The method of defects identification for underground heating networks

Abstract

In the recent years great attention has been paid to the issues arising during the technical inspection of the
underground heating networks with pipelines isolated in polyurethane foam run by the means of channelless pipe
lying. The defects arisen most often in the pipeline with polyurethane isolation have been classified. Having changed
three information-bearing parameters (the current in the pipeline walls, acoustical pressure on the soil surface, the
temperature of the near-surface soil above the heating network) which were measured along the inspection area the availability of defects in the pipelines with polyurethane foam isolation can be determined. The formulae have been
given for information-bearing parameters calculation. The method for all types of defects identification has been
developed in the underground heating networks which is based on the comparative rating measured along the inspection
area and calculated using analytical models of the information-bearing parameters for inductive, microphone
and thermal contact inspection methods. Test uncertainty predetermined by the identification algorithm of
types of defects according to three information-bearing parameters and calculated by the Bernoulli scheme equals
17.9%. The installation has been described for making test research of information-bearing parameters variations if
all types of studied defects of pipelines heating systems are available. To inspect the developed identification method
of all types of pipeline defects in the underground heating networks the information and measuring system has been
created and it was successfully tested at the community facilities.