L41020 Gas Hydrates and Their Relation to the Operation of Natural-Gas Pipe Lines

It became generally recognized that “freezing” of natural gas pipeline was caused by the formation of gas hydrates, which are crystalline compounds formed by the chemical combination of natural gas and water and which form under pressure at temperatures considerably above the freezing point of water.Benefit: Hydrate equilibrium data are presented for a number of natural gases, certain constituent gases, and synthetic mixtures of these gases, showing the temperature and pressures at which hydrates form. The ratios of gas to water in the gas-hydrate molecules are given. Data on pipeline and underground temperatures and their seasonal temperature variations are presented. Remedial measures to remove or prevent “freezes” in pipelines are discussed. Water is necessary for hydrates to form, the removal of water from natural gases is an effective way of combating the hydrate freezing of pipe lines. Dehydration plants of various types for drying natural gases are described, as well as the chemicals used in the drying processes. Methods and equipment for determining the water-vapor content of natural gases under pressure are described, and data are given on the water content of water-saturated natural gases under pressure.