Welding ferrous metals: How can you be sure of accurate preheat?

Preheat is frequently required for most welding applications. A major part of the equation is temperature indicators, to ensure the recommended level of preheat has been achieved. Welders know – and ASME codes reinforce – the need for preheating of many ferrous metals prior to welding. A successful weld unites the welding filler metal and the base-metal into one entity; a good weld is at least as strong as the base materials being joined. With many materials bringing the base metal “up to heat“ before welding improves the chances of achieving a successful weld by reducing the danger of crack formation and other problems. As a result, there is less need for factory rework, and performance of the finished piece is enhanced.