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today, Steel Buildings being widely applied in industrial, civil, military construction, ... Pre-engineered steel buildings are mainly composed of steel structures. (steel structure), so what is structural steel? How is it structured? Down here, FACTORY  Please introduce the concept of steel structure and general information about steel structure.

1. What is structural steel?

With improvements in metal quality and manufacturing processes, steel has become one of the most commonly used materials in the world and plays an important role in the construction industry.

Steel structure is the bearing structure of construction works designed and constructed by steel. This type of structure is widely used in the construction industry, especially in large-scale construction works (Pre-engineered steel buildings) because of the useful properties of steel. Thanks to the high strength of steel, this structure is very strong and requires less material than other types of structures such as concrete structures or wooden structures.

In modern construction, steel frame structures are commonly used for all kinds of structures such as industrial buildings, offices, fences, bridges, conveyors, etc.

Hai Long Steel Structure Factory

Hai Long Steel Structure Factory

Hai Duong thermal power conveyor project

Hai Duong thermal power conveyor

Overpass Nguyen Binh KhiemNguyen Binh Khiem Overpass Bridge, Hai Phong

2. Main types of textures

  • Frame structure: Beam, column, truss, brace, purlin
  • Mesh structure: mesh or dome structure
  • Prestressed structure
  • Bridge beams
  • Cable-stayed bridge
  • Truss structure: bar or truss
  • Arch bridge
  • Arch architecture
  • Suspension bridge
  • Truss bridge: truss structure

                        Hai Long's steel structure project                                                  Steel structure works of other contractors                                  

3. Reason for choosing steel structure

Fast construction time

The components are fabricated at the factory (conducted in parallel with the foundation construction on the construction site) and assembled on the construction site according to the specified architectural and technical drawings right after the construction is completed. foundation, helping to shorten the construction time at the construction site.

The ability to overcome great beats

Steel structure has the ability to create a large span space truss to create a larger space for many different uses. These spaces will not be affected by columns, and the distance between columns can be greater than 30m, convenient for processing and construction: processing in the factory (strictly controlling progress and quality) and transportation and erection at the construction site.

Increase the aesthetics of the project

Steel structure brings a unique beauty to the building, suitable for modern architecture, steel frame is usually light, easy to shape, helps create accents in architecture.

Guaranteed quality

Components are machined at the factory through rigorous processes, standards, and quality control prior to construction on site. This helps the construction process to take place safely and the quality of the work is guaranteed.


Easy to upgrade and modify in the future for new applications such as flexibility in expanding that space by adding additional steel frames. Besides, because the building is connected from bolts, it is possible to completely disassemble the components and reuse and install in a new location.

4. Input materials for the production of steel structures

For the production of steel structures, raw materials are carefully checked.

Input materials for steel structure production

5. Characteristics of steel structure 

* Dimensional characteristics and geometrical structure of steel structures

  • Between H and I section steel: I and H steel are two types of steel that are quite similar in design. H steel is a product that is widely used in constructions such as houses, houses, high-rise buildings, large bridges, public works. H steel is very rich in shape and size, depending on the pressure level, different types of H steel are used, in order to ensure cost savings and construction quality as well as safety in the process. construction process. I-shaped steel as well as H-shaped steel are products commonly used for construction such as houses, high-rise buildings, bridges.... but depending on the different impact, choose to use steel I or steel H

– Steel plate

– Shape steel: U, I, L, pipe, … 

– purlin billet

* Chemical and mechanical properties

  • Depending on the standards of different countries, steel is classified into different types (collectively referred to as steel grades). In Vietnam, steel is divided into 2 types based on the strength limit of steel: low-strength steel (SS400, Q235, ...) and high-strength steel (Q345, SM490, ...). The two most commonly used steels on the market are SS400 and Q345(*).
  • SS400: Low tensile strength (strength, yield strength, relative elongation). 
  • Q345: More advanced, the tensile index is higher than SS400.
  • Tensile strength includes: 
  • Liquid limit: use hydraulic clamps to pull the two ends of the steel, when the steel crystals begin to move → reach the yield limit.
  • Endurance limit: at break.
  • Elongation: subtract the original length from the length after stretching.

(*): Only steel plate has 2 types, section steel only type SS400

  • In the market, two commonly used plating products are electro-galvanized or hot-dip galvanizing (the product is plated when the contract requires it).
  • Features of 2 types of plating: 
Types of platingCharacteristicsApplication
Electro Galvanized Electroplating uses the method of passing an electric current through an electrolyte solution. The mode of action is to create a precipitation reaction on the surface of the base metal to give a thin metal layer. This thin metal layer will protect the product from corrosion, increase hardness, increase electrical conductivity, ...Electrolytic plating is commonly used for water pipe plating, railway plating applications, protective plating for outdoor equipment, plating for equipment that is often subjected to force. Electrolytic zinc plating is also used in repair plating of high-precision parts, while preserving the properties of the original metal, the shape and size of the original part.
Hot dipped galvanizedHot-dip galvanizing uses the method of dipping the plated object in a mixture of molten zinc. Steel after being cleaned with a specialized solution, is dried and dipped in a galvanized bath. The advantage of hot-dip galvanizing is to evenly cover the entire inside and outside of the product, the galvanized layer has a uniform thickness, shiny, not rough. Hot-dip galvanizing is very widely used today and is widely used in galvanizing: stair railings, ladders, antennas, steel pipes, bolts, screws, threaded rods, traffic structures, and traffic structures. ,...
* Characteristics of sensory perception
  • Good raw materials must have the company's identification mark by paint or badge, ..., have clear origin, CO/CQ(**), must be packed properly, surface not oxidized, not pitted, shall not have a different color than normal iron oxide.
  • Colored sheet must not scratch paint, must have proof of plating thickness, paint thickness, must be verified by ruler, tested by test tensile method.
  •  All materials must be digitally checked, appraised and accepted, ensuring the prestige and quality of Hai Long's products.

(**) CO/CQ: CO is certificate of origin, abbreviated from Certificate of Origin; CQ is a certificate of goods quality, which stands for Certificate of Quality.

6. Processing and product quality control process of Hai Long steel structure

The process of cutting, drilling

The cutting phase will be according to the drawing specifying the cutting phase, based on the Shop drawing, prepared and issued by the workshop manager, following these steps:

  • Conduct cutting phase on equipment: Hydraulic cutting, thermal cutting, Plasma cutting (CNC and semi-automatic)
  • Conduct drilling and punching on machines: CNC drilling, boom drilling, composite punching, CNC code punching.
  • Conduct self-test and check the probability of KCS right during the cutting phase.
  • Enter the nominal warehouse, hand over the semi-finished products to GH1 and GH2 groups after passing the test.
  • Importing stock of surplus embryos and scraps (For surplus embryos, if grafted and used immediately, the workshop technician will list and update it to the Production department, if it is necessary to import the warehouse, change the original size, make a request, after approved, import surplus workpiece and order raw materials to change).

The Production Department directs the warehouse to make a list of surplus embryos, reuse them as soon as possible, and not leave the excess embryos in stock for too long, causing waste.

Mounting, basic welding

  • Rough fixing: This is the basic forming stage by equipment and manual, the purpose is to create the basic shape by measures of shackles, assembling and positioning by welding; Fixing device: Attachment machine; Mount of horizontal welding machine. The details, panels, semi-finished components are prepared by the cutting team, braked, chamfered, and welded and attached.
  • Coarse welding: Performed on automatic welding equipment, semi-automatic welding with the product of the process and fully welding the welds that the roughing stage moves to, conducting wing shaping before switching to fine jigs.

Wing, jig, welding complete

  • Wings: For I or H-shaped beam cross-section, after basic welding (rough) is completed, it is put into the straightening machine, flattening to eliminate deformation due to welding (Pressing until all product turns)
  • Finishing: Mainly done manually, deploying welding to the coordinates specified in the manufacturing drawings, by ruler, gauge, depending on the skill of the jig.
  • Welding: Mainly done manually, by semi-automatic equipment, complete welding of the entire jig. 

Ball shooting, polishing, priming, straightening, color painting, packaging

  •  Ball shooting: is the stage of cleaning the oxidized layer, impurities and dirt on the surface of the semi-finished products, performed at the grinding chamber and the ball-shooting machine, brushing and wiping with solvents, the product after cleaning. has a bright surface, with a roughness of 30 ÷ 75 µm, meeting Sa 2.0 ÷ Sa 2.5 standards.
  • Grinding burrs: Performed immediately after cleaning, ensuring clean burrs, defects on semi-finished products.
  • Straightening (conducted before priming): After rough welding and welding, the product tree is deformed, so it is necessary to use the heat of the fire pit, red-heat the bend, pour cold water to shrink the steel, making the steel shrink. whole product straight 
  • Primer: Before priming, make sure the surface is clean of dust, oxidation, and oil. Paint with primers: Alkyd, Epoxy on request by vacuum coating equipment, high pressure, wet paint layer is measured and controlled by wet film gauge.
  • Packing, warehousing: Packing for convenience when exporting and unloading goods, increasing product protection and shortening the time of loading and unloading goods, enhancing image and brand recognition.
  • Shipment: Goods are shipped according to the order to be released from the warehouse.

* Requirements that Hai Long sets forth in the steel structure manufacturing process

  • The production process is only started after the document is signed by the factory director (the document includes a list of components to be manufactured, along with specifications, thickness, ...)
  • The production order is only issued after all materials and design drawings are approved.
  • Product quality control. Input materials must be certified, of clear origin, in accordance with standards.
  • Check machinery and equipment before use, whether it is stable to serve the maximum production process or not
  • Check bolts, paint surface, ... based on JIS standards and design contracts by measuring, based on sensory, CO, CQ, inspection -> materials are only used after KCS meets the requirements.
  • Manufacturing inspection: operations are performed probabilistically, but throughout the process (in special cases, 100% of the product is checked). Test measures: sensory, gauge, length, height, micrometer, caliper, magnetic permeation, ultrasound; in special cases using X-ray weld inspection method. Hai Long independently inspects and has full equipment and tools to test using the above methods. Highly qualified QC team, certified for testing: welding, ultrasonic, magnetic, penetrant; The QC department is fully equipped with equipment and supplies to conduct a comprehensive inspection of structural steel products 
  • The team of engineers and workers are professionally trained, experienced in the field of steel structure manufacturing for many years. QC staff have to work very responsibly, check products carefully before packing, leaving warehouse, timely detecting errors.


Hai Long Construction Joint Stock Company – General contractor for construction, processing and erection of steel structures

Hai Long is proud of the quality of products and services we have provided to our customers over the past 2 decades. Currently, we have a modern factory with an area of ​​46.000m2 and a capacity of 15.000 tons/year.

Hai Long Steel Structure Factory

Hai Long steel structure factory

Address: Truong Thanh commune, An Lao district, Hai Phong city.

With a team of experienced engineers, well-trained and proficient in technical support tools, and modern production machinery and equipment that are continuously invested in new, our factory has met production schedule up to 15.000 tons/year with quality satisfying the high standards set by customers. Moreover, Hai Long factory also owns a professional internal quality control process in all stages of the production process, ensuring investors absolute peace of mind about our products. .

Refer to Hai Long's steel structure projects here

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