Fastening system allowing component removal after fastener system failure

Abstract

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.

What is claimed is: 
     
         1 . A fastening system for attaching a cover to an underground vault comprising:
 a bolt having course threads; and   a composite fiber reinforced polymer nut having a threaded portion extending through at least a portion of the nut, wherein the threaded portion fails in sheer before the nut and bolt seize.   
     
     
         2 . The fastening system of  claim 1  further comprising a nut retainer sized to allow the nut to float within the nut retainer. 
     
     
         3 . The fastening system of  claim 1  wherein the nut further includes an unthreaded bolt alignment portion positioned above the threaded portion. 
     
     
         4 . The fastening system of  claim 1  wherein the nut has a bolt shroud section positioned below the threaded portion. 
     
     
         5 . The fastening system of  claim 1  wherein the nut further includes a lead-in chamfer and a lead-out chamfer adjacent the threaded portion. 
     
     
         6 . The fastening system of  claim 1  wherein the nut includes at least one lobe extending radially outwardly in an upper portion of the nut. 
     
     
         7 . The fastening system of  claim 6  wherein there are two lobes each having a hole for receipt of a fastener. 
     
     
         8 . The fastening system of  claim 2  wherein the nut retainer has a cavity for receipt of at least a portion of the nut and sized for preventing the nut from fully rotating in the nut retainer. 
     
     
         9 . The fastening system of  claim 2  wherein the nut retainer has mounting holes. 
     
     
         10 . The fastening system of  claim 1  wherein the composite fiber reinforced fiber polymer nut is glass filled nylon. 
     
     
         11 . The fastening system of  claim 1  wherein the composite fiber reinforced polymer nut is an engineering plastic with fiber or particulate filler. 
     
     
         12 . The fastening system of  claim 11  wherein the fiber is at least one of aramid fiber, carbon fiber, glass fiber or metal strand. 
     
     
         13 . The fastening system of  claim 11  wherein the particulate filler is at least one of carbide, ceramic or mineral. 
     
     
         14 . A fastening system for attaching a lid to an underground box comprising:
 a threaded bolt; and   a fiber reinforced composite nut having a threaded portion wherein particulates trapped between the bolt and the threaded portion of the nut are pressed into the nut or crushed and driven out of the bottom of the nut.   
     
     
         15 . The fastening system of  claim 14  wherein the nut further includes an unthreaded bolt alignment portion positioned above the threaded portion and a bolt shroud portion positioned below the threaded portion. 
     
     
         16 . The fastening system of  claim 14  further comprising a nut retainer and wherein the nut includes at least one lobe extending radially outwardly in an upper portion of the nut so that the upper portion of the nut floats within the nut retainer. 
     
     
         17 . The fastening system of  claim 14  wherein the fiber reinforced composite nut comprises glass-filled nylon. 
     
     
         18 . The fastening system of  claim 14  wherein the fiber reinforced composite nut comprises an engineering plastic with fiber or particulate filler. 
     
     
         19 . The fastening system of  claim 18  wherein the fiber is at least one of aramid fiber, carbon fiber, glass fiber or metal strand. 
     
     
         20 . The fastening system of  claim 18  wherein the particulate filler is at least one of carbide, ceramic or mineral.