Comprehensive Diagnostics of gas Pipelines

SPC "Lightning" has developed a technology for above-ground integrated technical diagnosis of such pipelines, which includes:
- determination of the position and depth of the gas pipeline;
- non-contact determination of damage to the insulation coating;
- determination of the effectiveness of electrochemical protection;
- identification of corrosive areas;
- identification of areas of increased mechanical stresses in the metal of the gas pipeline by the magnetometric method;
- detection of gas leaks using mobile leak detectors, as well as airborne optical and thermal surveys;
- pit surveys based on the results of elevated surveys to clarify the state of insulation, base metal and welded joints of the gas pipeline using non-destructive testing methods and determine the physical and mechanical properties of pipes, including instrumental quantitative measurements of mechanical stresses in a metal by x-ray diffractometry;
- mapping using satellite receivers (the coordinates of the gas pipeline, terrain features, landmarks, identified anomalies and damage).

Specialists of the Molniya Scientific and Production Center created the M-1 diagnostic complex for above-ground monitoring of pipelines, which simultaneously provides electrometric and magnetometric measurements and thus performs the functions of several instruments.

Landscape and geological changes, thermal and color anomalies on the gas pipeline route, gas leaks, economic disturbances in the security zone are detected during an air video thermal imaging inspection of the gas pipeline using helicopters and hang-gliders.

When examining gas pipelines in potentially hazardous areas where the appearance of geological faults, karst voids, landslide areas, waterways and areas of increased water cut of the soil, geophysical methods were used (electrical profiling, electrical discharge by natural electric field, vertical electrical sensing, seismic sounding and seismography). This made it possible to identify potentially dangerous sections of gas pipelines and then conduct detailed surveys of the state of gas pipelines there, as well as to evaluate the stress-strain state of gas pipelines using instrument and calculation methods. A survey of sections of mutual intersections of gas pipelines is also carried out.

The most dangerous sections of the gas pipeline detected during an above-ground inspection are drilled and the technical condition of the pipe metal is determined using the whole range of methods and means of non-destructive testing and diagnostics (visual and measuring methods; ultrasonic, including thickness measurement; magnetic and electromagnetic, including measurement of coercive force ; capillary; hardness measurement, etc.). The location of the most stressed sections of the pipe in the pit is specified by the magnetometric method in the contact version and there the stresses are measured by X-ray diffractometry.

Of great interest is the diagnosis of tees, in particular the identification of defects under the overlays. In this case, we use special methods of ultrasonic flaw detection.

The effectiveness of the applied methods, means and technologies of above-ground diagnosis by the types of detected defects is characterized by the following. Gas leaks were detected during an aerial video thermal and surface inspection, serious corrosion damage was found, mechanical damage and metal stratification (in pits) were found, unsatisfactory working means of electrochemical protection, violations in the security zone (buildings, including residential ones on the axis of gas pipelines - bends and in the zone of minimum permissible distances, unauthorized landfills, overgrowth of woody vegetation), numerous sections with insufficient depth and welded joints with permissible defects (in pits).

The newly created methods, tools and technologies for diagnosing gas pipelines must, first of all, satisfy the following conditions:
- increase the sensitivity and reliability of the detection of defects and deviations in the physicomechanical properties of materials used in the gas pipeline;
- increase productivity and reduce the complexity of diagnosis in the field;
- quantitatively determine the stress-strain state, residual life and the risk of operation of gas pipelines.