Patent ID: 8505458

Claim:
A venting cap system, comprising: a first open-ended sleeve of a first material for melting at a selected temperature, said first open-ended sleeve includes an internal region to commence at a first end thereof and defines a diameter D S , said first open-ended sleeve includes an externally-threaded region to commence at a second end thereof, wherein said externally-threaded region defines a minor diameter D T ; and an inner sleeve of a second material being a solid at said selected temperature, wherein said inner sleeve is coaxially fitted in said first open-ended sleeve so that said first open-ended sleeve is bonded to said inner sleeve, wherein said inner sleeve includes a first end flush with said first end of said first open-ended sleeve, wherein said inner sleeve includes a portion, which axially overlaps at least part of said externally-threaded region by an amount L, wherein L<(D T 2 −D S 2 ) 1/2 , and wherein said first material and said second material include coefficients of linear expansion that are about equal.