# ISO 15761 Manufacturing Process for Gate Valves

## Introduction to ISO 15761 Standard

The ISO 15761 standard specifies the requirements for the manufacturing process of steel gate valves used in petroleum, petrochemical, and related industries. This international standard ensures that gate valves meet stringent quality, performance, and safety criteria for critical 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:

– Valve bodies are typically made from carbon steel, stainless steel, or alloy steel
– Trim materials are selected based on service conditions
– All materials undergo thorough chemical composition analysis and mechanical testing

### 2. Casting or Forging of Valve Components

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

– Sand casting for complex shapes
– Investment casting for precision parts
– Forging for high-strength applications
– All castings and forgings undergo non-destructive testing (NDT)

### 3. Machining Operations

Precision machining ensures proper fit and function:

– CNC machining centers create accurate dimensions
– Specialized equipment for seat and stem machining
– Surface finishing to achieve required roughness values
– Dimensional inspection at each machining stage

## Quality Control Measures

### Non-Destructive Testing (NDT)

ISO 15761 mandates rigorous NDT procedures:

– Radiographic testing for internal defects
– Ultrasonic testing for material integrity
– Liquid penetrant inspection for surface flaws

– Magnetic particle inspection for ferromagnetic materials

### Pressure Testing

All gate valves undergo comprehensive pressure tests:

– Shell test at 1.5 times design pressure
– Seat leakage test according to API 598 standards
– High-pressure gas tests for severe service valves
– Documentation of all test results

## Final Assembly and Inspection

The assembly process includes:

– Careful cleaning of all components
– Proper lubrication of moving parts
– Torque verification for bolted connections
– Functional testing of operation
– Final visual inspection and marking

## Certification and Documentation

Manufacturers must provide:

– Material test certificates
– NDT reports
– Pressure test records
– Final inspection reports
– Compliance certificates with ISO 15761

## Conclusion

The ISO 15761 manufacturing process ensures gate valves meet the highest industry standards for performance and reliability. By following this rigorous process, manufacturers can produce valves that withstand demanding service conditions while maintaining safety and efficiency in critical applications.