API 650, API 620 STORAGE TANK SHOP FABRICATION AND INSPECTION PROCEDURE

Introduction

This tutorial provides a comprehensive guide on the fabrication and inspection procedures for storage tanks according to API 650 and API 620 standards. Understanding these procedures is essential for ensuring the structural integrity and safety of storage tanks used in various industries.

Step 1: Understand API Standards

Familiarize yourself with the relevant API standards for storage tanks:

• API 650: Covers welded tanks for oil storage.
• API 620: Pertains to the design and construction of large, low-pressure storage tanks.

Practical Tips:

• Review the complete guidelines of both standards to understand specifications, materials, and design criteria.
• Ensure compliance with local regulations that may also apply.

Step 2: Prepare for Fabrication

Gather necessary tools and materials for the fabrication process:

• Materials: Steel plates, welding rods, gaskets, and sealants.
• Tools Needed: Welding machine, cutting tools, measuring instruments, and safety equipment.

Common Pitfalls to Avoid:

• Using substandard materials that do not meet API specifications.
• Skipping safety protocols during the preparation phase.

Step 3: Design the Tank

Create a detailed tank design plan:

• Dimensions: Determine the diameter and height based on storage needs.
• Design Features: Consider features such as inlet/outlet pipes and venting systems.

Practical Tips:

• Use CAD software for precise design and modifications.
• Ensure the design adheres to the required API standards.

Step 4: Fabricate the Shell

Begin the shell fabrication process:

1. Cut Steel Plates: Use cutting tools to shape the steel plates according to the design.
2. Weld Plates Together: Employ a welding machine to join the plates along the edges.
3. Inspect Welds: Conduct visual inspections and non-destructive testing (NDT) on welds to ensure quality.

Common Pitfalls to Avoid:

• Inadequate welding preparation leading to weak joints.
• Failing to perform thorough inspections after welding.

Step 5: Assemble Additional Components

Integrate other necessary components into the tank:

• Nozzles and Flanges: Install nozzles for filling and emptying the tank.
• Roofing: If required, attach a roof that complies with design specifications.

Practical Tips:

• Ensure all components are compatible with the tank's design and material.
• Use proper sealing techniques to prevent leaks.

Step 6: Final Inspection and Testing

Conduct a final inspection and testing of the fabricated tank:

• Visual Inspection: Check for any visible defects or irregularities.
• Pressure Testing: Perform pressure tests to ensure the tank can withstand operational conditions.

Common Pitfalls to Avoid:

• Overlooking minor defects that can lead to major failures.
• Skipping pressure testing, which is crucial for safety.

Conclusion

By following these steps, you can effectively fabricate and inspect storage tanks compliant with API 650 and API 620 standards. Ensure you have a thorough understanding of the materials, adhere to safety protocols, and conduct detailed inspections throughout the process. For further learning, consider exploring advanced fabrication techniques or attending workshops on storage tank design and construction.