In most cases Type 1 pitting can be avoided by good working practices. Always use tubes that have been manufactured to BS EN 1057. Tubes greater than 10 mm in diameter made to this standard will always be marked the number of the standard, the nominal size, wall thickness and temper of the tube, the manufacturer’s identification mark and the date of production at least every 600 mm.  Tubes less than 10 mm in diameter will be similarly marked at each end. 
Once a system has been commissioned it should be either put immediately into service or drained down and dried. If either of these options is not possible then the system should be flushed though regularly until it is put into use. It should not be left to stand for more than a week. At present stagnation is the most common cause of Type 1 pitting.
Flux should be used sparingly. A small quantity should be painted over the areas to be joined and any excess removed after the joint has been made. Some fluxes are marked as water-soluble but under some circumstances they are not removed before pitting has initiated.