In industrial fields, from fluid transportation in petrochemical plants to pipeline networks in thermal systems, galvanized steel pipes are the preferred choice for many high-pressure applications due to their excellent corrosion resistance and comprehensive cost-effectiveness. However, the pressure-bearing performance of galvanized steel pipes is directly related to the safety and stability of industrial systems. Improper handling can lead to serious accidents such as leaks or bursts. A deep understanding of the key factors influencing the pressure-bearing performance of galvanized steel pipes and mastery of technical points to enhance pressure resistance are crucial for ensuring industrial production safety.
I. Core Factors Influencing the Pressure-Bearing Performance of Galvanized Steel Pipes
(1) Pipe Material and Wall Thickness
The base material of galvanized steel pipes is mostly carbon steel or low-alloy steel, whose chemical composition and mechanical properties directly determine the foundation of pressure-bearing capacity. For example, Q235B steel has lower yield strength and is suitable for low-pressure scenarios; while Q355B steel has higher strength and can withstand greater pressure. Meanwhile, wall thickness is an intuitive factor affecting pressure-bearing performance. According to the GB/T 3091 Standard for Welded Steel Pipes for Low-Pressure Fluid Transportation, for pipes with the same diameter, every 0.5mm increase in wall thickness can improve pressure-bearing capacity by 10%-15%. However, excessively thick walls increase costs and construction difficulties, requiring precise trade-offs during the design phase.
(2) Impact of Galvanizing Process on Pressure Resistance
Galvanizing processes are divided into hot-dip galvanizing and cold galvanizing. Hot-dip galvanizing forms a zinc-iron alloy layer through high-temperature molten immersion plating, which not only has strong corrosion resistance but also enhances the surface hardness of the pipe, indirectly improving its compressive capacity. Cold galvanizing forms a zinc layer on the surface through an electrochemical reaction. Although the process is simple, the zinc layer is thin and has weak bonding force, making it prone to peeling under high pressure, leading to substrate corrosion and reducing pressure-bearing performance.
(3) Potential Risks in Processing and Installation
During processing such as bending, welding, and threading, improper operations can cause stress concentration in pipes. For example, excessive welding current can cause embrittlement of the weld metal, making it prone to cracking under pressure; too small a bending radius can thin the pipe wall and reduce pressure-bearing strength. In addition, unreasonable pipeline support spacing and fixing methods during installation can cause local pressure overload, threatening system safety.
II. Testing and Evaluation of Pressure-Bearing Performance of Galvanized Steel Pipes
(1) Pressure Test Standards and Methods
Hydrostatic testing is commonly used in industry to detect the pressure-bearing performance of galvanized steel pipes. According to GB/T 241-2007 standards, the pipe ends are sealed and filled with water, then pressurized at a constant rate to the specified pressure (such as 1.5 times the design pressure), and maintained for 5-10 minutes to observe for leaks or deformations. Additionally, pneumatic testing is used in some scenarios, but due to explosion risks, strict control of environmental and operational specifications is required.
(2) Application of Non-Destructive Testing Techniques
Non-destructive testing techniques such as ultrasonic testing (UT) and radiographic testing (RT) can detect internal defects in pipes, such as air holes and slag inclusions, which weaken the pipe's pressure-bearing capacity. For example, a 0.5mm-diameter air hole can increase local stress by more than 30%. Early detection and treatment through non-destructive testing can effectively avoid sudden accidents under high pressure.
III. Optimization Strategies for Enhancing Pressure-Bearing Performance of Galvanized Steel Pipes
(1) Material Selection and Process Upgrades
High-strength steel should be prioritized for high-pressure scenarios, and hot-dip galvanizing processes should be adopted. In recent years, zinc-aluminum alloy coatings (such as Zn-Al-Mg alloys) have gradually emerged, with corrosion resistance 3-5 times that of ordinary galvanized coatings and resistance to cracking under pressure, becoming a new direction for improving pressure-bearing performance.
(2) Strict Control of Processing and Installation Specifications
Strict processing standards should be established, such as using multi-layer multi-pass welding and controlling interlayer temperature during welding; ensuring a minimum bending radius of ≥3 times the pipe diameter during bending. During installation, reasonable support spacing should be set, and sleeves should be installed for pipes passing through walls or floors to avoid external forces directly acting on the pipes.
(3) Regular Maintenance and Monitoring
A full lifecycle management system for industrial pipelines should be established, using pressure sensors and corrosion monitoring probes to collect real-time data, and predicting changes in pipe pressure-bearing performance through big data analysis. Regular wall thickness measurements and non-destructive testing should be conducted on key components, and pipes with degraded performance should be replaced in a timely manner.
The requirements for the pressure-bearing performance of galvanized steel pipes in industrial scenarios are increasingly stringent, and every link—from material selection and processing technology to installation and maintenance—requires a scientific and rigorous approach. Only by deeply understanding the mechanisms influencing pressure-bearing performance and combining advanced technologies with standardized operations can galvanized steel pipes operate stably in high-pressure environments and build a solid safety for industrial production.