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API 5L steel pipes (API 5L standard, mainly carbon and low-alloy steel) are widely used in oil and gas industry for onshore/offshore oil/gas transmission pipelines (including long-distance trunk lines, gathering pipelines and distribution pipelines); applied in petrochemical sector for crude oil refining plant process pipelines and oil product transportation pipelines; used in natural gas industry for city gas distribution networks and natural gas storage facility connecting pipes; suitable for energy sector like coalbed methane transmission pipelines and shale gas extraction gathering pipelines; and also adopted in industrial fields for high-pressure fluid transport pipelines (such as water injection pipelines in oilfields and chemical medium transmission pipes with low corrosion requirements).