Chapter 73 covers articles of iron or steel, including tube or pipe fittings, structures, containers, fasteners, etc. This chapter ranges from 7301 to 7326, involving iron and steel products made by casting, forging, welding, and other processes. 7307 covers tube or pipe fittings, 7308 covers structures, 7309 covers containers, 7310 covers small containers, 7311 covers compressed gas containers, 7312 covers stranded wire, 7313 covers barbed wire, 7314 covers cloth, 7315 covers chain, 7316 covers anchors, 7317 covers nails, 7318 covers screws, 7319 covers needles, 7320 covers springs, 7321 covers stoves, 7322 covers radiators, 7323 covers tableware, 7324 covers sanitary ware, 7325 covers castings, 7326 covers other articles of iron or steel. Heading 7307 covers tube or pipe fittings of iron or steel, including flanges, couplings, elbows, tees, caps, etc., used for connecting, branching, and sealing pipelines. Products under this heading are usually made by casting, forging, or machining, and must meet the pressure and temperature requirements of piping systems. Main subheadings include 730711 (cast flanges), 730719 (other cast tube or pipe fittings), 730721 (stainless steel flanges), 730722 (stainless steel threaded elbows), 730723 (stainless steel butt-welding elbows), 730729 (other stainless steel tube or pipe fittings), 730791 (carbon steel flanges), 730792 (carbon steel threaded elbows), 730793 (carbon steel butt-welding elbows), 730799 (other carbon steel tube or pipe fittings). First 2 digits 73: indicates Chapter 73, articles of iron or steel. Digits 3-4, 07: indicates heading 7307, tube or pipe fittings of iron or steel. Digits 5-6, 91: indicates subheading 730791, specifically carbon steel flanges. The 5th digit 9 indicates other carbon steel tube or pipe fittings (non-stainless steel), and the 6th digit 1 indicates flanges. Therefore, the complete meaning of 730791 is: carbon steel flange subheading under the tube or pipe fittings heading in the chapter of articles of iron or steel. This code applies to flanges made of non-stainless steel (i.e., carbon steel or alloy steel), whether cast, forged, or machined, but care must be taken to distinguish them from stainless steel flanges (730721). The product is a carbon steel flange, made of carbon steel, used for pipeline connection. According to HS classification rules, tube or pipe fittings are classified by material and type. Carbon steel flanges are not stainless steel flanges (730721), nor cast flanges (730711, which refers only to cast and not further worked), so they are classified under 730791. If the flange has been further worked (such as threaded or butt-welded), but the material is still carbon steel, it is still classified under 730791, because this subheading covers all carbon steel flanges regardless of manufacturing process.
Chapter
Chapter 73 covers articles of iron or steel, including tube or pipe fittings, structures, containers, fasteners, etc. This chapter ranges from 7301 to 7326, involving iron and steel products made by casting, forging, welding, and other processes. 7307 covers tube or pipe fittings, 7308 covers structures, 7309 covers containers, 7310 covers small containers, 7311 covers compressed gas containers, 7312 covers stranded wire, 7313 covers barbed wire, 7314 covers cloth, 7315 covers chain, 7316 covers anchors, 7317 covers nails, 7318 covers screws, 7319 covers needles, 7320 covers springs, 7321 covers stoves, 7322 covers radiators, 7323 covers tableware, 7324 covers sanitary ware, 7325 covers castings, 7326 covers other articles of iron or steel.
Heading
Heading 7307 covers tube or pipe fittings of iron or steel, including flanges, couplings, elbows, tees, caps, etc., used for connecting, branching, and sealing pipelines. Products under this heading are usually made by casting, forging, or machining, and must meet the pressure and temperature requirements of piping systems. Main subheadings include 730711 (cast flanges), 730719 (other cast tube or pipe fittings), 730721 (stainless steel flanges), 730722 (stainless steel threaded elbows), 730723 (stainless steel butt-welding elbows), 730729 (other stainless steel tube or pipe fittings), 730791 (carbon steel flanges), 730792 (carbon steel threaded elbows), 730793 (carbon steel butt-welding elbows), 730799 (other carbon steel tube or pipe fittings).
Digit Breakdown
First 2 digits 73: indicates Chapter 73, articles of iron or steel. Digits 3-4, 07: indicates heading 7307, tube or pipe fittings of iron or steel. Digits 5-6, 91: indicates subheading 730791, specifically carbon steel flanges. The 5th digit 9 indicates other carbon steel tube or pipe fittings (non-stainless steel), and the 6th digit 1 indicates flanges. Therefore, the complete meaning of 730791 is: carbon steel flange subheading under the tube or pipe fittings heading in the chapter of articles of iron or steel. This code applies to flanges made of non-stainless steel (i.e., carbon steel or alloy steel), whether cast, forged, or machined, but care must be taken to distinguish them from stainless steel flanges (730721).
Classification Basis
The product is a carbon steel flange, made of carbon steel, used for pipeline connection. According to HS classification rules, tube or pipe fittings are classified by material and type. Carbon steel flanges are not stainless steel flanges (730721), nor cast flanges (730711, which refers only to cast and not further worked), so they are classified under 730791. If the flange has been further worked (such as threaded or butt-welded), but the material is still carbon steel, it is still classified under 730791, because this subheading covers all carbon steel flanges regardless of manufacturing process.
📝 Declaration Elements
Product Name: Declared commodity name, which should be accurately described as carbon steel flange, avoiding colloquial names or brand names. Material: Indicate the specific grade or composition of carbon steel, such as Q235, 20#, A105, etc. Specification and Model: Includes nominal diameter, pressure rating, flange type (such as WN, SO, BL, etc.). Manufacturing Process: State whether it is cast, forged, or machined, and whether it has been further worked. Use: Describe the application scenario, such as pipeline connection, equipment interface, etc. Brand: If there is a brand, declare the brand name; if no brand, declare "none". Quantity and Unit: Declare in kilograms or pieces, and it must be consistent with the actual transaction unit. Origin: Declare the country or region of production, which affects tariffs and trade policies. Product Name: Carbon Steel Flange; Material: Carbon Steel A105; Specification and Model: DN100 PN16 WN RF; Manufacturing Process: Forged; Use: Pipeline connection; Brand: None; Quantity: 500 pieces; Origin: China. Mistakenly classifying carbon steel flanges as stainless steel flanges (730721), resulting in incorrect tax rates and regulatory conditions. Ignoring the manufacturing process and misreporting cast flanges as forged, which may affect classification (cast flanges are classified under 730711 if not further worked). Incomplete declaration of specifications and models, such as missing pressure rating, may cause customs to question the classification.
Product Name
Declared commodity name, which should be accurately described as carbon steel flange, avoiding colloquial names or brand names.
⚠️ Writing only "flange" without indicating the material, or mistakenly writing stainless steel flange.
Material
Indicate the specific grade or composition of carbon steel, such as Q235, 20#, A105, etc.
⚠️ Writing only "carbon steel" is too general, or misreporting as alloy steel.
Specification and Model
Includes nominal diameter, pressure rating, flange type (such as WN, SO, BL, etc.).
⚠️ Omitting pressure rating or flange type, causing classification difficulties.
Manufacturing Process
State whether it is cast, forged, or machined, and whether it has been further worked.
⚠️ Misreporting forged flanges as cast, affecting classification.
Use
Describe the application scenario, such as pipeline connection, equipment interface, etc.
⚠️ Use description is too broad, such as "industrial use".
Brand
If there is a brand, declare the brand name; if no brand, declare "none".
⚠️ Ignoring brand declaration, or confusing with trademark.
Quantity and Unit
Declare in kilograms or pieces, and it must be consistent with the actual transaction unit.
⚠️ Inconsistent units, such as mixing kilograms and pieces.
Origin
Declare the country or region of production, which affects tariffs and trade policies.
⚠️ Misreporting the origin, leading to incorrect tariff application.
Mistakenly classifying carbon steel flanges as stainless steel flanges (730721), resulting in incorrect tax rates and regulatory conditions.
Ignoring the manufacturing process and misreporting cast flanges as forged, which may affect classification (cast flanges are classified under 730711 if not further worked).
Incomplete declaration of specifications and models, such as missing pressure rating, may cause customs to question the classification.
🎯 Classification Logic
The core basis for classification is material and type. The difference between carbon steel flanges (730791) and stainless steel flanges (730721) lies in the material; the difference from cast flanges (730711) lies in the manufacturing process and whether they have been further worked. According to the Import and Export Tariff, 730791 covers all carbon steel flanges, whether forged, cast, or machined, but if cast flanges have not been further worked, they should be classified under 730711. In addition, attention should be paid to whether the flange is threaded or butt-welded, but 730791 does not distinguish these, because the subheading is divided by material. 730721 Stainless Steel Flanges: The material is stainless steel, while 730791 is carbon steel. They can be distinguished by material certificates or spectral analysis. 730711 Cast Flanges: Refers only to flanges that are cast and not further worked (such as turning, drilling); if cast and then machined, they are classified under 730791. 730792 Carbon Steel Threaded Elbows: The type is elbow, not flange. Flanges are used for connection, elbows are used to change direction. 730793 Carbon Steel Butt-Welding Elbows: The type is butt-welding elbow, which has a different function from flanges but the same material. 730799 Other Carbon Steel Tube or Pipe Fittings: Covers carbon steel tube or pipe fittings other than flanges and elbows, such as tees, caps, etc. Is the material carbon steel? Is it a flange (not an elbow or tee)? Has it been further worked (such as turning, drilling)? Is it threaded or butt-welded? Are the specifications and models complete?
Basis
The core basis for classification is material and type. The difference between carbon steel flanges (730791) and stainless steel flanges (730721) lies in the material; the difference from cast flanges (730711) lies in the manufacturing process and whether they have been further worked. According to the Import and Export Tariff, 730791 covers all carbon steel flanges, whether forged, cast, or machined, but if cast flanges have not been further worked, they should be classified under 730711. In addition, attention should be paid to whether the flange is threaded or butt-welded, but 730791 does not distinguish these, because the subheading is divided by material.
Confused Codes：
730721 - Stainless Steel Flanges
The material is stainless steel, while 730791 is carbon steel. They can be distinguished by material certificates or spectral analysis.
730711 - Cast Flanges
Refers only to flanges that are cast and not further worked (such as turning, drilling); if cast and then machined, they are classified under 730791.
730792 - Carbon Steel Threaded Elbows
The type is elbow, not flange. Flanges are used for connection, elbows are used to change direction.
730793 - Carbon Steel Butt-Welding Elbows
The type is butt-welding elbow, which has a different function from flanges but the same material.
730799 - Other Carbon Steel Tube or Pipe Fittings
Covers carbon steel tube or pipe fittings other than flanges and elbows, such as tees, caps, etc.
Self-Check：
✓ Is the material carbon steel?
✓ Is it a flange (not an elbow or tee)?
✓ Has it been further worked (such as turning, drilling)?
✓ Is it threaded or butt-welded?
✓ Are the specifications and models complete?
❓ FAQ
Are carbon steel flanges and alloy steel flanges classified under the same code? Yes, 730791 covers carbon steel and alloy steel flanges, as long as they are not stainless steel. Stainless steel flanges are classified under 730721. Alloy steel flanges need to be judged according to material composition; if the chromium content exceeds 10.5%, they may be considered stainless steel. Which code should cast carbon steel flanges be classified under? If they are not further worked after casting (such as turning, drilling), they are classified under 730711; if they are further worked, they are classified under 730791. Processing instructions must be provided at declaration. How to distinguish flanges from pipe couplings? Flanges are usually disc-shaped and used to connect pipes or equipment; pipe couplings are used to connect two pipes, such as threaded joints and butt-welding joints. Distinguish by shape and function, and accurately describe when classifying. In the declaration elements for carbon steel flanges, is the manufacturing process important? Yes, because the manufacturing process affects classification. For example, cast flanges are classified under 730711 if not further worked, while forged flanges are classified under 730791. It must be truthfully filled in at declaration. When exporting carbon steel flanges to the United States, what HS code-related matters should be noted? The first 6 digits of the U.S. HS code are the same as those of China, but the last 4 digits may differ. It is necessary to check the U.S. Customs website to confirm the specific code and tax rate. Also note anti-dumping and countervailing duty orders, which carbon steel flanges may involve. What are the regulatory conditions for carbon steel flanges? Regulatory conditions vary by country. China's exports usually have no special regulation, but imports may involve tariffs and value-added tax. For details, check the Import and Export Tariff and announcements of the General Administration of Customs. If carbon steel flanges are used for high-pressure pipelines, will the classification change? No, HS codes are mainly based on material and type, and use does not affect classification. However, high-pressure flanges may require pressure rating certificates to meet customs declaration requirements. How to check the import tax rate for carbon steel flanges? You can log on to the official website of the General Administration of Customs of China or use the "Customs Tariff" query system, enter HS code 730791, and check the MFN rate, general rate, etc. Tax rates may change, subject to the latest announcement.
Q: Are carbon steel flanges and alloy steel flanges classified under the same code?
A: Yes, 730791 covers carbon steel and alloy steel flanges, as long as they are not stainless steel. Stainless steel flanges are classified under 730721. Alloy steel flanges need to be judged according to material composition; if the chromium content exceeds 10.5%, they may be considered stainless steel.
Q: Which code should cast carbon steel flanges be classified under?
A: If they are not further worked after casting (such as turning, drilling), they are classified under 730711; if they are further worked, they are classified under 730791. Processing instructions must be provided at declaration.
Q: How to distinguish flanges from pipe couplings?
A: Flanges are usually disc-shaped and used to connect pipes or equipment; pipe couplings are used to connect two pipes, such as threaded joints and butt-welding joints. Distinguish by shape and function, and accurately describe when classifying.
Q: In the declaration elements for carbon steel flanges, is the manufacturing process important?
A: Yes, because the manufacturing process affects classification. For example, cast flanges are classified under 730711 if not further worked, while forged flanges are classified under 730791. It must be truthfully filled in at declaration.
Q: When exporting carbon steel flanges to the United States, what HS code-related matters should be noted?
A: The first 6 digits of the U.S. HS code are the same as those of China, but the last 4 digits may differ. It is necessary to check the U.S. Customs website to confirm the specific code and tax rate. Also note anti-dumping and countervailing duty orders, which carbon steel flanges may involve.
Q: What are the regulatory conditions for carbon steel flanges?
A: Regulatory conditions vary by country. China's exports usually have no special regulation, but imports may involve tariffs and value-added tax. For details, check the Import and Export Tariff and announcements of the General Administration of Customs.
Q: If carbon steel flanges are used for high-pressure pipelines, will the classification change?
A: No, HS codes are mainly based on material and type, and use does not affect classification. However, high-pressure flanges may require pressure rating certificates to meet customs declaration requirements.
Q: How to check the import tax rate for carbon steel flanges?
A: You can log on to the official website of the General Administration of Customs of China or use the "Customs Tariff" query system, enter HS code 730791, and check the MFN rate, general rate, etc. Tax rates may change, subject to the latest announcement.
⚠️ Disclaimer: HS code classification, declaration elements, tariff rates and regulatory conditions on this page are for reference only and do not constitute legal advice on customs classification. Tariff rates and regulations are subject to change; the latest announcements from the General Administration of Customs and on-site determinations shall prevail. Please consult professional customs brokers or customs authorities before import/export.