Guidelines for Material Selection and Cylinder Wall Thickness of Integrated Prefabricated Pumping Stations

Guidelines for Material Selection and Cylinder Wall Thickness of Integrated Prefabricated Pumping Stations

The cylinder body of an integrated prefabricated pumping station serves as the core structural component for load bearing, anti-seepage and anti-corrosion performance. Its material selection and wall thickness design directly determine the structural stability, operational safety and service life of the pumping station. All selections shall comply with national and industrial specifications, and be comprehensively determined based on burial depth, backfill load, geological conditions and water quality characteristics.

Four mainstream materials are widely adopted for pumping station cylinders, including Glass Fiber Reinforced Plastic (GRP), High-Density Polyethylene (HDPE), stainless steel and resin concrete. Among them, GRP is the preferred material for municipal engineering. Manufactured by fully automatic mechanical winding and integral forming, the GRP cylinder consists of anti-corrosion, anti-seepage and structural reinforcement layers without any splicing gaps. Featuring excellent aging resistance and corrosion resistance, it achieves a standard service life of 30 years. It is widely applied in municipal rainwater and domestic sewage projects. For highly corrosive environments such as chemical wastewater and seawater, vinyl resin lining can be upgraded to enhance anti-corrosion performance.

HDPE cylinders provide high toughness, impact resistance, low-temperature resistance and good overall sealing performance with convenient installation. They are mostly used for small-scale rural sewage pumping stations and shallow-buried projects in cold regions. Nevertheless, due to relatively low rigidity, HDPE materials are not suitable for deep-buried or high-backfill heavy-load working conditions. 304 and 316L stainless steel cylinders deliver high structural strength and sanitary performance. 304 stainless steel is applicable to domestic water supply and clean water lifting projects, while 316L stainless steel adapts to coastal high-chloride and mildly corrosive water environments. However, stainless steel has a higher cost and poor resistance to strong acid and alkali corrosion, making it unsuitable for industrial wastewater conditions. Resin concrete exhibits superior compression and corrosion resistance, yet it is only adopted for chemical high-corrosion and deep-buried complex working conditions due to its heavy weight and high cost, and is rarely used in conventional municipal projects.

Cylinder wall thickness is a critical indicator for structural design. As the most widely used material, GRP cylinders comply with a national minimum standard wall thickness of 10 mm, while municipal projects uniformly implement a minimum standard of 12 mm to avoid non-standard thin-walled products. Wall thickness is classified and selected according to burial depth, backfill thickness and cylinder diameter. For shallow conventional working conditions with a burial depth within 5 meters and backfill thickness within 3 meters, cylinders with a diameter of 1.0 to 2.0 meters adopt a recommended wall thickness of 12–16 mm, which ensures optimal cost performance and meets conventional drainage load requirements. For medium-depth working conditions with a burial depth of 5 to 8 meters and a diameter of 2.0 to 3.0 meters, the recommended wall thickness is 16–20 mm, which effectively resists lateral soil pressure and prevents cylinder deformation and leakage. For deep-buried heavy-load conditions with a burial depth over 8 meters, backfill thickness over 6 meters, or soft soil and high groundwater environments, the wall thickness shall be increased to 22–25 mm to significantly improve structural bearing capacity. For working conditions with high sediment and impurities, the wall thickness shall be no less than 32 mm to enhance wear resistance and impact resistance.

Wall thickness standards for other materials are standardized as follows: HDPE cylinders for shallow-buried pumping stations adopt a thickness of 10–12 mm with a maximum burial depth limited to 4 meters; stainless steel cylinders for water supply projects are 3–5 mm thick under conventional conditions and upgraded to 6–8 mm for coastal and large-diameter scenarios; resin concrete cylinders adopt a standard thickness of 150 mm and are thickened to adapt to high-load and corrosive environments. For complex geological conditions such as soft soil and quicksand, the wall thickness shall be increased by 10%–15% with graded gravel backfill and compaction to ensure structural stability.

Strict selection prohibitions shall be implemented in engineering applications. GRP cylinders thinner than 12 mm, HDPE products for deep-buried conditions, and ordinary stainless steel for strong corrosive or seawater environments are forbidden. During acceptance inspection, the measured wall thickness shall not be lower than the design value with a negative deviation no more than 0.5 mm. GRP cylinders must be integrally formed without delamination, hollowing or splicing defects. All products shall pass a hydraulic pressure test with 1.5 times the design working pressure and maintain stable pressure without leakage or deformation for 30 minutes, with complete material inspection and structural verification reports provided to ensure long-term safe and stable operation of pumping stations.