Overview of Galvanised Welded Steel Pipes
Core Advantages：
Galvanised welded steel pipe is a kind of pipe widely used in construction, industry and civil fields.
Strong corrosion resistance: the galvanised layer effectively protects the steel pipe from corrosion and extends its service life.
Long service life: Suitable for a wide range of environments, reducing maintenance and replacement costs.
Aesthetic appearance: smooth surface, suitable for indoor and outdoor applications.
Common international standards：
Galvanised welded steel pipes are usually manufactured in accordance with the following international standards:
ASTM: American Society for Testing and Materials standard, widely used in the North American market.
ISO: International Organisation for Standardisation standard, applicable to the global market.
EN: European Standard, applicable to the European market.
JIS G3444: Japanese Industrial Standard, STK400 is the commonly used material, applicable to construction, industry and other fields.
Application Scenario：
Galvanised welded steel pipes are widely used in construction, industry, agriculture and other fields, including:
Building structure, piping system.
Petroleum, chemical and machinery manufacturing.
Agricultural irrigation, greenhouse construction.
Marine engineering, bridge support.
Galvanised welded steel pipe theoretical weight, specification size table:
The following is the theoretical weight table of galvanised welded steel pipe, which is calculated according to the relevant provisions of the national standard GB/T 3091:
| Name | Size (mm) (Outer Diameter × Wall Thickness) | Unit (kg/m) | Theoretical Weight per Unit Length (kg/m) |
|---|---|---|---|
| Galvanized Welded Steel Pipe | 10×2 | kg/m | 0.429 |
| Galvanized Welded Steel Pipe | 13.5×2.75 | kg/m | 0.719 |
| Galvanized Welded Steel Pipe | 17×3.5 | kg/m | 0.961 |
| Galvanized Welded Steel Pipe | 21.3×3.15 | kg/m | 1.354 |
| Galvanized Welded Steel Pipe | 26.9×3.5 | kg/m | 1.764 |
| Galvanized Welded Steel Pipe | 33.7×4.0 | kg/m | 2.551 |
| Galvanized Welded Steel Pipe | 42.4×4.0 | kg/m | 3.559 |
| Galvanized Welded Steel Pipe | 48.3×4.5 | kg/m | 4.099 |
| Galvanized Welded Steel Pipe | 60.3×5.0 | kg/m | 5.613 |
| Galvanized Welded Steel Pipe | 76.1×4.5 | kg/m | 7.539 |
| Galvanized Welded Steel Pipe | 88.9×5.0 | kg/m | 8.877 |
| Galvanized Welded Steel Pipe | 114.3×7.0 | kg/m | 11.53 |
| Galvanized Welded Steel Pipe | 140×7.5 | kg/m | 14.19 |
| Galvanized Welded Steel Pipe | 168.3×7.5 | kg/m | 19.27 |
| Galvanized Welded Steel Pipe | 219.1×6.0 | kg/m | 31.53 |
| Galvanized Welded Steel Pipe | 219.1×6.5 | kg/m | 36.12 |
| Name | Size (Outer Diameter × Wall Thickness, Unit: mm) | Unit (kg/m) | Theoretical Weight per Unit Length (kg/m) |
|---|---|---|---|
| Galvanized Welded Steel Pipe | 273×6.0 | kg/m | 39.32 |
| Galvanized Welded Steel Pipe | 323.9×6.0 | kg/m | 50.88 |
| Galvanized Welded Steel Pipe | 355.6×6.0 | kg/m | 57.41 |
| Galvanized Welded Steel Pipe | 457.2×6.0 | kg/m | 81.99 |
| Galvanized Welded Steel Pipe | 508×6.0 | kg/m | 91.50 |
| Galvanized Welded Steel Pipe | 559×6.0 | kg/m | 101.01 |
| Galvanized Welded Steel Pipe | 610×6.0 | kg/m | 110.52 |
| Galvanized Welded Steel Pipe | 660×6.0 | kg/m | 120.03 |
| Galvanized Welded Steel Pipe | 720×8.0 | kg/m | 141.68 |
| Galvanized Welded Steel Pipe | 820×8.0 | kg/m | 167.72 |
| Galvanized Welded Steel Pipe | 920×10.0 | kg/m | 223.80 |
| Galvanized Welded Steel Pipe | 1020×10.0 | kg/m | 257.40 |
| Galvanized Welded Steel Pipe | 1220×12.5 | kg/m | 352.91 |
| Galvanized Welded Steel Pipe | 1420×14.0 | kg/m | 452.96 |
| Galvanized Welded Steel Pipe | 1620×15.0 | kg/m | 534.84 |
| Nominal Inner Diameter (mm) | Inches | Outer Diameter (mm) | Wall Thickness (mm) | Weight per Meter (kg) | Welded Pipe (6m Fixed Length) | Weight per Piece (kg) | Galvanized Pipe (6m Fixed Length) |
|---|---|---|---|---|---|---|---|
| DN15 | 1/2 | 21.3 | 2.8 | 1.28 | 7.68 | 1.357 | 8.14 |
| DN20 | 3/4 | 26.9 | 2.8 | 1.66 | 9.96 | 1.76 | 10.56 |
| DN25 | 1 | 33.7 | 3.2 | 2.41 | 14.46 | 2.554 | 15.32 |
| DN32 | 1.25 | 42.4 | 3.5 | 3.36 | 20.16 | 3.56 | 21.36 |
| DN40 | 1.5 | 48.3 | 3.5 | 3.87 | 23.22 | 4.10 | 24.60 |
| DN50 | 2 | 60.3 | 3.8 | 5.29 | 31.74 | 5.607 | 33.64 |
| DN65 | 2.5 | 76.1 | 4.0 | 7.11 | 42.66 | 7.536 | 45.21 |
| DN80 | 3 | 88.9 | 4.0 | 8.38 | 50.28 | 8.88 | 53.28 |
| DN100 | 4 | 114.3 | 4.0 | 10.88 | 65.28 | 11.53 | 69.18 |
| DN125 | 5 | 140 | 4.5 | 15.04 | 90.24 | 15.942 | 98.65 |
| DN150 | 6 | 168.3 | 4.5 | 18.18 | 109.08 | 19.27 | 115.62 |
| DN200 | 8 | 219.1 | 6.0 | 31.53 | 189.18 | ||
| DN200 | 8 | 219.1 | 6.5 | 36.12 | 216.72 |
Galvanised welded steel pipe production process and quality control points
1.Production process:
A: Raw material procurement
Select the high-quality steel that meets the standard, and ensure that the chemical composition and mechanical properties of raw materials meet the production requirements.
B: Pipe making
The steel will be processed into steel pipe through welding process, strictly control the welding quality and dimensional accuracy.
C: Cutting
According to customers’ requirements, cut the steel pipe into standard lengths (e.g. 6 metres, 12 metres) or customised lengths.
D: Pickling
The pickling process is used to remove oxidised skin and impurities from the surface of the steel pipe to ensure a clean surface ready for galvanising.
E: Galvanising
Hot-dip galvanising: the steel pipe is immersed in a molten zinc solution to form a uniform zinc layer, usually ≥70μm thick, which is corrosion-resistant and suitable for harsh environments.
Electro-galvanising: the surface of the steel pipe is coated with a zinc layer by an electrolytic process, which is cheaper, but the zinc layer is thinner and has a relatively weak corrosion resistance, suitable for general environments.
F: Inspection
Comprehensive testing of the finished steel pipe to ensure product quality in line with standards.
2. Differences in galvanising processes:
A: Hot-dip galvanising (dip galvanising process)
Process characteristics: steel pipe immersed in molten zinc solution, uniform thickness of zinc layer, strong adhesion, excellent corrosion resistance.
Galvanised welded steel pipe Applicable scenarios: suitable for outdoor, humid environments or scenarios with high corrosion resistance requirements.
B: Electro zinc plating (electrolytic process)
Process characteristics: zinc plated by electrolysis, thin zinc layer, low cost, bright appearance.
Applicable scenarios: suitable for indoor or general environment, cost-sensitive application scenarios.
3: Quality Inspection Points:
A: Appearance Inspection
Check the uniformity of the galvanised layer to ensure that the surface is free from defects such as leakage, skinning and scratches.
Check whether the surface of the steel pipe is smooth, free of cracks, scars, etc.
B: Chemical composition analysis
Test the chemical composition of raw materials to ensure compliance with standard requirements (e.g. Q235, Q345, etc.).
Test the composition of the galvanised layer to ensure the quality of the zinc layer.
C: Mechanical performance test
Pressure resistance test: Detect the pressure-bearing capacity of the steel pipe to ensure that it meets the design requirements.
Bending test: detect the flexibility of the steel pipe to ensure that it is not easy to break during processing and installation.
D: Dimension test
Detect the outer diameter, wall thickness, length and other dimensional parameters of the steel pipe to ensure compliance with standards and customer requirements.
E: Anti-corrosion performance test
Testing the thickness and adhesion of galvanised layer to ensure corrosion resistance.