Surveillance system including means for detecting impending failure in high pressure, high temperature fluid conducting pipes

Claim 1

A monitoring system for predicting structural failure in a member subject to stress by sensing strain, comprising sensing means for sensing strain disposed proximate to said member in a region of potential strain, said sensing means having an output terminal, said sensing means providing a voltage signal at said output terminal in relation to the amount of strain sensed in said member, a high level signal detector and a low level signal detector each comprising a differential operational amplifier, each said operational amplifier having an input terminal which is connected to said output terminal of said sensing means, each said high level signal detector and said low level signal detector not being interconnected, warning means, said warning means comprising a high level warning means and a low level warning means connected to the output of said high level operational amplifier and said low level operational amplifier respectively, said output voltage signal from said sensing means being provided to said high level operational amplifier and said low level operational amplifier substantially simultaneously, said low level operational amplifier actuating said low level warning means when said strain in said member is of a first predetermined value, said high level operational amplifier actuating said high level warning means when said strain in said member is of a second relatively larger predetermined value, said input terminal of said high level operational amplifier being maintainable at an adjustable voltage potential relative to a fixed voltage potential to generally fix said second relatively larger predetermined value of strain in said member at which Said high level warning means is actuated, said input terminal of said low level operational amplifier being maintainable at an adjustable voltage potential relative to a fixed voltage potential to generally fix said first predetermined value of strain in said member at which said low level warning means is actuated, said low level warning means comprising first and second low level warning sections, said first low level warning section comprising a first low level warning section electrical valve and a first low level warning section illuminating means with power supply mens, wherein said latter two means are interconnected electrically, wherein output electrical current from said low level operational amplifier actuates said last mentioned valve to cause said last mentioned illuminating means to visually indicate the presence of said first predetermined value of the strain in said member, said second low level warning section comprising a reset means, a second low level warning section electrical valve, and a second low level warning section illuminating means with power supply means, wherein aid latter two means are interconnected electrically, wherein output electrical current from said low level operational amplifier actuates said last mentioned valve to cause said last mentioned illuminating means to visually indicate the presence of said first predetermined value of said strain in said member and to continue to indicate the presence of said first predetermined value of said strain in said member until reset by said reset means.