Ductile iron tees are core pipe fittings for municipal water supply and drainage, industrial fluid transportation, and heating systems, valued for their high strength and corrosion resistance. However, long-term operation under complex working conditions often leads to faults such as leakage, cracking, and corrosion, which can affect the stability of the pipeline system. This paper examines the primary causes of faults and proposes targeted solutions.
Leakage is the most frequent fault, mainly caused by three factors: first, improper installation-uneven flange connection force or loose socket-and-spigot joint sealing rings lead to gaps; second, sealing material aging-rubber gaskets harden or crack after prolonged exposure to high temperature, pressure, or chemical media; third, pipe fitting deformation-external soil pressure or vehicle rolling causes tee body deformation, damaging the sealing structure. Solutions include standardizing installation operations to ensure uniform flange bolt torque, replacing aging gaskets with corrosion-resistant fluororubber materials, and installing reinforced brackets around buried tees to resist external pressure.
Cracking faults are mostly due to material defects and stress concentration. Residual casting stress, internal shrinkage porosity, or inclusions reduce the tee's structural strength; sharp turns in the flow channel or uneven wall thickness lead to local stress concentration under pressure changes. To address this, manufacturers should adopt centrifugal casting processes to optimize internal quality, conduct ultrasonic flaw detection on finished products, and design smooth transition flow channels to reduce fluid impact. For cracked tees, welding repair is prohibited for pressure pipelines; immediate replacement with qualified products is required.
Corrosion damage is prominent in harsh environments. Electrochemical corrosion occurs when ductile iron contacts different metals in humid soil; medium corrosion happens when the tee conveys acidic, alkaline, or high-salt media. Protective measures include applying anti-corrosion epoxy coatings to the tee surface, wrapping polyethylene anticorrosive tape for buried tees, and installing insulating joints to isolate dissimilar metals. For pipelines transporting corrosive media, tees with internal lining of cement mortar or polyurethane can be selected to enhance corrosion resistance.
Daily maintenance is key to preventing faults. Regularly inspect tee connections for loosening or leakage, check surface coating integrity, and promptly clean sediment in the flow channel to avoid local corrosion. By combining standardized installation, material optimization, and routine maintenance, the service life of ductile iron tees can be significantly extended, ensuring safe operation of pipeline systems.
