Ben Catanzariti was killed when the 39-metre boom from the concrete pump broke and fell on him at a Kingston Foreshore construction site in 2012.

The 21-year-old's death is currently being examined in an inquest and previously subject to a failed prosecution.

Cian Ebert and Joel Tenatahi Parone Baines were working nearby and also struck as the boom collapsed.

Mr Baines suffered a laceration to his head and injuries to his neck, chest, left ankle, left foot, and right knee, while Mr Ebert's right leg was crushed.

Mr Ebert and Mr Baines - along with Mr Catanzariti's parents, Kay and Roberto - are suing the concrete pump's owners, Belconnen Concrete, and the company that serviced the machine only weeks before the accident, Schwing Australia, for negligence and injuries suffered in the workplace accident.

Papers filed in the ACT Supreme Court said Mr Baines, Mr Ebert, and the Catanzariti's had suffered injury, disability, and psychological injuries as a result of the collapse.

The lawsuit claims for past and future economic loss for time off work, reduced capacity for work, ongoing wage loss, and medical expenses.

Belconnen Concrete and Schwing Australia have denied many of the allegations, and joined Mr Ebert's company – Ebert Concreting – as a third party to the case he has brought.

Both Schwing Australia and Belconnen have made claims for indemnity or contribution against each other if the case is proven.

Court papers claimed Belconnen Concrete owed the men a duty of care to provide a safe work place and safe system of work.

Particulars alleged include "directing, permitting or allowing the plaintiff to stand under the concrete pump boom", "failing to implement and/or enforce an exclusion zone below the concrete pump boom", and "continuing to use the concrete pump in circumstances where there were unusual noises emanating from the pump".

The lawsuits also claims the boom failed because of Schwing Australia's negligent service of the concrete pump, alleging the company had not carried out the work correctly, and had reassembled the pump in way a that made it unfit for use.

Belconnen Concrete, in its defence, argued the boom's collapse had not been reasonably forseeable and had been caused by defective bolts and/or inappropriate servicing by Schwing Australia.

In its defence against Mr Ebert, Belconnen Concrete said Ebert Concreting had been responsible for supervision and directions at the time of the accident.

"Ebert Concreting was responsible for coordinating the concrete pumping activities on site and the plaintiff was working with other workers to whom he was providing directions and supervisions," court papers said.

"Ebert Concreting owed a non delegable duty to provide a safe work place and a safe system of work."

Schwing Australia denied the allegations and sought to shift liability to Belconnen Concrete.

In a claim for indemnity or contribution against the pump's owner, Schwing Australia claimed a Belconnen Concrete employee had twice heard the pump make a "a metal on metal noise, like a hammer had hit something, lasting only for a split second" at an earlier job in Tuggeranong, before the fatal accident.

Schwing Australia argued the knowledge and awareness of the unusual noises meant Belconnen Concrete had breached it's duty of care as it had failed to cease the use of the concrete pump, failed to report the unusual noise immediately to an engineer, and failed to keep the pump out of use until the noises had been assessed and the equipment cleared for further use.

But Belconnen Concrete claimed Schwing Australia had breached it's service contract by failing to "exercise reasonable skill and care in providing professional services".

The case is expected to be heard early next year.