Round ducts are cylindrical sheaths. Flat ducts are formed profiles used where structural depth or tendon layout makes a round section impractical. DUSO flat sizes are produced from defined round diameters (for example round 60/65 → flat 72/21), so coupler and process selection still refer to the round origin.

Published production thicknesses are 0.40 / 0.45 mm, 0.50 mm and 0.60 mm. Not every diameter is produced in every thickness; use the technical tables.

EN 523:2003 is the European standard “Steel strip sheaths for prestressing tendons — Terminology, requirements, quality control.” It applies to uncoated cylindrical corrugated steel sheaths and couplers made from interlocked or welded strip, with nominal internal diameter up to 130 mm. Categories described in public summaries include Category 1 (normal) and Category 2 (rigid). Seals between sheath and coupler are outside its scope.

Yes. This is a core DUSO offering: production machines are shipped to site, configured, installed and operated with training and optional supervisor support.

Export packing and worldwide delivery are part of the commercial offer. Export destinations include Russia, Denmark, Italy, Iraq, Kuwait, Israel and France; destination and terms are confirmed per quotation.

Yes. DUSO supplies production machinery as capital equipment, including mobile/on-site configurations.