engleski

Grooving corrosion of welded galvanize pipes for distribution of warm water

Premature failure of galvanized pipes in the distribution network of a facility supplying numerous consumers with warm water has taken place. It was caused by grooving corrosion of longitudinal weldments resulting in intensive leakage of the system. Detailed analysis of the facility and of the way of its operation was carried out using various techniques. The analysis comprised physical and chemical data on - fresh water, - structural materials and - corrosion process and its products. It was established that the water in the network is contaminated with Cu2+ brought into existence by corrosion of copper pipes used in the central heater of the system. On the other hand the temperature of water is approximately 70 oC when the network is in operation. Under such circumstances significant changes of open circuit potentials of zinc and steel take place, influencing the corrosion behavior of the investigated system. Simultaneously, copper is deposited on galvanized steel by ionic replacement that makes possible intensive bimetallic corrosion localized on longitudinal weldments.

grooving corrosion; galvanized pipes; warm water.

nije evidentirano