After 2 years and 3 months, the ventilation system design, manufacture, installation and testing of YAMAL LNG construction project, which is in charge of by our company, has been successfully delivered. This project is the first LNG project in the Arctic Circle. Influenced by extreme polar climate, the ventilation duct design benchmark is implemented according to the winter ambient temperature of -42 C/94% RH (extreme mechanical design temperature - 50 C), the ventilation system design temperature in summer + 16 C/76% RH. According to the project specification "ventilation system design requirements", this project is the first application of SP 60.13330.2012 (ventilation system design). Design with SMAC NA (Ventilation Pipeline Design) standards results in that the manufacturing and inspection standards of ventilation pipes are much higher than those of similar offshore oil platforms.