TABLE OF CONTENTS The welded structures to be considered in this chapter include ships, steel frames for buildings and other purposes such as pipe racks, steel bridges and tubular structures for offshore drilling and oil production rigs. In all these fields there is a continuing need for improvements both in the quality of welded joints and in the properties of steel. Much progress has been made by the steel industry in the direction of higher standards during recent years, and for the most part these developments have lead to better weldability. It will be appropriate therefore to start by giving a brief outline of the way in which steelmaking methods have changed, and how such changes have affected welded structures.
Aluminium alloys are also employed to a significant extent in ship superstructures and for decking and living quarters on offshore oil rigs. These applications will be discussed later in this chapter.
Before about 1770, the materials used for bridges and major buildings in Britain were stone and timber. In the second half of the eighteenth century cast iron was employed to an increasing extent in structures, starting with the bridge that spans the river Severn at Coalbridge (1773). The displacement of charcoal as a means of reducing iron ore in blast furnaces by coke lowered the price of cast iron and increased its availability. Cast iron is brittle and is only safe to use as a structural material provided that any tensile stress is kept...
