Bent 316L HEB Beams for the AMS Testing Rig at CERN/ESA ESTEC
Through contacts with NASA, Montanstahl was introduced to the Italian Institute for Nuclear Physics (INFN) as a supplier of stainless steel structures for a testing rig at the European Space Research and Technology Centre (ESTEC) in the Netherlands. The facility was built to simulate operating conditions for the Alpha Magnetic Spectrometer (AMS), a particle physics experiment led by Nobel laureate Samuel Ting of MIT/CERN, later installed on the International Space Station. The gondola support structure required heavy bent stainless steel HEB beams in grade 316L with very low magnetic permeability, suitable for high vacuum operation across a temperature range of -60 °C to +100 °C, produced in single pieces up to 12 metres without butt welds, and tested to CERN’s stringent NDT standards before and after bending.
Space-Grade Requirements: Low Permeability, High Vacuum, No Butt Welds
The AMS gondola structure had to satisfy a set of requirements that went well beyond standard structural steel fabrication. The very low magnetic permeability requirement ruled out ferritic and martensitic grades and placed strict limits on the residual ferrite content of the austenitic weld metal. High vacuum suitability meant the sections had to be free of surface contamination, porosity, and any material that could outgas under vacuum. The temperature cycling from -60 °C to +100 °C required a material with sufficient toughness at cryogenic temperatures, a condition that 316L meets well. The no-butt-weld requirement for sections up to 12 metres meant that the HEB 300 and HEB 160 sections had to be produced at full length in a single piece before any bending operation, placing significant demands on both the laser fusion production line and the straightening capability.
Laser Fusion, Three-Roll Bending, and 100% NDT Before and After
Montanstahl produced the HEB 300 and HEB 160 sections using laser fusion, which provided the weld quality and dimensional consistency required for sections that would subsequently undergo precision bending. Bending was carried out by a specialist Italian partner using three-roll bending machines, delivering the precise radii required by the gondola geometry while preserving structural integrity through the bend. All beams underwent 100% dye penetrant testing, macro-etching, and permeability measurement before bending, and the same programme was repeated after bending to verify that no degradation had occurred during the forming operation. Production was completed on schedule, the AMS was successfully tested at ESTEC, and was subsequently transported to the International Space Station where it continues to operate.
Application Context
This project sits at the intersection of Montanstahl’s building and construction segment and precision industrial supply, where laser fused stainless steel structural sections are specified for research infrastructure, scientific equipment support, and applications requiring certified low magnetic permeability alongside structural performance. Testing rigs for space and particle physics programmes represent one of the most demanding procurement contexts in industrial steel supply: the quality requirements, traceability demands, and performance conditions exceed those of most commercial construction projects. Montanstahl supplies custom stainless steel structural sections for research, defence, and precision industrial clients worldwide.