Case outdoor hot tubs



Bathing outside in wintertime is an extraordinary indulgence, but for the material it means constant exposure to extreme conditions.


Modulpool meets this challenge by making their spas from Outokumpu Supra 316plus. This grade provides extensive corrosion resistance at a competitive price.


Steel grade: Outokumpu Supra 316plus
Steel form: sheet
Finish: 2B

Stainless spas upgrade to Supra 316plus

The raw nature of the Nordic climate has inspired man to invent the outdoor hot tub. To be able to look at the stars while bathing beneath the dark winter sky makes one feel alive. For man, it is an extraordinary indulgence, but for the material it means constant exposure to extreme conditions.

In Modulpool’s workshop in Rättvik, Sweden, Patrik Forsberg is cutting insulation while his father, Jan Forsberg, bends the steel plates that will be welded into a hot tub. “Our tubs are handmade,” says Anders Olsson, CEO and owner of Modulpool. “We take great pride in all the details. Our customers expect a quality product that is out of the ordinary."


As long-lasting as the house

Modulpool offers 12 standard sizes and 50 models, with or without a staircase and a wood burner. Last year, they sold 140 hot tubs, most of them in Sweden. But there is also a growing interest from abroad.

“Our solution is very unusual,” continues Olsson. “We have registered the design in 28 countries.”

Modulpool’s customers primarily demand a hot tub that is easy to maintain and lives a long life. Despite the fact that they are exposed to UV radiation, freezing weather, warm water, salt and air pollution, the company promises that their spas will “last as long as the customer’s house”, which means up to 100 years.


Goodbye to corrosion

“Corrosion is the material’s worst enemy,” says Olsson. “But hot tubs built of stainless steel in the 1980s still look as if they are new.”

In addition to durability, he lists hygiene and UV radiation resistance as the main reasons for choosing stainless steel. “And of course that it looks new, neat and clean even after many years,” he adds.

Since its inception, Modulpool has used steel quality Supra 316L/4404. “It meets our demands,” continues Olsson. “The plates are flat, even after cutting, plus they are easy to bend and weld.”

In 2015 Modulpool tried Outokumpu’s new steel grade, Supra 316plus first time and they were convinced for its performance.

“The fact that it is even more corrosion resistant is a strong selling point for us,” Olsson emphasizes. “That’s why we have decided to upgrade to Outokumpu’s new Supra 316plus, especially considering spa’s competitive price compared to 316L/4404,” he concludes.

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The Supra range contains stainless steel products designed for highly corrosive environments. Outokumpu Supra range stainless steels have a good resistance to uniform corrosion in many organic and inorganic chemicals. The addition of molybdenum enhances the alloy’s corrosion resistance in many acidic environments.

Cold rolled coil, strip and sheet

Available for use in a wide variety of applications, Outokumpu cold rolled coil, strip and sheet products are put to work across all industries and markets.