Hydrocarbon Dewpoint; the Gap Between Theory and Reality 

2025 Conference Workshop

For decades, hydrocarbon dewpoint has served as the industry’s standard for determining gas “dryness” in natural gas transmission and distribution. However, recent findings are suggesting that relying solely on hydrocarbon dewpoint is not enough to ensure dry gas. Widely variable results across dewpoint measurement methods highlight a significant accuracy gap that leads to undetected liquids in pipelines. This variability introduces risks to operations, making a case for advanced tools to provide a more comprehensive approach to gas quality.

Traditional hydrocarbon dewpoint is a key factor in gas sales contracts, determining if natural gas supplies meet the “dry gas” criteria essential for safe transmission. Even small volumes of liquids—mist or stratified flows of hydrocarbons—can cause increased risks, increased costs and operational challenges and downstream. When these go undetected, they can lead to equipment damage, costly disruptions, and inefficient operations. Unfortunately, variations in dewpoint measurement and calculation methods can create uncertainty about the true condition of gas in the pipeline, with the error for a single gas mixture sometimes spanning up to 186°F (103.6°C)​. This inconsistency is a growing concern for gas suppliers and end-users alike.

This paper will show examples of errors observed in the field and introduce a solution on how to bridge this reliability gap and how the introduction of advanced visual monitoring technologies can improve efficiency and performance of both gas processors and gas transportation.

Real-time visualisation of gas flows inside high-pressure pipelines allows operators to detect actual liquid presence directly. Unlike hydrocarbon dewpoint calculations, which provides only inferred data about liquid formation based on pressure and temperature calculations. This live video feed enables operators to spot liquid mist, stratified flows, and small volumes of natural gas liquids (NGLs) that traditional measurements fail to report.

The implications of this approach are transformative. With real-time visual data, operators can swiftly identify and address liquid contamination issues, improving pipeline integrity, optimising system maintenance, and protecting against costly disruptions. This paper advocates for a new approach into standard gas quality protocols, where advanced visual monitoring is incorporated as a complementary tool to hydrocarbon dewpoint, ensuring that gas quality measurements are both accurate and reliable.