# ISO 15761 Manufacturing Process for Gate Valves

## Introduction to ISO 15761 Standard

The ISO 15761 standard specifies 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 for critical applications.

## Key Stages in the Manufacturing Process

### 1. Material Selection and Preparation

Manufacturers begin by selecting appropriate materials according to ISO 15761 specifications. Common materials include:

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

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

### 2. Casting or Forging Process

The valve body manufacturing typically follows one of two methods:

– Sand casting for complex shapes
– Forging for higher strength applications

Both processes must adhere to strict quality controls to ensure proper metallurgical properties and dimensional accuracy.

### 3. Machining Operations

Precision machining transforms raw castings or forgings into functional valve components:

– CNC turning for body and bonnet surfaces
– Milling for flange faces and bolt patterns
– Drilling and tapping for connection points

Tolerances are maintained within ISO 15761 specified limits throughout these operations.

### 4. Assembly Process

The assembly stage involves:

– Installing the gate and stem mechanism
– Mounting seat rings and sealing components
– Applying proper gasketing and bolting procedures

Each assembly step follows documented procedures with quality checkpoints.

## Quality Control and Testing

### Non-Destructive Testing (NDT)

ISO 15761 requires various NDT methods:

– Radiographic testing (RT) for critical sections
– Ultrasonic testing (UT) for material integrity
– Liquid penetrant testing (PT) for surface defects

### Pressure Testing

All valves undergo rigorous pressure tests:

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

## Final Inspection and Certification

Before shipment, each valve receives:

– Dimensional verification
– Functional operation checks
– Surface finish inspection
– Marking and tagging per standard requirements

Successful completion of all tests results in issuance of ISO 15761 compliance certificates.

## Advantages of ISO 15761 Compliant Valves

Manufacturing gate valves to this standard ensures:

– Consistent quality across production batches
– Reliable performance in demanding applications
– Interchangeability between manufacturers
– Compliance with international industry requirements

The ISO 15761 manufacturing process represents a comprehensive approach to producing high-quality gate valves for critical service applications. By following this standardized methodology, manufacturers can deliver products that meet the exacting demands of the petroleum and petrochemical industries while ensuring safety, reliability, and long service life.