So says Peter Nordell, Project Manager at IVAB in Luleå. The company used Cromacore LDX and Cromarod LDX for re-lining four oil storage tanks in the port of Luleå. The tanks have been empty for several years and needed new floors as they would be used again for storing diesel oil for LKAB.

IVAB worked on the project during the winter and spring of 2012 in tanks that are 35 metres in diameter and 20 metres high. The floors consist of 3 mm LDX steel connected to the shell inside and out. Because of shell thickness (15-20 mm) pre-heating to 150°C was necessary and was carried out using a Miller Proheat 35.

The joints between the floor plates are 5 mm thick and they were welded together using Cromacore LDX flux cored wire. Cromarod LDX electrodes were used for welding on the outside, as these have somewhat better resistance against the elements.

LDX made its breakthrough as an alternative to conventional stainless steel as the latter became ever more expensive due to rising nickel prices. But LDX is not only cheaper, it also has better fatigue properties and is often used in bridges and similar structures.

“The Cromacore and Cromarod LDX consumables have a higher Ni content than the LDX steel to ensure the correct ferrite-austenite balance in the weld,” said Per Sundberg, Product Manager at Elga. “Electrodes have been on the market a long time, but good quality flux cored wire took a while. Cromacore LDX and Cromarod LDX mean we now have a full set of LDX products and I’m confident in saying that the best flux cored wire for LDX welding on the market is Cromacore.”

IVAB’s re-lining assignment on the four storage tanks comprised around 3,000 metres of weld, so maximum welding deposition rate played a major part in the choice of product.

“Flux cored wire provides higher productivity than electrodes,” says Håkan Pavasson, salesman at Elga in Luleå. “Deposition is a full 87 per cent compared to 60 per cent for an electrode, and cored wire requires fewer stops for electrode replacement, which made cored wire very attractive for IVAB. Following an initial test we opted for the cored wire, and despite its being our first time the welding job went entirely without problems.”

IVAB is an installation and pipe fitting company that works with such things as maintenance in process industries and oil installations. Although the head office is in Piteå, the company does business nationwide.