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680 Late detection of flange/web splitting on steel beam

Report ID: 680

Published: Newsletter 56 - October 2019

Report Overview

A reporter noticed a crack at the interface between the flange and web for a chord member in a steel truss.

Report Content

When loading fabricated members for a steel truss to be installed as part of a roof in a large industrial building on to a delivery lorry, a slight but unusual ridge was noticed by a reporter in the paint longitudinally along the interface between the flange and web for a hot rolled steel I section chord member. The beam, which was painted, was not deep and the web thickness was thin.

The paint was subsequently removed and revealed a crack. A section of the flange was then cut out to investigate the crack with a view to carrying out a local welded repair if possible. When the flange was cut across its width, well beyond both ends of the visible crack, the flange fell away revealing rusting at the connection of the flange to the web, extending further than originally thought. A crack through the web appears to have existed undetected and there was no significant connection between the flange and the web, says the reporter.

Despite having rigorous quality assurance/inspection procedures in place, this issue appears to have slipped through many 'nets'. The reporter states that only the vigilance of yard staff has potentially averted disaster since, had the flange been subjected to significant compression, local flange/web buckling could have occurred leading to failure of the member and possibly the truss.

The reporter feels that while this may be an isolated incident, others should be alerted to it due to the difficulty in detection, which could result in hidden and dangerous defects.

Comments

This is an unusual case which the CROSS Panel have not come across before, demonstrating that new safety issues continue to come to light. The fact that the crack surface was rusty as shown in the picture, suggests that it must have been there for a considerable period of time.

The crack cannot be due to lamellar tearing as this only occurs where there is welding, and this beam was a hot rolled I section. The beam was painted, not galvanized, so Liquid Metal Assisted Cracking (LMAC) can also be ruled out. It is possible for steel to have laminations, but this crack is across the thickness of the web.

The most likely conclusion is that the manufacturing of the hot rolled I section did not comply with the required standard. The advice is to be alert, conduct visual inspections and only purchase steel from organisations who meet the appropriate manufacturing standard. For steelwork, BCSA/TATA Steel publication Steel Construction - CE Marking is a useful document and states that in order for steelwork contractors to demonstrate their right to CE Mark their products, they must provide the following three documents:

  1. Factory Production Control (FPC) Certificate - issued by a notified body
  2. Welding Certificate - issued by a notified body
  3. Declaration of Performance (DoP) - issued by the steelwork contractor

 

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View other CROSS reports published in Newsletter 56

Images

Flange/web splitting on steel beam


Approximate crack location shown in red



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