Patent Application
20060162786
The present invention relates generally to railroad tank cars and more specifically to manway covers for railway cars.
Railroad tanks are used to transport a wide variety of different types of commodities. Tank cars must be designed to accommodate a variety of commodities that create high internal pressure within the tank.
Railroad tank cars typically have one or more manway access openings on their top surface which allow workers to climb into the tank car to inspect, repair or clean the interior thereof. The manways typically comprise a cylindrical tube that communicates with an access opening in the tank and a manway cover assembly that is positioned in sealing relationship to the manway nozzle.
Manway covers have heretofore typically been flat or outwardly convex in shape and have been provided with sealing gaskets to maintain the pressure within the tank when the cover is in its closed position. Examples of such manway covers are disclosed in U.S. Pat. No. 6,076,471.
However, such flat or outwardly convex manway covers are susceptible to failure at high internal pressures (i.e. psi), particularly when the manway cover is made of stainless steel.
Accordingly, there is a need for a manway cover design that can accommodate higher internal tank pressures whether made from either carbon steel or stainless steel or a combination thereof.
A manway cover assembly is provided for a railroad tank car that is moveable between a closed position, in covering relationship with the manway nozzle that communicates with the manway access opening, and an open position, that permits entry into the manway nozzle. The open position of the cover also facilitates bulk loading of certain non-hazardous or low level hazardous commodities. In accordance, with one aspect of the invention, the manway cover assembly includes a manway cover member that has a generally inwardly convex central portion that extends into the manway nozzle.
In accordance with a further aspect of the invention, the manway cover member may a have a generally flat annular portion, having an inwardly facing recess formed therein, for receipt of an upper portion of the manway nozzle. A sealing gasket may be positioned in the recess.
In accordance with a further aspect of the invention, an outer ring member may be secured to the outer surface of the generally flat annular portion of the cover member. The outer ring member may be provided with openings formed therein for receipt of the locking lugs when the manway cover is in its closed portion.
In accordance with another aspect of the invention, a generally flat weather shield member may be attached to the outer ring in covering relationship with the central inwardly convex portion of the manway cover member.
Referring to
Referring to
Manway cover assembly 20 includes a manway cover member 22, an outer ring member 24, a weather shield member 26, a sealing gasket 28, and a spring biased mounting bracket assembly 30.
Manway cover member 22 has a generally inwardly convex central portion 32 that extends into the manway nozzle when the cover member is in the closed position. It has been determined that the inwardly convex shape of the cover member minimizes the cumulative effects of bending and membrane stresses to contain an internal pressure of the commodity up to about 165 psi. The manway cover member 22 includes a generally flat annular outer portion 34. Referring to
A generally flat weather shield member 26 is suitably attached to the outer ring member 24 of the manway cover assembly 20.
The manway cover assembly 20 is pivotally attached to the manway nozzle 18 in a conventional manner. A bracket member 38, having a horizontal opening formed therein, is attached to the outer ring member 24 and a pair of cooperating spaced apart bracket members 40, having horizontal openings formed therein, are attached to the manway nozzle 18. A pivot pin 42 extends through the openings formed in the bracket members 38 and 40. In order to facilitate the lifting of the cover assembly 20, a conventional biasing spring mechanism is provided that includes spring members 44 that are received about the pivot pin 42. The respective ends of the springs are suitably attached to the brackets 40 and an upstanding bracket member 46 that is attached to the cover member 22.
The outer ring member 24 is formed with a plurality of spaced apart open slots 48 formed for receipt of pivotal locking bolts 50 to secure the cover member 22 in its closed position. One end of the bolts 50 is pivotally mounted to a bracket member 52 that is attached to manway nozzle 18 and the other end receives a locking nut 54 to clamp the manway cover assembly 20 into sealing engagement with the upper edge of the manway nozzle 18.
In accordance with the present invention, it is presently envisioned that the manway cover member 22 and the outer ring member 24 may both be made of carbon steel or stainless steel. It is also envisioned that the manway cover member 22 may be made of stainless steel and the outer ring member 24 may be made of carbon steel.
Although certain preferred embodiments have been described above, it will be appreciated by those skilled in the art to which the present invention pertains that modifications, changes, and improvements may be made without departing from the spirit of the invention defined by the claims. All such modifications, changes and improvements are intended to come within the scope of the present invention.
