Case study – Strengthening of a 3 inch CHS
Integrity issue
A 3 inch CHS (carbon steel) as part of a walkway truss support frame was suffering from external corrosion. The external corrosion was sufficiently severe that the remaining wall thickness would not provide sufficient strength to withstand the acting structural in-plane axial compressive loads. It was proposed to use a FutureWrap Structural composite repair to reinstate the strength of the 3 inch CHS.
Design
The design of the FutureWrap Structural repair was to replace the strength reduction due to loss of wall thickness. The design parameters were; thickness of steel to be replaced 4 mm, temperature 200C, design lifetime 20 years. The repair design resulted in a thickness of 2.5 mm (2 layers) of FutureWrap Structural Carbon/LT composite repair with an axial length of 725 mm.
Installation
The installation steps are shown in the photographs. The surface preparation was to ST3. Full QA/QC measurements were made to demonstrate that the FutureWrap repair was applied in accordance with ISO 24817
Summary
A 3 inch stub suffering external corrosion was repaired using FutureWrap Structural Carbon/LT composite repair. The repair was completed within 2 days returning the strength of the stub to its original value.
