Patent ID: 8475103

Claim:
An assembly comprising: a mounting surface having an aperture; a main washer located on the mounting surface, the main washer having a top surface, a bottom surface, a central recess in the top surface, an annular groove in the bottom surface, and a central hole; an O-ring located in the annular groove; a sealing washer located in the central recess; and a fastener with a head and a shaft, the shaft passing through the sealing washer and main washer and secured so that a first seal is formed between the main washer and the mounting surface by clamping the bottom surface of the main washer tightly against the mounting surface, a second seal is formed between the main washer and the mounting surface by compressing the O-ring, and a third seal is formed between the head and the main washer by compressing the sealing washer, such that the head is situated within the central recess when secured.