7.9km of spiral welded steel, tape coated, concrete lined pipe

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Following a severe storm in July 2008 that damaged the above ground concrete pipeline, the need to replace Nelson’s ageing (circa 1960s) water supply
line became critical.

Steelpipe successfully won the tender to supply 7.9km of 650.2mm OD x 4.8mm WT x 12m (spiral welded steel, tape coated, concrete lined) pipe with hemispherical slip in joints (HSJ), over a two year period.

The proximity of the pipeline to the Maitai River bank with its steep gradients and the rough surrounding terrain meant that the strength of welded joints and the ability of the steel pipe to support itself was a major advantage.

The hemispherical slip in joints that were supplied on each pipe offered a number of significant advantages to the Maitai pipeline project over alternative methods. The ease of connection from one pipe to another meant that on-site welding was also quick and easy. The welded joint also has the added benefit of providing extra strength to the joints, eliminating the use of support thrust blocks and reducing the affect of circumferential stress. The ability of the HSJ joint to deflect pipes up to 3 degrees at each joint reduces the number of fabricated bends required.

To ensure a minimal amount of disruption to the contractor, the pipes were delivered direct to site by truck, with the first shipment being accompanied by a Steelpipe representative. This close contact was maintained throughout the project and was crucial to reducing risks to the project and for the successful, on time completion.