API 650 STORAGE TANK- BANDING AND PEAKING SOULTIONS. TUTORIAL.

Introduction

This tutorial provides step-by-step instructions on controlling banding and peaking on shell joints in API 650 storage tanks. Understanding these techniques is crucial for maintaining structural integrity and ensuring the longevity of storage tanks. By following these guidelines, you can effectively manage these common issues during tank construction and maintenance.

Step 1: Understanding Banding and Peaking

• Banding refers to the distortion that can occur in the shell of the tank, typically due to improper welding or assembly techniques.
• Peaking occurs when there is an upward bulge or deformation in the shell joint, often caused by thermal expansion or contraction during the welding process.

Practical Advice:

• Familiarize yourself with the tank design and welding standards as specified in API 650.
• Assess the potential for banding and peaking before beginning any welding operations.

Step 2: Preparing the Shell Joint

• Ensure that all surfaces to be welded are clean and free of contaminants.
• Align the shell plates properly to minimize the risk of distortion during welding.

Practical Advice:

• Use clamps or other alignment tools to hold plates in place.
• Inspect the fit-up of the shell plates to ensure they meet specifications.

Step 3: Selecting the Right Welding Technique

• Choose a welding method that minimizes heat input, as excessive heat can lead to distortion.
• Common techniques include:
  • TIG Welding for precision and control.
  • MIG Welding for speed and efficiency.

Practical Advice:

• Adjust the welding parameters (voltage, amperage) based on the material thickness and type.
• Consider using multi-pass welding for thicker sections to distribute heat evenly.

Step 4: Implementing Control Measures

• During welding, use techniques such as backstep welding or skipping to reduce heat concentration.
• Monitor the temperature of the weld area to avoid overheating.

Practical Advice:

• Use thermal imaging or pyrometers to keep track of temperatures.
• Allow for cooling periods between passes when welding thick materials.

Step 5: Post-Welding Inspection

• Conduct a thorough inspection of the completed welds for signs of banding or peaking.
• Use non-destructive testing methods, such as ultrasound or radiography, to ensure weld integrity.

Practical Advice:

• Document any defects found and assess whether corrective action is needed.
• Perform a visual inspection for alignment and shape conformity.

Conclusion

Controlling banding and peaking in API 650 storage tanks is essential for structural reliability. By following these steps—understanding the issues, preparing the shell joints, selecting appropriate welding techniques, implementing control measures, and conducting thorough inspections—you can mitigate these problems effectively. For your next project, apply these principles to enhance weld quality and extend the lifespan of your storage tanks.