Sometimes the simplest ideas are the best ones. To simplify the job of changing the bolts that hold pipelines together, Statoil engineer Kjell Edvard Apeland came up with an idea borrowed from a tractor. And in doing so, he saved us and our partners a small fortune.

When problems arose with the riser pipes on the Norne production and storage ship, Statoil managers knew whom to call. Kjell Edvard Apeland, project leader for pipeline and repair technology, has more than 20 years’ experience from Statoil’s specialist Pipeline Repair and Subsea Intervention centre at Killingøy, near Haugesund in Norway.

Here, in a windswept facility clinging to the edge of the coast, a team of experts are on constant standby to solve the most challenging pipeline problems—either when things go wrong, or when new solutions are needed. 

Kjell Edvard has worked on all manner of projects since he began here as a student in 1997. Some are routine, involving repairing pipelines and general underwater operations. Some of them are emergencies, such as when a passing ship snagged the 30 inch Kvitebjørn pipeline with a trailing anchor, causing significant damage. 

On this occasion, however, the problem was so-called ‘singing risers’ at Norne—a field in the Norwegian Sea which has been on stream since 1997—and one which Kjell Edvard knew well. Risers are the pipes that bring the well stream to the surface vessel, and at certain flows, the vibrations of the passing well stream can induce ‘singing’ resonances that can shake the platform and fracture couplings and mountings. And it was when these vortex-induced vibrations occurred on Norne in 2013 that Kjell Edvard was called in to help. 

Kjell Edvard Apeland is project leader for pipeline and repair technology at Statoil’s specialist Pipeline Repair and Subsea Intervention centre, PRSI.
Photo: Rune Solheim — Statoil ASA

What is a pipe flange? Pipelines are often connected together using bolted couplings called flanges, as shown here. It can be a challenging task to remake such connections on the sea bed using remotely operated equipment.
Photo: Dreamstime

 “The situation in 2013 was quite acute because they had to reduce flow to below the resonance point, and of course that affects production,” he recalls. “We immediately installed an emergency replacement riser, but we always knew it was only going to be a temporary fix, since it wasn’t qualified for long-term operation,” says Kjell Edvard. “So we had to start planning for its replacement.”

The particular challenge was that the flexible risers on Norne had been connected using bolted flanges, which were cheap to install, but challenging to replace—and the only equipment available for the job of tightening the bolts was complex, expensive and slow to operate, and dependent on a single specialist vendor. So he got to work finding a simpler and better way of replacing bolted flanges. 

“We decided that the best solution would be to reuse some of the technology we already had, combining it with new technology for actually tightening the bolts. We hooked up with a small, Rogaland-based company called 4C Solutions AS, to engineer the process,” says Apeland.

“It’s really important to be hands-on with this kind of development,” he says. “You have to be prepared to understand the complexity, do enough testing and really put your soul into making improvements,” he says.

 

With their broad experience and unique position as a resource centre for several pipeline operators in the North Sea, Kjell Edvard and his colleagues at PRSI have specialist knowledge of remote control systems and operations spanning several decades.

“We combined our knowledge, experience and the new bolt-tightening apparatus in an entirely new machine,” he explains. And the pivotal point of this machine was inspired by something Kjell Edvard saw in rural Rogaland.

“If you watch the animation you can see how the vertical arm descends into position with the bolts. So, I said, let’s design it like the front-loader of a tractor, unloading the pipe and squeezing it into position. It’s almost agricultural in its approach,” he laughs. But the real innovation is actually in the way the bolts are tightened.

Facts about Norne

Norne lies 85 kilometres from Heidrun in the Norwegian sea, in a water depth of 380 metres.

The field has been developed with a production and storage ship tied to subsea templates. Flexible risers carry the wellstream to the ship, which rotates around a cylindrical turret moored to the seabed. Risers and umbilicals are also connected to the turret. The ship has a processing plant on deck and storage tanks for stabilised oil.

Gas has been exported from Norne since February 2001. It travels through the Norne Gas Export Pipeline and the Åsgard Transport trunk line via Kårstø north of Stavanger to continental Europe.

Gassco are the operator of the pipeline system on behalf of Gassledning JV

“You have a sort of bridge, an extra block, a gearbox and lots of ‘rallarmik’ (gadgetry), as we say in Haugesund! We redefined the hydraulic piston that tightens the bolts, making it into a washer. It’s the same idea as the washers you use on the screws when you build an IKEA kitchen. There’s no reason why you can’t have washers like that on a subsea pipeline! And we have tested and verified the design, and specified long-life materials, so we can leave it in place permanently,” he explains.

The resulting simplification to the bolt-tightening process is impressive.

“The solution was designed, built and formally qualified in six months. It took only 30 hours to make the actual connection. That’s a saving of 20 offshore vessel days relative to similar work in 2013. The vessel costs are now less than half what they were, and the total cost of replacing the Norne riser was cut by roughly 25 per cent,” says Apeland with barely concealed pride.

Norne is a field in the Norwegian Sea, 85 km from Heidrun and lying in 380 metres of water. The field is equipped with a production and storage ship (FPSO) tied to subsea templates. Flexible risers carry the wellstream to the ship, which rotates around a cylindrical turret moored to the seabed. Photo: Kenneth Engelsvold — Statoil ASA

The new connection solution for the gas export riser for Norne is simpler, more reliable, and more economical than the solution previous vendors had provided under market-monopoly conditions.

It’s essential to be hands-on. You must be prepared to understand complexity, commit to thorough testing and invest your soul into making improvements.

“You have a sort of bridge, an extra block, a gearbox and lots of ‘rallarmik’ (gadgetry), as we say in Haugesund! We redefined the hydraulic piston that tightens the bolts, making it into a washer. It’s the same idea as the washers you use on the screws when you build an IKEA kitchen. There’s no reason why you can’t have washers like that on a subsea pipeline! And we have tested and verified the design, and specified long-life materials, so we can leave it in place permanently,” he explains.

The resulting simplification to the bolt-tightening process is impressive.

“The solution was designed, built and formally qualified in six months. It took only 30 hours to make the actual connection. That’s a saving of 20 offshore vessel days relative to similar work in 2013. The vessel costs are now less than half what they were, and the total cost of replacing the Norne riser was cut by roughly 25 per cent,” says Apeland with barely concealed pride.

The new connection solution for the gas export riser for Norne is simpler, more reliable, and more economical than the solution previous vendors had provided under market-monopoly conditions.

“We saved both time and money. Thinking outside the box we simply managed to energise the Killingøy community and qualify a new technology,” adds Steinar Kristoffersen, project leader for Norne.


Photo: PRSI animation

Photo: PRSI animation

Photo: PRSI animation

Photo: PRSI animation

Photo: PRSI animation

Photo: PRSI animation

Photo: PRSI animation

Photo: PRSI animation

And Gro Stakkestad, head of Diving Operations and Remote Pipeline Repairs and Kjell Edvard Apeland’s immediate supervisor, says:

“So much new and pioneering technology has seen the light of day in these fabrication halls since we started in 1987. We are proud of the things we have engineered here at Killingøy, in partnership with our vendors,” she says.

Director of projects and technology in 4C Solutions, Espen Møller, praises Statoil’s approach at Killingøy.

“By gathering development and operational use of new technology under one roof, and involving the suppliers at all stages of the project, Statoil fosters the kind of trust, cooperation and incurable optimism that make projects like the Norne riser possible,” he says.