M4 Helical Spring Lock Washer
A small helical spring lock washer made of carbon steel, designed for M4 metric bolts to prevent loosening from vibration. It features a split ring that compresses under the bolt head or nut, creating tension. Classified under HTS 7318.21.0030 as a non-threaded helical spring lock washer of iron or steel.
Import Duty Rates by Country of Origin
Alternative Classifications
This product could be classified differently depending on its characteristics or intended use.
If externally threaded
Threaded lock washers shift to non-threaded spring washers subheading in the same chapter.
If part of a bolt assembly set
Washers sold as components in headed bolt sets may classify under other non-threaded articles.
If for industrial machinery use only
If specifically fabricated for a particular machine, it could be classified as other steel articles.
Not sure which classification is right?
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Import Tips & Compliance
• Verify steel composition meets HTS iron/steel requirements; provide mill test certificates for customs
• Ensure packaging labels specify 'helical spring lock washers' to avoid misclassification as plain washers
Related Products under HTS 7318.21.00.30
1/4 Inch Helical Spring Lock Washer
Standard 1/4 inch helical spring lock washer from alloy steel, used with SAE bolts in automotive applications to resist vibration-induced loosening. The helical split design provides axial flexibility and locking tension. Falls under HTS 7318.21.0030 for helical spring lock washers.
M8 Zinc-Plated Helical Spring Lock Washer
Zinc-plated M8 helical spring lock washer of carbon steel for corrosion resistance in construction and machinery. The helical coil deforms to lock fasteners under load. HTS 7318.21.0030 covers these non-threaded spring lock washers.
M10 Stainless Steel Helical Spring Lock Washer
Austenitic stainless steel (AISI 304) M10 helical spring lock washer for marine and food processing equipment, offering high corrosion resistance. Its split helical shape ensures reliable fastening. Classified in HTS 7318.21.0030 as iron/steel helical lock washers.
5/16 Inch Alloy Steel Helical Spring Lock Washer
Heavy-duty 5/16 inch alloy steel helical spring lock washer for high-vibration truck suspensions and engines. Provides superior locking via elastic deformation. HTS 7318.21.0030 for these non-threaded helical lock washers.
M6 Black Oxide Helical Spring Lock Washer
Black oxide coated M6 helical spring lock washer for indoor machinery, reducing friction and corrosion. Helical design locks nuts effectively. Under HTS 7318.21.0030 as steel spring lock washers.
M12 High-Carbon Steel Helical Spring Lock Washer
High-carbon steel M12 helical spring lock washer heat-treated for maximum elasticity in heavy equipment. Prevents fastener rotation under dynamic loads. HTS 7318.21.0030 designation for helical types.