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CROSS Safety Report

Contractor installs incorrect steel grade

Report ID: 634 Published: 1 April 2018 Region: CROSS-UK

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Overview

A reporter came across an issue where the fabricator had used cold formed S235 commodity steel SHS rather than the specified hot formed S275 structural steel SHS.

Key Learning Outcomes

For construction professionals:

  • Substitution of construction elements should not be made without verification from the design engineer

  • Consider introducing a quality assurance process that covers the correct use of products, components, and materials on site

For civil and structural design engineers:

  • Share your knowledge of the behaviour of products, components and materials and routinely raise the risks associated with substitutions to contractors and the wider project team

  • If you are concerned that the incorrect material may have been installed on site, consider asking the contractor for the material certificates to confirm what has been installed

Full Report

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A reporter came across an issue where the fabricator had used cold formed S235 commodity steel SHS rather than the specified hot formed S275 structural steel SHS. The change was discovered during a review of material certificates, after the job was finished.

The project, in a football stadium, was for gantries to hold sound and lighting equipment (with access for technicians) slung beneath the stadium roof directly over the public seating. Apparently, the fabricator had difficulty getting the S275 steel and the steel stockholder told him the S235 was easily available and an acceptable alternative.

The reporter did not agree, and the gantries had to be replaced using the correct grade of steel. An expensive lesson for the contractor but sadly all too common says the reporter.

The reporter did not agree, and the gantries had to be replaced using the correct grade of steel. An expensive lesson for the contractor but sadly all too common says the reporter

Expert Panel Comments

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Expert Panels comment on the reports we receive. They use their experience to help you understand what can be learned from the reports. If you would like to know more, please visit the CROSS-UK Expert Panels page.

It is not possible to distinguish different grades of steel simply by looking at them. Likewise, it is not possible to distinguish different grades of concrete just by looking at the cast material. To overcome this, it is important to operate a proper quality assurance (QA) and quality control (QC) system to assure that what is built is what it is intended would be built. There needs to be detailed specifications of workmanship and materials, and inspection and test plans to provide quality control to meet those specified requirements.

This report also has echoes of a comment made for report 736 about the vital importance of change control: never change anything unless the designer has agreed. This is a Golden Rule in temporary works management (BS5975 refers), where the Temporary Works Coordinator has a stated duty to ensure that design intent equals constructed manifestation.

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