# 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 used in petroleum, petrochemical, and natural gas industries. This international standard ensures that gate valves meet stringent quality and performance criteria for critical applications.

## Key Stages in the Manufacturing Process

### 1. Material Selection and Preparation

The manufacturing process begins with careful material selection according to ISO 15761 specifications:

– Valve body: Typically carbon steel or alloy steel
– Trim materials: Stainless steel or other corrosion-resistant alloys
– Gaskets and seals: Materials compatible with service conditions

### 2. Casting or Forging of Valve Components

Manufacturers use either casting or forging methods to create valve components:

– Investment casting for complex shapes
– Sand casting for larger components
– Forging for high-stress components like stems and wedges

### 3. Machining Operations

Precision machining ensures proper fit and function:

– CNC machining of valve bodies and bonnets
– Boring and threading of connection ends
– Surface finishing to required roughness values

### 4. Assembly Process

The assembly phase includes:

– Installation of stem, gate, and seating surfaces
– Proper alignment of moving components
– Torque application according to specifications

## Quality Control and Testing

### Non-Destructive Testing (NDT)

ISO 15761 requires various NDT methods:

– Radiographic testing for critical welds
– Ultrasonic testing for material integrity
– Liquid penetrant testing for surface defects

### Pressure Testing

All valves undergo rigorous pressure tests:

– Shell test at 1.5 times design pressure
– Seat leakage test according to API 598
– Backseat test for stem sealing capability

## Final Inspection and Certification

Before shipment, each valve undergoes:

– Dimensional verification
– Functional testing
– Surface finish inspection

– Marking and tagging per standard requirements

## Benefits of ISO 15761 Compliance

Manufacturing gate valves to ISO 15761 standards provides:

– Consistent quality across manufacturers
– Interchangeability of components
– Reliable performance in harsh environments
– Global acceptance in the oil and gas industry

## Conclusion

The ISO 15761 standard manufacturing process for gate valves ensures that these critical components meet the highest quality and performance standards. By following this comprehensive process, manufacturers can produce gate valves that provide reliable service in demanding petroleum and natural gas applications while maintaining safety and operational efficiency.