Forge welding process

A tubular string comprising tubulars that have been joined by a forge welding method the method comprising the steps of:

• heating the tubular ends to be joined in a welding chamber to a predetermined temperature while the heated tubular ends are maintained substantially aligned and parallel relative to each other at a spacing;
• pressing the heated tubular ends against each other while a reducing shield gas is injected into the chamber;
• and
• cooling the tubular ends;
• wherein during at least part of the heating, pressing and/or cooling steps the positions of the tubular ends are monitored by a number of circumferentially spaced cameras which are coupled to a pyrometric and position monitoring system, which automatically adjusts the position of the tubular ends relative to each other and the heat supplied to the tubular ends during the heating step at least until the pyrometric monitoring system indicates that the tubular end faces have reached a predetermined temperature, whereupon the tubular ends are moved towards each other along a distance which exceeds the spacing monitored between the tubular ends during the heating step with a selected extra distance.