Abstract: There is disclosed a quick change plug and socket blow lance for use in steel conversion. To expedite exchange of an exhausted lance body (2) the lance body (2) has a plug (4) formed at an upper end adapted for reception in a socket (3) formed in a head (1). The socket and head are provided with various sealing surfaces whereby coolant water and oxygen for the conversion process can reliably be delivered to passages in the lance body (2). A locking mechanism is provided whereby the plug (4) can quickly be secured into the head socket (3) and separated after use. The locking mechanism consists of a plurality of circumferentially spaced projections (7) formed on a rotatable head ring (5) mounted at the mount of the socket (3). A lance body ring is secured to the lance body immediately below the plug (4) and provides a plurality of circumferentially spaced flange segments (8a) separated by gaps (8) through which the projections can pass as the plug (4) is inserted axially into the socket (3).

Abstract: An oxygen lance assembly includes a lance body which can be coupled and decoupled from a head through the use of a plug and socket junction. The plug part of the junction can be located on the lance body and provided with a plurality of axially spaced cylindrical male sealing surfaces. These are adapted to mate with corresponding female sealing surfaces provided in the head. The sealing surfaces mate with a clearance and the required seal is achieved by mounting O-rings exclusively on each male sealing surface. This provides for convenient inspection of the O-rings. Damage to the O-rings caused by vibration is prevented by cylindrical guide surfaces having a close sliding fit which serve to keep the plug part coaxial in the socket. Alignment of the plug in the socket is achieved by increasing the radius of each cylindrical sealing surface the further it is from the top of the socket via frusto-conical guide surfaces.