Abstract: The invention relates to wear resistant parts for process valves. The use of said parts can be particularly advantageous in the chemical and petrochemical industry, in the mining industry and in other processing industries. According to the invention, the wear resistant parts for process valves are characterized by a 50 to 500 &mgr;m thick coating applied by thermal spraying on the valve surfaces subjected to wear, particularly on the bearing and sealing faces. The coating is characterized by the fact that one or more cubic hard material phases containing Ti and/or Ti and a second metal and a metal binder phase can be demonstrated therein, and by the fact that when the coatings are rubbed against each other within a temperature range of from room temperature to 600° C., the friction coefficient is <0.6.

Abstract: A method and equipment for controlling a pipe network comprising piping (1), a pump (2) and at least two control valves (3), whereby the valve position and the flow through the valve are monitored, and in order to achieve desired flows the rotational speed of the pump and the position of each valve are adjusted on the basis to the position and flow data received. The rotational speed of the pump (2) is adjusted to be as low as possible, but at the same time sufficient for maintaining the gain of the valves (3). The positions of the valves (3) are adjusted to be as open as possible, the valve opening being, however, for the major part of the time, not more than a certain predetermined portion of the opening of the totally open position.

Abstract: A method and a valve apparatus for surveying the condition of a control valve. The position of the valve (101) is adjusted by means of an actuator (103) controlled by an electropneumatic positioner (104) and operated by means of pressure medium. The operation of the valve is monitored by sensors (109, 110, 107) that read the readings from the control signal, the input pressure of the positioner, the difference between the input and output pressure of the actuator, and the position of the valve. A fault causing a deviating reading will be located by using the readings given by the sensors and deduction rules stored in the microprocessor of the actuator. In an initial situation, when the valve is in balance state, the readings given by the sensors are stored at least from the control signal, valve position and the difference between the input and output pressure of the actuator. When the operation is continued, the readings given by the sensors are compared with the readings of the initial situation.

Abstract: A control valve comprises a valve body (1) including two flow channels (2, 2'); a cup-formed, steplessly turnable closure member (5); and a shaft (6) for turning the closure member. On the sides of the closure member there is at least one opening (14). The second flow channel (2') has in the valve body (1) an extension (10), the outer surface of which forms a surface of revolution concentric with the inner surface of the closure member (5), and which extends within the closure member. On the sides of the flow channel extension there is at least one opening (21). The opening or openings (14) of the closure member are located so that in the open position of the valve they at least partly overlap the opening or openings (21) of the flow channel extension (10). In the closed position of the valve the openings of the flow channel are covered by the closure member.

Abstract: A method and apparatus for detecting a fault of an automatically operated control valve assembly. Data consisting of several values of the control signal (i) and corresponding values of the position (h) of the control valve is measured and recorded. A mathematical model for the control valve assembly is defined. The mathematical model is fitted to the data measured from the control signal (i) and the position (h) of the control valve. At least one critical parameter for each component of the valve assembly, that is the valve (2) itself, the actuator (3) and the positioner (5), is chosen. The values and changes of the critical parameters are computed from the mathematical model fitted to the measured data. The component in which the fault is located is detected on the basis of the computed values of the critical parameters.