Sealing nut with nylon insert

A sealing nut which is adapted to be screwed onto a male threaded stud or the like and brought into axial end engagement with the bearing surface of a body through which the stud threadedly extends in order to seal the joint defined by the stud and body and to lock the nut onto the stud while the joint is so sealed, the nut comprising:

• A. a metal nut body having a generally conventional solid axial end and having an annular socket provided at its second axial end, the nut body having a through axial bore, the annular socket being
• i. symmetrical with respect to the axis of the bore,
• ii. formed by the interior cylindrical surface of an axially extending generally cylindrical wall integral with said nut body and a second interior surface of the body which intersects with said interior cylindrical surface whose radius extends generally at an angle with the axis of the bore,
• iii. open to the second axial end of the nut body and to the bore along the axial length of the socket,
• B. an annular symmetrical, independently fabricated insert of relatively stiff polyamide resin locked into the socket and having its exterior surface and its first axial end facing the solid axial end of the nut body configured snugly to seat against the interior cylindrical surface and the second interior surface of said body, said insert
• i. having a central axial bore formed as a continuation of the bore of said nut body, both bores being threaded by a continuous thread,
• ii. having a relatively flat annular surface formed at its second axial end providing a shoulder on the radially outer edge thereof and an annular axially extending crown at the radially inner edge thereof,
• C. the free end of the axially extending cylindrical wall of the nut body being bent over the shoulder and engaging upon a narrow area of said flat annular surface whereby to form a lip comprising the outermost extend of the metal of said nut body at said second axial end, and to lock the insert into the socket,
• D. the crown being radially spaced from the lip and having at least a portion of said threaded bore on the inner surface of said crown whereby to provide a gallery between the lip and the crown upon the flat annular surface of the insert,
• E. the crown extending in a radial direction away from the solid axial end of the nut body substantially beyond the lip, and
• F. the crown being folded outwardly when axial pressure is applied to the end thereof so that it inverts and is forced into the gallery.

A sealed joint comprising:

• A. a metal body containing a fluid under pressure and having a threaded passageway extending through a wall of the body from the interior to the exterior thereof,
• B. a threaded member engaged in said passageway and having a stud-like portion on the exterior thereof,
• C. the body having a planar bearing surface surrounding the passageway on the exterior thereof,
• D. a combined sealing and locking nut threadedly engaged on the stud-like portion and having one axial end thereof in metal-to-metal engagement with said bearing surface, said nut comprising:
• i. a nut body having a socket in the one axial end,
• ii. a polyamide resin independently fabricated insert of substantial stiffness locked into the socket, there being a continuous threaded bore through the body and insert, the insert having a narrow annular extension having at least a portion of said threaded bore on the inner surface of said extension engaged against the bearing surface and inverted in an outward fold,
• iii. the nut body having a lip around the socket engaged upon and locking the insert in place, the lip providing the said metal-to-metal contact there being an annular gallery between the lip and the extension into which the outward fold is pressed and confined between the lip and stud-like portion, but said gallery being somewhat less in volume than said fold so that in the process of screwing the nut against the bearing surface the insert is subjected to compression force which cold flows portions of said insert against the stud-like portion and into clearances between said stud-like portion on the one hand and threads of the nut body and the threaded passageway on the other hand.