Malibongwe Ridge Linepipe Project

Location: Northriding to Cosmo City, North West of Johannesburg

Project Owner: Johannesburg Water

Project Starting Date: July 2015

Project Completion Date:  Including field joint & specials -  up to inspection - 2017

Background:

The Malibongwe Ridge pipeline was installed in order to deliver water to Cosmo City and surrounding areas in the north west of Johannesburg. Due to harsh conditions that pipelines in South Africa are subjected to, including extremely high levels of stray current, it has become a priority to find coating solutions that will be able to withstand these harsh conditions.

If a completely homogenous coating could be applied over the entire pipeline, one that would be completely self-amalgamating regardless of whether it is factory or field applied, the weakness of the inferior bond between the parent coating and the field applied coating would be eliminated.

Our GRE linepipe system was selected because this system provides a completely homogeneous pipeline whereby the Linepipe, field-joints and all specials are completely corrosion protected with the same corrosion prevention system and material namely visco-elastic Polyisobutene as a corrosion protection layer. This Visco-elastic Polyisobutene coating cold flows, thus providing a coating system that is completely sealed at the joint areas between the parent coating and the field applied coating, to form a single homogenous corrosion protection layer throughout the pipeline. The outer mechanical glass reinforced epoxy coating, provides an extremely resilient outer mechanical protection which protects the corrosion protection layer beneath it.

The benefit of a homogenous coating ensures that the same coating is used over the entire pipeline, thus alleviating the areas of weakness where coatings often fail over time. Generally, field joint repairs and specials are the area of most concern and are often the areas that fail as the pipeline ages, due to disparity between the linepipe coating and the field joint coating.

Prior to the introduction of our system, there were no systems that could provide a totally homogenous corrosion prevention coating for the entire pipeline, but with our visco-elastic technology and cold flow properties, we managed to address the need.

Our corrosion protection layer that has been applied to the linepipe amalgamates with the field joints and specials by a simple and quick field joint and specials application which is completed in the field. Our technology ensures that the corrosion protection layer cold flows together with the field joint corrosion protection layer, becoming one coating.

Application Details:

The Cosmo City Project pipes were coated in a shed about 2km away from the construction site using our mobile coating plant system.

Bare pipes with a 1016mm diameter and 18 metres in length, weighing approximately 5.5 tons with an internal epoxy lining were delivered to the coating shed, these pipes are then coated according to our requirements.

Technical Developments

Our Linepipe corrosion system is currently the only system that provides a truly homogenous coating system because the same material which is factory manufactured is applied both in the factory and in the field.

Our products which are based on nanotechnology, do not cure or age, it has no internal stress, is practically impermeable, and is unaffected by all normal environmental factors, ensuring the longevity of the coating and hence the protection of the pipeline throughout the lifetime of the pipeline - this is a first in South Africa.

The pipeline has also had DCVG and PCM testing carried out- no defects at all were found. This trial project is proving that a pipeline coated with the our GRE linepipe system along with all the specials being coated with the same material to form a homogenous coating through the entire system is the way forward in the pipeline coating arena and a number of other projects in South Africa have been completed using this system since its introduction.