Smart Lock makes short work: Hong Kong sewer drain repair

Feb 20, 2023

When the Hong Kong Drainage Services Department identified a badly damaged pipe, it was Smart Lock’s sleeve solution that empowered contractors to successfully rehabilitate the damaged section.

Challenging from the start

The concrete drainage pipe was aged, partially collapsed, and had sustained severe damage from hydrogen sulphide attack.

Freyssinet Hong Kong was engaged by the Department to carry out a DN825 repair on the pipe. It was a challenging task from the start, with an access shaft required to commence the rehabilitation and other associated works that needed to be done on the important drainage asset.

Time was of the essence, as the sewer flow could not be reduced for any extended period of time. Engineers from the contractor company required a structural sleeve that would allow them to complete the job and was able to facilitate a fast-as-possible installation so that the sewer flow would not be greatly impacted during the work. 

Adding to the growing list of requirements to execute the work, the proposed air packer needed a full flow through in the event that a short capacity drop was required upstream of the works. This flow through would need to be to be substantial.

Excellent execution

After the necessary technical consultation, the Smart Lock sleeve solution was proposed by distributor Astra Syntech as it met all the criteria to successfully complete the works. The contractor was briefed, and the Smart Lock was accepted as the best solution. The job was commissioned shortly after. 

Freyssinet’s sewer maintenance staff are accomplished with fibreglass silicate resin patching and experienced in the correct use of an air patch packer. The Smart Lock installation methodology is a close match to the teams’ existing skill set in the field of point repairs. 

All installers require accreditation to purchase a Smart Lock. With time an important factor in the execution of the work, Smart Lock’s technical support team were able to remotely provide training in the use of the product for the crew and the manager who would be undertaking the work.

The installation took place in normal working hours in September 2022. The depth of the access shaft required a crane to lower the installation equipment and the 825 mm stainless steel sleeve. This was not a job for rope-lowering and retrieval. 

After all pipe surfaces had been cleaned using high pressure water jetting, the Smart Lock wheeled-installation-trolley was set up and a trial placement was carried out to gauge position and pipe entry clearances. 

With everything in order, the Smart Lock sleeve was positioned on the trolley at transport holding pressure. The trolley was pushed into the pipe and centred on the pipe defect. An installation air pressure of 35 psi was applied to the Smart Lock via the packer.

In just a few minutes the defect was successfully rehabilitated, and further reinstatement works were able to proceed.

This was the first project for the Australian-made trenchless solution outside of Australia and New Zealand. 

The installation was observed by the drainage authority engineers at Hong Kong Drainage Services Department and the Freyssinet contractor management team and deemed a favourable outcome for all those involved.

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