LineVu has been deployed on temporary and permanent bases at gas hubs and custody transfer points
A Transmission System Operator (TSO) responsible for a European National Transmission System (NTS) has, for the past five years, deployed LineVu systems on temporary and permanent bases at gas hubs and custody transfer points to better understand the presence of liquid carryover in its incoming gas supply
The results revealed that hydrocarbon dewpoint (HCDP) does not respond to liquid events, making it unfit for purpose. Based on these findings, they have standardised the use of LineVu systems across their transmission network, making them an essential tool for monitoring gas quality, protecting compressors and infrastructure, enhancing compliance with regulations, and ensuring supplier accountability.
THE CHALLENGE
They discovered that liquids would occasionally enter their network without tripping alarms. This breaches supply agreements and results in higher operational costs due to increased pressure drop, increased pigging, and increased compressor and instrumentation servicing.
Measurements for moisture and hydrocarbons, conducted in accordance with BS EN ISO 10715:2022 for gas sampling, were conducted with frequent calibration, but indicated that the gas was dry. The company wanted to improve its compliance with the Gas Safety (Management) Regulations (GSMR) and ASME B31.8S for the Management of System Integrity of Gas Pipelines.
THE SOLUTION
After three years of testing, they now deploy LineVu high-resolution process cameras at all of their custody transfer points. Certified for hazardous areas, the cameras can provide continuous, real-time footage of the gas stream, locally for control room operators and via the online dashboard to enable managers and remote engineers to see mist flow and liquid flows at the bottom of the pipe. Smart alarms were developed to alert operators when abnormal conditions appear.
IMPROVEMENTS
It has been found that during onset and throughput liquid events, HCDP does not move from a low to a high dewpoint; it remains unchanged.
Process Vision has investigated this phenomenon across installations worldwide and concluded that the gas flow and liquid are not necessarily in equilibrium when gas is flowing in a pipeline.
The evidence shows that HCDP, on its own, is not a reliable method for assessing gas dryness. Although it has been used for years, it can mislead process engineers into believing the gas is dry when it is not. With video evidence, operators can make better decisions to maintain a dry transmission system from inlet to outlet.
With a better understanding, the TSO hopes improve safety using this approach. In the short term, reductions in pigging frequency, compression costs, and erosion and corrosion of valves and regulators are anticipated. Additional cost reductions are expected in the long term due to fewer compressor trips, reduced servicing requirements, and extended asset life.
BUSINESS CASE
The use of these automated liquid detection systems helps the TSO ensure that the gas entering the NTS is free of liquid contaminants and supports the Safety & Compliance innovation strategy objective.
With each contamination event thought to cost at least £50,000, there is a rapid ROI. There are also benefits for suppliers to the NTS. Even a small liquid volume fraction (0.1%) can increase NGL revenue by over £4m annually. For TSOs, catching liquids early prevents compressor trips and extends the dry-gas seal life from 1 year to 3+ years.
The TSO has standardised the use of LineVu systems across the National Transmission Network, ensuring consistent monitoring, transparent supplier accountability, and proactive protection of downstream assets.
