For more than 75 years, the globally active EEW Group has been a specialist for the production of pile structures and pipe components. EEW Special Pipe Constructions GmbH as a subsidiary company of the EEW Group, located in Rostock, Germany, is considered to be a guarantor for the successful production of offshore foundations as well as the associated pile.
As a leading specialist in submerged arc welded (SAW) pipes covering the widest material range, EEW Group offers the industry’s broadest product portfolio targeted at offshore, oil and gas processing and steel construction companies. Increasingly, EEW SPC is regarded as a pioneer in monopile foundations for the offshore industry.
As offshore wind turbines are being set in everdeeper waters and supporting increasing turbine sizes, monopiles are also growing in size. XL, high-strength monopiles present their own production challenges, however.
Preheating the obvious choice
To enable the production of XL, high-strength steel monopiles at a new fabrication hall of EEW SPC in Rostock, EEW needed to maximise the quality of circumferential weld seams (connection points for monopole sections).
Preheating was the obvious and most effective way of ensuring the necessary quality gains. However, EEW SPC was keen to avoid the bottlenecks that can often accompany preheating. As an additional process step, preheating can be extremely time-consuming.
EEEW SPC was looking for a rapid, costeffective, preheating solution for its monopile production flow that could achieve the following:
→ Optimise heating productivity
→ Reduce the risk of hydrogen cracking in high-strength steels
→ Improve safety in the production process
→ Support automation
The chosen solution needed to support the following production conditions in Rostock:
→ Type of steel: S355 – S690 M/QT
→ Wall thickness: 40–120 mm
→ Diameter: 3500 mm
→ Rate of feed: 1000 mm/min
→ Preheating temperature: 60–120 °C
Solution
One possible option was preheating with propane. This fuel gas was in use at other EEW sites for preheating. However, EEW SPC was keen to find a solution that is more efficient than propane.Based on the trials conducted in collaboration with Linde, EEW SPC realised that acetylene offered clear performance gains over the slower‑burning fuel gas propane. In order to optimise productivity, Linde engineered a tailor‑made acetylene LINDOFLAMM ® burner to meet EEW SPC’s specific production conditions.
“Since the first design blueprints for our new offshore facility, Linde has been the partner of choice every step of the way – most recently working closely with us to test all viable preheating options for circumferential weld seams in offshore monopile foundations and work out the solution best suited to our productivity and quality goals.” Karl Klös-Hein, Managing Director EEW SPC.
Reduced preheating time from 75 to 30 minutes
With the LINDOFLAMM applications, EEW SPC is confident that it can enhance the quality of circumferential weld seams and reduce the risk MNof hydrogen cracking in monopiles while avoiding the productivity bottlenecks associated with propane-based preheating. In fact, tests with LINDOFLAMM show that it reduces preheating at EEW SPC from:
→ 75 minutes (based on five rotations) with propane and a standard burner to
→ 30 minutes (based on two rotations) with the custom-developed LINDOFLAMM burner and acetylene
“Preheating with acetylene means we are ideally positioned to take the lead in the fast-growing, technically challenging market for monopiles and deliver the wider diameters and thicker walls demanded by this fast-evolving sector as it moves into deeper waters and bigger turbines.” Tobias Hinz, Technical Director EEW SPC.
Do you want to know more?
Contact our application engineer Bogoljub Hrnjez for more information. Phone: +46 (0)73-867 62 19, e-mail: bogoljub.hrnjez@linde.com