British Gas Plc

Lattice Intellectual Property Limited

Bg Transco Plc

Roger Philip Ashworth

David J Gunton

Mark Harper

Paul B Cordes

Howard F Scott

Mehrdad Z Tabari

Stephen Antony Rowe

Michael P Stansfield

Kenneth Watson

A pipe leakage detection system which includes a flexible probe with a body portion of sufficient length to pass along a pipe. Pairs of seals define a seal volume with the inner pipe wall. An adjacent test region can be used to determine leakage. A source of fluid pressure is applied to lines. With equal pressure in both seal and test regions as indicated by a manometer no leak will occur around the seals. A deliberate outgoing flow rate is allowed from a line and any differential in flow, as detected by flow meters, will indicate an actual leakage rate.

Measuring leakage through ducts

An acoustic temperature measurement system for pipeline fluids comprises a loudspeaker ( ) with spaced microphone ( ) in a sealed pipe ( ) with end cap ( ). A computer arrangement ( ) provides a tone burst signal which drives the speaker via power amplifier ( ) and the outgoing and reflected signal is detected by the microphone ( ) and following amplification in amplifier ( ) passes to the computer ( ) for processing. The signals are processed to determine phase relationships indicative of temperature and can be used in correcting leakage measurement readings.

Fluid temperature measurement

A pipe leak testing arrangement which includes a device having sealing bags joined by a coupling. When inflated, the bags form a seal volume chamber. The bags may not form a perfect seal, and as a result leakage past the bags may occur when a differential pressure is present. A remaining portion of the pipe forms a test volume chamber. A first transducer measures differential pressure between the chambers and a further transducer measures the test chamber pressure. Measured pressure information is used by a control device to track pressure change and to adjust the seal pressure so as to maintain equal pressures even if the test pressure decays due to a pipe fracture. In an alternative arrangement, two separate devices with associated circuitry are provided to facilitate two temporary seal pressure chambers with the test chamber therebetween.

Pipe leak detection

Air is passed under pressure into a pipe under test and into a reference chamber connected to the pipe by a valve while recording at intervals of every few seconds the temperature in the reference chamber, the temperature in the pipe and the absolute pressure in the reference chamber. When the test pressure has been reached the valve is closed and the differential pressure between the pipe and the reference chamber is measured. The valve is opened to equalize the pressure and then closed again and the differential pressure drift rate is measured. This is repeated several times. A computer is used to calculate a creep prediction curve. A comparison is made to see whether the pressure drift rate due to creep and leak only in the pipe independent of any temperature change in the pipe is trending towards crossing the curve or not.

Method of testing pipes for leakage

The vehicle has two groups 24, 26 of foils which transfer flux to and return flux from a wall 10 of a pipeline. The flux is from a coil 20 or from a permanent magnet or magnets. Each group is a single group of common foil members 59 interleaved with spacers 69; or alternatively each group contains sets of common foil elements such as six sector-shaped sets, for example. Each foil 59 and each spacer 69 is cut from steel for example stainless steel. Each foil 25 is an outwardly-directed resiliently-deflectable foil integral with the common foil member forming an array around the vehicle. The foils are separated by slots 63 preferably V-shaped. The sets are clamped together by retainers 73 and pins 71. In the pipe 10 the foils deflect as indicated by broken lines 32, 34. The length of each foil is at least 200 times its thickness. The foil separation divided by their thickness is at least unity. Sensors 28 detect leakage flux due to metal loss from the wall.

Foil assembly for magnetic inspection machines

A pipeline inspection vehicle comprises a body 18 an electromagnet 20 for generating magnetic flux, and two foil packs 24, 26 for conducting the flux into and out of the pipewall 10. An array of defect sensors is arranged around the body 18, each sensor being mounted on a respective assembly 28. Each assembly 28 comprises a steel sledge 40 which runs along the pipewall and which is secured to a sensor housing 42. A length of belting 44 is sandwiched between the two and end portions form a leading member 46 and a trailing member 48 linking the sledge to the vehicle. Each assembly 28 is positioned against a spring 64 which is also positioned against the vehicle. The assembly collapses out of the way when the vehicle traverses a sharp bend and the foil pack 24 is deflected to the right. The two members 46 and 48 both counteract the force of the spring 64 when the sledge crosses a void in the pipewall. However, only the leading member 46 is effective during normal running of the sledge along the pipewall to transfer the motion of the vehicle to the sledge.

Pipeline inspection vehicle

Vehicle with plastic suspension

A wheeled support assembly 10 is manually pushed over the ground and has a motor 22 rotating an antenna assembly 60 about a vertical axis 24. Encoders 28 on the antenna shaft 20 and on a wheel axle encode antenna angular position and position over the ground. Transmitted pulses and received data pass through a rotary microwave connector 26. For example, 400 sets of pulses are emitted at equal angular intervals in each revolution of the antenna assembly. The interval between pulses is e.g. 12 microseconds, with 256 pulses per set. Noise reduction is achieved by processing the received data accordingly. In a modification the rotary connector 26 is single channel with some electronic stages mounted on the rotating antenna assembly. Power is coupled to them via the microwave cable. An umbilical connects the assembly 10 to a support facility including a computer. Alternatively, battery power is used with data transferred radiatively.

Growing community of inventors

Loughborough, United Kingdom

Roger Philip Ashworth