with uniformly distributed mass of just...
  4. yamoffathoo

    What is Supporting the Annular Outer Ring at Bottom Draw-off Drains per API 650 Appendix O?

    A 40ft x 32ft high diesel storage tank at my plant has provided excellent service since 1978 with some minor pitting on the underside of the floor plates, which have been patched. Recently, localized thinning below 0.1" of the 0.25" outer annular ring (chine) adjacent to the 12" wide concrete...
  5. yamoffathoo

    How Does Polarity Influence Two Part Epoxy Bonding to Neodymium Magnets?

    I made an intriguing discovery while epoxying plastic knobs to neodymium magnets. I didn't pay attention to polarity when epoxying them but discovered that, thankfully, all but 3 out of 16 were configured so that they repelled each other. This was fortuitous because they are prone to spalling...
  6. yamoffathoo

    Does aeration of a vinyl acetate based emulsion containing carbon fibers reduce LDV?

    thread135-433434 At our plant we use a leak sealing agent comprising carbon fibers (.007 x .1) mm dia/length in DUR-O-SET A-802 emulsion for sealing minor leaks from pinholes (2 mm dia) in pipe. My question is: would aeration while diluting in water reduce the LDV (Lowest Deposition Velocity)...
  7. yamoffathoo

    How does a 8" Crane 465.5 Gate Valve Stem Separate ? (cast iron gate & manganese bronze ste

    thread408-405652 The damaged valve was disposed of before inspectors could characterize the failure mode. Turning the handle raised the stem but UT indicated the gate did not move. To fail the stem in torsion and compression, calculations indicate very low yoke sleeve/nut friction and very large...
  8. yamoffathoo

    How to Calculate the Maximum Valve Stem Stuffing Box Pressure for Sealant Injection

    A leaking control valve stem packing requires on-line sealant injection through the existing leak-off port at the lantern ring. I calculated the maximum stuffing box pressure using thick shell formulae and area replacement methodology (for the injection hole) and got approx. 10,000 psig based on...
  9. yamoffathoo

    Boiler Blow-off Blues

    Engineering is proposing to install 4"nps tell-tale drains immediately downstream of 4"nps boiler blow-off valves on horizontal lines. The idea is to give operators 'handier' drains to monitor. This arrangement is probably going to produce flow disturbances from drain water entrainment...
  10. yamoffathoo

    PIPE FLATTENING TEST ACCEPTANCE PER ASME A530

    I am looking for testimonials from test labs (or literature) on the frequency that Clause 19.3.4 acceptance criteria is involked for small diameter A312 TP304L pipe. This will help form a risk argument for the probability of cracks forming during an emergency crimp on a 3/4"nps sch40 pipe...
  11. yamoffathoo

    TANK CLEANUP WITH POM-POMS

    I am looking for an oil absorbent rope that can be compressed into a 2" tube, which would be inserted into a 24" dia by 18 foot long horizontal tank half filled with water that has a layer of oil on its surface. The only access to this tank is through a 2" dia nozzle. 30 pom-poms on a 50 foot...
  12. yamoffathoo

    High Temperature Leak Sealant that Floats

    The normally closed, 1500lb 10"nps wedge gate valve body/bonnet gasket is leaking 1200 psig and 500 degF subcooled water at about 1.5 lb/min. The idea to plug this leak is to back seat the valve, hook a jacking pump to the packing blow-out line, close the valve and inject sealant. The...
  13. yamoffathoo

    Looking for Leak Sealant that Floats

    The normally closed, 1500lb 10"nps wedge gate valve body/bonnet gasket is leaking 1200 psig and 500 degF subcooled water at about 1.5 lb/min. The idea to plug this leak is to back seat the valve, hook a jacking pump to the packing blow-out line, close the valve and inject sealant. The...
  14. yamoffathoo

    Emergency shut-off crimp for 3/4"nps sch80 A106B pipe

    thread330-16741 I am looking for equipment and expertise to crimp a 3/4"nps sch80 A106B pipe pressurized with stagnant water at 1200 psig and 500 degF. It is an inter-gate pressure equalizing line on a closed gate valve that has a passing body/bonnet gasket joint. I have been advised that two...
  15. yamoffathoo

    Malleable Iron Rupture Pressure?

    I'm looking for empirical data on rupture pressure for malleable iron fittings manufactured to ASME B16.3 to provide a basis for a Safety Margin argument. The only other data I have is five 1"nps threaded elbows that were all exposed to 2500 psig air and did not leak!
  16. yamoffathoo

    Vortex Shedding and Tube Frequency Assumptions

    A flow induced vibration analysis of a steam surface condenser uses the following methods to determine the propensity to vibrate: 1) how close the tube structural frequencies lie to the vortex shedding frequency 2) the maximum tube vibration amplitude at resonance 3) Connor's fluid elastic...
  17. yamoffathoo

    Is dual mode surface/spray condenser operation asking for problems?

    The steam condenser in question is a vertical, four pass, U-tube design with a spray header. The ring steam header is mounted inside of the ring spray header above the centrally hung tube bundle. Both spray and surface condensing capacities are sized for maximum steam flow, they are supplied...
  18. yamoffathoo

    Expansion Versus Weld Repair

    1978 TEMA C recommended that for 300 psig+ and 350 degF + heat exchangers with 5/8" dia and larger tubes you should either expand the tubes over 1-1/4" min. length in a two-grooved tubesheet or use full strength seal welds. If the 5/8" dia tubes are presently rolled 3" long in a 6" thick...
  19. yamoffathoo

    Sum of Squares Solution to Pressure Drop?

    If a liquid in a long pipe vaporizes along its entire length due to uniform heat input, may I take advantage of the 1/3 pressure drop factor to calculate peak pressure? If the pipe is closed at one end and open at the other, then vapour bubbles will grow uniformly and displace liquid towards...
  20. yamoffathoo

    Heat Exchanger tube Failure mechanism

    I am very interested in a failure mechanism that is associated with low and intermittent tube flow that causes tube failure and tube movement. This has been observed in verticaly oriented, u-tube heat exchangers and requires a hot shell (secondary) side, cold tube (primary) side, liquid medium...

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