Abstract: An electrically operable rotary actuator assembly is disclosed for opening and closing a rotary gate valve. The assembly comprises an operating shaft for operating the valve, an electrically operable actuator for imparting a rotational drive to the shaft to cause the shaft to rotate from a first rotational orientation to a second rotational orientation and biasing means for imparting a rotational bias to the shaft to cause the shaft to rotate from the second rotational orientation to the first rotational orientation. The assembly further comprises a clamp arrangement for clamping the shaft in the second rotational orientation.

Abstract: A gate valve has opposed valve seats respectively held in position by seat holders within an outer body of the valve. Each seat is fitted into the respective holder from the outer side of the latter and retained in position, against displacement, between that holder and the surrounding valve body and in sealing engagement with a corresponding sealing/locating recess in the body. On assembly of the valve wedge members are inserted between the seat holders so that the seats are wedged tightly in location positions within the body.

Abstract: A pipe connection joint comprises two coaxial tubular joint members which are telescopically engaged, one within the other. The outer joint member has a bore, and the inner joint member a through bore, of the same diameter as that of the pipeline with which the joint is to be used. The inner joint member is received in a counterbore in the outer joint member, being an interference fit therein over an interface region to provide both a seal and a friction lock precluding relative axial separation of the joint members under internal working pressure. One of the joint members incorporates an externally connectible duct which leads to the interface region, whereby fluid under pressure can be introduced through the duct to relieve said friction lock.