The connection between pipeline and rotating equipment, such as the connection between pipeline and pump and the connection between pipeline and compressor unit, is common in the piping installation of chemical plants. The suction / discharge pipeline of compressor has large diameter, high technical requirements for piping, and strict requirements for installation quality and internal cleanliness of pipeline. In order to avoid displacement or vibration of compressor during operation due to pipeline adhesion stress, which will affect the normal operation, stress-free piping must be carried out during the installation of its connecting pipeline, and this is particularly important for the compressor. In the piping construction of cracking gas compressor unit in the ethylene plant of PetroChina Dushanzi Petrochemical Company, the stress-free piping technology has been adopted successfully. Through practice, summary and refinement, this paper discusses the construction technology of stress-free piping and standardizes its construction method.