Concrete delivery pipeline failures

Background

Concrete delivery pipelines deliver pressurised concrete from the pump to the concrete pour location. They are made from multiple components, including pipes, reducers, bends, hoses and couplings.

WorkSafe has investigated many pipeline failures that exposed workers and the public to the risk of being struck by high pressure concrete or metal debris.

A significant contributing factor in these incidents has been poorly manufactured pipes/pipeline components.

Safety issue

Importers and manufacturers of pipes/pipeline components should ensure their pipes/pipeline components are safe and without risk to health and safety when they are used for the purpose for which they were designed, manufactured or supplied.

However, WorkSafe has identified defects with:

• imported complete pipes, and
• pipes manufactured locally from separate components (such as pipes, reducers, bends, hoses and couplings).

Defective pipes have also been found on preassembled boom pumps.

Recommended control measures

Do not rely on the supplier's quality assurance

Principal contractors and employers should be aware that the quality of pipes/pipeline components may vary between batches. In this context, solely relying on the supplier's quality assurance accreditation, test reports or mill certificates may not ensure that pipes/pipeline components are safe for use.

Regular inspection and testing

Employers should implement a system of work that includes regular inspection and testing before each use.

Inspection and testing may be carried out by a third party who is independent of the manufacturer.

The inspection should include checks for:

• defective welds
• misaligned welded components
• poorly manufactured pipeline restraint/weld rings that are irregular in size and shape
• inadequate restraint/weld ring grooves, which can lead to a lack of contact with the next pipe in the pipeline and/or coupling
• porosities in the metal created by the cold drawing manufacturing process that may lead to cracks developing, and
• the compatibility of separate pipeline components.

Provide adequate training

Employers should ensure employees know how to identify pipe and pipeline component defects.

Failure to adequately train operators and their supervisors could result in inconsistent maintenance, undetected damage, or structural failure. Even if only one pipe is defective or compromised it could cause concrete to be ejected from the pipeline at high pressure, or cause sections of the pipeline to break and fall from height placing persons at risk of injury.

Remove failed or defective pipes/pipeline components from service

If issues are identified with pipes or pipeline components they should be taken out of service until testing or remedial action has been undertaken.

This may include:

• destructive testing
• non-destructive testing
• pressure testing
• cyclic testing, or
• hardness testing.

The testing should confirm that pipes and pipeline components perform in accordance with their original design and will not fail under the maximum rated pipeline pressure.

Failed pipes or pipeline components should not be used until they are repaired. Alternatively, they should be destroyed.

Ensure quality welds

When welding pipeline components, a competent person should be engaged to produce a welding specification and welding procedure.

The welder should be competent to perform the required weld, as welding hardened steel incorrectly can lead to issues such as brittleness.

Before use, a weld inspection should be undertaken by a competent person to ensure that the weld meets the original welding specification.

Australian Standards

• AS2550.15 - Cranes, hoists & winches - Safe use - concrete placing equipment
• AS1418.15 - Cranes (including hoists and winches) - concrete placing equipment
• AS4041 - Pressure piping.