Steel pipe piles are specialized steel pipes used as load-bearing components in foundation engineering. The diameter of these piles is usually above φ400mm, and their length can be adjusted as needed for construction, either lengthened or shortened. Steel pipe piles are generally divided into two types: round steel pipe piles and square steel pipe piles. Round steel pipe piles are made from seamless steel pipes or spiral steel pipes, while square steel pipe piles typically have square or rectangular cross-sections. Nowadays, SSAW steel pipes are frequently used as steel pipe piles. Today, we will explore the advantages of SSAW steel pipes as steel pipe piles.
SSAW steel pipes, also known as spiral steel pipes or spiral welded pipes, are made by rolling low carbon structural steel or low alloy structural steel strips into pipe billets at a certain helix angle (called the forming angle) and then welding the seams. They can produce large-diameter steel pipes using narrower strips of steel. SSAW steel pipes are mainly used in water supply engineering, petrochemical industry, chemical industry, electric power industry, agricultural irrigation, and urban construction. They are one of the twenty key products developed domestically. They are used for liquid transportation: water supply, drainage, sewage treatment engineering, mud transportation, and marine water transportation. They are also used for gas transportation: coal gas, steam, liquefied petroleum gas. They are used structurally: as piling pipes, bridges, docks, roads, building structural pipes, and marine piling pipes.
SSAW spiral welded pipes include ordinary spiral steel pipes and thick-walled spiral steel pipes. Compared to ordinary wall thickness spiral steel pipes, thick-walled spiral steel pipes have the advantages of high pressure resistance, high impact resistance, high safety performance, and longer service life. The strength of SSAW spiral welded pipes is generally higher than that of longitudinal welded pipes. They can use narrower raw materials to produce larger diameter welded pipes and can also use the same width of raw materials to produce welded pipes of different diameters.
The production process of SSAW steel pipes is simple, the production efficiency is high, they can produce larger diameter welded pipes, and can also use the same width of raw materials to produce welded pipes of different diameters. However, compared to LSAW steel pipes of the same length, the weld length is increased by 30% to 100%, and the production speed is lower. Therefore, smaller diameter welded pipes mostly use longitudinal welding, while larger diameter welded pipes mostly use SSAW welding.
The installation speed of SSAW steel pipe piles is fast, with no curing period required. Installation can be completed in 2 minutes, and after the installation of SSAW steel pipe piles is completed, the next step of bracket installation can be carried out. This greatly shortens the construction period of photovoltaic power station projects. For example, the 20MWp spiral pile foundation installation of the Ningbian photovoltaic power station can be completed in 28 days. Calculated at 1800 piles per 1MWp, five pile drivers can install an average of 300 piles per machine per day.
The demand for freshwater is low. According to the Ningbian photovoltaic power station project, 20% of the pile foundations use grouted steel pipe piles, which require a small amount of freshwater. According to C25 concrete calculations, each grouted pile requires 0.14m³ of concrete, and according to the mix ratio, about 0.00006m³ of water is needed. A 4WMp grouted pile requires 0.432m³ of water.
During the installation process, spiral piles minimally disturb the ground vegetation (pipe diameter of 76), maximizing the reduction of soil erosion. Additionally, after the service life of the photovoltaic power station (25 years) is completed, the spiral piles can be pulled out and recycled, which has certain effects on material cost savings and environmental protection. During the installation of spiral piles and grouted steel pipe piles, the requirements for measurement points and elevation control are not very strict. Since the bracket can move up and down within the pipe pile during installation, it is easy to adjust the bracket. This overcomes the problem of large height differences in photovoltaic bracket installations caused by uneven terrain in mountainous areas.
Using spiral piles or grouted steel pipe piles during the construction of mountain photovoltaic foundations does not require extensive land leveling, significantly saving costs. After the photovoltaic power station is built, shade-loving economic crops can be planted under the photovoltaic panels, which is beneficial for environmental protection and achieves true agricultural-photovoltaic complementarity.
In conclusion, SSAW steel pipes, with their high strength, flexible production, cost-effectiveness, fast installation, environmental protection, and recyclability, have become the ideal choice for steel pipe piles, especially in photovoltaic power station projects. With the rapid development of photovoltaic power stations and other infrastructure projects, the application prospects of SSAW steel pipes will become even broader.