Piping Installation Principles
The pipeline installation sequence follows a regional and system-based approach, prioritizing large diameters over small ones, lower levels over upper ones, difficult tasks over easy ones, and above-ground tunnels before connecting equipment. The principle for connecting pipes to machinery is to fit them from the inside out to minimize the impact of welding stress on installation accuracy. The junctions between indoor and outdoor pipelines should be left outdoors.
I. Pipeline Installation Requirements
Prior to installation, the pipeline should be reviewed for items related to pipeline installation, including equipment pipe ends, embedded parts,预留 holes, and steel structures.
2. The pipeline gradient should be adjusted according to the drawings' specifications. Adjustment methods can utilize supports to meet the gradient requirements, with welds positioned for easy maintenance and observation.
3. Pipes connected to transmission equipment should be cleaned internally prior to installation. The welding of fixed pipe ends should generally be located away from the equipment to avoid stress from welding affecting the installation accuracy of the transmission equipment.
Before connecting pipes and machinery, prevent strong relative forces and check the parallelism and coaxiality of the flange in a free state.
5. Safety valves should be installed vertically, and timely adjustment of the safety valve is required during trial operation. The final adjustment of the safety valve is made on the system, with the opening and seating pressures complying with the specifications of the design documents.
6. Prior to valve installation, verify the model against the design documents and determine the installation direction based on the medium flow direction. When connecting the valve to the pipe with a flange or threaded connection, the valve should be installed in the closed position; if installed by welding, the valve must not be closed.
7. Temporary Replacement of Instrument Components: All instrument components are temporarily replaced during installation. They are then formally installed after the pressure testing, flushing, and blow-off operations are completed and before the material is introduced.

Section II: Pipe Support and Hanger Fabrication and Installation
The on-site manufactured pipe racks are strictly constructed according to specifications and drawings, and are painted for protection. The吊耳 supports for the rod hangers and spring hangers should be welded according to steel structural manufacturing standards and undergo penetration or magnetic particle inspection.
All pipe rack locations should be indicated on the single-line diagram.
During pipeline installation, brackets should be promptly secured and adjusted. The bracket positions must be accurate, installations should be level and firm, and the contact with the pipe should be tight.
④ The fixed bracket should be installed according to the design documents and should be secured before the compensator is pre-stretched.
The sliding surface of the guide bracket or sliding bracket should be clean and flat, without any misalignment or binding. The installation position should be offset from the center of the support surface in the opposite direction, with the offset amount being half of the displacement value or in accordance with the design specifications. The insulation layer must not hinder its movement.
When using temporary supports for pipeline installation, they must not conflict with the position of the formal supports and should be clearly marked. Temporary supports should be removed after the pipeline installation is completed.
FRP/PVC pipes and pipe racks (including supports) must not be directly bonded or welded together. The pipe fittings (pipe clips, supports, or clamps) for fixing FRP/PVC pipes to the pipe racks should be supported by rubber blocks or other soft pads with a thickness of not less than 3mm, between them and the outer wall of the pipe.
After pipeline installation is completed, the forms and positions of the supports should be checked individually according to the design documents.