image

Diagnostics

A whole range of methods are used to secure safe and reliable gas transmission, and these are widely applied at NET4GAS.

Strict quality requirements are specified during the construction of pipelines and other important components of the gas system, and compliance with these requirements is consistently monitored.

During operation, key information is then collected regarding operation, failures and maintenance, along with diagnostic data relating to the technical condition of the monitored equipment and facilities.

Internal pipe inspections, during which an inspection device known as a “smart pig” passes through the pipes without interruption of operation, are a basic tool for performing pipeline diagnostics. Smart pigs are piston-like measuring devices which are propelled by the pressure of the gas flowing in the pipe. They can detect most pipe defects, whether these result from the manufacturing process, the actions of third parties, or corrosion resulting from damage to the pipe insulation. Repeating these inspections every few years and repairing any dangerous defects found ensures the safe, long-term operation of the pipeline. Most defects which are discovered can be repaired simply by replacing the pipe insulation. In exceptional cases, plastic “Clock Spring” sleeves are used for repairs, and as a last resort the damaged section of pipe may be cut out. NET4GAS has technologies at its disposal which allow even highly demanding pipe repairs to be carried out without interrupting gas transmission. Its comprehensive approach includes checking the quality of the pipe insulation, the precise localisation of all structures and defects using a Geographic Information System (GIS), and the careful maintenance of a database recording the condition of the pipeline from the time of its construction through to the present. The optimal use of all this information is ensured by its application of a Pipeline Integrity Management System (PIMS).

An important role in gas transmission is also played by compressor stations. Their safe and reliable operation is supported by the implementation of a diagnostic system, which simultaneously allows improved accident prevention and enables the performance of maintenance and repairs to be coordinated according to the actual technical condition of key technological facilities and equipment. The fundamental technique used in examining turbines and compressors is vibration diagnostics, which uses the measurement and evaluation of vibrations to make an assessment of the mechanical condition of the machinery and the nature of any defects. Other methods include measurement of the performance parameters of turbines and compressors; tribotechnical diagnostics, which assesses the condition of machinery based on the contaminants found in its lubricating oil; boroscopic testing, which allows internal inspections of machines to be made without dismantling them; as well as, for example, thermal imaging, which identifies incipient defects on the basis of the abnormal warming of certain parts of a machine. The majority of these techniques are employed by NET4GAS as part of its comprehensive system for monitoring the condition of compressor station technology.

At the present time, the current trend is towards the interlinking of diagnostic monitoring systems and management information systems, a greater focus on operational and maintenance efficiency, the performance of maintenance based on the results of systematic monitoring of the reliability of individual technology components and the evaluation of operational risks.

Over the entire history of its operation of more than 3,800 km of pipelines, NET4GAS has not experienced a single accident that endangered lives, significantly damaged the property of third parties or restricted the transmission of gas. Only two major pipe ruptures have occurred in the whole forty years of its operation, and both were before scheduled internal inspections of the respective sections of pipeline were begun.