HS Code 5402.51 – Yarn, synthetic; filament, monofilament (less than 67 decitex), of nylon or other polymides (not high tenacity or textured), single, twisted more than 50 turns per metre, not for retail sale, not sewing thread

HS code 540251 is a 6-digit subheading in the Harmonized System that covers: Yarn, synthetic; filament, monofilament (less than 67 decitex), of nylon or other polymides (not high tenacity or textured), single, twisted more than 50 turns per metre, not for retail sale, not sewing thread. This category specifically targets fine, single filament yarns made from nylon or other polyamides, characterized by a low decitex count (less than 67) and a significant twist level (more than 50 turns per meter). These yarns are not high tenacity or textured, meaning they offer a smooth finish but with enhanced strength, cohesion, and reduced pilling due to the higher twist. They are traded in bulk for industrial and textile manufacturing, not for retail or as sewing thread. Importers are typically manufacturers of fine hosiery, lightweight technical fabrics, specialized apparel linings, or delicate woven and knitted goods where the strength, fineness, and smooth hand of twisted nylon are essential. Exporters are specialized synthetic yarn producers with precision twisting capabilities. Key trade factors include the exact decitex, the precise twist count, and the specific polyamide type (e.g., Nylon 6, Nylon 6.6), which all influence the yarn's performance in high-demand applications requiring durability and a refined aesthetic.

Fine nylon monofilament yarn (high twist), polyamide hosiery yarn, lightweight technical nylon yarn, fine nylon lining yarn, specialized woven nylon yarn, fine knitted polyamide yarn, nylon fishing line yarn.

Can be confused with 540249 (other synthetic monofilament, low twist) if the twist level is not accurately measured, or with 540231 (textured nylon yarn) if the non-textured aspect is overlooked.

In 2025, the top exporters of HS code 540251 in UN Comtrade data were China ($11M, 18% of world exports), India ($6.9M) and Malta ($6.1M). World exports came to about $64M, adding countries' reported figures and partner-based estimates for those that did not report (UN Comtrade data). Taiwan did not report 2025 data, and its estimate from partner records misses its trade with other countries that did not report: in 2024 that was 24% of its exports here ($2.0M, CEPII BACI), so it may also belong among the top exporters.

In 2025, the top importers of HS code 540251 in UN Comtrade data were Austria ($5.7M, 9.9% of world imports), Italy ($4.6M) and India ($4.2M). World imports came to about $57M, adding countries' reported figures and partner-based estimates for those that did not report (UN Comtrade data). Vietnam did not report 2025 data, and its estimate from partner records misses its trade with other countries that did not report: in 2024 that was 39% of its imports here ($2.0M, CEPII BACI), so it may also belong among the top importers.

HS code 540251 is a 6-digit subheading under the Harmonized System. The first 2 digits (54) identify the chapter, digits 3-4 (02) identify the heading, and digits 5-6 (51) specify the subheading. This code is standardized globally by the World Customs Organization.

Brazil splits HS code 540251 into 2 NCM codes: 5402.51.10 (Aramid single yarn, over 50 turns/m), 5402.51.90 (Non-aramid polyamide single yarn, over 50 turns/m). The first 6 digits of each match the HS code.