Chapter 70 covers glass and glassware, including glass in various forms (such as blocks, tubes, plates, sheets, fibers, etc.) and finished glass products (such as glassware, glass instruments, glass fiber products, etc.). This chapter is subdivided based on the chemical composition, processing technology, and use of glass, and is the main chapter for the classification of glass commodities in international trade. Heading 7002 covers unworked glass in the form of balls, rods, tubes, or similar shapes (but not optically worked), including glass of non-fused quartz. Specifically, it includes glass balls, glass rods, glass tubes, etc., but excludes processed glass products or optical elements. Code 700231 is a six-digit subheading: the first 2 digits "70" represent Chapter 70 (glass and glassware); digits 3-4 "02" represent heading 7002 (unworked glass in the form of balls, rods, tubes, etc.); digits 5-6 "31" represent subheading 700231, specifically "glass tubes of fused quartz." Among these, "fused quartz" refers to glass with an extremely high silica content (usually >99.9%), with an extremely low coefficient of thermal expansion and excellent optical properties. This subheading covers only the tubular form, and not further worked (such as cut, bent, ground, etc.). This commodity is a glass tube made of fused quartz, belonging to unworked glass tubes, and conforms to the description of heading 7002. Because fused quartz glass tubes have a special chemical composition and use, subheading 700231 specifically lists them. It differs from other glass tubes (such as borosilicate glass tubes, classified under 700232), and also differs from processed glass tube products (such as laboratory glass tubes, which may be classified under 7007 or 7020).

Product name: The specific name of the declared commodity should be accurately described as "fused quartz glass tube," avoiding colloquial or general names. Material: Explain the chemical composition of the glass, and state it as "fused quartz" (silica content ≥99.9%), and provide relevant test reports. Use: Describe the main use of the glass tube, such as for semiconductors, optical fibers, laboratory instruments, etc., which helps confirm classification. Appearance: Describe the physical characteristics of the glass tube, such as shape, dimensions (outer diameter, wall thickness, length), color, transparency, etc. Processing status: State whether it has undergone further processing (such as cutting, grinding, bending, etc.); unworked ones are classified under 700231. Brand: If there is a brand, declare the brand name; if there is no brand, declare "no brand." Model: Declare the model or specifications of the product for easy identification and statistics. Manufacturer: Declare the name of the manufacturing enterprise, which helps with traceability and verification. Product name: fused quartz glass tube; Material: fused quartz (SiO2≥99.9%); Use: used in semiconductor diffusion furnaces; Appearance: transparent tubular, outer diameter 20mm, wall thickness 2mm, length 1000mm; Processing status: unworked (only drawn); Brand: no brand; Model: FQ-20; Manufacturer: XX Quartz Products Co., Ltd. Mistakenly classifying fused quartz glass tubes under 700232 (other glass tubes), ignoring the special nature of the material. Still declaring cut or ground glass tubes as unworked, resulting in classification errors. Failure to provide a material test report, unable to prove it is fused quartz, which may raise doubts about classification.

The core criteria for classification are: 1) whether the material is fused quartz (with extremely high silica content); 2) whether the form is tubular; 3) whether it has undergone further processing (such as cutting, bending, grinding, etc.). Only when all three conditions of fused quartz material, tubular form, and unworked are met is it classified under 700231. If processed, it may be classified under 7007 (safety glass) or 7020 (other glass products). 700232 Other glass tubes: 700232 covers tubes made of other glass (such as borosilicate glass), unworked. The difference from 700231 lies in the material: fused quartz vs other glass. 700239 Other unworked glass tubes: 700239 covers other glass tubes not elsewhere specified, usually referring to unworked glass tubes, but the material is neither fused quartz nor other specific glass. 700600 Worked glass: 700600 covers glass that has been bent, edge-worked, engraved, etc., but not combined with other materials. If glass tubes have undergone such processing, they should be classified under 700600. 702000 Other glass products: 702000 covers glass products not elsewhere specified, such as laboratory glassware, glass instruments, etc. If glass tubes have been made into specific products, they should be classified under 702000. Is the material fused quartz (SiO2≥99.9%)? Is the form tubular? Has it not undergone cutting, grinding, bending, or other processing? Is it used for further manufacturing rather than direct use? Does it not belong to optical elements or laboratory vessels?

How can it be determined whether a glass tube is made of fused quartz? The silica content of fused quartz glass is usually ≥99.9%, which can be confirmed through test reports or composition analysis provided by the supplier. Its coefficient of thermal expansion is extremely low, and its thermal shock resistance is strong, so it is often used in high-temperature environments. What is the difference in classification between fused quartz glass tubes and borosilicate glass tubes? Fused quartz glass tubes are classified under 700231, and borosilicate glass tubes under 700232. The main difference lies in the material: fused quartz has a higher SiO2 content and better performance. If a glass tube has been cut but not further processed, which code should it be classified under? Cutting is further processing. If it is still a glass tube after cutting, it is usually classified under 700600 (worked glass). However, if the cutting is only for ease of transportation and does not change the basic characteristics, it may still be classified as unworked, depending on the specific circumstances. If a fused quartz glass tube is used in a laboratory, should it be classified under 700231? If the glass tube has not been made into laboratory-specific vessels (such as test tubes or beakers) and is only used in the laboratory as a material, it is still classified under 700231. If it has been made into specific vessels, it is classified under 702000. Is a material test report required when declaring? It is recommended to provide one, especially when customs has doubts about the material. The test report can prove the silica content, ensure accurate classification, and avoid disputes. How can fused quartz glass tubes be distinguished from quartz glass tubes (non-fused)? Quartz glass usually refers to fused quartz, but sometimes also refers to other quartz products. The key is the silica content and process: fused quartz is made by high-temperature melting, with SiO2≥99.9%; non-fused quartz may contain other components. If a glass tube is used for optical fiber preforms, which code should it be classified under? Optical fiber preforms are usually classified under 700231, because they are unworked fused quartz glass tubes. However, if other materials have been deposited or it has been processed, it may be classified under other codes. What documents may customs require when importing fused quartz glass tubes? Usually a contract, invoice, packing list, bill of lading, material certificate, composition test report, etc. are required. When necessary, an explanation of use is also required to prove correct classification.