Lessons Learned and Key Takeaways in ASME Section VIII, Division 1 (2023 Edition)

### In-depth Analysis and Insights

ASME Section VIII, Division 1, is a crucial code for the design, fabrication, inspection, and testing of pressure vessels. This code ensures the safety, reliability, and efficiency of pressure vessels used in various industries. Let's delve into the lessons learned, key takeaways, and detailed analysis of some frequently asked questions related to ASME Section VIII, Division 1.

### Statutory Codes Governing Pressure Vessel Fabrication

Several statutory codes govern the fabrication of pressure vessels, ensuring compliance with safety and quality standards:

- ASME Section VIII, Division 1: This is the most widely used code for pressure vessel fabrication in the U.S. It provides guidelines for the design, materials, fabrication, inspection, testing, and certification of pressure vessels.

- TEMA (Tubular Exchanger Manufacturers Association): Governs the design and fabrication of heat exchangers.

- EN 13445/PED 5500: European standards for the design, manufacture, and inspection of pressure vessels.

- A.D. Merkblatter: German standards for pressure vessel fabrication.

### Progressive or Complete Inspection

The term "progressive or complete inspection" refers to the systematic and thorough inspection process followed by inspectors. This process includes:

1. Correct order and amendments

2. Drawing approval

3. Weld procedure approval

4. Weld procedure qualification approval

5. Welder qualification

6. Mill test certificate check

7. Material identification

8. Fit-up inspection

9. Consumable check

10. Root pass inspection

11. Component/sub-assembly check

12. Review radiographs

13. Dimensional inspection

14. Hardness check

15. Heat treat chart review

16. Hydrostatic test

17. Data book review

### Plate Stamping Information

According to ASME, plates used in the fabrication of pressure vessels must be stamped with the following information:

- Name or brand of the manufacturer

- Heat and slab number

- Material specification number and grade, class, and type

### Crimping Plates Prior to Rolling

Crimping plates before rolling into cylinders or strakes is essential to prevent peaking and ensure a good fit-up. This process enhances the overall structural integrity of the pressure vessel.

### Fit-Up Inspection Points

When performing fit-up inspections, the following points should be checked to ensure quality:

- Cleanliness

- Root gap

- Bevel configuration

- Alignment

- Correct material used

### Fit-Up Inspection of Plate Seams

When checking fit-ups on plate seams, the following should be verified:

- Alignment

- Tolerances

- Root gap

- Weld bevel/proper angle

### Plate Edges Inspection

Inspecting plate edges before welding is crucial as it may disclose serious laminations that could affect the structural integrity of the weld.

### Nozzle Forging Reinforcement

It is possible for a nozzle forging to have the necessary reinforcement as an integral part of the forging, eliminating the need for a separate plate.

### Constrictive Weld Grooves Issues

Constrictive weld grooves can prevent proper electrode manipulation, leading to issues such as:

- Insufficient removal of slag

- Lack of sidewall fusion

### Tack Weld Conditions

- Condition: Tack welds should be free from porosity, cracks, or pinholes.

- Removal: Tack welds should normally be removed to ensure weld integrity.

### Temporary Attachments Removal Issues

Removing temporary attachments used for fit-up can damage the base material. If this occurs, non-destructive testing methods like dye penetrant or magnetic particle testing should be used, followed by grinding to remove defects and re-testing.

### Weld Production Test Plate

A weld production test plate is an extra piece of material from the same heat, which has weld deposited using the same welding procedure. This plate is used to ensure the quality of the welds in the actual pressure vessel.

### Test Plate Requirements

A test plate is normally required when impact requirements are part of the welding procedure.

### Nozzle Reinforcement Plate Welding

It is permissible to weld a nozzle reinforcement plate at the same time the nozzle is being welded.

### Nozzle Inspection Criteria

Nozzles should be checked for:

- Level

- Squareness

- Height

- Orientation/elevation

### Final Dimensional Inspection

During the final dimensional inspection of a pressure vessel, elevation measurements should be made from the bottom of the base ring, ensuring the distance between the tangent line and the bottom of the base ring is correct.

### Tray Support Rings Inspection

The dimensions of tray support rings should be checked after fit-up and prior to welding.

### Visual Inspection Before PWHT

A visual inspection should be conducted before the final post-weld heat treatment (PWHT) to ensure all necessary welding has been completed.

### Hydrostatic Test Timing

The hydrostatic test is conducted after the PWHT to verify the integrity of the pressure vessel.

### Post-PWHT Testing

After the heat treatment of a pressure vessel, a hardness check is performed to ensure it has been properly post-weld heat treated.

### Internal Bracing During PWHT

Large thin-wall vessels should be internally braced during PWHT to prevent deformation or collapse of the shell.

### Post-PWHT Welding

It is permissible to perform welding on a vessel that has been post-weld heat treated, provided the welding follows the specified preheat, fillet weld size, and guidelines of ASME Section VIII, Para. UCS-56.

### Hydrostatic Test Witnessing

When witnessing a hydrostatic test on a pressure vessel, the following should be checked:

- Pressure pump operation

- Pressure/time recorder operation

- High point vent

- Pump to vessel pressure line disconnection

- Water temperature

- Gauge calibration

- Visual check of reinforcing pads

- Leak inspection

- Holding time

- Use of two gauges (one on pump discharge, one on the highest point of the vessel)

### Welding on Post-PWHT Vessels

Welding on a vessel that has been post-weld heat treated is allowed, following the specified preheat and fillet weld size within the guidelines of ASME Section VIII, Para. UCS-56.

## Conclusion

Adhering to ASME Section VIII, Division 1, ensures that pressure vessels are designed, fabricated, inspected, and tested to meet the highest safety and quality standards. Understanding and implementing the lessons learned and key takeaways from this code will contribute to the successful and safe operation of pressure vessels in various industries.

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