Research on the service life of longitudinal submerged arc welding (LSAW) steel pipe

Posted by BAOWI STEEL MANUFACTURING CO.,LTD on June 17th, 2024

Introduction

As an important industrial material, longitudinal submerged arc LSAW steel pipe is widely used in the fields of oil and gas transportation, water supply engineering, building structure, etc. Its service life is a key factor affecting its application scope and economy. This paper will discuss the service life of LSAW steel pipe in detail from the aspects of manufacturing process, material properties, use environment and maintenance, and combine actual case analysis to provide reference for related industries.

1. Manufacturing process of LSAW steel pipe

The manufacturing process of LSAW steel pipe is one of the important factors affecting its service life. LSAW steel pipe adopts high-frequency welding and submerged arc welding process to ensure the high strength and high toughness of the weld. Specifically, the manufacturing process of LSAW steel pipe includes the following steps:

Raw material selection: High-quality steel plate is the basis for manufacturing high-performance LSAW steel pipe, usually low-alloy high-strength structural steel.

Forming process: The steel plate is gradually bent into a tube by the JCOE forming method. This process ensures the uniformity of the pipe wall and the stability of the weld.
Welding process: Double-sided submerged arc welding (SAW) process is used to ensure the quality of internal and external welds. This process has the advantages of fast welding speed and high weld quality.
Heat treatment: The welding stress is eliminated through the overall heat treatment process to improve the comprehensive mechanical properties of the steel pipe.
2. The influence of material properties on the service life of LSAW steel pipes

The material properties of LSAW steel pipes directly affect their service life. High-quality LSAW steel pipes usually have the following material properties:

High strength and high toughness: The strength and toughness of the material determine the bearing capacity of the steel pipe under high pressure and impact loads. High-strength steel can improve the durability of the steel pipe, while high toughness can improve its crack resistance.
Corrosion resistance: Steel pipes often face corrosive environments during use, such as seawater, acidic soil, etc. Materials with good corrosion resistance can effectively extend the service life of steel pipes.
Wear resistance: In pipelines that transport particulate materials such as sand and gravel, the wear resistance of the material is crucial. Materials with good wear resistance can reduce the wear of the pipeline and extend its service life.
3. The influence of the use environment on the service life of LSAW steel pipes

The use environment of LSAW steel pipes is complex and diverse, which has a significant impact on their service life. The following are several typical use environments and their impact on the life of steel pipes:

Marine environment: In the marine environment, steel pipes are exposed to erosion by salt water and marine organisms. The corrosion effect of chloride ions in salt water on steel is particularly significant, so in this environment, special anti-corrosion treatment of steel pipes is usually required, such as coating protection or cathodic protection.
Underground environment: Buried pipelines are often exposed to corrosion by moisture, acid and alkali substances in the soil. In areas with high soil corrosiveness, steel with good corrosion resistance, or external coating and cathodic protection are required.
High temperature and high pressure environment: In high temperature and high pressure environments, the mechanical properties and heat resistance of steel pipe materials are crucial. It is necessary to select appropriate materials and design solutions to ensure the stability and durability of steel pipes in such extreme environments.
4. The impact of maintenance on the service life of LSAW steel pipes

Scientific and reasonable maintenance is an important means to extend the service life of LSAW steel pipes. The following are some effective maintenance measures:

Regular inspection and testing: Regularly conduct appearance inspection and internal inspection of steel pipes to promptly detect and deal with potential defects and damage. Commonly used detection methods include ultrasonic detection, radiographic detection, etc.
Anti-corrosion treatment: For steel pipes with corrosion factors in the use environment, regular anti-corrosion treatment is required, such as re-coating the anti-corrosion layer, replacing damaged anti-corrosion facilities, etc.
Repair and replacement: For the damage and defects that have been found, they need to be repaired or replaced in time to prevent the damage from expanding and affecting the overall performance of the pipeline.
V. Actual case analysis

Through actual case analysis, we can more intuitively understand the service life of LSAW steel pipes and its influencing factors. For example, in a large oil and gas pipeline project, high-quality LSAW steel pipes were used, and strict anti-corrosion treatment and scientific maintenance management were carried out. After 20 years of operation, these steel pipes still maintain good performance without serious corrosion and damage, which fully verifies the positive role of high-quality materials and scientific management in extending service life.

Conclusion

In summary, the service life of LSAW steel pipes is affected by many factors such as manufacturing process, material properties, use environment and maintenance. By selecting high-quality materials, adopting advanced manufacturing processes, and scientific and reasonable maintenance measures, the service life of LSAW steel pipes can be significantly extended. In practical applications, corresponding management and maintenance plans should be formulated according to the specific use environment and needs to ensure the safe operation and long-term use of LSAW steel pipes.

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