Chapter 84 is a major category in the HS classification system covering machinery, mechanical appliances, and their parts, including power machinery, agricultural machinery, machine tools, office equipment, automatic data processing equipment, bearings, transmission devices, seals, etc. Goods in this chapter usually have power-driven or mechanical motion characteristics, distinguishing them from the electrical equipment of Chapter 85. Heading 8487 is specifically for machine parts not specified or included in other headings of this chapter, serving as a residual heading applicable to mechanical parts without more specific classification. Heading 8487 covers machine parts not specified or included in other headings of this chapter, including mechanical seals, ship propellers, machine blades, oil seals, bearing housings, etc. This heading is the residual parts heading of Chapter 84, and goods are classified under 8487 only when preceding headings (such as 8481 valves, 8482 bearings, 8483 transmission shafts) do not cover them. 848790 is a subheading therein, specifically referring to mechanical seals, i.e., dynamic sealing devices used to prevent fluid leakage. Code 848790 has 6 digits: the first 2 digits 84 represent Chapter 84 (machinery, mechanical appliances, and their parts); digits 3-4, 87, represent heading 8487 (machine parts not specified or included in other headings of this chapter); digits 5-6, 90, represent subheading 848790 (mechanical seals). The 5th digit 9 indicates further subdivision under 8487, and the 6th digit 0 indicates the specific variety of mechanical seals. Therefore, the complete meaning of 848790 is "mechanical seals," a specific subheading under the residual parts heading of Chapter 84. Mechanical seals are shaft-end sealing devices used in rotating equipment such as pumps, compressors, and agitators to prevent fluid leakage along the shaft. They are not valves (8481), bearings (8482), transmission devices (8483), or electrical seals (8547). Since there is no more specific heading, they are classified under 848790 under the residual heading 8487. If the seal is made of rubber or plastic and used for static sealing, it may be classified under Chapter 40 or Chapter 39, but mechanical seals have a dynamic sealing function and should be classified under this heading.

Product Name: The Chinese and English names of the declared goods, which should accurately reflect the product attributes, such as "mechanical seal" or "mechanical sealing device." Use: Explain the application equipment of the mechanical seal, such as shaft-end sealing for centrifugal pumps, reactors, compressors, and other rotating equipment. Material: List the material of the sealing faces (such as silicon carbide, graphite, hard alloy) and the material of auxiliary sealing rings (such as fluororubber, nitrile rubber). Structural Composition: Describe the main components of the mechanical seal, such as rotating ring, stationary ring, spring, sealing ring, drive seat, etc. Brand: Declare the brand of the goods (if no brand, fill in "none"); the brand helps customs confirm the source of goods and intellectual property status. Model: Fill in the manufacturer's or industry-standard model, such as "M7N," "108-25," etc., to facilitate identification of specific specifications. Working Principle: Briefly describe the working principle of the mechanical seal, such as achieving sealing by pressing the rotating ring and stationary ring faces together through spring and fluid pressure. Product Name: Mechanical Seal; Use: For shaft-end sealing of centrifugal pumps to prevent liquid leakage; Material: rotating ring silicon carbide, stationary ring graphite, auxiliary sealing ring fluororubber, spring stainless steel; Structural Composition: rotating ring, stationary ring, spring, drive seat, sealing ring; Brand: None; Model: M7N-45; Working Principle: The spring provides initial compression force, and fluid pressure presses the rotating ring and stationary ring faces tightly together to form a dynamic seal. Misreporting mechanical seals as "oil seals" or "sealing rings," leading to classification under Chapter 40 or 8484. Failure to declare the working principle, making it impossible for customs to determine whether it is a dynamic seal, possibly raising classification doubts. Incomplete material declaration, such as writing only "metal" without listing key sealing face materials such as silicon carbide and graphite.

Core classification determination basis: whether the mechanical seal is a machine part not specified or included in other headings of Chapter 84. First, confirm that it is used for shaft-end sealing of rotating equipment (such as pumps, compressors) and has a dynamic sealing function. Second, check whether it is covered by a more specific heading: 8481 valves do not include shaft seals; 8482 bearings do not involve sealing; 8483 transmission shafts do not include sealing functions; 8484 gaskets or similar joints are static seals and are not applicable to dynamic seals. Therefore, mechanical seals should be classified under 8487, specifically subheading 848790. 848420 Mechanical Seals: 848420 was the old code for "mechanical seals" (before 2007) and has now been merged into 848790. Currently, 848420 refers to "gaskets or similar joints," used for static sealing, often made of metal or soft materials, different from mechanical seals used for dynamic sealing. 848410 Metal Gaskets: 848410 refers to metal gaskets used for static joint face sealing, such as flange connections, with no moving parts, whereas mechanical seals contain springs and rotating rings and are used for rotating shafts. 401693 Rubber Sealing Rings: 401693 refers to sealing rings made of vulcanized rubber, usually O-rings, oil seals, and other static or low-speed dynamic seals, made of rubber, without metal springs and silicon carbide structures, whereas mechanical seals contain metal and ceramic components. 848180 Valves: 848180 refers to valves and similar devices used to control fluid flow, and although they contain seals, the overall function is a valve, whereas mechanical seals are independent parts used for shaft-end sealing. 848330 Bearing Housings: 848330 refers to bearing housings and sliding bearings used to support shafts, and although they may contain seals, the main function is support, whereas the main function of mechanical seals is sealing. Is it used for dynamic sealing of rotating shafts? Does it include components such as rotating ring, stationary ring, and spring? Is it not a valve, bearing, or transmission device? Does the material include sealing faces such as silicon carbide and graphite? Is it not more specifically covered by Chapter 40 or Chapter 39?

What is the difference between mechanical seals and oil seals? Are the HS codes the same? Mechanical seals consist of a rotating ring, stationary ring, spring, etc., and are used for dynamic sealing of rotating shafts to prevent liquid leakage, classified under 848790. Oil seals are usually rubber lip seals used for low-speed rotation or static sealing, made of rubber, generally classified under 401693. The two have different structures and functions, and their HS codes are also different. How do I check the import tariff rate for mechanical seals? First confirm the HS code is 848790, then check according to the destination country's customs tariff. For example, China Customs can consult the "Import and Export Tariff of the People's Republic of China," or check through the General Administration of Customs website or the single window. Tariff rates vary by country and trade agreement (such as RCEP), and the latest tariff schedule should prevail. When declaring mechanical seals, must the brand and model be provided? Yes, brand and model are important declaration elements. The brand helps customs with intellectual property protection, and the model facilitates identification of specific specifications. If there is indeed no brand, declare "none"; the model should be filled in with the manufacturer's or industry-standard model and cannot be left blank. If mechanical seals are imported as complete sets of unassembled parts, how are they classified? If the complete set of unassembled parts already has the essential character of a complete mechanical seal, it should be classified as a mechanical seal under 848790. If the parts are unassembled and clearly do not constitute a complete product, they must be classified separately. It is recommended to keep the complete packaging and instructions for customs determination. Does classifying mechanical seals under 848790 mean there is no other more specific code? Yes. 8487 is the residual parts heading of Chapter 84, and goods are classified under 8487 only when other headings (such as 8481, 8482, 8483) do not cover them. Mechanical seals are classified under 848790 because there is no more specific heading. If the seal is dedicated to a valve and imported together with the valve, it may be classified as a valve. For cross-border e-commerce small parcel exports of mechanical seals, is HS code declaration required? Yes. Whether general trade or cross-border e-commerce, export declaration requires an HS code. Mechanical seals should be declared as 848790. Cross-border e-commerce may simplify declaration, but the code must be accurate; otherwise, it may affect tax refunds or lead to customs penalties. What points do customs inspections of mechanical seals usually focus on? Customs inspection will verify whether the product name, use, material, structural composition, brand, model, etc. are consistent with the declaration. The focus is on confirming whether it is a dynamic seal, whether it contains springs and rotating rings, and whether the material contains silicon carbide or graphite. If declared as a "sealing ring" but the actual product is a mechanical seal, it may be determined as a classification error. Do mechanical seals have export tax rebates? What is the rebate rate? Mechanical seals (848790) usually have export tax rebates, but the rebate rate changes with national policy adjustments. The specific rebate rate needs to be checked in the latest export tax rebate rate database or consulted with the local tax bureau. Enterprises should declare with the accurate HS code to ensure smooth tax rebates.