TS EN 523

TS EN 523 is the standard for steel strip sheaths used with prestressing tendons, defining the terminology, characteristics and quality-control framework for this component family. Its technical focus is the corrugated cylindrical sheath system that forms the duct in post-tensioned prestressed concrete elements.

What the standard covers

The scope applies to uncoated cylindrical steel sheaths with a corrugated profile and a nominal internal diameter of up to 130 mm, together with the connectors or couplers assembled with them to form ducts. A key boundary is the construction method: the standard applies only to sheaths and couplers made from interlocked or welded strip steel.

In general prestressing practice, the sheath is the conduit that maintains the tendon path within the concrete member before and during stressing, and later supports the duct used for grouting where that process is specified elsewhere. Dimensional consistency, profile integrity and connector fit are important because they affect tendon passage and the continuity of the duct system. The coupler is the joining element that allows separate sheath lengths to be assembled into a continuous run.

The standard also refers to quality control, indicating that the product family is not only named and characterised but also treated as a controlled manufactured system. Seals between sheaths and couplers are expressly outside the scope of this standard.

• Uncoated cylindrical steel sheaths with a corrugated profile
• Products with a nominal internal diameter up to 130 mm
• Duct components for prestressing tendons in post-tensioned concrete elements
• Connectors or couplers assembled with the sheaths
• Sheaths and couplers made from interlocked or welded strip steel