A coaxial coupling comprising a male part and a female part; the male part to be fitted into the female part; the coaxial coupling comprises a bypass valve located in the female part, the female part to be decoupled from the male part while pressurized fluid passes through the female part, including incoming fluid and return fluid; an inner pipe of the female part for pressurized fluid comprises at least one front hole and one rear hole, which holes are arranged for said bypass valve, the inner pipe and an outer pipe body of the female part are guided for coupling into a nipple pipe and a nipple pipe body of the male part, wherein the nipple pipe of the male part pushes the spring-loaded bypass valve, which is in the female part over said rear hole(s), so that pressurized fluid is introduced into the nipple pipe of the male part through a relief valve located in the male part; characterized in that the female part has a rotatable locking sleeve, which is coupled to a sleeve accommodating pins rotatable about the center axis of the female part, in that the nipple pipe body of the male part has helical grooves; wherein, upon said coupling and rotation of the locking sleeve, the pins, through rotation of the pins, when the pins fall into the grooves, catch in walls of the grooves and cause the nipple pipe body of the male part to be pulled into the female part; wherein, when the male part and the female part are coupled together and the locking sleeve is begun to be rotated, one end of the inner pipe of the female part simultaneously meets the relief valve of the male part and opens the relief valve, and the pressurized fluid is discharged against the bypass valve of the female part prior to continued opening of two valves (115, 122) in the nipple pipe body of the male part in order to couple the male part to the inner pipe of the female part and separately connect the male part to the outer pipe body of the female part. the male part to be fitted into the female part; the coaxial coupling comprises a bypass valve located in the female part, the female part to be decoupled from the male part while pressurized fluid passes through the female part, including incoming fluid and return fluid; an inner pipe of the female part for pressurized fluid comprises at least one front hole and one rear hole, which holes are arranged for said bypass valve, the inner pipe and an outer pipe body of the female part are guided for coupling into a nipple pipe and a nipple pipe body of the male part, wherein the nipple pipe of the male part pushes the spring-loaded bypass valve, which is in the female part over said rear hole(s), so that pressurized fluid is introduced into the nipple pipe of the male part through a relief valve located in the male part; characterized in that the female part has a rotatable locking sleeve, which is coupled to a sleeve accommodating pins rotatable about the center axis of the female part, in that the nipple pipe body of the male part has helical grooves; wherein, upon said coupling and rotation of the locking sleeve, the pins, through rotation of the pins, when the pins fall into the grooves, catch in walls of the grooves and cause the nipple pipe body of the male part to be pulled into the female part; wherein, when the male part and the female part are coupled together and the locking sleeve is begun to be rotated, one end of the inner pipe of the female part simultaneously meets the relief valve of the male part and opens the relief valve, and the pressurized fluid is discharged against the bypass valve of the female part prior to continued opening of two valves (115, 122) in the nipple pipe body of the male part in order to couple the male part to the inner pipe of the female part and separately connect the male part to the outer pipe body of the female part.