1. Inspection: Polyurethane insulation pipes need to have dual properties of insulation and waterproofing materials. After the materials enter the site, they need to be rechecked. The re inspection of sprayed polyurethane mainly includes the density, compression performance, dimensional stability, and impermeability of the material.

2. Waterproof performance testing: Use water storage or rainwater to check its waterproof effect, and do not allow water accumulation or leakage.

3. Spray thickness inspection: Use a steel needle insertion and measurement method to check the thickness.

4. Surface flatness testing: Measure with a 1-meter ruler and a wedge-shaped feeler gauge, with an allowable deviation of 5 millimeters.

5. The rigid foam polyurethane shall be firmly bonded with the base course, and the surface shall be free from damage, delamination, bulge, holes and cracks.

6. The density of foam at any position of polyurethane insulation layer shall not be less than 60kg/m3. The surface of foam is smooth, non sticky, non shrinking, uniform foam pores, and free from collapse and cracking.

7. Check the surface pretreatment quality of each steel pipe one by one. The surface of the pipe should be free of oil stains and dust. The quality of rust removal should be visually compared with the standard version of "Rust Grades and Removal Grades of Steel Surface before Coating", and should not be lower than Sa2 level.

8. Check the quality of the anti-corrosion coating on each steel pipe one by one. The appearance of the anti-corrosion layer should be uniform, continuous, and free of leakage. The thickness of the anti-corrosion layer should be checked using a magnetic thickness gauge to ensure that the thickness is less than the design thickness.

9. The insulation layer should be free of defects such as shrinkage, shrinkage, uneven bubbles, and burnt cores.