Railroad tank car manway assembly

1. A manway assembly for a railroad tank car, the manway assembly comprising:

a nozzle defining a central opening and having a sidewall;

a cover;

a hinge attaching the cover to the nozzle so that said cover is pivoted between an open position, where the central opening is generally uncovered, and a closed position, where the central opening is generally covered by the cover; and

a seal assembly to seal the cover with the nozzle, the seal assembly including a circumferential seal and a circumferential seal channel, the circumferential seal including a top portion, a bottom portion opposite the top portion, and a side portion between the top portion and the bottom portion,

wherein an underside edge portion of the cover is provided with the circumferential seal channel and the circumferential seal is positioned within the circumferential seal channel, wherein the circumferential seal has a C-shaped cross section and is positioned in the circumferential seal channel such that the top portion of the seal is seated against a top wall of the circumferential seal channel and the bottom portion of the seal is seated against a circumferential ledge of the nozzle.

2. The manway assembly of claim 1 , wherein the circumferential seal and the circumferential seal channel are oriented horizontal with respect to the nozzle and the cover.

3. The manway assembly of claim 1 , wherein the circumferential seal and the circumferential seal channel are angle oriented at 30 degrees with respect to the nozzle and the cover.

4. The manway assembly of claim 1 , wherein the circumferential seal and the circumferential seal channel are angle oriented at 60 degrees with respect to the nozzle and the cover.

5. The manway assembly of claim 1 , wherein the circumferential seal and the circumferential seal channel are oriented vertically with respect to the nozzle and the cover.

6. A manway assembly for a railroad tank car, the manway assembly comprising:

a nozzle defining a central opening and having a sidewall and a circumferential ledge on the sidewall of the nozzle;

a cover defining a circumferential stop portion that provides a metal-to-metal contact with the circumferential ledge when the cover is in a closed position on the nozzle;

a hinge attaching the cover to the nozzle so that said cover is pivoted between an open position, where the central opening is generally uncovered, and the closed position, where the central opening is generally covered by the cover; and

a seal assembly to seal the cover with the nozzle, the seal assembly including a circumferential seal and a circumferential seal channel, the circumferential seal including a top portion, a bottom portion opposite the top portion, and a side portion between the top portion and the bottom portion, and the circumferential seal channel including a front wall, a back wall opposite the front wall, and a top wall to form the circumferential seal channel,

wherein an underside edge portion of the cover is provided with the circumferential seal channel and the circumferential seal is positioned within the circumferential seal channel, wherein the circumferential seal has a C-shaped cross section and is positioned in the circumferential seal channel such that the top portion of the seal is seated against the top wall of the circumferential seal channel, the bottom portion of the seal is seated against the circumferential ledge of the nozzle, and the side portion of the seal is seated against the back wall of the circumferential seal channel.

7. The manway assembly of claim 6 , wherein an internal pressure of the railroad tank car presses the circumferential seal against the circumferential seal channel and the circumferential ledge of the nozzle.

8. The manway assembly of claim 7 , wherein the internal pressure of the railroad tank car presses the top portion of the seal against the top wall of the circumferential seal channel, the side portion of the seal against the back wall of the circumferential seal channel, and the bottom portion of the seal against the circumferential ledge of the nozzle.

9. The manway assembly of claim 6 , wherein the circumferential seal and the circumferential seal channel are oriented horizontal with respect to the nozzle and the cover.

10. The manway assembly of claim 6 , wherein the circumferential seal and the circumferential seal channel are angle oriented at 30 degrees with respect to the nozzle and the cover.

11. The manway assembly of claim 6 , wherein the circumferential seal and the circumferential seal channel are angle oriented at 60 degrees with respect to the nozzle and the cover.

12. The manway assembly of claim 6 , wherein the circumferential seal and the circumferential seal channel are oriented vertically with respect to the nozzle and the cover.

13. A manway assembly for a railroad tank car, the manway assembly comprising:

a nozzle defining a central opening and having a sidewall and a circumferential ledge on the sidewall of the nozzle;

a cover defining an underside edge portion with a circumferential stop portion and a circumferential seal channel, wherein the circumferential stop portion provides a metal-to-metal contact with the circumferential ledge when the cover is in a closed position on the nozzle;

a hinge attaching the cover to the nozzle so that said cover is pivoted between an open position, where the central opening is generally uncovered, and the closed position, where the central opening is generally covered by the cover;

a latch mechanism to secure the cover to the nozzle; and

a seal assembly to seal the cover with the nozzle, the seal assembly including a circumferential seal and a circumferential seal channel, the circumferential seal including a top portion, a bottom portion opposite the top portion, and a side portion between the top portion and the bottom portion, and the circumferential seal channel including a front wall, a back wall opposite the front wall, and a top wall to form the circumferential seal channel,

wherein an underside edge portion of the cover is provided with the circumferential seal channel and the circumferential seal is positioned within the circumferential seal channel, wherein the circumferential seal has a C-shaped cross section and is positioned in the circumferential seal channel such that the top portion of the seal is seated against the top wall of the circumferential seal channel, the bottom portion of the seal is seated against the circumferential ledge of the nozzle, and the side portion of the seal is seated against the back wall of the circumferential seal channel, and further wherein an internal pressure of the railroad tank car presses the circumferential seal against the circumferential seal channel and the circumferential ledge of the nozzle.

14. The manway assembly of claim 13 , wherein the internal pressure of the railroad tank car presses the top portion of the seal against the top wall of the circumferential seal channel, the side portion of the seal against the back wall of the circumferential seal channel, and the bottom portion of the seal against the circumferential ledge of the nozzle.

15. The manway assembly of claim 13 , wherein the circumferential seal and the circumferential seal channel are oriented horizontal with respect to the nozzle and the cover.

16. The manway assembly of claim 13 , wherein the circumferential seal and the circumferential seal channel are angle oriented at 30 degrees with respect to the nozzle and the cover.

17. The manway assembly of claim 13 , wherein the circumferential seal and the circumferential seal channel are angle oriented at 60 degrees with respect to the nozzle and the cover.

18. The manway assembly of claim 13 , wherein the circumferential seal and the circumferential seal channel are oriented vertically with respect to the nozzle and the cover.