A size-adjustable fastener includes: a first fastener and a second fastener. The first fastener is arranged with connection strips; an end of the connection strip is arranged with a limiting block; a transverse cross section of the limiting block is larger than that of the connection strip; the second fastener defines connection holes; each connection hole is communicated with a limiting hole, and the limiting hole is located at a side of the connection hole; the connection strip is inserted into the connection hole from a side of the second fastener; the connection strip is moved to approach the limiting hole to enable the limiting block to abut against the other side of the second fastener, enabling an end of the second fastener is connected to an end of the first fastener. The other end of the second fastener is connected to the other end of the first fastener.

A fluid end having its fluid flow bores sealed without threading a retaining nut into the walls of each bore. The fluid ends may be assembled using a plurality of different kits that each comprise a fluid end body, a component, a retainer element, and a fastening system. The retainer element holds the component within each of the bores formed in the fluid end body and the fastening system secures the retainer element to the body. The fastening system comprises a plurality of externally threaded studs, washers and nuts in some embodiments. In other embodiments, the fastening system comprises a plurality of screws.

A two-way fastener includes a first member threaded for being screwed into a first workpiece; a polygonal wall for receiving a tool to screw the first member into the first workpiece, the polygonal wall located at a base end of the first member; and a second member extending in an opposite fastening direction from the first member, the second member configured to be fastened to a second workpiece. A fastening method includes enabling the threading of a first member of a fastener into a first workpiece; and enabling the threading of a second workpiece to a second member extending outwardly from the first member and the first workpiece.

A hardware apparatus includes a washer/nut member and a cap. The washer/nut member includes a plurality of outer surfaces disposed in a hexagonal shape, an inner cylindrical surface disposed radially internal to the plurality of outer surfaces, an intermediate cylindrical surface disposed radially between the plurality of outer surfaces and the inner cylindrical surface, and an annular surface disposed radially between the inner cylindrical surface and the intermediate cylindrical surface. The cap is disposed within the intermediate cylindrical surface, and the inner cylindrical surface is configured to contact a shaft portion of a bolt and the annular surface is configured to contact a head portion of the bolt.

A hardware apparatus includes a washer/nut member and a cap. The washer/nut member includes a plurality of outer surfaces disposed in a hexagonal shape, an inner cylindrical surface disposed radially internal to the plurality of outer surfaces, an intermediate cylindrical surface disposed radially between the plurality of outer surfaces and the inner cylindrical surface, and an annular surface disposed radially between the inner cylindrical surface and the intermediate cylindrical surface. The cap is disposed within the intermediate cylindrical surface, and the inner cylindrical surface is configured to contact a shaft portion of a bolt and the annular surface is configured to contact a head portion of the bolt.

A tie bolt for joining two parts together has a shaft. The shaft in turn has a primary thread for engaging a first part and a secondary thread for engaging a second part, wherein the primary thread and the secondary thread have different pitches. The tie bolt may be used to join together any two parts which are to be locked together to transmit torque.

A fastening system for attaching a cover to an underground vault having a bolt with course threads and a composite fiber reinforced polymer nut having a threaded portion extending through the nut which will fail in sheer before the nut and bolt seize. The fastening system can also include a nut retainer sized to allow the nut to float within the retainer.

A fastening system for attaching a cover to an underground vault having a bolt with course threads and a composite fiber reinforced polymer nut having a threaded portion extending through the nut which will fail in sheer before the nut and bolt seize. The fastening system can also include a nut retainer sized to allow the nut to float within the retainer.

A fastening system for attaching a cover to an underground vault having a bolt with threads and a composite fiber reinforced polymer nut having a thread engagement portion extending through the nut which will fail in shear after the bolt is inserted before the nut and bolt seize. The fastening system can also include a nut retainer sized to allow the nut to float within the retainer.

A coating system applicator component, e.g. a valve or bell cup, which may be used to be wetted and/or flown through at least in some sections by a coating agent, is provided. The applicator component includes a cylindrical holding part configured to releasably couple a mount of the coating system, as well as an applicator thread on the holding part. The applicator thread includes first and second applicator flank surfaces each obliquely oriented to a radial direction of the holding part, the first and second applicator flank surfaces being asymmetric about the radial direction of the holding part. The first and second applicator flank surfaces are configured to be parallel to and interface with first and second mount flank surfaces of a thread of the mount, respectively, upon a coaxial, threaded engagement between the holding part and the mount.