Abstract: An explosion welding method for metal tube liners in which a metal tube of smaller outside diameter is positioned coaxially within a metal tube of larger inside diameter with one or more shims inserted at opposed tube ends to form a uniform annular gap. The tubes are vertically positioned on a flat surface, and the smaller tube is filled with explosive material detonated from its top surface. The detonation initiates a uniform explosive front traveling down the smaller tube expanding the internal surface of the smaller tube with sufficient velocity to weld the tubes. A vacuum may be formed within the annular gap and/or gas(es) introduced therein to prevent build-up of excessive heat at the explosive front.

Abstract: A refiner plate clash detection system and method for plate clash detection is provided herein. The system includes a receiver for a first signal having a significant increase in level at at least one distinct predetermined frequency related to the clash and the characteristics of the discs of the refiner. A filter is provided having a passband matched to pass the distinct frequency of the signal to provide a filtered output signal in which the center frequency of the passband of the filter is determined by the formulaf.sub.o =n.SIGMA..sub.Rwhereinf.sub.o is the center frequency (expressed in Hertz) of said passbandn=the number of segments at a given radius, per single disc and.SIGMA..sub.R =the sum of the rotational rates (expressed in Hertz) of the two discs enclosing a given refining volume.The filtered signal is then smoothed. A threshold level is established.