Abstract: A liner or other elongated duct is made by joining lengths of thin-walled polyethylene fusion. Typical thickness 2-4 mm, diameter 200 mm. Pipe ends are clamped in clamps which restore circularity. The ends are trimmed leaving aligned ends normal to pipe length. The clamps force the ends against a heated body, which is retracted and the ends are then forced together. The total heating period, say 15 seconds, and the periord between separation from the body and engagement of the ends, say 1 second, are very short. Good joint strengths and small beads result. The liner can be pulled into burst cast-iron gas main before a new main is passed through the liner; or the liner is a seal in a pipe. The method is applicable to other polyolefins e.g. polyropylene.

Abstract: Pipes, typically of medium density polyethylene for use in underground distribution systems for natural gas are joined by fusion using a very short period (25 seconds) for heating the pipe ends and a very short period (3 seconds) between separation of ends from the heater body and engagement of the ends. Those periods are such that the beads formed by upset of the softened end material of the pipes are relatively small, e.g. beads have a cross-sectional area of 10mm.sup.2 for pipe for 250 mm outside diameter and wall thickness 15 mm. Typically such a bead extends only some 2.5 mm away from the adjacent pipe wall surface. Tensile, bending and impact tests show joint strength equivalent to the parent wall strength. In accelerated lifetime tests at high pressure and temperature the joints are at least equal to conventionally made joints.

Abstract: A fuel-fired burner of the gas-fired fully premixed type comprises a plenum chamber 2 formed by walls 5, 7, 8, 9, 10 and 11, the wall 11 having an inlet port 4 to enable the plenum chamber 2 to receive a mixture of gas and air from a mixing chamber 3 and the wall 5 comprising a plate having therein several through-going rectangular slots 6 which communicate with the chamber 2. The mixing chamber 3 has an inlet end 15 for connection to a source of pressurized air and a further inlet opening 17 in a wall 13 formed with a stub pipe 18 by means of which the chamber 3 can be connected to a source of fuel gas.

Abstract: In a pipeline through which a vehicle such as a pig is travelling, a magnetically activated detector detects the presence of the approaching pig and sends a signal to switch on a transmitter unit which supplies an alternating current to an AC coil. This generates a magnetic field for a preselected period, the flux signal being then sensed by a pair of crossed coil sensors on board the pig after which the signal is processed in a unit on-board the pig. A reference pulse is then output for recording on a tape recorder also on-board the pig. This technique enables a geographical reference of the vehicle to be fixed.

Abstract: A burner control system includes an input interface 10 for receiving burner status inputs. These are passed to address bus 14 and used to access addresses within EPROM 18. Data at the accessed addresses are output on bus 20 to control the burner via output interface 23 with related relays. Oscillator 16 and counter 17 sequence the selected address areas of the EPROM via bus 15 and a start up sequence, for example, can thus be effected. Incorrect status of the inputs from input block 10, flame detector 12 or the internal system checks in blocks 28 or 29 to bus 14 will cause the EPROM to be addressed at locations which contain data in a form that will cause shutdown or lockout via relay 25. Parity check block 22 also actuates lockout if errors are detected. System status can be provided by display 19.

Abstract: A peripheral toroidal blower has a stripper consisting of a central block part and two curved vanes projecting one from each end of the block part and extending in opposite directions around the toroidal chambers to at least partially cover the inlet and outlet ports. The active surfaces of the stripper are of porous material whereby to provide a substantial reduction in blade passing frequency noises. The active surfaces may be of inherently porous material such as polyurethane foam or of a nominally closed cell plastics foam of which the active surfaces are made porous by machining or cutting.

Abstract: Components of gaseous mixtures, which are present in the gas as a fluid, e.g. a gas, vapor or mist are assayed biochemically by conducting an enzymatic reaction wherein the fluid substrate is added to a liquid medium containing the enzyme. Particular reactions include the measurement of monoethylene glycol in natural gas employing a glycol dehydrogenase/NAD.sup.+ system and determing the amount of NAD.sup.+ reduced.

Abstract: The present invention relates to a valve assembly for controlling fluid flow in a fluid flow regulator. The valve assembly comprises a deformable plug 1 e.g. of rubber, having a cylindrical body formed with a circumferential groove 5 and a pair of backing plates 2 and 3 located at either end of the plug 1. The plates 2 and 3 are bonded to the plug 1 and, in use, plate 2 is moved to stress the plug 1 and cause it to expand radially to restrict an annular clearance between the plug 1 and a valve seat (not shown) in which the plug 1 is located. This enables fluid flow through the clearance to be controlled. A flanged steel ring 4 is mounted on the backing plate 2 and a circular neck portion 10 of the plug 1 is located between the ring 4 and the plate 2, the portion being bonded to the plate 2. The ring 4, and especially the groove 5, serve to prevent or inhibit erosion of the plug surface in use.

Abstract: An antenna assembly is provided for use in locating buried objects, particularly long thin objects such as pipes can be located, determining the position, and ascertaining the pipe direction by taking measurements from a single point, without mechanical movement of the antenna, and allowing a better suppression of spurious signals and reduction in false indications; which assembly has a plurality of antenna arms adapted and arranged to transmit and receive radiation into the ground and is characterized in that the arms have, on at least the surface nearest the ground, a cladding of a substantially lossless dielectric material, the relative permitivity of said dielectric being at least 3.5 and the thickness of said coating being at least .lambda..sub.d /20 where .lambda..sub.d is the wavelength of lowest frequency of the radiation to be transmitted from the antenna.

Abstract: A method for replacing an existing buried pipe of a crackable, fracturable material. By the application of a local intense pressure, the pipe is cracked and fractured into irregular fragments which are spread outwardly to provide space for a new replacement tubular assembly which is moved into the space as the pipe is fractured and the fragments spread. At least a portion of the outward spreading of the fragments occurs under the action of the intense local pressure. An apparatus used to carry out the method may be pushed and/or pulled through the existing main, and the pushing force may be applied by percussive action.

Abstract: The invention relates to a process for the removal of acid gases from gaseous mixtures wherein said mixture is contacted with an aqueous alkaline solution comprising a compound of an alkali metal or ammonia and an alkanolamine-based promoter characterized in that the promoter is a mixture of at least one secondary alkanolamine and at least one N-alkyl-2-aminoethanol, said alkyl radical containing up to 3 carbon atoms.

Abstract: A method and antenna assembly for transmitting into the ground polarizeable radiation whereby buried objects, and particularly long thin objects such as pipes can be located, the position determined, and the pipe direction ascertained, by taking measurements from a signle point, without mechanical movement of the antenna, and thereby allowing for good suppression of spurious signals and a reduction in false indications. The method includes the steps of transmitting into the ground polarizeable radiation, receiving reflected signals, indicative of the objects, incident upon at least two co-located angularly disposed transducers and comparing the signals thus received, wherein the radiation is transmitted from a transducer source which is co-located but angularly disposed with respect to each receiver transducer.

Abstract: A device for removing a weld bead from the external periphery of a plastic gas pipe.The device (FIG. 2) has a body 10 with an inclined reaction surface 13 and a blade 21. The blade 21 is engaged with a bead 22 and the portion 22a of the bead 22 which is lifted is gripped between a toothed wheel 17 and the inclined surface 21. As the wheel 17 is rotated by use of a lever 18 operating via a ratchet, the device is moved bodily around the circumference of a pipe 31 to remove the bead 22.Retractable and adjustable stabilising means 25, 28 etc. are provided and there is a hardened end portion 20 on the body 10 to enable the device to be hammered to engage the blade in the bead initially.

Abstract: Resistance faults, for example across insulating joints of cathodically protected pipelines may be evaluated by comparing magnetic field strengths associated with a test current of predetermined frequency flowing into and away from the joint.

Abstract: An apparatus for replacing an existing buried pipe of a crackable, fracturable material. The apparatus has a fracturing structure which applies an intense local pressure to crack and fracture the existing buried pipe into irregular fragments. This fracturing structure can include one or a plurality of blades, some of which may be retractably and expandably movable. The structure which exerts the intense local pressure is also operable to effect at least some outward movement of the fragments. An expansion structure moves the fragments radially outwardly, generally about the axis of the existing main, to provide a passage for a replacement tubular assembly. The apparatus is moveable through the existing main by the action of either a pushing or a pulling force, and the pushing force may be applied by percussive action.

Abstract: The probe is of the withdrawable type and consists of an elongated cylindrical body made up of a tube 10 joined to an upper T-connector and to a lower tip portion 18. The tip portion 18 is of stepped shape and has a through-passage 34 beneath the step. A pressure tapping 36 opens at a port 38 in the wall of the through-passage 34 to sense reduced pressure at a vena contracta in the passage 34. Another tapping 40 opens at a port 42 in the step face 26 adjacent a concave face 28 which causes a pressure higher than static pressure. The total pressure difference can be three velocity heads and is communicated through tubes 20, 22 to a differential valve so that changes in flow rate in the pipe 16 affect the valve. The probe is relatively of small diameter and is especially applicable to control of the pressure in relation to the rate of flow of natural gas in distribution systems.

Abstract: A pipe scraper for scraping the end of a plastics pipe such as a plastics gas main or water main has a framework (10) in which is journaled a helically bladed rotary cutter (14) driven by means of a lever (17). On the shaft carrying the cutter is a pinion (16) which meshes with a larger pinion (19) driving a friction surface roller (21). The cutter is held in a Reed clamp and as the lever (17) is turned it rotates the helically bladed rotary cutter so as to scrape a low angle helical scrape approximating a longitudinal scrape. At the same time the rotation of the roller (21) causes the whole framework to rotate around the surface of the pipe so as to scrape the whole end peripheral surface.

Abstract: A tool has a hollow elongated body 10 made up of a leading section 12 attachable to a tow-cable by a clevis 28, an intermediate section 14 and a trailing section 20 housing a hydraulic cylinder 24 and attachable to a main liner 30. The intermediate section includes a frusto-conical wall in two parts 16 and 18, each of 180.degree. angular extent. The ram 24 operates a wedge 22 longitudinally to move the first part 16 outwardly or inwardly transversely of the body. The parts 16, 18 are slidably trapped to the wedge by slide components projecting into grooves. The tool is pulled by the two cable into the main with the part 16 retracted. Then the part 16 is moved outwardly to burst and enlarge the main, allowing the tool to advance further after retraction of the part 16. The parts 16, 18 each have an external longitudinal rib 68, 70. The part 16 has longitudinal marginal extensions overlapping the longitudinal margins of the part 18.

Abstract: The invention relates to a self-propelled apparatus 1 for replacing main such as a gas main 2, comprising a single double acting hydraulic piston and cylinder combination 3 connected with slidable devices 4, 6 operable by the device for step-by-step movement of the apparatus through the main on alternate strokes of the combination, the devices 4 and 6 being operative in only a forward direction to slide to grip the main, the apparatus drawing a vibratable breaker device 20 (FIG. 2) or 30 (FIG. 3) through the main, the device being vibratable to precess about an axis and the device 30 being vibratable by percussive means longitudinally of the main.

Abstract: A method for sealing a pipe-joint comprises injecting from a point or points 5 externally of the pipe an anaerobically curable monomer into the joint gap in such quantity that the monomer forms a contiguous band 9 within the joint gap and allowing the monomer to cure within the joint gap.