Statoil is about to commence drilling for oil at 73 degrees north and is thus simultaneously preparing to deal with the materials technology challenges it will face when the air temperature is below minus 40 degrees Celsius and the ice is full of highly concentrated saltwater. Standards play animportant role in these conditions, which is why Statoil is heavily involved in the standardisation work.
Statoil’s chief engineer within materials technology, Mons Hauge, chairs the ISO "Arctic Materials" working group and has concrete examples of the materials technology challenges one faces when temperatures can approach minus 60 degrees Celsius and the ice can wear down and damage structures.
Must withstand very low temperatures
"The materials you use in the Arctic must withstand very low temperatures. Steel becomes brittle, plastic become hard and brittle, and repeated freezing and thawing can cause cracking.
Given the distances from the platforms to the mainland, our requirements regarding reliability, long lifetimes and minimum maintenance must be very high," says Mons Hauge, "which is a real challenge for the steel industry."
Dramatic drop in ductility
"All structural steel experiences a dramatic decrease in ductility when temp-eratures drop into the so-called ’transition range’ at which brittle fractures can occur. Welded zones are particularly susceptible. This means that the characteristics of the steel that will be used in such conditions must be carefully tested at the relevant temperatures and under the relevant welding conditions. These are precisely the type of specifications we are trying to draw up in our ISO working group to allow the oil industry to coordinate requirements for its suppliers," says Hauge.
A standard will not in itself improve the steel, but it can encourage producers to produce better steel.
"At the same time, we end up with testing and qualification requirements, meaning we can be confident that the structures are fit for purpose," says Mons Hauge.
Icing and darkness
The steel does not just have to withstand a very tough climate. Opportunities for maintenance are also very limited. The conditions in the relevant drilling areas in the Arctic are characterised by a lot of bad weather, icing, snow, the polar night during the winter half of the year, poor communications, and long distances to land and existing infrastructure.
Ice, salt and corrosion
The materials will also be worn down by ice and corrosion:
- Ice formed from seawater always contains a small amount of water that has not solidified. Salt concentrations in this water are always high. This can result in faster corrosion than seawater alone would have caused. The ice also tears off paint and corrosion products,increasing the damage.
- The hardness of ice crystals varies, with hardness increasing as temp-eratures drop. This increases wear and tear.
- Ice that rubs along a hull creates static electricity that is discharged and affects the conditions for corrosion.
Adaptations for such conditions are also being specified in the material requirements Hauge’s group is working on.
Material requirements in Arctic operations
"ISO/TC 67 is the technical committee for the entire oil industry and our working group that is looking at Arctic operations is responsible to this. When Sub Committee 8 was established we were asked if there were topics we could standardise within materials technology. That is when we aired the need for material requirements for structures in the Arctic climate," says the committee’s chair, Mons Hauge.
The committee is working on:
- Material requirements for load-bearing structures
- Production requirements
- Operation and maintenance task requirements
- Corrosion control
- Integrity and lifetime calculations
"The actual standardisation work has not come very far yet, but part of the reason why we dared to propose these material requirements is that we believe Norwegian knowledge and experience in the field of petroleum is key, and SINTEF and DNV have done so much good research in this area in a wide-ranging research project funded by the Research Council of Norway and a number of companies in the industry. This project provided recommen-dations that were a useful contribution to the standardisation work," says Mons Hauge.
Aiming to be an important player
"Statoil is aiming to be an important player in the Arctic regions, both in Norway and internationally. We regard standards as an important factor in ensuring predictable conditions for our operations. They are also a way of developing common working methods in the industry. After all, we do not build the platforms ourselves so we have to rely on the industry adopting standards that suit our needs. That is why we actively participate in the standardisation work," says Mons Hauge.
ISO TC67/SC8/WG5 Material Requirements for Arctic Operations
ISO working group drawing up standardised material requirements for Arctic production installations. Must take into account factors like: may be far from land and other infrastructure, temperatures can drop to minus 60 degrees Celsius, tough climate, and difficult snow and ice conditions. The committee has representatives from Russia, Canada, the Netherlands, Italy, France, Germany and Norway, and is chaired by Mons Hauge from Statoil.
Research project: Fundamental studies of materials' behaviour in cold climates
10-year research project (2008-2018) supported by the Research Council of Norway. The project is investigating fracture and damage mechanisms in steel, aluminium and plastic materials that might be used in the Arctic. The results will provide a basis for the requirements and quality criteria for using materials in the Arctic and defining serviceability limits. The participating companies in phase 2 (2013-2018) are: Statoil, ENI Norge, Total, Lundin, Aker Solutions, Kværner Verdal, Bredero, FMC, Hydro, JFE Steel, Kobe Steel, Nexans, Posco Steel, Ruukki Metals, Sapa, Scana, Steel Trelleborg and Borealis.
Text: Jakob Berg