Underground routing
Underground routing of pipelines, directly buried or in service ducts. The service ducts are required for pipeline protection against external impacts. There are 3 types of service ducts: 1) non-accessible, when many small diameter pipelines or a pair of pipelines (supply and return) run together; 2) semi-accessible, for complex construction conditions of heat supply utilities; 3) accessible, when there are many pipelines, and access is required to them.