ISO 15761 Standard Manufacturing Process for Gate Valves

# ISO 15761 Standard Manufacturing Process for Gate Valves

## Introduction to ISO 15761 Standard

The ISO 15761 standard specifies the requirements for the design, manufacturing, and testing of steel gate valves used in petroleum, petrochemical, and related 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 selection of materials that comply with ISO 15761 specifications. Common materials include:

• Carbon steel (ASTM A216 WCB)
• Stainless steel (ASTM A351 CF8/CF8M)
• Alloy steel (ASTM A217 WC6/WC9)

Raw materials undergo thorough inspection and testing before being approved for production.

### 2. Casting or Forging Process

Casting Method

For cast bodies, the process involves:

1. Pattern making and mold preparation
2. Pouring molten metal into molds
3. Cooling and solidification
4. Removal of casting from molds

Forging Method

Forged components are produced through:

1. Heating metal billets to forging temperature
2. Shaping under high pressure
3. Heat treatment for improved mechanical properties

### 3. Machining Operations

Precision machining ensures all components meet dimensional tolerances specified in ISO 15761:

• CNC turning of valve bodies and bonnets
• Milling of flange faces and sealing surfaces
• Drilling and tapping of bolt holes
• Grinding of critical sealing surfaces

### 4. Assembly Process

The assembly stage includes:

1. Installation of stem, gate, and seats
2. Application of appropriate gaskets and packing
3. Torqueing of bolted connections to specified values
4. Lubrication of moving parts

## Quality Control and Testing

### Non-Destructive Testing (NDT)

ISO 15761 requires various NDT methods:

• Radiographic testing (RT) for critical castings
• Ultrasonic testing (UT) for thickness verification
• Liquid penetrant testing (PT) for surface defects
• Magnetic particle testing (MT) for ferromagnetic materials

### Pressure Testing

All gate valves undergo:

1. Shell test at 1.5 times the design pressure
2. Seat leakage test according to ISO 5208
3. Backseat test for valves with backseat feature

## Final Inspection and Certification

Before shipment, each valve undergoes:

• Dimensional verification
• Visual inspection
• Operation testing
• Painting and marking according to ISO 15761 requirements

Upon successful completion, the valve receives certification documenting compliance with ISO 15761 standards.

## Advantages of ISO 15761 Compliant Gate