Answers

• 
  What are the main categories of steel sheet piling?

  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.

  
  
• 
  What customs clearance documents are generally required for steel exports to Southeast Asia?

  Standard required documents include:
  Commercial Invoice;
  Packing List;
  Bill of Lading;
  Mill Test Certificate;
  Certificate of Origin (CO or FORM E) – FORM E can enjoy tariff preferences between ASEAN and China; be sure to confirm this in advance.
  Sales Contract
  In addition, some countries may require an import license or Port of Destination Inspection (PSI). It is recommended to confirm the latest requirements with the customs clearance agent before shipment.

  
  
• 
  What is passing off Q235 as Q355? How to prevent material counterfeiting?

  It involves using low-strength Q235 steel to impersonate high-strength, high-value Q355 steel.
  
  The core properties differ: Q235 is carbon structural steel with a yield strength of approximately 235 MPa; while Q355 is low-alloy high-strength steel with a yield strength of at least 355 MPa and significantly higher tensile strength. Q355 has superior overall performance due to the addition of more alloying elements (such as manganese).
  
  Because of its superior performance, Q355 is more expensive. Unscrupulous merchants use Q235 to impersonate Q355 for illegal profit.
  
  Using Q235 instead of Q355 would significantly reduce the load-bearing capacity of the building's main structure, seriously jeopardizing the inherent safety of the project.
  
  Because they look almost identical, and are even more difficult to distinguish after painting, professional methods are needed to prevent counterfeiting.
  First, check the material certificate, verifying each item's grade, performance indicators, official seal, and batch number, and checking for any alterations.
  Seek third-party testing. Testing personnel will use a handheld spectrometer to test the content of key elements such as carbon and manganese on-site to ensure they meet standards.
  Entrust a qualified institution to conduct comprehensive testing on the steel's chemical composition and mechanical properties (yield strength, tensile strength), etc.