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Weld Geometry A-B Flange:A Possible Alternate to the Extended Shim/ Double Fillet Weld For welds with overlaps – consider the above to make TIG welding.

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Presentation on theme: "Weld Geometry A-B Flange:A Possible Alternate to the Extended Shim/ Double Fillet Weld For welds with overlaps – consider the above to make TIG welding."— Presentation transcript:

1 Weld Geometry A-B Flange:A Possible Alternate to the Extended Shim/ Double Fillet Weld 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) Grind 30 0 chamfer to improve TIG access. This is necessary to improve fusion to surfaces. 1/2” – 3/8” or 0.289” ?? 2” worst case

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 Flange:A Possible Alternate to the Extended Shim/ Double Fillet Weld 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) Grind 30 0 chamfer to improve TIG access. This is necessary to improve fusion to surfaces. 1/2” – 3/8” or 0.289” ?? 2” worst case

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 it’s 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. We’ll 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, we’re probably OK. –Possible for EWI to compare our shear values & NCSX’s 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 doesn’t 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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