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  1. mjcook

    Tantalum and galvanic corrosion

    Moltenmetal, I may be responding too late to your inquiry, but I have lots of experience with Tantalum and may be able to help. Some literature sources warn about galvanic corrosion caused by coupling Tantalum and graphite. I have seen this phenomenon occur in Zirconium 702 when graphite gaskets...
  2. mjcook

    What thread types are standard for chemical plants?

    That's the question. UNC fasteners would have 7 TPI for 1-1/8" through 1-1/4", 6 TPI for 1-3/8" through 1-1/2", etc. There are also constant pitch series (UN series), like the 8 TPI series my pllant uses. In John Bickford's book, " An Introduction to the Design and Behavior of Bolted Joints"...
  3. mjcook

    What thread types are standard for chemical plants?

    The chemical plant I work in uses the constant-pitch 8-thread series for fasteners over 1" in diameter. Many items we get that have tapped holes in them like valves and expansion joints, though, are tapped for coarse thread fasteners, or 7 TPI for 1-1/8" and 1-1/4" diameters. What do most of...
  4. mjcook

    elastomer gasket Y factor

    For what it's worth, in past conversations with Garlock, they have recommended 600 PSI minimim clamping stress, and 900 PSI max clamping stress for rubber less than 70 durometer, 1200 PSI max clamping stress for rubber greater than 70 durometer. Although, in agreement with tothepoint, I've seen...
  5. mjcook

    What thread pitch for larger fasteners?

    The chemical plant I work in uses B-7 bolting for all piping flange assembly. Confusion has surfaced recently regarding what thread pitch we standardize on for bolting over 1" diameter. For 1-1/8" and 1-1/4" bolts we have a mix of 7 TPI and 8 TPI fasteners. I consulted John Bickford's "An...
  6. mjcook

    Wear of PTFE (Teflon) for Spinner Support

    Posted values for maximum stress on PTFE before it starts to cold flow are around 5000 PSI. Will there be enough pressure on the PTFE block that it will cold flow rather than wear?
  7. mjcook

    Fouling factor for plate & frame HXs

    I'm in a debate over fouling factors for plate & frame heat exchangers. A customer requirement is 0.005 fouling factor on all heat exchangers for a project, but one HX is a plate and frame unit, so the fouling factor doesn't apply. The plate and frame suppliers talk in terms of % excess area...
  8. mjcook

    Plate & Frame HX rupture disk sizing

    Thanks for your reply Art. I need to clarify my original post. This plate and frame HX is a gasketed unit. The hot side I am trying to protect from overpressure contains distilled water. The cold side contains a 30% Ethylene Glycol, balance water solution. It is not possible to overpressure...
  9. mjcook

    Plate & Frame HX rupture disk sizing

    I'm trying to size a rupture disk for the hot side of a plate and frame heat exchanger. The fluid can potentially be trapped in the heat exchanger by actuated valves on the inlet and outlet. What should I use as the wetted surface area for the fire sizing case? I was considering treating the...

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