Method of tightening threaded fasteners

Details Method of tightening threaded fasteners Method of tightening threaded fasteners

1991-09-30

1994-01-11

Chin, Gary

Boots, shoes, and leggings

36455101, 73761, G01L 524, G05D 1702

Patent

active

052787753

ABSTRACT:
The invention provides a method for tightening threaded fasteners in a flange joint or the like, which comprises initially tightening each fastener to a predetermined initial load or stress, measuring the final load, stress, strain or elongation of each fastener after all fasteners have been tightened, and calculating interaction coefficients from the experimental data thus obtained. The interaction coefficients are representative of elastic interactions occurring between each fastener in the system, and enable an initial fastener strain value or load to be predicted for each fastener in the system. Using the predicted initial strain, stress or load values and the interaction coefficients for each fastener and applying an initial stress to each bolt in a second test in accordance with these calculations, allows updating of the interaction coefficient values along with the predictions of initial loads so as to enable calculation of preloads on each bolt which will yield essentially uniform bolt stress. The method compensates for elastic interactions between fasteners in the system and is self-correcting to reduce effects of flange surface misalignment.

REFERENCES:
patent: 4375120 (1983-03-01), Sigmund
patent: 4413396 (1983-11-01), Wallace et al.
patent: 4563734 (1986-01-01), Mori et al.
patent: 4685050 (1987-08-01), Polzer et al.
patent: 4969105 (1990-11-01), Gaenssle
D. H. Van Campan; A Systematic Bolt-Tightening Procedure for Reactor Vessel Flangs; First International Conference on Pressure Vessel Technology; Sep. 1969-Oct. 1969; pp. 131-141.
J. H. Bickford; The Bolting Technology Council and the Search for More Accurate Preload; Advances in Bolted Joint Technology, PVP vol. 158, Honolulu, HI; Jul. 1989.

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