Pretreatment of the Products

Certain requirements concerning the purity of the product to be transported must be fulfilled. For natural gas, the water content should be kept below a certain level to reduce hydrate formation. In addition, oxygen and sulfur must be controlled effectively. Some issues are presented in Table 11-1. 

Methods used to control presumptive corrosion include deaeration and dehydration. Carbon dioxide and hydrogen sulfide are the main corrosives in pipelines for natural gas, but they are only aggressive in the presence of water. Therefore sweetening and drying the gas are useful to prevent corrosion. In oil pipelines, water emulsified in crude oil can cause corrosion problems [251]. Emulsified crude oil in separated produced water is also an environmental and disposal problem. 

Main Classes of Additives and Chemicals Used for Transport 

Pour-point depressants Reduce pour points of waxy cmdes 

Gas hydrate inhibitors For gas and multi-phase transport to prevent hydrate deposits 

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