Weld Geometry A-B Flange:A Possible Alternate to the Extended Shim/ Double Fillet Weld - PowerPoint PPT Presentation

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Weld Geometry A-B Flange:A Possible Alternate to the Extended Shim/ Double Fillet Weld

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For welds with overlaps consider the above to make TIG welding easier. weld size seems excessive, but the re-analysis will take time (at least 1 day/run) – PowerPoint PPT presentation

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Title: Weld Geometry A-B Flange:A Possible Alternate to the Extended Shim/ Double Fillet Weld


1
Weld Geometry A-B FlangeA Possible Alternate to
the Extended Shim/ Double Fillet Weld
Grind 300 chamfer to improve TIG access. This is
necessary to improve fusion to surfaces.
3/8 or 0.289 ??
2 worst case
1/2
  • For welds with overlaps consider the above to
    make TIG welding easier.
  • ½ weld size seems excessive, but the re-analysis
    will take time (at least 1 day/run)

2
Double Fillet Weld
  • Fastest and easiest
  • But more distortion
  • Can easily peen to reduce distortion.
  • Candidate for testing.
  • NOTE have to be sure there is enough shelf
    for this.
  • CONCLUSION USE THIS FOR A-B WELD GEOMETRY.
  • Proceed without clamp bolts add if needed.
  • Improvise clamping as needed.

3
Weld Geometry A-B FlangeA Possible Alternate to
the Extended Shim/ Double Fillet Weld
Grind 300 chamfer to improve TIG access. This is
necessary to improve fusion to surfaces.
3/8 or 0.289 ??
1/2
  • For welds with overlaps consider the above to
    make TIG welding easier.
  • ½ weld size seems excessive, but the re-analysis
    will take time (at least 1 day/run)

4
Casting Weld Test B6 and A6
  • Shim and bolt casting as it will be.
  • Use steel shims but fit as it really will be.
  • Outboard Shim drawings available this afternoon.
    Loose fitting central hole. Non-coated shims
    will be used for this test.
  • Inboard shims go with U feature, ½ radius, ½
    tab, ½ deep. (may need to adjust depth
    depending on analysis. Bill thinks its OK).
    Drawings early next week.
  • Torque bolts to 100 value for through bolts
    75 for tapped bolts.
  • 316 LN weld shims (bar stock?) or 5/8 thick
    plate. All shims water jet cut, grind to
    thickness, anneal/rapid air cool/check
    permeability. MV will order material.
  • Lincoln weld wire
  • Peen intermediate weld passes.
  • Monitor distortion during welds with laser
    scanner.
  • Jim will ask Steve to measure B6 and A6 next
    week.

5
Pre-Casting Weld Tests
  • Use water jet cut A-B flanges.
  • Use 316-LN shims with U feature and without.
  • Use clamp bolts to simulate casting restraint
    somewhat.
  • Use Lincoln weld wire keep temp to 300F.
  • Mike Cole will make the CAD model. (2) flanges
    with 4 shims ½ thick.
  • Monitor distortion during welding with laser
    scanner.
  • MC will give shim profile.
  • Target date week of June 25 to perform tests.
  • Well use 316 L for this test.

6
Casting-Casting Demo Weld Test
  • Casting-casting weld test
  • Use actual shim design details.
  • Water jet cut, grind to thickness, anneal
  • Monitor distortion during welds with laser
    scanner.
  • Peening should be considered on inter-passes.

7
Fatigue Considerations
  • Fatigue analysis is not extremely sensitive to
    material properties often carbon steel
    properties is adequate. (ref. Fatigue Strength
    Analysis of Offshore Structures).
  • British Standard 7910 address flaw size
    assessment.
  • Bill suggests doing a preliminary assessment to
    get a handle on sensitivity.
  • Center crack panel is ok but tension test
    capacity may be an issue.
  • EWI uses single edge notch bend tests.

8
Design standards for fatigue
  • Structual Welding Code for Steel
  • Has table for different geometries.
  • Grade of material based on yield not much of an
    issue.
  • Shear on throat of welds 8 ksi (55 MPA) in their
    fatigue design table.
  • This suggests NCSX is close to threshold for
    shear fatigue for 5 million cycles.
  • Since NCSX fatigue life of 4 x 130,000 for flaw
    size fracture analysis is about 1/10 of this,
    were probably OK.
  • Possible for EWI to compare our shear values
    NCSXs N to a number of code criteria.
  • Will do. Kevin will supply peak shear locations
    (peak values).
  • Irv will get (3) center crack panels made and
    tested.
  • Size and details will be determined after
    discussions with Westmorland.
  • Effect of 77 K is relatively small minor
    differences in elastic properties between RT and
    77K.
  • If state is mostly elastic, it really doesnt
    matter much of stress range or strain range is
    used.
  • Question how much weld does NCSX need, given we
    have discrete shims?

9
Clamping
  • Flange geometry will not permit clamping pressure
    to be applied where you need it behind the
    welds!
  • Peening should be tried.
  • Bolts will improve clamping and should be
    retained.
  • Butting the shims together to make a continuous
    weld possible IS NOT a good idea the shim
    intersections will probably result in stress
    concentrations that will crack though the welds.
  • Outer bolts will be fully torqued prior to
    welding.
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