Definition - What does Sour Service mean?
Sour service describes a type of pipeline or storage vessel that is filled with substances that contain hydrogen sulfide (H2S) or sulfuric acid (H2SO4). In order for the service to be considered a sour service, the hydrogen sulfide levels must be above a certain threshold. Sour service can subject the vessel material to corrosion.
Corrosionpedia explains Sour Service
Sour service occurs when a substance being transported or stored in a vessel has high amounts of hydrogen sulfide or sulfuric acid. There may be several ways in which hydrogen sulfide is introduced to a substance. However, one of the most common ways is through biochemical means. When a substance contains sulfates and is exposed to microorganisms, hydrogen sulfide may be created because the microorganisms use the oxygen molecules and the leftover sulfur bonds with hydrogen, forming hydrogen sulfide. From there, the hydrogen sulfide can be oxidized to form sulfuric acid. The sulfuric acid can then lead to corrosion.
Sour service is a major concern for the oil and gas and wastewater industries. Bacteria in the product collected during the extraction process in the oil and gas industry mixed with high amounts of sulfates can result in a sour service condition. This same risk exists frequently in the wastewater industry as well.
There are several ways to combat the risk of sour service. One way is through materials selection, such as selecting stainless steel or low alloy steel with extremely low levels of sulfur in its chemical composition. Organic inhibitors can be used to kill the microorganisms that commonly create a sour service environment.