1. What are spiral steel pipe piles?
(1)What is a steel spiral pipe?
Spiral pipes(https://www.nan-steel.com/carbon-steel-pipe/ssaw-steel-pipe.html) are also called spiral steel pipes or spiral welded pipes. They are made by rolling low carbon structural steel or low alloy structural steel strips into pipe blanks at a certain spiral angle (called forming angle), and then welding the pipe seams. , which can produce large-diameter steel pipes from narrower strips.

Spiral pipes are mainly used in oil and natural gas transmission pipelines, and their specifications are expressed by outer diameter * wall thickness. Spiral pipes are either single-sided or double-sided welded. Welded pipes should ensure that the hydraulic pressure test, tensile strength and cold bending performance of the weld meet the regulations.

Features of spiral pipe: The production process of straight seam welded pipe is simple, the production efficiency is high, the cost is low, and the development is rapid. The strength of spiral welded pipes is generally higher than that of straight seam welded pipes. Welded pipes with larger diameters can be produced from narrower billets, and welded pipes with different diameters can also be produced from billets of the same width. However, compared with straight seam pipes of the same length, the weld length is increased by 30~100%, and the production speed is lower. Therefore, smaller diameter welded pipes mostly use straight seam welding, while large diameter welded pipes mostly use spiral welding.

(2) What are pipe piles?
Pipe piles are a type of pile foundation and an indispensable building material in industrial and construction industry construction. They were produced in the late 1960s.

Pipe piles are mainly made of concrete and steel materials. Concrete pipe piles mainly use concrete as raw material and are manufactured by centrifugal pile making or prefabricated piles; steel pipe piles are based on steel and are manufactured by welding or threaded connections.

During the construction of high-speed railway bridges, steel pipe piles are the main part of the bridge support system, and their construction technology has a direct impact on the bridge's support capacity. Steel pipes are the main materials used in construction. The actual selection standards of steel pipes should be determined according to the construction design requirements and clearly stated in the construction plan. The quality of steel pipe materials is mainly affected by the material, thickness, and thickness. The selection of the steel pipe pile foundation construction method needs to be finalized according to the actual conditions of the construction site. The crawler crane clamp hydraulic vibration hammer pile sinking method is widely used on bridges with narrow width. The implementation process of this method is to make the steel pipe Complete settlement root by root.

2. How to deal with steel spiral pipe piles corrosion?
Corrosion is a process in which the interaction between a material and its environment results in changes in the properties of the material. Such changes may include loss of material, reduced performance, or complete failure.

In the marine environment, steel spiral pipe piles are subject to the interaction of various corrosion damage factors such as ocean atmosphere and wave erosion, causing damage to the integrity and stability of the pipe pile structure.

The anti-corrosion measures for steel piles at home and abroad mainly include corrosion margin method, corrosion-resistant steel, coating anti-corrosion, cathodic protection, combined anti-corrosion methods of coating and cathodic protection, etc.

(1)Corrosion allowance method
Seaport terminals often use the annual corrosion rate of steel piles to increase the wall thickness of the entire steel pile to achieve the design service life. This method cannot reduce the amount of corrosion, and corrosion will cause a lot of damage. This method is basically adopted by domestic steel pile terminals to increase their safety factor. The corrosion margin method cannot solve the hazards caused by local corrosion. This method is generally used as an auxiliary means and not as an anti-corrosion measure alone.

(2) Corroded steel
Adding other elements to the steel from which steel piles are made can improve their resistance to seawater corrosion. Because the change range of seawater environment is greater than that of atmospheric environment. Therefore, this environmental change also directly affects the changes in the steel added elements within the steel pile. For different sections of the seawater environment, the effective added elements in the splash zone are P, Cu, and Ni, and in the seawater part are SI, Cr, and Al. In addition, elements such as Ni and Mo also have the effect of reducing corrosion in seawater. The corrosion resistance of seawater-resistant steel can be 2-3 times higher than that of ordinary carbon steel in the above-mentioned areas; it is not as obvious as the above-mentioned areas when all seawater enters. Seawater-resistant steel should be developed according to the use environment, and the research and development costs are relatively high. Corrosion-resistant steel is expensive, and the anti-corrosion effect varies greatly with the marine environment. The anti-corrosion effect is difficult to guarantee, and individual anti-corrosion measures are generally not recommended.

(3) Coating anti-corrosion
Coating anti-corrosion measures include organic coatings, electrodeless coatings, epoxy fiberglass sheaths and metal coatings. For the atmospheric zone and splash zone of steel piles, it is a more effective method because it can be repaired. However, the anti-corrosion effect is not good for the underwater sections of steel piles that have been repaired. Coated steel piles will cause local damage or peeling during construction processes such as lifting and piling. Rapid local corrosion will occur in seawater media, and they are prone to perforation, which affects the safety of steel piles.

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