A method of feeding nitrogen to replace gas between two scrapers is adopted in Beijing Gas Loop Line originating from Huabei Oil Fields which is the source of gas supply for Beijing City.

• 承担着为首都供气任务的华北油田北京供气复线工程,为确保安全投产,采用了双清管器间加充氮气形成隔离带进行置换的方法。