Using thin-coated zinc pipes does indeed pose potential risks, primarily poor corrosion resistance and a short service life.

The thin zinc layer cannot provide sufficient "sacrificial anode" protection, making it easily penetrated in corrosive environments, leading to pipe rust. It also results in poor corrosion resistance and susceptibility to rust.
The weak bond between the thin zinc layer and the steel pipe substrate makes it prone to peeling during transportation, installation, or use, exposing the pipe directly to air and accelerating corrosion.

The acceptable thickness standard depends primarily on the galvanizing process and the pipe wall thickness.
For national standard galvanized pipes used in building fire protection, outdoor steel structures, and greenhouses, the average zinc layer thickness should be no less than 85μm, with a zinc layer weight ≥650g per square meter. For buried water supply and drainage pipes used in long-term damp underground applications, the zinc layer thickness needs to reach at least 100μm to improve resistance to soil corrosion.

The zinc layer thickness should be selected based on the actual application; do not choose products with substandard galvanized layers simply to reduce costs.

Steel pipes of the same specifications on the market may appear to have the same dimensions, but in reality, their wall thickness, material, zinc coating, weight, and manufacturing process are completely different. This leads to price discrepancies, with lower prices often corresponding to hidden cost reductions.

Some suppliers attract customers with low prices by using significantly thicker wall thicknesses with large negative tolerances. Compared to products meeting national standards or with positive tolerances, this reduces steel consumption by about 30%. Costs are thus drastically lowered, resulting in extremely low prices. Purchasing only based on the specification name without actually measuring the wall thickness may seem like "saving money," but in reality, you're buying substandard products with insufficient load-bearing capacity.

20# steel is passed off as alloy steel, Q235 as Q355, 201 stainless steel as 304 stainless steel, and recycled materials are used as genuine products, resulting in huge price differences due to material variations. Inferior materials have strength, corrosion resistance, and high-temperature resistance far below design values, posing long-term hidden dangers to engineering structures and easily failing quality inspection and acceptance.

Low-priced pipes often use thin zinc layers, cold galvanizing, or no zinc layer, or are refurbished old pipes regalvanized, with costs far lower than national standard hot-dip galvanizing. The steel pipes may appear smooth temporarily, but their corrosion resistance is extremely poor, and rusting and peeling will occur in a short period, significantly shortening their service life.

Insufficient actual delivery weight leads to disguised price increases when priced by the ton. Short lengths, mixed defective ends, and selling used pipes cleaned and passed off as new are all common low-price tactics. While the unit price may seem cheap, considering the effective usage, pass rate, and service life, the actual procurement cost is higher.

When purchasing steel pipes, one should not only look at specifications and unit price, but also clearly stipulate wall thickness tolerances, material grade, zinc layer thickness and process standards, weighing method, and fixed length, and reserve the right to conduct random inspections upon arrival. Prioritize suppliers with complete qualifications who can provide material certificates and test reports to avoid losing more than you gain.

Depending on their load-bearing characteristics and construction requirements, steel sheet piles are primarily classified into the following categories:
1. Z-shaped steel sheet piles
These have a Z-shaped cross-section, with interlocking joints located at the edges of the sheet piles. They offer excellent flexural strength and are particularly suitable for withstanding high lateral earth pressures. They are commonly used in permanent retaining structures and heavy-duty projects with high load-bearing requirements.
2. U-shaped steel sheet piles
With a U-shaped cross-section and interlocks situated near the neutral axis, these form a stable, symmetrical wall when assembled. This type of steel sheet pile is widely used, being suitable for both temporary shoring and permanent structures.
3. Straight-web (Flat) Steel Sheet Piles
These have a relatively straight or slightly curved cross-section and are fitted with high-strength interlocks. They are primarily used in circular or cellular structures, where overall stability relies more on the structural geometry and the tensile forces between the interlocks than on pure bending resistance.
4. Combi Wall System
Comprising large-diameter main piles and steel sheet pile infill panels, this system offers extremely high overall rigidity and load-bearing capacity. It is frequently used in port and marine engineering projects where conditions are complex and structural requirements are stringent.