Depending on how thermal expansion and contraction are managed, the installation of prefabricated polyurethane-insulated direct-buried pipes is primarily categorized into three methods: cold installation, preheating installation, and installation using one-time compensators. Cold installation is the most straightforward approach; the pipes are welded at ambient temperature and then backfilled immediately. Once the system is in operation, the thermal stress resulting from temperature increases is borne entirely by the pipes themselves and the friction from the surrounding soil. While this method offers simple construction, allows for prompt backfilling, and is the most cost-effective, it results in higher operational stress on the pipes. Preheating installation involves heating the pipes to a specific fraction of their operating temperature before backfilling the trench, with welding and backfilling performed while the pipes are in this preheated state. As the pipes cool and contract, a compressive stress is established within the insulation layer; during operation, this helps offset a portion of the tensile stress caused by thermal expansion, effectively reducing the overall operational stress. Installation using one-time compensators involves placing compensators at set intervals throughout the pipe network to absorb deformation. The pipes are backfilled at ambient temperature; once the system is operational and the pipes have reached their designed elongation, the compensators are welded into a fixed position and then backfilled. This method also significantly reduces axial stress on the pipes, though it entails higher construction costs. Furthermore, "uncompensated" electric preheating technology-which has gained traction in recent years-uses electrical heating to warm the pipes; this approach is simpler and more uniform than traditional preheating methods, offering greater construction efficiency. Regarding the layout, direct-buried installation is currently the predominant choice for centralized heating networks, while overhead and trench-based installations are used less frequently. The specific installation method should be selected based on a comprehensive assessment of project conditions, investment budgets, and construction schedule requirements.