QLD: safety alert issued over concrete pump delivery pipeline end fittings

The following article is a news item provided for the benefit of members. Its content does not necessarily reflect the views of the Australian Institute of Health & Safety.
Date: 
Tuesday, 19 January, 2021 - 12:45
Category: 
Policy & legislation
Location: 
Queensland

Workplace Health & Safety Queensland recently issued a safety alert highlighting the risk of concrete pump delivery pipeline hose ends failing.

Businesses that fit end fittings to concrete delivery hoses and pipes should follow and document sound engineering practices and provide information on inspection methods to customers.

The alert said concrete pump owners should obtain information from suppliers of pipes and hoses on the manufacturing methods used and appropriate inspection methods.

There have been incidents in Queensland where the ends of both rubber and steel concrete delivery lines have failed and sprayed concrete under pressure.

Failures included a:

  • swaged ferrule cracking with the end breaking away
  • ferrule starting to separate from the rubber hose with the concrete spraying out of the gap
  • flange cracking and breaking away from a steel 90-degree, 6-inch to 5-inch reducer bend, located at the hopper.

 

Concrete pumping pressure can be in excess of 85 bar, especially when blockages occur, and the alert said all of these incidents had the potential for serious injuries if workers had been near to where the failure occurred.

In one incident, a car’s windscreen was broken approximately 15 metres away.

Swaged ferrules can fail due to:

  • incorrect tolerances on the external and internal parts of the ferrules
  • inadequate swaging force so that the dies do not contact one another during swaging
  • incorrect specifications for the rubber hose
  • incorrect material specifications for the inner and outer parts of the ferrule
  • excessive wear—especially on the internal part of the fitting from concrete flow.

 

Flanges on steel pipes can fail due to:

  • poor welding due to incorrect electrodes, incorrect preparation, lack of penetration, or other welding irregularities
  • flanges and pipes being made from steel types that can be difficult to weld
  • poor matching of flanges to pipes (i.e. the flange doesn’t fit well on the pipe end)
  • mishandling of the pipe flange (i.e. bashing the flange or pipe with a hammer when the adjacent pipe and/or hose clamp isn’t aligned)
  • poorly fitting hose clamps (e.g. incorrect size, concrete build up).

 

Concrete pump owners must take reasonable steps to ensure that a quality assurance program is followed while attaching the end fittings so that failure of the end fittings is avoided.

It is generally easier to obtain certification from a local supplier when purchasing equipment, and if a concrete pump owner imports components from overseas, it may be more difficult to obtain trustworthy information on the manufacturing process.

This is the case when the overseas supplier is unknown or there is no manufacturer’s mark. The alert said unscrupulous manufacturers have also been known to copy manufacturers’ names and trademarks, so marking of products alone may not provide adequate evidence that the product is fit for purpose.

A concrete pump owner who imports equipment from overseas takes on the duties of an importer under the Work Health and Safety Act 2011.

The importer must carry out, or arrange to have carried out, any calculations, analysis, testing, or examination of the equipment to control safety risks.

Suppliers of hoses and pipes with end fittings should ensure a quality assurance program is followed while attaching the end fittings and that information on this program is available for the purchaser.

Suppliers should also provide documented instructions on the operating parameters of the product along with inspection methods to be used.

The same principles apply to fitting swaged ferrules to rubber hoses that apply to swaged ferrules on hydraulic hoses.

Testing of the swaged ferrule is one way to help demonstrate the integrity of the connection.

The alert also said welding flanges to steel piping used for concrete pumping is a complex issue and requires high levels of technical input and skill to ensure the welding process will result in a quality product.

All operators of concrete pumping equipment also need to carry out ongoing inspection of pipes and hoses.

Inspection methods and intervals for measuring pipe thickness is outlined in the Concrete Pumping Code of Practice 2019.

However, in addition, an inspection program should be applied to rubber hoses, swaged ferrules on these hoses and flanges on steel pipes.

Documented information on inspection of hoses should be provided by the business who fits the swaged ferrules, and this should be passed on by the hose supplier to the end-user.

Hose suppliers should provide information on the maximum recommended volume of concrete that can be pumped before the hose is discarded.

In addition to thickness testing of steel pipeline (specified in the Code of practice) and checking the pipeline for damage, it is important to check flanges on concrete pumping pipe.