Answers

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  Connection methods for anti-corrosion steel pipes？

  Generally speaking, due to the relatively low cost of anti-corrosion steel pipes, welding is the preferred method for their connection. Due to limitations such as construction period, construction conditions, and geographical environment, some projects will also adopt other connection methods, such as threaded connection, flange connection, socket connection, and grooved connection.

  
  

  1. Flange connections generally have advantages such as speed, ease of construction, and simple tools, but they cannot meet the requirements of most projects in terms of safety and sealing. Generally, this type of connection is suitable for low-pressure pipelines, such as sludge discharge pipelines.

  
  

  2. Grooved connection: also known as clamp connection technology.

  
  

  The application of grooved pipe fittings technology has made the complex process of pipe connection simple, fast, and convenient. This represents a significant step forward in pipe connection technology.

  Grooved connectors include two product categories: rigid joints, flexible joints, mechanical tees, and grooved flanges; bends, tees, crosses, reducers, blind flanges, spiral welded pipes, etc.

  Grooved pipe fittings that serve to connect and seal mainly consist of three parts: sealing rings, clamps, and locking bolts. The rubber sealing ring located in the inner layer is placed on the outside of the connecting pipe and overlaps with the pre-roll groove. Then tighten the clamp to the outside of the rubber ring, and then secure it with two bolts. Because the rubber sealing ring and clamp adopt a special sealing structure design, the grooved connection has good sealing performance, and its sealing performance is improved accordingly as the fluid pressure in the pipeline increases.

  
  

  Grooved connections facilitate pipe connection operations, improve construction safety, enhance system stability, facilitate maintenance, save time and labor, and offer good economic benefits. Although the individual price of clamps is higher when using clamp connections, the overall benefits of the entire pipeline installation are higher than those of flange connections.

  
  

  3. As an advanced method of connecting anti-corrosion steel pipes, clamp-type pipe fittings can be installed either openly or concealed, i.e., steel joints or flexible joints. Therefore, it has broad application prospects. It is suitable for fire-fighting water supply systems, air conditioning hot and cold water systems, water supply systems, petrochemical pipeline systems, thermal power military pipeline systems, sewage treatment pipeline systems, etc.

  
  
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  What are the testing items for steel?

  Common testing items for steel:

  
  

  1. Mechanical and technological performance testing: various hardness tests, tensile tests, compression tests, bending tests, flattening tests, impact tests, drop hammer tests, torsion tests, winding tests, bond strength, weld joint inspection, welding procedure qualification, etc.

  
  

  2. Metallographic structure inspection: low magnification structure and defects, microstructure, grain size, hardenability, fracture surface inspection, carbides, graphite grading, sulfur markings, inclusions, decarburized layer, carburized layer, nitrided layer, corrosion test, taper hairline cracks, intergranular corrosion of stainless steel, etc.

  3. Chemical composition analysis: the testing range covers most elements in the periodic table, up to about 70, including: carbon, silicon, manganese, phosphorus, sulfur, chromium, nickel, copper, molybdenum, vanadium, titanium, tungsten, cobalt, aluminum, niobium, zinc, cadmium, calcium, magnesium, boron, arsenic, antimony, tin, bismuth, lead.

  4. Bending Test: Bending, Repeated Bending

  5. Tensile Test: High Temperature, Room Temperature, Low Temperature Tensile Test

  6. Hardness Test: Rockwell Hardness Test, Brinell Hardness Test, Vickers Hardness Test

  7. Impact Test: Room Temperature Impact Test, Low Temperature Impact Test, High Temperature Impact Test

  8. Compression Test: Compression Yield Point, Compressive Strength, Specified Non-proportional Compressive Stress, Specified Total Compressive Stress, Compression Modulus

  9. Mechanical Property Tests for Welded Parts: Deformation, Fracture, Adhesion, Creep, Fatigue, etc.

  10. Mechanical Property Tests for Fasteners: Tensile Test, Proof Load, Wedge Load Test, Torque Test, Hole Enlargement Test, Torque Coefficient, Anti-Slip Coefficient, etc.

  11. Performance Tests: Tensile Load, Stress Relaxation Test, Zinc Plating Amount Test, Adhesion Test, Copper Immersion Test, etc.

  
  
• 
  What is the typical service life of hot-dip galvanized and plastic-coated fencing?

  There is no uniform standard for the typical service life of hot-dip galvanized and plastic-coated fences, which can vary significantly depending on the quality of the base material, the thickness of the coating/plastic coating, the level of processing, and the usage environment. In summary, the expected lifespan of hot-dip galvanized fences is typically 20 to 40 years or more, while the lifespan of plastic-coated fences (with galvanized steel as the base material) is usually determined by the weather resistance of the plastic layer, typically ranging from 10 to 30 years, provided the plastic coating is intact.

  
  

  In terms of service life, hot-dip galvanized and plastic-coated fencing can remain rust-free for over fifty years; even when exposed to the outdoors or submerged in water, it will show no signs of rust for many years.