Special Beams for Medical Applications

A Special Situation

The challenge is to produce two special beams in 304 stainless steel. The input data are the following limits: the minimum moment of inertia (80.7 by 106 millimeters to the fourth), as well as the maximum acceptable section height of 160 millimeters. In addition, the request is for fully penetrated weld.

Optimization by Montanstahl

The solution designed by the engineering company is a tough welding challenge and is significantly heavy as far as weight is concerned. There is potential for improvements.
With the support of our technical department, we at Montanstahl designed a weight-lighter section with 26 kilograms per meter weight savings. Due to this, it is easier to laser weld, but satisfies the structural and dimensional requirements at the same time.
The section is a beam with three webs, with wider flanges but foresees strongly reduced material thickness.
The appointed engineering company approves and signs off the suggested variant. The clinic needs two of those special beams with a length of approximately 6650 millimeters. The final length to which the beams will be precision cut, is defined by measures performed on site once the concrete works are ultimate.

Medical Applications require Special Stainless Steel Beams

The bars are installed in the private medical clinic Ars Medica in Lugano in the Tessin Region of Switzerland. They will be the structural support for the equipment of a magnetic resonance imaging (MRI). This is also the reason for the choice of an austenitic stainless steel, in order to keep the magnetism of the supporting structure extremely reduced. The use of the expensive non-magnetic stainless steels, such as 316LN or 1.4435 (a 316L with a minimum of 12.5 per cent nickel content), is not necessary.
At first the central web is laser fused. The heat input for welding the ten millimeter thin web with full penetration from two sides is limited.

Thus distortion is minimal and we only need to straighten it a little prior to stich the two external webs. Afterwards, the welder laser fuses them with full penetration, too. The agreement is to cut to measure and release the bars within two days, once the cutting length is established.

Our Solution Proves Itself Successful for Medical Applications Once Again

With the enlargement of the range of expertise, another private clinic in Lugano needs  new heavy magnetic resonance imaging equipment.

The clinic Sant’Anna also belongs to the Group Genolier Swiss Medical Network – one of Switzerland’s leading private clinic group. Ars Medica also belongs to it.

The requirements are similar and so we adapt the proven concept in the same way. In this project the beams with three webs are significantly bigger, both higher and wider, as well as much heavier (245 kilograms per meter), forcing the production manager and his team to explore new limits thanks to this challenge.
For this job, the client sets a two days deadline for precision cutting of the 6.9 meter long bars and release. We successfully accomplish that.