Joining aluminium to steel

This website is intended to look at Triclad structural transition joints (STJ) as marketed by Merrem & la Porte in many countries around te world and give insight into the history, applications and technical aspects of these joints.

Firstly, what is a transition joint, what is it used for, and how does Merrem & la Porte come to market the product ?

Transition joints are bimetallic strips or pads used to facilitate the joining of dissimilar metals by welding. Particularly where those metals cannot be joined by conventional welding processes, and where, if mechanical joining techniques are used, corrosion sets in after a relatively short service life.

Their uses are generally found in marine construction, but are equally applicable in other industries where a permanent, maintenance free joint between aluminium and steel is called for. Increasingly, aluminium is being used in shipbuilding to reduce weight. However, on grounds of cost and durability, it is not normally used for the whole of the hull, which may be mainly steel. With aluminium being used to a greater or lesser degree for structures above the waterline to reduce overall deadweight or to lower the centre of gravity, thus improving roll performance. This is paticularly beneficial on RO-RO ferries.

Typical applications of Transition Joints are to:

  • Join aluminium superstructures to steel decks.
  • Join aluminium decks (or even bulkheads) to   steel hulls.
  • Fit shelter decks to steel fishing boats.
  • Retrofit “containers” of electronic equipment to   steel decks of warships during refits.
  • Add additional accommodation to existing    vessels (these can be prefabricated).
  • Fit any other components, such as pillars,  partitions, etc., where a permanent joint is required between steel or stainless steal and aluminium.

They can even be used to:

  • Fit steel components to aluminium hulls (engine   mounts in High Speed Catamarans, davits, etc.).
  • Repair or strengthen corroded mechanical-   gasketed joints on ships where transition joints   were not originally specified (even to make    these watertight by welding over the joint face)
  • Provide a wear resistant keel on beach launched   aluminium vessels.

Other uses are to:

  • Fit helidecks to ships or oil rigs.
  • Fix aluminium walkways or accommodation   modules on oil rigs.

Additionally, there may be potential applications in road- and rail vehicles or  even in civil engineering and chemical plants. Specialised joints, incorporating an extra layer, in this case titanium, can be used to attach aluminium cryotanks to steel decks.

Read more about Triclad:

Merrem & la Porte's involvement in Triclad | General background of explosion cladding | What is Triclad? | Triclad fabrication guidelines | Corrosion resistance | Welding parameters general guidelines | Repair of corroded mechanical joints | Frequently Asked Questions

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