The bonded thermoplastic composite pipe (TCP) being made to Brazil’s deep-water specifications is built by laying down layers of carbon fibre material and a polymer such as PEEK or PVDF, writes Russell McCulley.

The process creates a wall of material that resembles a solid steel pipe but is stronger, weighs much less and is impervious to rust and corrosion.

The load-bearing strength of the pipe can be customised by varying the orientation of the fibre layers during manufacturing. But the stronger the pipe, the less flexible it becomes.

Charles Tavner, chief operating officer at Magma Global, which is working with TechnipFMC and Ocyan in Brazil on TCP applications for deep-water developments, says the move to all-TCP riser systems will necessitate development of a specialised installation fleet that can handle larger reels, given the wider bend radius for TCP built to extreme axial tension specifications.

“The operators recognise that, long-term, that’s not an issue. But in the intermediate term you have to play the cards you’re dealt,” he says.

TechnipFMC’s proposed hybrid flexible, using Magma’s PEEK-based M-Pipe in a traditional non-bonded flexible, “strip out much of the complexity of the flexible”, Tavner says. The combination of TCP and an outside armour “gives it its tension capability, gives it a little bit more weight so that it behaves itself in the water, but it still goes onto a conventional reel.

“They can stick it on a conventional (pipelay support vessel), they can install it with all their standard equipment, they can treat it like a flexible, but at a stroke they’ve removed the stress-corrosion cracking problem.”

Airborne Oil & Gas, Magma’s closest competitor in TCP, insists that its PVDF-based all-TCP riser under development in Brazil will be compatible with currently available installation vessels as well as capable of handling high temperatures, extreme pressure and corrosives such as carbon dioxide and hydrogen sulphide.

“Installation from day one has been a very important part of the riser design and development,” says Airborne chief technology officer Henk de Boer.

Airborne conducted extensive analysis of designs based on about 15 different polymers and five fibres, he says.

“Out of that analysis considering installability, specific gravity and cost, carbon fibre PVDF was the optimal solution for deep-water risers,” De Boer says.

Airborne has also developed a weight coating based on the same polymer but uses heavy fillers in place of the fibre.

The coating gives some heft to the riser configuration to maintain stability in ocean currents but does not reduce “spoolability”, he says.

“It’s integrated in the product — it’s part of the solid wall, so it doesn’t compromise the robustness of the solution,” De Boer says.

The goal of a deep-water TCP riser has been in the works for many years and in Brazil is moving closer to becoming a reality. Airborne seems well-positioned to get there first.

“Hopefully,” says De Boer. “I strongly believe in it, but there’s also competition. We’ll see in the end.”

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Pipe 'installability' key for industry adoption