8th April 2026
The castings of large axial flow pumps are their core components, directly affecting the pump's performance, efficiency, and service life. These castings are typically structur complex and massive in size and weight, imposing extremely high requirements on material properties and manufacturing processes.
Main casting components
The large axial flow pump (such as the common ZLB type vertical axial flow pump) is mainly composed of the following key castings:
Suction bell: As the water inlet chamber of the pump, it is used to guide the water flow uniformly to the impeller with minimal loss. It is usually made of cast iron.
Impeller: The core working part of the pump, consisting of a hub and multiple blades. The water flow gains energy through the high-speed rotation of the impeller. The impeller is typically cast from cast steel or stainless steel, and the blade angle can sometimes be adjusted to meet different working conditions.
Guide vane body/diffuser: Located above the impeller, it is used to eliminate the rotational motion of the water flow after leaving the impeller, reduce head loss, and convert part of the kinetic energy into pressure energy. This is a very complex casting with high manufacturing difficulty.
Pump casing/outlet elbow: Collects the water flowing out of the guide vane body and directs it to the outlet pipeline.
Advanced Manufacturing Technology and Industry Cases,
With technological advancements, the manufacturing of large axial flow pump castings is moving towards higher precision, better performance, and more complex structures.
Large tonnage and complex structures: Domestic manufacturers have the capability to produce large and complex castings. For instance, Xinhua in Xiangtan successfully delivered a single-piece guide vane body casting weighing 5.5 tons and with a diameter of 2.5 meters, made of martensitic stainless steel, which presented a significant casting challenge.
Application of new materials: To meet special working conditions (such as corrosion resistance and lightweight), new materials like titanium alloys are being adopted. Aerospace Haiying (Harbin) Titanium Industry successfully developed a key component of a titanium alloy marine pump body weighing 1.8 tons, solving the quality control issues of super-large and complex titanium alloy castings.
Key application areas
With its characteristics of high flow rate and low head, the axial flow pump is widely used in the following fields:
Agricultural water conservancy: Irrigation and drainage of large-scale farmland.
Municipal flood control: urban stormwater drainage and flood diversion pumping stations.
Industrial circulation: cooling water circulation systems in power plants and chemical plants.
Water treatment: Water conveyance and mixing in wastewater treatment plants.
Other uses: Dock drainage, water level regulation for canal locks, and water-jet propulsion for shallow-draft vessels.