Following the incident that occurred on Friday in the main gas pipeline in Pasvalys district, the gas pipeline restoration works were carried out this weekend. In parallel, adjacent sections of the pipeline were checked. X-ray examination of the welds showed that the pipeline is safe to operate. The gas supply to Latvia through the pipeline is scheduled to be restored on Monday.
The trunk pipeline, built in 1980, supplies gas to Lithuanian consumers and to Latvia. The diameter of the pipeline affected by the incident is 700 mm and the wall thickness of the steel pipe is approximately 7-8 mm. The pipeline was insulated with a protective coating during construction and a cathodic protection system was installed to protect the metal from natural corrosion. The pipeline is laid at a depth of approximately one and a half metres. This is almost twice the legal requirements.
Lithuanian legislation requires the gas transmission operator to inspect it every 8 years. The most recent diagnostics of this pipeline were carried out in 2011 and 2016. Regular inspections have been scheduled for this year as well. The inspections carried out did not reveal any damage to the pipelines. Amber Grid specialists are currently reassessing the data collected during the inspections.
According to Amber Grid, pre-planned maintenance work on the pipeline was carried out last week further away from the site of the incident, with the replacement of the pipeline insulation coating. This is a routine and ongoing maintenance work, where the pipeline is dug up and the insulation coating is replaced after the damaged insulation layer is detected by special equipment. This protects the metal pipeline from corrosion.
Whether the works carried out may have contributed to the gas pipeline incident will be determined during the investigation carried out by law enforcement authorities and Amber Grid specialists. The part of the pipeline affected by the incident has been cut out and handed over to law enforcement authorities. This part will be examined by an accredited laboratory at a later stage and the composition of the metal and the condition of the seam will be assessed.
"Consistent maintenance and safety of gas pipelines is one of Amber Grid's top priorities. Every year we draw up annual maintenance plans and work schedules for trunk pipelines, and allocate tasks to our employees according to these plans. Inspection work is recorded in databases and a photo archive of the work is kept. However, main gas pipelines are considered to be high-risk all over the world, so protection zones are established around them, regulating the distance from which residential houses or other facilities can be built," says Nemunas Biknius, Amber Grid's CEO.
Amber Grid specialists check an average of 200-300 km of gas pipelines each year by means of internal diagnostics. The inspections are carried out by means of internal diagnostics - smart devices that scan the walls of the pipeline and provide the specialists with information about its condition. This year, Amber Grid had planned to inspect as many as 600 km of gas pipelines. In total, there are 2,285 km of main gas pipelines in Lithuania.
Amber Grid, the operator of the gas transmission system, employs 330 people, two-thirds of whom (around 200) are regularly involved in the operation, maintenance and repair of gas pipelines. This work is also carried out by contractors. In 2022, EUR 2.6 million was allocated for pipeline maintenance and repair. The planned investment for 2023 is around EUR EUR 4.5 million.
The maintenance work is primarily aimed at identifying possible damage to the pipeline insulation. If damaged insulation is detected, a section of the pipeline is dug up and the pipeline is reinsulated using special equipment that is used without digging the pipeline. Gas pipelines are also regularly inspected by specialist walkarounds or drone surveys for possible gas leaks. All information is recorded not only according to defined parameters, but also in a photo archive.
Following annual pipeline diagnostics plans, special devices are allowed inside the pipelines to initially dislodge any extraneous material that may have accumulated in the pipelines. Later on, smart devices are allowed in to search for potentially damaged areas based on parameters set by experts. Once the internal diagnostics have been carried out, repairs to the pipeline are planned and carried out.
Amber Grid makes sure that residents, businesses and people's property close to the pipelines remain safe even in the event of a rare accident. Protection zones have been established for all high-pressure trunk pipelines. These are an area of land along the axis of the pipeline, 25 metres in both directions. The pipeline protection zone allows agricultural activities. However, there is a restriction on the construction of buildings in the pipeline protection zone for human safety reasons. This is also important for maintenance or reconstruction work: the pipeline protection zone must be open and undeveloped to allow access to the pipeline route for professionals.
No digging deeper than 30 cm, no strong vibrations, no storage of chemicals and fertilisers, no fires and no camping in the pipeline protection zone.
Most of the main gas pipelines run through private land. People planning to buy or rent land or property should check whether the area is subject to restrictions related to the gas transmission system. Activities near the gas pipeline require the consent of Amber Grid.
Why can gas catch fire in a pipeline incident?
Trunkline pipelines transport gas by compressing it under extremely high pressure. As a result, if a weld in the pipeline breaks or for any other reason the gas starts gushing out of the pipeline, it exposes the ground above the pipeline, and the gravel or rubble in the ground can ignite a spark. In this case, the gas ignites and burns until the section of the pipeline up to the closed taps is burnt out. In Friday's incident, the gas in the 18 km of pipeline between the closed taps burned for about 4 hours.
If you hear whistling noises from the ground or see a fire in the vicinity of the pipeline, please call 112 immediately.
