CROSS Safety Report
Weld de-specification without design approval
This report is over 2 years old
Overview
A reporter's firm was engaged as fabricators for a main contractor and asked by them to de-specify full and partial penetration butt welds and replace them with fillet welds without approval from the main design engineer.
Key Learning Outcomes
For civil and structural design engineers:
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Review and comment on connection designs to ensure that the fabricators detailed designs meet with the specified requirements
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Inspect safety critical connection designs on site to ensure they have been fabricated and constructed in accordance with the design details
For construction professionals:
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Changes to connection details and weld specifications should be approved by the designer
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Raising of health and safety concerns should be encouraged and not criticise
Full Report
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The Full Report below has been submitted to CROSS and describes the reporter’s experience. The text has been edited for clarity and to ensure anonymity and confidentiality by removing any identifiable details. If you would like to know more about our secure reporting process or submit a report yourself, please visit the reporting to CROSS-UK page.
A reporter's firm was engaged as sub-contract fabricators to complete 90 tonnes of steelwork for a main contractor. In the commercial negotiations at the onset of the project, the main contractor looked at ways to reduce costs.
They agreed that to hit their target prices the sub-contractors should de-specify all full and partial penetration butt welds from all steel and replace them with 6-8mm fillet welds.
Any changes to drawings should go through a proper change process
The sub-contractor had several conversations with the main contractor who refused to change the drawings to match the changed description of the welds. The main contractor assured the sub-contractor both in writing and in person that it was okay to proceed with de-specification of the welds, but they would not re-issue the drawings.
How de-specifying welds can have structural implications
Eventually the sub-contractor declined to participate further due to this and other issues. The reporter's firm sought advice from the original designers and were told that for structural reasons the proposed changes to some of the welds should not be made.
When the sub-contractor raised this with the main contractor as a health and safety issue, they were told it was none of their business. The reporter is concerned that such practices exist.
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Feedback
Our experience is that in some cases, the structural engineer for the frame (not for connections) does not size up welds. The choice of weld type as partial pen would only make sense if it is reducing fillet weld size (the alternative would be large fillet weld size with risk of so many passes leading to cost and overheating). If the frame structural engineer has not sized up the weld, they would not be able to recommend partial pen over fillet.
With regards to full pen, I have only come across cases where fillet weld won't be recommended when fatigue is a risk. Unless this is a concern, I can not see why a frame structural engineer would insist on it.
As an observation, I feel it would have been worthwhile mentioning in the report that structural engineers should not over specify. We are seeing cases of specifications for projects with small sections sizes but the structural engineer still includes a statement such as 'minimum fillet weld of 8mm' when some web thicknesses on the project are only 6mm to 8mm.
Thanks a lot for the great work.
Expert Panel Comments
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.
Health and safety is everyone’s business and there should be no criticism of those who raise these issues. There are numerous examples of concerns being ignored which have resulted in subsequent failures and lessons have to be learned.
Designers are aware of the time, cost and difficulty of producing butt welds and will specify fillet welds wherever suitable. They also know that fillet welds will generally be cheaper than butt welds.
Therefore, if butt welds have been specified it will have been for good reason and they should not be changed without formal approval from the design authority.
The risk of changing weld types
Proposals to change butt welds to fillet welds should always be treated with caution. They have very different characteristics, particularly in fatigue. Contractors may not be well versed in the longer term implications of the changes they make, or wish to make, when reducing cost or accelerating the build process. Their emphasis on this aspect of the product lifecycle can cloud a wider perspective and be dangerous.
Whilst not necessarily applicable here, it is not good for a main contractor to coerce a sub-contractor or have decisions made by persons who are not competent/qualified to make them. There are legal and ethical issues to be considered. If there had been a failure the consequences could have been severe for the firms and individuals concerned. Indeed, the Health and Safety Executive could be interested in such behaviour.
Whilst not necessarily applicable here, it is not good for a main contractor to coerce a sub-contractor or have decisions made by persons who are not competent/qualified to make them. There are legal and ethical issues to be considered.
Two ways to avoid unapproved changes from occurring
To avoid such situations the following steps should be taken:
Ensure that the frame designer always has the opportunity to review and comment on connection designs and ensure that those detailed designs meet with the specified requirements
Ensure that execution of works is in accordance with checked drawings only. If the drawings need to change, they should be changed through a design change process to ensure adequate redesign and rechecking.