Hazards And Preventive Measures of Mixing Stainless Steel Pipe Fitting Materials

Clear cognition

Stainless steel pipe fittings provide stable operating environment for piping systems with excellent corrosion resistance and strength.

Stainless steel is mainly divided into austenitic stainless steel, ferritic stainless steel and martensitic stainless steel according to its metallographic structure and chemical composition. In addition, there are duplex steel, precipitation hardened stainless steel and high alloy steel.

Understanding the different types and grades of stainless steel is critical to selecting the right material to meet the requirements of a specific application. 200 series, 300 series, and 400 series are the names of American standards.

Different materials have differences in chemical composition, crystal structure and physical properties. These differences are especially obvious during the welding process.

(1) Different degrees of fusion, which may cause defects in the welded joints, such as lack of fusion, slag inclusion, etc.

(2) Different thermal expansion coefficients may produce residual stress or deformation when cooling after welding.

(3) Corrosion resistance is different. In a medium containing acidic substances, stainless steels of different materials will form a potential difference, leading to electrochemical corrosion. It will cause serious accidents such as pipeline rupture and leakage.

Measures

1. Material identification and recording

During the procurement and installation process, clearly mark the material of each pipe fitting and welding point, and establish detailed records to facilitate subsequent maintenance.

2. Quality Control

3. Strict Standard

Develop and follow strict technical standards and operating specifications, avoiding the mix of material.

4. PMI & NDT test

PMI test is on-site test of reliability of material used. Non-destructive testing (NDT) methods to regularly inspect and evaluate piping systems.

5. Corrosion monitoring system

Install corrosion monitoring systems at key locations to monitor the corrosion status of pipelines in real time