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 300 chamfer to improve TIG access. This is necessary to improve fusion to surfaces.

1/2” –

3/8” or 0.289” ??

2” worst case

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.

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 300 chamfer to improve TIG access. This is necessary to improve fusion to surfaces.

1/2” –

3/8” or 0.289” ??

2” worst case

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.

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.

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.

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.

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?

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.