# ISO 15761 Standard Manufacturing Process for Gate Valves

## Introduction to ISO 15761

The ISO 15761 standard specifies the requirements for the design, manufacturing, and testing of steel gate valves for petroleum, petrochemical, and related industries. This international standard ensures that gate valves meet stringent quality and performance criteria, making them suitable for demanding applications.

## Key Stages in the Manufacturing Process

### 1. Material Selection and Preparation

The manufacturing process begins with the careful selection of materials that comply with ISO 15761 requirements. Common materials include:

– Carbon steel
– Stainless steel
– Alloy steel

Raw materials undergo rigorous testing for chemical composition and mechanical properties before being approved for production.

### 2. Casting or Forging

The valve body and other major components are typically created through:

– Sand casting for complex shapes
– Investment casting for precision parts
– Forging for high-strength applications

Each method must meet the dimensional tolerances and surface finish requirements specified in the standard.

### 3. Machining Operations

Precision machining ensures proper fit and function of all components:

– CNC turning for accurate dimensions
– Milling for flat surfaces and complex geometries
– Drilling and tapping for bolt holes
– Grinding for sealing surfaces

### 4. Assembly Process

The assembly phase includes:

– Installation of the gate and stem
– Seat ring placement
– Packing gland assembly
– Bonnet attachment

All components must be properly aligned to ensure smooth operation and tight sealing.

## Quality Control and Testing

### Non-Destructive Testing (NDT)

ISO 15761 requires various NDT methods:

– Radiographic testing (RT)
– Ultrasonic testing (UT)
– Magnetic particle inspection (MPI)
– Liquid penetrant testing (PT)

### Pressure Testing

Every valve undergoes rigorous pressure tests:

– Shell test at 1.5 times the rated pressure
– Seat test at 1.1 times the rated pressure
– Backseat test when applicable

### Final Inspection

Before shipment, each valve receives:

– Dimensional verification
– Functional testing
– Surface finish inspection
– Marking and documentation review

## Benefits of ISO 15761 Compliance

Manufacturing gate valves according to ISO 15761 offers several advantages:

– Ensured reliability in critical applications
– International recognition and acceptance
– Improved safety and performance
– Standardized quality across manufacturers
– Easier maintenance and replacement

## Conclusion

The ISO 15761 standard provides a comprehensive framework for manufacturing high-quality gate valves. By following this standardized process, manufacturers can produce valves that meet the rigorous demands of the petroleum and petrochemical industries while ensuring safety, reliability, and long service life.