Duplex Angle Profiles for Pressure Vessel Support Rings
A chemical company needed to build a watertight pressure vessel and looked for profiles to form the skeleton of the container. The vessel is cylindrical, so the sections had to be calendered to the radius of the shell before assembly, and the service environment is highly corrosive with exposure to toxic chemicals. Montanstahl supplied sharp corner angle profiles of 150x150x16 mm in duplex 1.4462, produced with hybrid laser welding and validated by tensile and crash testing on the welds, and the customer carried out the calendering on site before using the angles as composite support rings.
The Skeleton of a Watertight Pressure Vessel
Pressure vessels are containers built to store liquids or gases under pressure, and they appear across the chemical, petrochemical and pharmaceutical industries wherever a process needs to hold a medium safely rather than simply move it. The structure inside and around the shell carries a large part of the mechanical duty, which is why the profiles used for the skeleton are specified with the same rigour as the shell itself. In this project the vessel is cylindrical, so the sections could not be supplied straight and bolted into place. They had to be calendered to follow the curvature of the container. Montanstahl is equipped to perform calendering, but given the specific nature of the project the customer chose to carry out that operation on site immediately before assembly, which meant the profiles had to arrive in a condition that would tolerate cold forming without losing the properties they were selected for.
Corrosion, Toxic Media and Welds That Had to Be Proven
The environment around the vessel is highly corrosive and involves exposure to toxic chemicals, and the customer translated that into four requirements. The sections had to be sharp corner angle profiles, so the geometry would fit tightly against the shell without the generous root radii typical of hot rolled products. The material had to be duplex 1.4462, still the most widely used duplex grade, chosen because its ferritic austenitic structure delivers high resistance to pitting and stress corrosion cracking together with roughly double the yield strength of standard austenitic grades, as described in our overview of duplex and super duplex grades. The production route had to be hybrid laser welding. Finally, the welds themselves had to be validated by tensile and crash tests, because in duplex the joint is where the phase balance can shift and where the corrosion performance of the whole section is decided.
Application Context
Montanstahl supplied laser welded angles of 150x150x16 mm in duplex 1.4462, joined with hybrid laser welding, which pairs the laser with a MIG source. Using a high quality filler metal, the process keeps the ferrite to austenite balance of the duplex structure within specification, so the corrosion resistance of the parent material carries through the joint rather than dropping at the weld line. The profiles were calendered on site by the customer and installed as composite support rings inside the vessel. The same combination of grade and process applies wherever a structure has to resist aggressive media while carrying load, a subject covered in our article on duplex steel in extreme industrial environments. Montanstahl produces laser welded angles in duplex, super duplex and austenitic grades in standard and custom dimensions, and questions on sizes, tolerances and testing are answered in the technical Q&A.