De conclusies van EP 630 luiden in de oorspronkelijke taal als volgt.
1. A system for cutting steel plate (33), in particular for cutting the bottom and/or the wall of an oil storage tank, comprising a pressurized liquid source (2) and a cutting device (1) comprising a hydraulic or pneumatic motor (4) for driving the cutting device (1), wherein the pressurized liquid source (2) and the motor (4) are hydraulically or pneumatically interconnected by means of hoses, wherein the cutting device is a mobile cutting device provided with means for driving the cutting device independently relative to said steel plate by means of said hydraulic or pneumatic motor (4), characterized in that the pressurized liquid source is a hydraulic or pneumatic pump (2), and in that the cutting device (1) comprises at least one nozzle (17) for squirting an abrasive liquid under high pressure against and through the plate (33).
2. A system according to claim 1, wherein the nozzle (17) is supported by at least one wheel (16), which can travel over the steel plate (33).
3. A system according to claim 1 or 2, wherein the nozzle (17) is spring-connected to the driven portion of the cutting device (1).
4. A system according to any one of the preceding claims 1 - 3, wherein the cutting device (1) is fitted with two spaced-apart nozzles (17), in such a manner that the cutting device (1) is capable of cutting a strip from the steel plate (33) in one movement.
5. A system according to any one of the preceding claims 1 - 4, wherein the cutting device (1) comprises a container for an abrasive agent.
6. A system according to any one of the preceding claims 1 - 5, wherein the cutting device (1) is fitted with caterpillar tracks (8) for riding the device (1).
7. A system according to any one of the preceding claims 1 - 6, wherein the transmission ratio is such that the velocity of movement of the device (1) will be less than 0.5 m/s, preferably less than 0.1 m/s, more preferably less than 0.06 m/s, with an engine speed of about 3000 rpm or a hydraulic output of about 25 l/min.
8. A method for cutting steel plate, wherein a pressurized liquid source (2) is connected to a hydraulic or pneumatic motor (4) of a cutting device (1) by means of hoses, wherein the cutting device (1) is a mobile cutting device (1) which is driven independently relative to said steel plate by means of said hydraulic or pneumatic motor (4) during the cutting operation, characterized in that the device is driven over the bottom (33) of a storage tank and said steel plate is the bottom (33) and/or the wall of said storage tank, in that the pressurized liquid source (2) is a hydraulic or pneumatic pump, in that said pump (2) is disposed outside said storage tank, and in that said cutting is effected by squirting an abrasive liquid under high pressure against and through the bottom and/or the wall.
9. A method according to claim 8, wherein said abrasive liquid contains sand and/or garnet.