Alternatively, heat tints can be removed by pickling after welding. However,
this is not always possible when considering the welding of piping containing natural
waters. To avoid this kind of failures one should use water as clean as possible with low amounts of solids, chlorides, manganese and iron as well as a low amount of organic substances. Additionally,stagnant conditions or very low flow rates should be avoided as well. If continuous flow is not possible, the water should be changed frequently enough and the amounts of bacteria should be checked regularly. When necessary, the water should be treated to minimise bacterial activity.In Case 1, no failures had been detected in the system using the same water with regular use (once a week).