Risk controls for on-site structural welding
Employers and managers must understand and control the risks associated with on-site structural welding.
WorkSafe has identified unsafe practices with on-site structural welding that could result in catastrophic structural collapse causing serious or fatal injuries to workers and others in the vicinity.
Examples of unsafe practices observed by WorkSafe include:
- poor quality structural welds
- absence of documentation verifying the qualifications or competency of the persons performing structural welding works
- incomplete welding specifications in the structural engineering documentation
- insufficiently detailed, or complete lack of the necessary welding procedures for welders
- failure to have welds inspected and signed-off by a competent person (e.g. welding inspector) before a structural engineer approves the removal of the temporary structural supports or the welds are grouted over.
Situations where these deficiencies have been identified include:
- welding of stitch/fish/connection plates on pre-cast concrete panels
- welding of structural steel members to cast in plates (e.g. awnings to a precast panel)
- on-site welding of structural steel members.
Recommended control measures
Understand what constitutes a structural weld
Structural welds include welds required to resist structural loads or restrain structural elements temporarily.
For example, precast panel stitch plates and associated welds designed as temporary restraints to enable the removal of panel bracing prior to casting and curing of concrete floor slabs are structural welds and should be managed accordingly.
Relevant duty holders (generally the builder) must ensure that both temporary and permanent works are constructed in accordance with the structural engineer’s or the designer's specifications.
To meet the National Construction Code the specifications typically require compliance with the relevant Australian Standards (see below).
Use a quality assurance system
Australian Standards specify that a quality assurance system must be used to ensure the integrity of structural (i.e. on-site) welding.
The system should include:
- provision of a welding specification with the structural design
- development of a welding procedure by a qualified person, which must be communicated to the welder(s)
- verification of the qualifications and/or competency of the welder(s) engaged
- oversight of the welding works by a qualified welding supervisor, and
- completed welds signed off by a qualified welding inspector in compliance with the design.
AS1554.1:2014 'Structural steel welding, Part 1: Welding of structural steel' provides further information regarding each of these items, including details of acceptable qualifications.
Even if compliance with Australian Standards is not specified in the structural engineer’s, or the designer’s specifications, you must use an alternative and equivalent quality assurance system to ensure the integrity of the structural welding. This system should be followed and documented.
Use an alternative structural solution if required
Where site conditions or fabrication errors do not allow for the original design to be followed, an alternative structural solution should be designed and documented by a structural engineer before rectification works are undertaken.
Examples of poor on-site structural welding
The images below are examples of poor on-site structural welding, including slag inclusions, pitting, undercutting, corrosion, inconsistent fillet size, broken fillet runs and jerry-built stitch plate connections.
- AS3850:2015 Part 1 & 2 - Prefabricated concrete elements
- AS/NZS 1554.1:2014 - Structural steel welding, Part 1: Welding of Steel Structures
- AS4100:1998 (R2016) - Steel Structures
- AS/NZS 5131:2016 - Structural steelwork—Fabrication and erection