Chapter 39 covers plastics and articles thereof, and is an important chapter in the HS classification organized by material. This chapter includes plastics in primary forms, waste and scrap, semi-manufactures, and various finished plastic products, but excludes plastic articles already classified in other chapters (e.g., plastic footwear falls under Chapter 64). Heading 3917 specifically covers tubes, pipes, and hoses of plastics and their fittings, and is a widely applied category among plastic products. Heading 3917 includes tubes, pipes, hoses, and fittings thereof (such as joints, elbows, flanges) of plastics. It covers rigid tubes and flexible hoses, whether or not reinforced or combined with other materials, provided that the essential character is of plastics. However, it excludes tubes reinforced with textile materials where the textile material constitutes the essential character (classified under Chapter 59) or assembled machine parts (classified under Chapters 84/85). The first 2 digits "39" represent Chapter 39: Plastics and articles thereof. Digits 3-4 "17" represent heading 3917: Tubes, pipes, and hoses of plastics and fittings thereof. Digits 5-6 "31" is a subheading further limited to "flexible tubes and pipes" and requires a burst pressure of ≥27.6 MPa. Under this subheading, it is further subdivided into different third-level subheadings (such as 3917.31.10, etc.) based on whether reinforced, whether fitted with fittings, etc. Therefore, 391731 specifically refers to high-strength flexible plastic tubes, commonly used in hydraulic, pneumatic, and other pressure-bearing applications. The product is a flexible tube of plastics with a burst pressure of ≥27.6 MPa, which meets the description of subheading 3917.31. If the burst pressure is below 27.6 MPa, it should be classified under subheadings such as 3917.32 or 3917.33; if it is a rigid tube, it is classified under 3917.21-3917.29; if it is reinforced with textile materials and the textile material constitutes the essential character, it may be classified under Chapter 59. Therefore, the burst pressure indicator is the key to distinguishing 391731 from adjacent codes.

Product Name: Fill in the standard name of the commodity, such as "flexible tube of plastics", avoiding colloquial names or brand names. Material: Specify the type of plastic, such as polytetrafluoroethylene (PTFE), nylon (PA), polyurethane (PU), etc. Use: Explain the specific application scenario, such as hydraulic systems, pneumatic tools, automotive braking, etc. Burst Pressure: Provide the burst pressure value under the test standard, in megapascals (MPa), which must be ≥27.6. Reinforcement Material: If reinforced, indicate the material (such as steel wire, fiber) and whether it constitutes the essential character. Whether Fitted with Fittings: Indicate whether it is fitted with joints, flanges, and other fittings, as well as the material of the fittings. Brand and Model: Fill in the brand and model for easy identification and verification. Specifications and Dimensions: Include inner diameter, outer diameter, wall thickness, length, etc., in millimeters or meters. Product Name: Flexible tube of plastics; Material: Polytetrafluoroethylene (PTFE); Use: High-pressure oil pipe for hydraulic systems; Burst Pressure: 40 MPa (test standard GB/T 5563); Reinforcement Material: Braided stainless steel wire reinforcement; Whether Fitted with Fittings: Both ends with stainless steel fittings; Brand: Parker; Model: HT-2000; Specifications: Inner diameter 6mm, outer diameter 10mm, wall thickness 2mm, length 50m/roll. Misreporting burst pressure as working pressure, leading to classification errors. Ignoring reinforcement materials; if textile material constitutes the essential character, it should be classified under Chapter 59. Failing to indicate whether fittings are installed, affecting subheading subdivision and tax rates.

The core basis for classification is: 1) the commodity material is plastics; 2) the structure is a flexible tube; 3) the burst pressure is ≥27.6 MPa. According to the Import and Export Tariff and its notes, subheading 3917.31 explicitly requires "flexible tubes and pipes, burst pressure ≥27.6 MPa". If the burst pressure is insufficient, it is classified under 3917.32 (not reinforced or otherwise reinforced) or 3917.33 (fitted with fittings). If it is a rigid tube, it is classified under 3917.21-3917.29. If the tube is reinforced with textile materials and the textile material constitutes the essential character, it is classified under Chapter 59. Therefore, it must be determined by comprehensively considering material, structure, pressure indicator, and reinforcement. 391732 Other flexible tubes and pipes of plastics (burst pressure <27.6 MPa, not reinforced or only reinforced with textile materials): The core difference lies in whether the burst pressure reaches 27.6 MPa. 391731 requires ≥27.6, while 391732 has no such requirement and may include unreinforced or textile-reinforced tubes. 391733 Flexible tubes and pipes of plastics (burst pressure <27.6 MPa, fitted with fittings): 391733 emphasizes being fitted with fittings and pressure below 27.6 MPa, whereas 391731, even if fitted with fittings, is still classified under 391731 as long as the pressure meets the requirement. 391721 Rigid tubes and pipes of plastics (polymers of ethylene): 391721 is a rigid tube, not flexible, and the material is limited to polymers of ethylene. 391731 is a flexible tube, not limited in material, but must meet the pressure requirement. 590390 Plastic tubes reinforced with textile materials (textile material constitutes the essential character): If reinforced with textile materials and the textile material constitutes the essential character, it should be classified under Chapter 59, not 3917. The key is whether the textile material is the essential character. 848180 Taps, cocks, valves, etc., for machines or pipes: If the plastic tube is already fitted with valves, etc., and constitutes a machine part, it may be classified under Chapter 84. However, a simple tube with fittings is still classified under 3917. Is the material plastics? Is it a flexible tube? Is the burst pressure ≥27.6 MPa? Is there a reinforcement material? Is the textile material the essential character? Is it fitted with fittings? Do the fittings lead to classification under other chapters?

How to inquire about the import tax rate for 391731? It can be inquired through the official website of the General Administration of Customs, China International Trade Single Window, or the Import and Export Tariff. The tax rate varies by country, trade agreement (such as RCEP), and country of origin, so it is recommended to refer to the latest tariff. Also note whether anti-dumping, countervailing, and other additional duties are involved. What information is required in a burst pressure test report? The test report should include product name, model, material, test standard (such as GB/T 5563, ISO 6803), test date, burst pressure value, seal of the testing institution, etc. The report must be issued by a qualified laboratory to ensure customs acceptance. If the burst pressure is exactly 27.6 MPa, can it be classified under 391731? According to the tariff, subheading 391731 requires "burst pressure ≥27.6 MPa", so equal to 27.6 MPa also meets the condition. However, attention should be paid to the test method and tolerance, and it is recommended to provide a report slightly above this value to avoid disputes. Is a plastic tube with fittings necessarily classified under 391733? Not necessarily. If the burst pressure is ≥27.6 MPa, even with fittings, it is still classified under 391731. 391733 only applies to flexible tubes with burst pressure <27.6 MPa and fitted with fittings. Therefore, the pressure indicator takes precedence over fittings. How are textile-reinforced plastic tubes classified? If reinforced with textile materials and the textile material constitutes the essential character, they should be classified under Chapter 59 (such as 5903). If plastics constitute the essential character, they are classified under 3917. When determining, consider the proportion, function, and appearance of the textile material. What is the main difference between 391731 and 391732? The main difference lies in the burst pressure. 391731 requires ≥27.6 MPa, while 391732 has no such requirement and is typically used in low-pressure scenarios. In addition, 391732 may include unreinforced or only textile-reinforced tubes, while 391731 is usually reinforced. How to fill in the "Use" element during declaration? Fill in the specific end-use application, such as "for hydraulic systems", "for automotive brake lines", "for pneumatic tools". Avoid filling in "industrial use" generically, so that customs can determine whether it is a dedicated part. If a commodity meets both 391731 and 848180, how should it be classified? If the plastic tube is already fitted with valves, etc., and constitutes a dedicated part of a machine or equipment, it should be classified under Chapter 84 first. However, if it is only a tube with simple fittings, it is still classified under 3917. When classifying, refer to the Tariff notes and General Rules for the Interpretation of the Harmonized System, and consider the main function of the commodity.