Riveted, lock-seam, or otherwise mechanically closed large-diameter line pipe — a residual category for joining methods other than longitudinal or spiral welding — is a relatively low-volume heading used in specialized infrastructure and rehabilitation applications. Taiwan and Vietnam lead US import supply under this heading, an unusual sourcing pattern that reflects niche fabrication capacity rather than the integrated steel mill base that dominates other large-diameter pipe headings. The US schedule follows the same diameter and alloy-type structure as 730511 and 730512, with nonalloy steel lines split by diameter bracket and a separate alloy steel line (7305195000). Section 232 tariffs apply, and importers should confirm that the joining method is accurately described in mill documentation to avoid misclassification into the more common welded-pipe headings.

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