FIELD: test technology.SUBSTANCE: invention relates to a method of hydraulic water testing performed to check the quality of a welded pipe, for example a pipe welded by electrical contact welding, or a spiral pipe and a seamless pipe. Distinctive feature of the claimed solution is the use of a plurality of booster cylinders 41 installed parallel to the test tube and having corresponding gain factors, which are sequentially increased. As the driving source for the plurality of booster cylinders 41, a plurality of pumps 51 driven by servomotors that are installed in parallel are used. Aforementioned plurality of pumps 51, driven by servomotors, are operated simultaneously until the water pressure at the output side of the booster cylinder 41 reaches a pressure close to the test pressure. Thereafter, said plurality of pumps 51 actuated by servomotors are stopped, with the exception of one, and the water pressure at the outlet side of the booster cylinder 41 is increased to the test pressure by means of said one
