Anti-corrosion systems deployed in Saudi Arabia

Paul Boughton

A challenging application in the Middle East was no problem for one coating expert, as Sander Hofstee reveals.

Following a successful partnership lasting more than a decade, two organisations have once again worked together to successfully deploy a new coating system in the Middle East.

The Dutch company Stopaq first introduced its non-crosslinkable visco-elastic technological system to Saudi Aramco, with the support of the AlSuwaiket group, in 1998.

As a result of this ongoing partnership, Stopaq (now part of the Seal For Life group) was recently invited by Saudi Aramco to introduce its factory-applied glass reinforced epoxy (GRE) system.

The system consists of a visco-elastic 'primer' layer with a GRE mechanical protective top layer directly applied on top. Since the introduction of Stopaq factory-applied linepipe coating systems, this new coating has been primarily used on pipelines in highly concentrated city areas, horizontal directional drilling situations and at refineries.

Clients and contractors discovering the advantages of the system are now also using it on big-diameter thrust boring applications and protection of uncoated and fusion bonded epoxy-(FBE) coated pipes exposed to corrosive conditions.

The most recent challenge was found in Saudi Arabia, where Seal For Life Middle East (formerly known as Stopaq Middle East) was invited to coat pipes on site at the new-build Dhahran Techno Valley. The project involved the coating of 12-inch diameter pipes that each had an individual length of 26.2m and were to be used for thrust boring.

The pre-coated FBE pipes were already in possession of Saudi Aramco and stored in the company's yard. For this project the equipment was brought to site, allowing the coating to take place directly next to the trench, thereby minimising any logistical activities that could damage the pipes.

As a result of the very low coating surface tension, Stopaq's first visco-elastic layer shows excellent wetting on all surfaces including - but not limited to - steel, PE, PP and FBE. This combination of low surface tension and the fluid-like behaviour of the coating causes full impregnation of the complete surface into the finest pores, which favours corrosion prevention.

The coating does not require an anchor profile to ensure that adhesion occurs, unlike the commonly used epoxy coating materials or adhesives. The application of this primer layer can take place after the minimum surface preparation, ST2 derusting.

End of any weak spots

The application of the field joint coating system consists of the same materials as the mainline coating, so the primary layer also consists of the same non-curing, non-crosslinkable, fully amorphous, liquid-like polymer composition. This makes the two layers flow together after application at all times and in any circumstance. It also means there are no weak links and removes the need to preheat and provide anchor pattern for optimal adhesion.

The above mentioned method is known as 'Stopaq FAST' (Factory-Applied Stopaq Technology). In summary, applying the Stopaq FAST system overcomes a number of issues, including high soil stress, stress corrosion, hydrogen-induced corrosion and undercreep corrosion.

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Sander Hofstee works for Seal For Life Industries in the Netherlands.