Self-sealing fastener and method of use

Abstract

A self-sealing fastener for reducing leaks between the self-sealing fastener and a substrate. The self-sealing fastener includes a shank that extends longitudinally between a first end and a second end. The shank has an outer surface. The self-sealing fastener also includes a head that extends radially outwardly from the first end of the shank. The head has an underside surface that is adjacent to the first end of the shank and a topside surface opposite the underside surface. A mastic sealant is disposed on at least one of the outer surface of the shank and the underside surface of the head to provide a water-tight seal between the self-sealing fastener and the substrate after the self-sealing fastener is installed in the substrate.

What is claimed is: 
     
         1 . A self-sealing fastener comprising:
 a shank extending longitudinally between a first end and a second end, the shank having an outer surface;   a head extending radially outwardly from the first end of the shank, the head having an underside surface adjacent to the first end of the shank and a topside surface opposite the underside surface;   a mastic sealant for providing a water-tight seal after installation of the self-sealing fastener disposed on the outer surface of the shank adjacent to:
 the first end of the shank, 
 at least one of the second end of the shank and the underside surface of the head, or 
 a combination thereof. 
   
     
     
         2 . The self-sealing fastener of in  claim 1 , wherein the mastic sealant is disposed on the underside surface of the head. 
     
     
         3 . The self-sealing fastener of in  claim 2 , wherein the head comprises an outer rim, wherein the underside surface of the head comprises a concave portion defined by a trough that extends annularly about the first end of the shank and a flat radial portion that is positioned radially between the concave portion and the outer rim, and wherein the mastic sealant is disposed on the flat radial portion and the concave portion on the underside surface of the head. 
     
     
         4 . The self-sealing fastener of in  claim 2 , wherein the shank has a shank diameter, wherein the shank comprises a conical buttress at the first end, and wherein the shank diameter progressively increases along the conical buttress moving towards the head. 
     
     
         5 . The self-sealing fastener of in  claim 4 , wherein the mastic sealant is disposed on the conical buttress of the shank. 
     
     
         6 . The self-sealing fastener of in  claim 1 , wherein the mastic sealant comprises a first sealant layer and a second sealant layer, wherein the first sealant layer directly contacts the outer surface of the shank, the underside surface of the head, or a combination thereof and wherein the second sealant layer is disposed on the first sealant layer. 
     
     
         7 . The self-sealing fastener of in  claim 6 , wherein the second sealant layer effective as a protective skin around the first sealant layer. 
     
     
         8 . The self-sealing fastener of in  claim 7 , wherein the mastic sealant in the second sealant layer has a higher viscosity than the mastic sealant in the first sealant layer. 
     
     
         9 . The self-sealing fastener of in  claim 6 , wherein the mastic sealant in the first sealant layer is compensationally different from the mastic sealant in the second sealant layer. 
     
     
         10 . The self-sealing fastener of in  claim 6 , wherein the mastic sealant in the first sealant layer has a first sealant layer thickness and the second sealant layer has a second sealant layer thickness that equals 25 to 50 percent of the first sealant layer thickness. 
     
     
         11 . The self-sealing fastener of in  claim 1 , wherein the mastic sealant is one of a silicone-based sealant, an elastomer-based sealant, a caulk-based sealant, an epoxy-based sealant, a petroleum byproduct sealant, coal tar, or a combination thereof. 
     
     
         12 . The self-sealing fastener of  claim 1 , wherein the shank comprises a threaded portion. 
     
     
         13 . The self-sealing fastener of  claim 12 , wherein the threaded portion is a helical threaded portion. 
     
     
         14 . The self-sealing fastener of  claim 1 , wherein a portion of the shank comprises a helical threaded portion. 
     
     
         15 . The self-sealing fastener of  claim 14 , wherein the mastic sealant is disposed on the helical threaded portion. 
     
     
         16 . A self-sealing fastener comprising:
 a shank extending longitudinally between a first end and a second end, the shank having an outer surface and a threaded portion;   a head extending radially outwardly from the first end of the shank to an outer rim, the head having an underside surface adjacent to the first end of the shank and a topside surface opposite the underside surface;   the underside surface of the head including a concave surface defined by an annular trough and a flat radial surface positioned radially between the concave surface and the outer rim; and   a mastic sealant disposed on the outer surface of the shank adjacent to
 the first end having a first thickness, 
 the concave surface of the underside surface of the head having a second thickness, and 
 the flat radial surface of the underside surface of the head having a third thickness. 
   
     
     
         17 . The self-sealing fastener of in  claim 16 , wherein the first thickness of the mastic sealant, the second thickness of the mastic sealant, and the third thickness of the mastic sealant are equal. 
     
     
         18 . The self-sealing fastener of in  claim 16 , wherein the second thickness of the mastic sealant is greater than the third thickness of the mastic sealant and wherein the third thickness of the mastic sealant is greater than the first thickness of the mastic sealant. 
     
     
         19 . The self-sealing fastener of in  claim 16 , wherein the first thickness of the mastic sealant is greater than the second thickness of the mastic sealant and wherein the third thickness of the mastic sealant equals the second thickness of the mastic sealant. 
     
     
         20 . A method of installing a self-sealing fastener in a substrate, the method comprising the steps of:
 applying a first layer of mastic sealant to the shank that that extends from an underside surface of a head and comprises a threaded portion, of the self-sealing fastener, the underside surface of the head of the self-sealing fastener, or a combination thereof;   applying a second layer of mastic sealant over the first layer of mastic sealant before the first layer of mastic sealant is fully cured such that the second layer of mastic sealant forms a protective skin over the first layer of mastic sealant, wherein a thickness of the second layer of mastic sealant is in a range of 25 to 50 percent of a thickness of the first layer of mastic sealant;   curing the mastic sealant in the second sealant layer to a different degree than the mastic sealant in the first sealant layer, wherein the mastic sealant in the second sealant layer has a higher viscosity than the mastic sealant in the first sealant layer; and   forcing the shank of the self-sealing fastener into the substrate wherein the second layer of mastic sealant ruptures as the second layer of mastic sealant makes contact with the substrate to flow the first layer of mastic sealant between the self-sealing fastener and the substrate and form a water-tight seal.