ITU‐T's Technical Reports and Specifications 391 Figure 2 – Functional classification of underground pipelines [source: CJJ 61‐2003, b‐26] Underground pipelines Water supply pipelines Drainage pipelines Gas pipelines Heat pipelines Electricity pipelines Telecom pipelines Industry pipelines Other pipelines Municipal water pipelines Firefighting water pipelines Industrial water pipelines Agricultural irrigation water pipelines Effluent pipelines Rainfall pipelines Effluent/rainfall interflow pipelines Coal gas pipelines Natural gas pipelines Hot water pipelines Steam pipelines Telecommunication cable Radio and television cable Special communication cable Petroleum pipelines Chemical industry pipelines Deslagging pipelines Liquefied petroleum gas pipelines Power cable Lighting cable