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CROSS Safety Report

Substitution of cold rolled hollow sections for hot rolled hollow sections

Report ID: 158 Published: 1 October 2009 Region: CROSS-UK

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Overview

A reporter was advised by two of their manufacturers that their buyers have purchased cold formed hollow sections rather than the hot formed hollow section which we clearly identified in our calculations.

Key Learning Outcomes

For construction professionals:

  • Substitution of construction elements, for a lower grade material, should not be made without design team verification

  • Talk to the design team and regularly discuss your use of products, components, and materials

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

For designers:

  • Share your knowledge of the behaviour of products, components, and materials

  • Routinely raise the risks associated with substitutions to contractors and the wider project team

  • If you are concerned that the correct material grade may not have been installed on site, consider asking the contractor for the material certificates

Full Report

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We, says another reporter, carry out the structural design work for a number of modular building manufacturers. Very recently we have been advised by two of them that their buyers have purchased cold formed hollow sections rather than the hot formed hollow section which we clearly identified in our calculations.

They have done this because cold formed sections are cheaper although of a lower specification. We are concerned that buyers of structural materials sometimes seem to be cost driven and do not appreciate the importance of the steel grade.

Whilst we have become aware of at least two instances where this has happened and have been able to take steps to remedy it, there may be others where there are buildings with structurally inadequate members.

Expert Panel Comments

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This is not the first time that CROSS has become aware of unauthorised changes being made without the knowledge of the designers. The unauthorised use of non-structural steel box sections and changes to structural fixings are two more examples. It is difficult for the designer to prevent others from effecting changes other than by making it clear, on drawings, or in accompanying issue slips, that all changes are to be referred to the designer. 

Those responsible for value engineering also need to ensure that their decisions do not affect the original design criteria. Concerns of this type need to be brought to the attention of buyers and quantity surveyors. Designers need to remain vigilant to ensure that the materials they specify are used on site.

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