Assessing adequacy of the bolted joins antifriction anti-seize coating design with the Spiralock self-locking thread for the ITER blanket modules

The paper presents main provisions of the experimental and computational method in forecasting the tightening torque of the heavily loaded self-locking bolted joints of the ITER blanket modules (M24?3 — LK24?3, M52?4 — LK52?4, M64?4 — LK64?4) manufactured using the Spiralock technology under conditions of the elastic-plastic deformation of the bolt thread tops. It provides results of the tribotechnical testing the VNII NP-212 solid lubricant coating using the ball-on-disk scheme in vacuum at the temperature of 20?C and the sliding speed of 0,1?10–3 m/s. Dependences are obtained of the VNII NP-212 solid lubricant coating sliding friction coefficient on the physical and mechanical properties of the friction pairs (M24?3, M52?4, M64?4) and the average contact pressure on the thread turns. The paper establishes variation ranges in the tightening torque of the blanket module three bolted connections in the tightening force range of 90…1200 kN. It shows that tightening torque of the self-locking bolted connections using the Spiralock technology without lubrication being computed using the well-known method for fastening the threaded connections with the elastic frictional interaction, is significantly higher than that of the similar bolted connections with the VNIINP-212 solid lubricant coating taking into account plastic deformation of the bolt thread turn tops.
EDN: AGYDPX, https://elibrary/agydpx

References

[1] Thompson V., Eaton R., Raffray R. et al. Properties of low friction anti-seize coatings for fusion applications. Fusion Eng. Des., 2019, vol. 146-A, pp. 345–348, doi: https://doi.org/10.1016/j.fusengdes.2018.12.064

[2] Tomilov S., Sviridenko M., Leshukov A. et al. EHF FW panel for ITER BM with mechanical attachment of the plasma-facing components. Fusion Eng. Des., 2019, vol. 146-B, pp. 2407–2411, doi: https://doi.org/10.1016/j.fusengdes.2019.04.002

[3] Sviridenko M., Leshukov A., Tomilov S. et al. Analysis of enhanced heat flux first wall behavior under ITER pulsed loads. Fusion Eng. Des., 2020, vol. 158, art. 111897, doi: https://doi.org/10.1016/j.fusengdes.2020.111897

[4] Hirai T., Bao L., Barabash V. et al. Hypervapotron heat sinks in ITER plasma-facing components—process qualifications and production control toward series production. Fusion Eng. Des., 2023, vol. 189, art. 113454, doi: https://doi.org/10.1016/j.fusengdes.2023.113454

[5] Pitts R.A., Gribov Y., Coburn J. et al. First wall power flux management during plasma current ramp-up on ITER. Nucl. Fusion, 2022, vol. 62, no. 9, art. 096022, doi: https://doi.org/10.1088/1741-4326/ac8062

[6] Kim S.W., Jang J.S., Chung S.K. et al. A parametric study of low friction coating by PVD method on the spiralock female thread for ITER application. Fusion Eng. Des., 2023, vol. 192, art. 113836, doi: https://doi.org/10.1016/j.fusengdes.2023.113836

[7] Tremsin A.S., Yau T.Y., Kockelmann W. Non-destructive examination of loads in regular and self-locking Spiralock® threads through energy-resolved neutron imaging. Strain, 2016, vol. 52, no. 6, pp. 548–558, doi: https://doi.org/10.1111/str.12201

[8] Zaytsev A.N. Assessing the maximum permissible friction coefficient in bolted joints of the ITER blanket modules. Izvestiya vysshikh uchebnykh zavedeniy. Mashinostroenie [BMSTU Journal of Mechanical Engineering], 2024, no. 1, pp. 3–20. EDN: MIRROY (In Russ.).

[9] Salova O.S. Design and technological solutions for modernization of machine devices operating under high vibration load. Studencheskiy, 2020, no. 38–1, c. 77–82. (In Russ.).

[10] Croccolo D., De Agostinis M., Vincenzi N. Influence of tightening procedures and lubrication conditions on titanium screw joints for lightweight applications. Trib. Int., 2012, vol. 55, pp. 68–76, doi: https://doi.org/10.1016/j.triboint.2012.05.010

[11] Morozov A.V. Experimental estimate of tribological characteristics of epilam-coated materials that operate in threaded joints under dry friction. Trenie i iznos, 2014, vol. 35, no. 3, pp. 236–243. (In Russ.). (Eng. version: J. Frict. Wear, 2014, vol. 35, no. 3, pp. 170–176, doi: https://doi.org/10.3103/S106836661403009X)

[12] Hosoya N., Niikura T., Hashimura S. et al. Axial force measurement of the bolt/nut assemblies based on the bending mode shape frequency of the protruding thread part using ultrasonic modal analysis. Measurement, 2020, vol. 162, art. 107914, doi: https://doi.org/10.1016/j.measurement.2020.107914

[13] Evtikhin V.A., Lyublinskiy I.E., Vertnik A.V. et al. Development of the experimental lithium blanket module for testing in the ITER reactor and its external liquid-metal systems. VANT. Ser. Termoyadernyy sintez [Problems of Atomic Science and Technology. Ser. Thermonuclear Fusion], 2003, no. 4, pp. 3–35. (In Russ.).

[14] Lyytinen J., Tikka P., Määttä T. et al. Development of the remote handling connector for ITER divertor diagnostic system. Fusion Eng. Des., 2021, vol. 165, art. 112243, doi: https://doi.org/10.1016/j.fusengdes.2021.112243

[15] Martínez-Albertos P., Sauvan P., Catalán J.P. et al. Dust contamination of Divertor Remote Handling System in ITER Hot Cell: a novel approach to model complex superficial radiation sources. Fusion Eng. Des., 2024, vol. 199, art. 114157, doi: https://doi.org/10.1016/j.fusengdes.2024.114157

[16] Yuto N., Kentaro N., Tomoyuki I. et al. Design updates of ITER Blanket Remote Handling System to accommodate in-vessel environment. Fusion Eng. Des., 2023, vol. 194, art. 113918, doi: https://doi.org/10.1016/j.fusengdes.2023.113918

[17] Merola M., Escourbiac F., Raffray A.R. et al. Engineering challenges and development of the ITER Blanket System and Divertor. Fusion Eng. Des., 2015, vol. 96–97, pp. 34–41, doi: https://doi.org/10.1016/j.fusengdes.2015.06.045

[18] Dobychin M.N., Sachek B.Ya. The method of prediction of the life of the dry friction bearing unit with a solid grease coating. Trenie i iznos, 2008, vol. 29, no. 3, pp. 246–250. (In Russ.). (Eng. version: J. Frict. Wear, 2008, vol. 29, no. 3, pp. 188–191, doi: https://doi.org/10.3103/S1068366608030069)

[19] WS2 Coatings Ltd: website. URL: https://www.ws2.co.uk/ (accessed: 06.05.2024).

[20] Titov V.V. Tests of structural materials and lubricants for frictional systems in airplanes. Vestnik mashinostroeniya, 2008, no. 1, pp. 26–33. (In Russ.). (Eng. version: Russ. Eng. Res., 2008, vol. 28, no. 1, pp. 23–30.)

[21] Wani M.F., Stepanov F.I., Torskaya E.V. et al. The elastic and frictional properties of nanoscale coatings based on molybdenum disulfide at micro and nano levels. Trenie i iznos, 2023, vol. 44, no. 5, pp. 435–445, doi: https://doi.org/10.32864/0202-4977-2023-44-5-435-445 (in Russ.). (Eng. version: J. Frict. Wear, 2023, vol. 44, no. 5, pp. 291–297, doi: https://doi.org/10.3103/S1068366623050112)

[22] Sutyagin O.V., Bolotov A.N., Rachishkin A.A. Tribological tests of solid lubricating coatings at elevated temperatures and loads. Izvestiya MGTU MAMI, 2015, vol. 4, no. 1, pp. 88–91. (In Russ.).

[23] Takahashi A., Hashimoto K. Evaluation of frictional properties of tungsten disulfide bonded films at high temperature in vacuum environments. J. Jpn. I. Met. Mater., 2016, vol. 80, no. 4, pp. 289–296, doi: https://doi.org/10.2320/jinstmet.JBW201502

[24] Sutyagin O.V. Friction of a single roughness model under the condition of elastoplastic contact. Mekhanika i fizika protsessov na poverkhnosti i v kontakte tverdykh tel, detaley tekhnologicheskogo i energeticheskogo oborudovaniya, 2013, no. 6, pp. 50–57. (In Russ.).

[25] Lu X., Sui X., Zhang X. et al. Influence of V doping on the microstructure, chemical stability, mechanical and tribological properties of MoS2 coatings. Ind. Lubr. Tribol., 2023, vol. 76, pp. 29–40, doi: https://doi.org/10.1108/ILT-09-2023-0306

[26] Spiralock® load distribution. stanleyengineeredfastening.com: website. URL: https://www.stanleyengineeredfastening.com/en/brands/Optia/Spiralock/Load-Distribution (accessed: 12.05.2024).

[27] Babuska T.F., Curry J.F., Dugger M.T. et al. et al. Quality control metrics to assess MoS2 sputtered films for tribological applications. Tribol. Lett., 2022, vol. 70, art. 103, doi: https://doi.org/10.1007/s11249-022-01642-y