Abstract: A test cell (10) for containing equipment (12) subject to pressure testing comprises a plurality of metal plate wall panels (14) and a mesh roof panel (16) formed from mesh strands (26) of a high strength material. Each wall panel has a lapped connection (18) with an adjacent wall panel. The mesh panel (16) may be formed from a ballistic fabric, and the mesh strands (26) may be wire, rope and braid of steel, metal, plastic, natural or composite fiber, or a combination thereof. In the event of a pressure failure of the equipment (12) under test, the roof panel (16) captures fragments of the equipment while allowing the dissipation of pressure shock waves through the apertures (28) in the mesh. The lapped connections (18) between wall panels (14) result in increased friction between adjacent wall panels (14) and thus an increase in the strength of the connection when subject to pressure shock waves.

Abstract: A test cell (10) for containing equipment (12) subject to pressure testing comprises a plurality of metal plate wall panels (14) and a mesh roof panel (16) formed from mesh strands (26) of a high strength material. Each wall panel has a lapped connection (18) with an adjacent wall panel. The mesh panel (16) may be formed from a ballistic fabric, and the mesh strands (26) may be wire, rope and braid of steel, metal, plastic, natural or composite fibre, or a combination thereof. In the event of a pressure failure of the equipment (12) under test, the roof panel (16) captures fragments of the equipment while allowing the dissipation of pressure shock waves through the apertures (28) in the mesh. The lapped connections (18) between wall panels (14) result in increased friction between adjacent wall panels (14) and thus an increase in the strength of the connection when subject to pressure shock waves.

Abstract: A strain-responsive visual indicator comprises a pair of overlapping shutter strips (1, 2) adapted to be mounted to a substrate such that strain in the substrate causes relative movement M between them. Each shutter strip comprises an alternating set of windows (5) or (6) and bars (7) or (8) and the distal strip (2) is backed by a strip (3) of a different color exposed through its windows (6), or the distal strip can instead be printed with a set of alternating colors in place of its windows and bars. The effect is that under different strain conditions different color indications from the distal strip (2) will be visible through the windows (5) of the proximal strip (1), in accordance with the relative positions of the two strips. The indicator can be incorporated e.g. in the shaft of a toothbrush to give a visual warning in response to flexure of the shaft if excessive brushing pressure is applied. Numerous other applications and the use of different types of indicia are indicated in the specification.

Abstract: A method of transmitting data acoustically through a tubular structure, such as a drill string or production tubing in an oil or gas well, predominantly comprising a series of tubing sections (1)joined end to end by couplings (2), at least a preponderance of the tubing sections having an axial length of at least a dimension X between couplings and at least a preponderance of the couplings having an axial length of no more than a dimension x, where X is substantially greater than x. The method comprises propagating acoustic signals along the structure, between transducers (9,10) over a distance N of at least 10X, in the form of tone bursts at least predominantly comprising a selected guided wave mode (preferably the L(0, 1) mode at low frequency) with a wavelength of at least 2x, and each burst having a temporal length of substantially less than 2N/C and preferably no more than 2X/C, where C is the phase velocity of the selected mode.

Abstract: A strain-responsive visual indicator comprises a pair of overlapping shutter strips (1, 2) adapted to be mounted to a substrate such that strain in the substrate causes relative movement M between them. Each shutter strip comprises an alternating set of windows (5) or (6) and bars (7) or (8) and the distal strip (2) is backed by a strip (3) of a different colour exposed through its windows (6), or the distal strip can instead be printed with a set of alternating colours in place of its windows and bars. The effect is that under different strain conditions different colour indications from the distal strip (2) will be visible through the windows (5) of the proximal strip (1), in accordance with the relative positions of the two strips. The indicator can be incorporated e.g. in the shaft of a toothbrush to give a visual warning in response to flexure of the shaft if excessive brushing pressure is applied. Numerous other applications and the use of different types of indicia are indicated in the specification.