How to determine whether the material of the vertical long shaft semi submersible turbine pump is suitable?

To determine whether the material of a vertical long shaft semi submersible turbine pump is suitable, a comprehensive evaluation should be conducted from multiple dimensions such as medium characteristics, operating conditions, material performance, and economy. The following are specific judgment methods:
1、 Clarify the medium characteristics and operating conditions of vertical long axis semi submersible turbine pumps
Analysis of Medium Composition
Corrosive media such as acid, alkali, and salt solutions require the selection of corrosion-resistant materials (such as 316L stainless steel, fluoroplastics, and Hastelloy) for vertical long shaft pumps based on the concentration and temperature of the media.
Abrasive media: such as liquids containing sand, coal powder, and slag, wear-resistant materials (such as high chromium cast iron, hard alloy, ceramic coating) should be selected for vertical long shaft pumps.
High temperature medium: such as hot water and steam, high-temperature resistant materials (such as duplex steel and titanium alloy) should be selected for vertical long shaft pumps.
Viscous media: such as oils and slurries, it is necessary to choose materials with smooth surfaces and low adhesion (such as stainless steel, polytetrafluoroethylene) for vertical long shaft pumps.
Confirmation of working conditions
Temperature range: Ordinary materials (such as cast iron) are suitable for temperatures ≤ 80 ℃, and high-temperature resistant materials (such as duplex steel that can withstand temperatures above 120 ℃) should be selected for high-temperature conditions.
Pressure requirement: Higher strength materials (such as alloy steel) should be selected for high-pressure working conditions.
Running time: For continuous operation, materials that are resistant to fatigue and creep (such as stainless steel) should be selected.
2、 Evaluate the material performance and adaptability of vertical long shaft semi submersible turbine pumps
Corrosion resistance test
Reference standard: Refer to the Corrosion Data Manual based on the type of medium and select materials that match the corrosion resistance level.
Case: When transporting a 30% sulfuric acid solution, the corrosion rate of 316L stainless steel is ≤ 0.1mm/year, while the corrosion rate of ordinary carbon steel can reach 5mm/year or more. Obviously, 316L is more suitable.
Wear resistance verification
Hardness comparison: The wear resistance of high chromium cast iron (HRC ≥ 60) is 3-5 times that of ordinary cast iron (HRC ≤ 30).
Coating protection: Spraying tungsten carbide coating on the surface of the impeller can extend its service life by 2-3 times.
Physical performance matching
Density and specific gravity: When transporting high-density media, it is necessary to ensure that the pump body has sufficient strength (such as titanium alloy with low density but high strength, suitable for lightweight and high-strength requirements).
Thermal expansion coefficient: Materials with low thermal expansion coefficient (such as ceramics) should be selected for high temperature conditions to avoid sealing failure caused by thermal expansion and contraction.
3、 Maintainability
Maintainability assessment
Replacement of vulnerable parts: Choose a modular design vertical long shaft semi submersible turbine pump, where the impeller and shaft sleeve can be replaced separately to reduce maintenance difficulty.
Spare parts supply: Ensure that materials are common and suppliers can quickly provide spare parts (such as stainless steel spare parts, which are easier to obtain than special alloys).
4、 Suggestions for material selection in typical scenes
Municipal water supply and drainage
Medium: Clear water or wastewater containing a small amount of impurities.
Recommended materials: cast iron (high economy) or stainless steel (better corrosion resistance).
Key point: If the water contains chloride ions, 316L stainless steel should be selected to avoid pitting corrosion.
Mining Metallurgy
Medium: Mud containing sand and slag.
Recommended material: high chromium cast iron (impeller) or rubber lining (pump body).
Key points: The impeller surface needs to be sprayed with wear-resistant coating, and the pump body adopts rubber lining to reduce wear.
Food and Medicine
Medium: Clean liquid or food containing particles.
Recommended material: 304/316L stainless steel (compliant with hygiene standards).
Key point: The surface needs to be polished to avoid bacterial growth.
5、 Verification and testing methods
Laboratory testing
Soak the material sample in the medium and observe the corrosion rate (such as weight loss method).
Conduct wear tests (such as sand impact tests) to measure mass loss.
On site trial operation
Test run a vertical long shaft semi submersible turbine pump under similar operating conditions and monitor parameters such as vibration, noise, and temperature.
Regularly inspect the wear of vulnerable parts such as impellers and shaft sleeves to verify the durability of the materials.
Refer to industry standards
Follow standards such as "Vertical Long Axis Semi submersible Turbine Pump" (CJ/T 235-2017) to confirm whether the material meets the requirements.
Reference industry case (such as a certain oil field extending the service life of a dual phase steel vertical long shaft semi submersible turbine pump to 10 years).