Building an environmentally friendlier future with Lean Duplex
Lean Duplex steel is a relatively new material in the oil & gas sector, despite being used for decades in, for example, the paper industry and nuclear power plants. As a material Lean Duplex has great combination of higher strength with thinner wall thickness and good corrosion resistance. That enables a lighter, more durable and maintenance-free end result, it is also highly suited to the demanding conditions on oil rigs. And it brings considerable savings.
“Lean Duplex steel has an estimated maintenance-free lifetime of 50 years, which in itself brings savings in maintenance costs,” says Production Engineer Markku Lindstam.
Lean Duplex also results in transport and erection savings, as less material is needed. General estimates put the costs of transporting and erecting material for an oil rig in the range of EUR 300 million.
“The interest in lighter materials was sparked by the customer. Weight is always an issue, especially under challenging conditions. In that respect, Lean Duplex is the answer to customers’ needs,” says Lindstam.
Although the advantages of duplex are undeniable, from its properties to its environmental friendliness, switching from a material that is well-established in the industry to a new one is no easy task. And one factor that is slowing down this shift is price. Lean Duplex has a slightly higher acquisition cost than mild steel, although it pays itself back quickly.
“And even though the cost per kilo is slightly higher, the price per metre might not be,” Lindstam points out. “Despite this, it seems that a lower price at the time of purchase is often more appealing.”
Another issue is that industry standards are slow to change. First, a new material must make it onto a list of approved materials for specific uses, then be brought to the attention of engineers, and finally be approved by the party paying for the product.
“So far, the experiences with and feedback on Lean Duplex have been good, which is promising,” says Lindstam.
“There is, however, only limited information available on the new material. It’s not enough that we are talking about its advantages – the entire steel industry has to get on board,” adds Sales Manager Petri Kotilainen.
Big ships, however, turn slowly, even if the benefits of the new course are obvious. One significant advantage for suppliers is Lean Duplex’s price predictability. Since it has a relatively low nickel content, the changing price of nickel will not have a great impact on the price of duplex.
“The price can be agreed on well in advance, and the value of the warehoused product will not fluctuate greatly. That means that where Lean Duplex is concerned, the supplier always knows what he will get for the product,” explains Kotilainen.
“Just 20 years ago, one car contained couple of different grades of steel. Nowadays, that figure is dozens. The transport industry understands that certain grades are optimal in certain applications. The same goes for oil rigs, but hopefully optimisation is done in a larger scale in the future,” says Kotilainen, pointing out the differences between the industries.
Nevertheless, it is precisely in the oil & gas industry that there is scope – and good reason – to become a forerunner in optimisation matters, at least when it comes to environmental impacts.
“The environmental benefits of duplex in enabling lighter structures and as a more durable material are undeniable,” Kotilainen sums up.
Lean Duplex facts:
- Various Lean Duplex alloys have been used for several decades in demanding applications such as line pipes in paper and pulp mills and for oil pipelines.
- The latest Lean Duplex, i.e. ATI 2003 steel alloy, contains 20% chrome and just 3% nickel.
- Lean Duplex has greater strength than mild steel. Thus, a smaller amount of Lean Duplex can achieve a significantly lighter end result than mild steel, and it also has greater corrosion resistance.
Lean Duplex requires no surface treatment. Its maintenance-free lifetime, for example in North Sea conditions, is calculated at 50 years.