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  • Users: NBR90
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  1. NBR90

    How to expand a metal seat ring (SS316) with a teflon insert to fit in a bore that is too big?

    the repair sleeve is SS316 just like the seat with teflon insert in the middle. I can heat the bore, but wouldn't that negate the sleeved seat that is chilled by liquid nitrogen? As the -200 degree sleeved seat would melt as soon as it is placed into or near the bore. Why not just freeze the...
  2. NBR90

    Reading an optical flat correctly

    Correction for last sentence, it should read "Without knowing the test piece (A) was [highlight #CC0000]1/8[/highlight] wave flat..."
  3. NBR90

    Reading an optical flat correctly

    So I have three optical flats of 1/20, 1/10 wave and 1/4 wave accuracy. The surface test piece (A) that is being measure is flatter than 1/4 wave. Let's assume it has accuracy of ~1/8 wave. So from my understanding, the 1/4 wave optics should show all flat parallel lines when places above...
  4. NBR90

    How to expand a metal seat ring (SS316) with a teflon insert to fit in a bore that is too big?

    tbuelna, from my understanding of your post, it is ok to make a sleeve about 3 mm 'fit' the seat OD (by cold-shrinking), then machine the sleeve to less than .8 mm over the seat? The sleeve would not crack or lose its integrity?
  5. NBR90

    How to expand a metal seat ring (SS316) with a teflon insert to fit in a bore that is too big?

    Yes the inteference is 0.30 mm. Sometimes it can be even larger up to .50 mm. Its for high pressure fluid services. LN2 can shrink it up to .50 mm, Ive done it many times. Just this time the wrong part was given to me and there is no time to reorder right part. Those inteference is per...
  6. NBR90

    How to expand a metal seat ring (SS316) with a teflon insert to fit in a bore that is too big?

    The OD of the metal seat ring is about 75 mm (3") and about 25 mm thick. It is suppose to be fit into a bore with ID of approximately 75.5 mm (standard carbon steel). So obviously this is not a correct size as the bore needs to be smaller than the OD of the metal seat by about .30 mm. So the...
  7. NBR90

    Hydraulic press design need help.

    Jstephen, Im asking for help, a way to calculate the dimensions required to withstand the forces. These dimensions are not random gibberish, they are based on information offered by few machinists and even a similar 200 ton model that was shown to me, no one is expecting them to design it for...
  8. NBR90

    Hydraulic press design need help.

    Typical carbon steel, the two cylinder posts will be heat treated, hardened to 50 degrees hrc. There is only one hydraulic jack that will go up to 300 ton at 6000 psi. The 200 mm is the rod diameter of 300 ton hydraulic jack that will be pushing the green plate. On the right side I chose a...
  9. NBR90

    Hydraulic press design need help.

    Hello, I'm designing a typical hydraulic press. I'm using 2 posts [2 solid cylinders] instead of usual 4 posts for support. It is used for hydro-testing valves. [jpeg pic included] The two cylinder posts [Grey color in the jpeg pic] ~ 130 mm diameter. The thickness of two plates [purple...
  10. NBR90

    Safety Valve - Full life, Cv & pipe sizing for testing SV

    Hello, Is there a formula for determining the maximum Cv or flowrate for say a 1.5" inner pipe diameter (Air pressure range: 100 - 2000 psi)? The pipe is about 1 meter horizontal and 1 meter vertical from a 70 liter pressure vessel. I'm trying to find out what will be the minimum Cv, given...
  11. NBR90

    O-RING Groove design for hydrostatic testing

    Sweguy, Thanks for your input; your ideas sound great. I have a few questions: How thick are your thin round plates? What is your maximum valve size you can test to? I suppose you need to drill two holes in each side of the thin plates for air/water passage? How did you cut your O-Ring...
  12. NBR90

    O-RING Groove design for hydrostatic testing

    Ed, What would be the best material for sealing water? Viton? Thanks.
  13. NBR90

    O-RING Groove design for hydrostatic testing

    Thanks all for your kind help. I will eventually follow Parker's guide :) - but then we have to do a Dovetail groove because else the Oring will just fall out from the top plate. Our machinist is not so fond of doing Dovetail, says it is very difficult. Waiting on the bit.... Right now, I'm...
  14. NBR90

    O-RING Groove design for hydrostatic testing

    So for 7.0 mm Oring, should I cut it 7.0 mm wide and 4.5 mm (or 5.0 mm deep)? I would like to cut it 8.0 mm wide, 4.5 mm deep (Similar to what Parker suggest I tihnk) but then all the O ring will stay inside the ring. There is also the Dovetail design, but again, this design will swallow all...
  15. NBR90

    O-RING Groove design for hydrostatic testing

    Yes, perhaps plates are the problem. The plates are about 60 mm thickness. 960 mm in diameter. The older plates are only 450 mm in diameter but 65 mm in thickness. We do use blind flanges for emergencies but when you are testing hundred of valves, it becomes impractical to bolt them...
  16. NBR90

    O-RING Groove design for hydrostatic testing

    I'm having trouble with coming up with the right groove design. Briefly, I do hydrostatic testing on valves from 2" to 36". For 2" - 12" I need to test them for leakage up to 5000 psi water pressure. I have a 200 ton hydraulic clamping system with 200 mm cylindrical rod in the middle...

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