Metal working – Method of mechanical manufacture – Repairing
Reexamination Certificate
2000-08-18
2002-04-30
Hughes, Tom (Department: 3726)
Metal working
Method of mechanical manufacture
Repairing
C029S402010, C029S407010, C029S407050, C073S040700, C073S052000
Reexamination Certificate
active
06378188
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
Aspects of the present invention generally relate to a method and apparatus for facilitating the repair of a fuel tank and testing of repair work. More specifically, aspects of the invention relate to a system and related method for preparing a fuel tank for repair by hotwork by rendering the tank non-reactive and testing the repair work upon completion by pressurizing the tank.
2. Description of Background Information
On occasion, fuel tanks acquire tears, cracks, and holes that require repair. Some repairs require the use of so-called hotwork, i.e., welding. However, when such repair work is to be completed on a fuel tank, there is always concern for the potential of a fire or explosion.
In order for a fire or an explosion to occur, three elements are required—an ignition source, fuel, and oxygen. Since welding is necessary to repair the tank, in order to avoid a fire or an explosion, elimination of either an oxygen source or a fuel source during such repair is necessary.
In the marine and petroleum industries, welding on tanks containing combustible or flammable substances is sometimes achieved by inerting the tank's atmosphere. Inertion of a tank involves blowing gas, such as carbon dioxide or nitrogen, into the tank, rendering the tank environment inactive by reducing the oxygen content by replacing it with an inert gas. To verify the repair work, the tank is ventilated and a localized air or fire hose test is performed on the repaired area. In this industry, these methods of testing repair work involve placing a human inside the tank to look for air or water leaking into the tank during such air or fire hose tests. Due to the size of these fuel tanks, it is not practical to test the entire tank.
Unlike the marine industry, the common method of repairing a fuel tank using hotwork involves draining the fuel from the tank and steaming the inside of the fuel tank, reducing the fuel hydrocarbon levels to below a lower explosive limit. This renders the tank safe for repair by hotwork.
Verifying tank repairs in the locomotive industry also differs from the marine industry. Locomotive fuel tanks are not large enough to place a human within to test repair work. One common method to verify repair work in the industry is to use a standing water test, where the repaired tank is filled with water above the repaired area and the repaired area is inspected externally for any leaking water.
In the locomotive industry, as with any industry, there is always an ongoing need to develop new methods and techniques for procedures. Thus, there remains a need in the locomotive industry to develop a method for preparing a tank for hotwork repair and testing the repair work.
In addition, each of these processes—preparing a fuel tank for repair by welding and testing the repair work—requires the use of different equipment. Currently, there is no comprehensive equipment capable of performing both of these processes to repair work. Thus, there remains a need for such equipment in the locomotive industry, as well as in other industries.
U.S. Pat. No. 3,590,559 (Bragg et al), herein incorporated by reference in its entirety, discloses an inerting system to prevent fires and explosions in fuel tanks by removing dissolved oxygen in the fuel when pressure changes within the fuel tank.
U.S. Pat. No. 5,668,308 (Denby), herein incorporated by reference in its entirety, describes a method of detecting leaks in storage tanks by pressurizing the tank and measuring the drop in pressure over a specified time period. Similar U.S. patents exist for testing motor vehicle's evaporative fuel systems by pressuring the tank and measuring the change in pressure over time.
Currently, there remains a need for improved effective methods to prepare a locomotive fuel tank for hotwork repairs and to test the repair work. Also, there is a need for comprehensive equipment that performs both of these functions. In addition, there remains a need for an apparatus and method that allow repairs to be performed and verified back-to-back until the repair is, in fact, complete.
SUMMARY OF THE INVENTION
An embodiment of the present invention includes an apparatus for preparing a fuel tank for repairs and verifying repair work upon completion. The apparatus includes a supply system constructed and arranged to be coupled to the fuel tank for providing a supply of inert gas into the fuel tank, for purging the fuel tank of oxygen to a certain level and for making inert the fuel tank with the gas. The supply system includes a gas release system constructed and arranged to provide the supply of inert gas. The supply system further includes an arrangement for connecting and facilitating transport of the inert gas. A supply mechanism is configured and positioned to facilitate and regulate a transfer of gas from the gas release system to the fuel tank. A connector mechanism is for coupling the supply mechanism to the gas release system. A relief system is constructed and arranged to be coupled to the fuel tank to regulate and relieve pressure in the fuel tank. A plurality of connectors is for connecting the apparatus system to the fuel tank. The plurality of connectors include a first of the plurality of connectors constructed and arranged to couple the supply system to the fuel tank, and a second of the plurality of connectors constructed and arranged to couple the relief system to the fuel tank.
REFERENCES:
patent: 5295391 (1994-03-01), Mastandrea et al.
patent: 5668308 (1997-09-01), Denby
patent: 9809702 (1999-04-01), None
Database WPI, Week 199931, Derwent Publications Ltd., London, GB; AN 1999-37521, XP002164177.
International Search Report PCT/US 00/41175 mailed Apr. 9, 2001.
Cozart Jermie E.
CSX Transportation, Inc.
Hughes Tom
Pillsbury & Winthrop LLP
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