CROSS Safety Report
Contractor installs incorrect steel grade
This report is over 2 years old
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:
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Substitution of construction elements should not be made without verification from the design engineer
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Consider introducing a quality assurance process that covers the correct use of products, components, and materials on site
For civil and structural design engineers:
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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
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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
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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
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Feedback
The statement that the duty of care lies with the TWC to ensure the design intent is transferred to the final as-built construction is considered misleading, if not legally incorrect. The duty of care and contractual responsibility lies with the Principal Contractor and ultimately the Client. IF the steel fabricator (sub-contractor) substituted a lesser material (S235 in lieu of S275) then under CDM they have become Designer. Under statute law and contract law they become liable for any loss or injury caused thereunder. The TWC is NOT a CoW nor an RE and is not there to protect the PC or Client from their own inadequacies in terms of QA/QC. The role of the TWC is difficult enough without pushing additional liabilities upon them, especially where there is an ongoing lack of TWCs with the commensurate knowledge of civil/structural design as suggested by the TWf in their suggested competencies of a TWC.
CROSS Response
We understand that the statement you are referring to is the CROSS Panel's comment below on Report 634 Contractor installs incorrect steel grade.
"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."
'Design intent' in this statement refers to the design intent for the temporary works design. It does not refer to the design intent of the permanent works design. As you rightly say, it is not the TWCs responsibility to ensure that the design intent of the permanent works is transferred to the as-built construction. Section 10.1 of BS 5975 below is what the CROSS Panel were referring to.
10.1 Work on site should be the subject of careful direction, supervision and inspection to ensure that the temporary works is constructed safely in accordance with the design and specified materials, and that only when all checks have proved satisfactory is the works loaded, used, maintained and then dismantled in accordance with the design documentation and method statement.
Expert Panel Comments
An Expert Panel 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-US Expert Panel 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.