Abstract: To estimate a fracture starting point of steel due to hydrogen embrittlement with high accuracy. A steel fracture starting point estimation device includes a hydrogen concentration distribution calculation unit adapted to calculate a hydrogen concentration distribution in steel-to-be-estimated when the steel fractures due to hydrogen embrittlement; a local critical hydrogen content calculation unit adapted to calculate critical hydrogen content at which the steel-to-be-estimated fractures due to hydrogen embrittlement; and a fracture starting point estimation unit adapted to read the hydrogen concentration distribution out of a storage unit. To estimate, calculate, from the hydrogen concentration distribution, a location in the steel in which hydrogen concentration of the critical hydrogen content is distributed, and designate the location in the steel as the fracture starting point of the steel-to-be-estimated.

Abstract: To easily detect a crack having occurred in a steel material. A current measurement device measures a value of a current flowing through a target steel material that is immersed in an electrolyte aqueous solution and applied with tensile stress while subjected to hydrogen charging, and a device for detecting the occurrence of a crack or the like uses the measured current value to determine the occurrence of a crack in the target steel material when the amount of change in the current flowing through the target steel material, the change rate of the amount of change in the current, or the change rate of the change rate of the amount of change in the current exceeds a threshold value.

Abstract: A multiple valve includes first and second valve units respectively having first and second valve bodies. The first and second valve bodies have respective spool bores therein; and a respective spool is inserted in the spool bore of each of the first and second valve bodies. The first and second valve bodies of the first and second valve units also have inlet ports, tank ports, and first and second blocks having mounting holes, the blocks and a respective valve body being fixedly coupled together by means of stud bolts. The first block has a first threaded hole on one side surface thereof for receiving the stud bolt, and a second threaded hole on another side surface thereof for receiving a cover bolt. A pump passage, a main passage and a tank passage extend between the one side surface and the another side surface of the first block, and a stud bolt extends through the second block and is engaged with the first threaded hole.

Abstract: A pressurized fluid supply system, in which a plurality of pressure compensation valves are connected to a pump discharge line of a hydraulic pump in parallel, and direction control valves are provided at the outlet side of each pressure compensation valve to supply a discharged pressurized fluid from the hydraulic pump to a plurality of actuators. The pressure compensation valves include a check valve portion establishing and blocking communication between the pump discharge line and the inlet port of the direction control valve, and a pressure reduction valve portion for supplying a reduced pressure from the pump discharge line. The check valve portion shifts in a valve opening direction in response to an inlet pressure and shifts in a valve closing direction in response to an outlet pressure. The pressure reduction valve portion has a first and a second pressure chamber.

Abstract: A pressure compensation valve is capable of distributing of an output pressurized fluid of single pressurized fluid supply source to a plurality of hydraulic loads. The pressure compensation valve is constructed with a check valve portion formed by providing, in a valve body, a valve for establishing and blocking communication between an inlet port and an outlet port, and a pressure reduction valve formed by providing, in the valve body, a spool establishing communication between a second port and a third port by a pressure in a first pressure chamber communicating with a first port and blocking communication between the second port and the third port by a pressure in a second pressure chamber communicating with the third port. The spool is biased in a direction for blocking communication between the second port and the third port by a spring while contacting the valve.