ilway" class="mw-redirect">railway</a> lines, many of which had previously used their own standard both for threads and for bolt head and nut profiles, and improving manufacturing techniques, it came to dominate British manufacturing.</p>
<p>In the USA, BSW was replaced when steel bolts replaced iron, but was still being used for some aluminium parts as late as the 1960s and 1970s when <a href="//en.wikipedia.org/wiki/ISO_metric_screw_thread" title="ISO metric screw thread">metric</a> based standards replac