Hot Extruded Guide Rails for Onboard Helicopter Handling Systems
An onboard helicopter handling system is a precision engineering solution designed for the safe movement and controlled positioning of helicopters on naval vessels, whether on deck or in a hangar. Predominantly used on frigates and aircraft carriers, these systems must function reliably under challenging sea conditions, including vessel motion, salt spray, and the mechanical loads of manoeuvring a multi-tonne aircraft across a moving deck. The Type 210 onboard helicopter handling system from Montanstahl’s defence customer represents the latest development in this field, enabling lateral crosswise movement of helicopters across the vessel without additional effort. This unique capability required tailored engineering solutions that went beyond standard supply. Montanstahl designed and manufactured four custom hot extruded profiles in stainless steel 1.4571 (316Ti) and duplex 1.4462, subsequently welded into guide rails up to 15 metres in length and approximately 1.6 tonnes each, welded directly to the ship’s deck.
From Double-Rail to Two-Part Solution: Engineering Around a Size Constraint
The originally proposed design was a single double-rail section approximately 310×155 mm. This could not be implemented because the envelope dimensions of the section fell outside the production capability for a single extrusion of that size. A two-part solution was devised instead, splitting the guide rail cross-section across two separately extruded profiles that are subsequently welded together. This introduced a new problem: each individual profile in the two-part solution fell significantly below the minimum weight per metre required for the extrusion process to run efficiently and produce consistent quality. A straightforward increase in wall thickness to meet the minimum weight without adding functional geometry was not acceptable, as it would add unnecessary mass to a naval structure where weight is a design constraint. The solution required close engineering collaboration between Montanstahl and the customer to redesign the cross-section geometry so that the added material served a functional purpose within the guide rail system. This is one of the capabilities that distinguishes hot extrusion from other production routes: the process allows complex cross-section geometries with undercuts, internal features, and variable wall thicknesses that cannot be achieved by rolling or laser welding alone.
316Ti and Duplex 1.4462: Material Selection for a Permanent Marine Application
Guide rails welded to a ship’s deck are a permanent structural component operating in one of the most corrosive environments in industrial use: marine atmospheres combine chloride salt, humidity, mechanical wear, and, in the case of naval vessels, periodic immersion or heavy spray exposure. Stainless steel 1.4571 (316Ti) was selected for its combination of molybdenum-enhanced chloride resistance and titanium stabilisation, which prevents sensitisation at the weld zones and maintains corrosion performance around the welds throughout the service life of the structure. Duplex 1.4462 brings approximately twice the yield strength of 316L at equivalent corrosion resistance, allowing sections to be dimensioned for structural loads without the weight penalty that an equivalent austenitic section would carry. Both grades are available as hot extruded profiles from Montanstahl in custom cross-section geometries. For further information on grade selection for marine and naval applications, Montanstahl’s technical Q&A covers the key differences between austenitic, duplex, and high-alloy stainless steel grades.
Application Context
This project sits within Montanstahl’s Defence segment, where hot extruded special profiles in stainless steel and high-performance alloys are specified for naval equipment, shipboard systems, and defence infrastructure requiring complex cross-section geometries, marine-grade corrosion resistance, and co-engineering with the customer. Hot extrusion is the production route that makes custom structural profiles in 316Ti and duplex stainless steel commercially viable at the quantities and cross-section complexity that naval applications require. Montanstahl’s hot extrusion capability covers a wide range of stainless steel, duplex, nickel alloy, and titanium grades, with single-bar prototypes available and series production up to 16-metre bar lengths. Profiles of this type are supplied to defence and naval projects worldwide.