The execution standards for polyurethane-lined pipelines in China cover materials, processes, performance, and testing throughout the entire process. The specific standard system is as follows:
I. Core National Standards
GB/T 29047-2012
This standard sets the core specifications for polyurethane-insulated pipes, detailing the structural requirements for high-density polyethylene outer casing and pre-fabricated rigid polyurethane foam plastic buried insulation pipes. Key indicators include:
Insulation layer density ≥ 60 kg/m³, closed-cell rate ≥ 88%, thermal conductivity ≤ 0.033 W/(m·K) (at 50°C);
Outer casing density ≥ 950 kg/m³, tensile strength ≥ 19 MPa.
It is applicable to municipal heating and industrial pipeline fields.
GB/T 29046-2012
Focuses on testing methods, specifying procedures for insulation layer thickness, air-tightness tests, and thermal conductivity measurements, requiring a random check of closed-cell rate ≥ 88%, and insulation layer thickness tolerance ±3 mm.
2. Structural Design and Material Specifications
Composite Structure Layer Requirements
Working steel pipe: DN800 pipes should use Q235B spiral welded pipes (SY/T 5037-2000) or 20# seamless steel pipes (GB/T 8163-2018), with anti-corrosion treatment reaching Sa2.5 grade and coated with 3PE layers;
Insulation layer: Polyurethane density ≥ 55 kg/m³ (national standard lower limit), with silicon carbide felt or aerogel interlayers required for high-temperature scenarios, thickness 50–100 mm (adjusted based on operating conditions);
Outer casing: HDPE outer casing must pass a 15 kV spark test, and fiberglass outer casing improves chloride ion permeability by 30%.
Special Scenario Adaptation Standards
Oil/Gas Field: Working steel pipes must comply with GB/T 9711-2017 (standard for spiral seam submerged arc welded steel pipes);
High-Temperature Pipes (>140°C): Use steel-clad steel outer structures, with galvanized steel tape thickness ≥ 0.5 mm.
3. Production Process and Inspection Acceptance
Pre-fabrication Process Specifications
Standard length of pre-fabricated pipe sections is 12 meters per piece, with a 200 mm welding net area reserved at the joints;
High-pressure foaming process controls void ratio < 0.5%, insulation layer gap ≤ 0.5 mm.
Inspection and Acceptance Requirements
Outer casing thickness tolerance ±0.2 mm, heat loss rate per kilometer ≤ 2% (water temperature ≤ 140°C);
Third-party testing must verify thermal conductivity (≤ 0.033 W/(m·K)) and closed-cell rate (≥ 90% for high-performance scenarios);
High-temperature pipes need to provide short-term temperature resistance test reports up to 300°C.
4. Industry Auxiliary Standards
CJ/T 114-2000
Supplementary norms for insulated pipes with conveying medium temperatures ≤ 120°C, specifying requirements for working steel pipe wall thickness and insulation layer density;
EN 253
Aligns with international standards, suitable for underground thermal network integrated pre-fabrication systems.
Through this comprehensive standard system, polyurethane-lined pipelines achieve full-process standardized control from material selection to project acceptance, ensuring reliability and durability under complex operating conditions.
