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In addition to meeting the requirements specified in the contract, heat exchange tubes must also satisfy the following conditions: 1. Document numbers: NB/T47019-2021 and NB/T47019.X-2021 (where X is determined based on the material of the heat exchange tube). 2. Product names: seamless straight heat exchange tubes, seamless U-shaped heat exchange tubes, finned tubes. 3. Material grades: The heat exchange tubes must meet the standards 10# and 20# as specified in GB/T9948-2013#； S30408, S31603 in GB/T13296-2023 ； TA2 in GB/T3624-2023 ； NCu30 in GB/T2882-2023 ； For S22053 and S25073 in GB/T21833.1-2020, the manufacturing method is cold rolling or cold drawing. 5. Delivery condition: normalizing (carbon steel), solution treatment (stainless steel), bright annealing (stainless steel), annealing (titanium), soft or stress-relieved condition (nickel). 6. Specifications and grade: φ19×2, L=6000, Grade I seamless pipe; allowable deviation for outer diameter: ±0.08 ； Allowable wall thickness deviation: 0~+15%S (S is the wall thickness) ； The allowable length deviation is 4–6 mm for L ≤ 6000, and 4–8 mm for 6000 < L ≤ 9000. The heat exchange tubes must be delivered as complete units; splicing is not permitted. 8. Number of roots: XXX roots (including spare tubes; the number of spare tubes is generally calculated at 1.5‰ and rounded up) ； Delivery method: Steel pipes are delivered based on their actual weight. If delivery is to be based on theoretical weight, it must be specified in the contract. 9. The heat exchange tubes shall be subjected to a hydrostatic test one by one. The test pressure shall be determined in accordance with the relevant provisions of the manufacturing standard NB/T 47019-2021; relevant test reports must be provided, and eddy current or magnetic flux leakage testing shall not be used as a substitute for the hydrostatic test. The chloride content in the water used for hydrostatic testing should not exceed 25 mg/L, and the residual water must be removed after the testing. 10. Each heat exchange tube shall be subjected to ultrasonic testing, and the inspection results shall meet or exceed the requirements of GB/T13296-2023; relevant test reports shall be provided. 11. Each heat exchange tube shall undergo 100% eddy current testing, and this shall not replace the hydrostatic test; relevant test reports must be provided. 12. The out-of-roundness and wall thickness variation of the heat exchange tubes shall not exceed 80% of the tolerances for outer diameter and wall thickness, respectively. 13. Requirements for pipe end cutting: The cut should be smooth, free of burrs and cracks ； The cutting bevel shall be carried out in accordance with Table B.6 in Appendix B of NB/T 47019.1-2021. 14. After manufacturing, each heat exchange tube shall have a testing blind zone at both ends of not less than 200 mm, or the length of the clamping area plus 20 mm, whichever is greater; the cutting of these ends must be witnessed by the purchaser. Additionally, about 5% of the tube ends shall be sampled for PT testing, and the results must meet the requirements of Grade I as specified in NB/T47013.5-2015. 15. U-shaped heat exchange tubes shall be bent using the cold bending process; hot bending is not permitted. 16. After bending the U-shaped heat exchange tube, once the specified degree of deformation is achieved, stress-relief heat treatment (for carbon steel) or solution heat treatment (for stainless steel) must be applied to the U-shaped bent section as well as to at least 150 mm of the straight pipe section. For carbon steel and low-alloy steel heat exchange tubes, stress-relief heat treatment should be carried out when the deformation rate exceeds 5% ； For duplex steel heat exchange tubes, when the deformation rate exceeds 10%, solution treatment should be carried out ； For austenitic stainless steel and nickel-chromium (molybdenum) alloy steel heat exchange tubes, solution treatment should be carried out when the deformation rate exceeds 15%. Formula for calculating the deformation rate: Deformation rate (%) = 100 × r / R17. After bending the U-tubes, each tube must undergo a hydrostatic test, with the test pressure not being lower than XX MPa (the specific value of XX is determined as the higher of the pressure thresholds required for the tube side and the shell side tests). 18. After the hydrostatic test of U-tubes, penetrant testing shall be conducted on the outer surface of the U-shaped section of each batch of U-tubes at their minimum bending radius, and the results shall meet the requirements of Grade I specified in NB/T47013.5-2015. When non-conformities are detected, at least 3 U-tubes with a smaller bend radius should be inspected further. 19. The other requirements for U-shaped heat exchange tubes shall comply with the relevant provisions in Appendix B of NB/T 47019.1-2021. 20. The outer surface of the heat exchange tubes shall be derusted (for carbon steel) or pickled (for stainless steel); for stainless steel heat exchange tubes that have been brightened, pickling may not be necessary. 21. Stainless steel heat exchange tubes shall undergo intergranular corrosion testing in accordance with Method E of GB/T4334-2020. 22. The procurement requirements for the heat exchange tubes of different projects must also meet the technical specifications set by the owner.