Square & Rectangular Tube HS Code 730661 (Guide 2026)

In international trade, accurately declaring the correct HS code for your products is a critical step to ensure smooth customs clearance and avoid unexpected tariff costs. For common steel products such as square hollow sections (SHS) and rectangular hollow sections (RHS), the HS code classification follows a clear logic.

Based on the latest available information, this guide provides a systematic overview of HS code classification, applicable scenarios, and key declaration points for square and rectangular steel tubes.

Core HS Code: 730661

For the most common carbon steel welded square tubes and rectangular tubes, the core HS code is 730661.

This six-digit code is the internationally standardized customs classification, applicable to steel tubes meeting the following criteria:

● Material: Primarily iron or non-alloy steel (carbon steel).
● Manufacturing Process: Welded forming, including high-frequency electric resistance welding (ERW).

● Cross-Section Shape: Square or rectangular.

Square and Rectangular Tube HS Code: Quick Reference

The table below summarizes the HS code correspondence for different product types:

Product Type	Core HS Code
Carbon Steel Square Tube	730661
Carbon Steel Rectangular Tube	730661
Galvanized Square/Rectangular Tube	730661
Square Hollow Section (SHS)	730661
Rectangular Hollow Section (RHS)	730661
Other Welded Steel Tubes and Shaped Sections	730669

Note: The codes listed above are the six-digit international codes. Many countries add additional national digits to create eight or ten-digit local subheadings for more detailed statistical and tariff management purposes.

Common Sub-Classification Dimensions for HS Code 730661:

While 730661 is the universal six-digit base, different countries may add their own national digits to form 8 or 10-digit subheadings for more detailed statistical and tariff management.

1. By Material

While 730661 primarily applies to carbon steel, some countries distinguish stainless steel square/rectangular tubes. For example, tariff numbers such as 73066101 have been used for stainless steel square tubes in some countries' export data. If your product is stainless steel, you should verify whether the importing country has a dedicated code.

2. By Wall Thickness

Wall thickness is a key factor affecting tariff rates in some countries. Taking the EU and certain other customs territories as an example:

● Products with a wall thickness ≤ 2mm may fall under subheadings such as 73066192.
● Products with a wall thickness > 2mm may fall under subheadings such as 73066199.

3. By Processing Status or Application

For example, some countries have separate local subheadings for galvanized square/rectangular tubes.

△ Important Reminder: For actual customs declarations, you must confirm the latest, complete local tariff code with a licensed customs broker or freight forwarder in the importing country, as tariff rates and regulatory requirements can vary significantly between countries.

Required Documentation for Declaration:

Selecting the correct HS code is only the first step. Customs authorities typically require supporting documents to verify product information. It is recommended to prepare:

1. Commercial Invoice: Declares product description, quantity, and transaction value.
2. Packing List: Confirms package quantity, dimensions, and shipping weight.
3. Mill Test Certificate (MTC): Verifies the steel grade and material specifications.
4. Technical Specification Sheet: Identifies tube size, wall thickness, and manufacturing method.
5. Certificate of Origin (CO): May be required to qualify for preferential tariff treatment.

Common Classification Mistakes:

1. Confusing Welded Tubes with Seamless Tubes: 730661 applies only to welded square/rectangular tubes. Seamless square/rectangular tubes (less common) or seamless round tubes should be classified under HS Code 7304. Ensure your documents clearly state "Welded".

2. Confusing Different Shapes: Round tubes or other shaped sections fall under other subheadings within HS Code 7306, such as 730630 (for round tubes), not 730661.
3. Using Vague Product Descriptions: Use specific terms like "Square Hollow Section (SHS)" or "Carbon Steel Square Tube" instead of a generic "Steel Tube".
4. Inconsistent Descriptions Across Documents: Ensure the product description on the commercial invoice, packing list, and mill test certificate are consistent, and include keywords such as "Welded Carbon Steel Square/Rectangular Tube" to avoid classification disputes.

Frequently Asked Questions (FAQ)

Q1: What is the HS code for SHS (Square Hollow Section)?

Square Hollow Sections (SHS) are typically classified under HS Code 730661 when they are welded carbon steel hollow sections.

Q2: Does the HS code for square tubes vary based on size or wall thickness?
No. At the six-digit HS code level, tube size and wall thickness do not change the classification. Classification is primarily based on the manufacturing method (welded) and product category (square/rectangular). However, in some countries' local subheadings, wall thickness may determine the final applicable tariff rate.

Q3: Can the same product use different HS codes in different countries?
The first six digits are internationally standardized. However, countries may add their own national digits, so you must confirm the full local tariff number required by the importing country.

Q4: Does galvanized square tube also fall under 730661?
Yes. Generally, galvanizing is considered a processing method and does not change the classification under 730661, unless the importing country's tariff schedule specifies otherwise.

Q5: What documents are typically required when declaring square tubes?
Typically, you will need a Commercial Invoice, Packing List, Mill Test Certificate (MTC), Technical Specification Sheet, and a Certificate of Origin (if required).

Related Resources:

For more technical information on carbon steel square tubes, please see below:

● Carbon Steel Square Tube Size Chart

● What is MS Square Tube?

● EN 10219 Cold-Formed Welded Structural Hollow Sections

● Square Tube Weight Calculation Formula

● S235JRH and S355J2H Structural Steel

● ASTM A500 Structural Tubing