MANUAL OF PLUG VALVES

1. Introduction

Scope

This manual provides guidelines for the installation, operation, maintenance, inspection, warranty coverage, and service procedures for Plug Valves used in water supply, wastewater, industrial, chemical, and utility applications.

Applications

Plug Valves are quarter-turn rotary valves designed for isolation and flow control. They utilize a cylindrical or tapered plug with a flow passage that aligns with the pipeline when open and blocks flow when closed.

Plug Valves are commonly used in:

• Water Distribution Systems
• Wastewater Treatment Plants
• Sewage Networks
• Industrial Process Pipelines
• Chemical Plants
• Oil & Gas Facilities
• Irrigation Systems
• Utility Services

Purpose

The primary function of a Plug Valve is to provide reliable shut-off, flow diversion, and isolation with minimal pressure loss and quick operation.

2. Installation Guidelines

Pre-Installation Inspection

Before installation:

• Verify valve size, pressure rating, and material specifications.
• Inspect the valve for transportation damage.
• Ensure plug rotation is smooth.
• Check sealing surfaces and coatings.

Pipeline Preparation

• Flush the pipeline thoroughly.
• Remove rust, welding slag, debris, and foreign particles.
• Ensure proper pipe alignment.
• Provide adequate support to the piping system.

Installation Position

• Plug Valves may be installed in horizontal or vertical pipelines.
• Ensure sufficient operating clearance for lever, gearbox, or actuator.
• Follow flow direction markings where applicable.

Flange Installation

• Use approved gasket materials.
• Tighten flange bolts uniformly in a cross pattern.
• Avoid excessive tightening force.

Installation Precautions

• Do not use valve handles or gear operators for lifting.
• Protect valve internals from contamination.
• Ensure valve is partially open during installation when recommended.

3. Operation Instructions

Opening Procedure

1. Rotate the lever, handwheel, or gearbox 90°.
2. Ensure the plug passage aligns fully with pipeline flow.
3. Confirm unrestricted flow through the valve.

Closing Procedure

1. Rotate the operating mechanism 90° in the opposite direction.
2. Ensure the plug completely blocks the flow path.
3. Confirm positive shut-off.

Operating Precautions

• Operate smoothly without excessive force.
• Avoid using extension bars.
• Operate within rated pressure and temperature limits.
• Ensure valve is fully open or fully closed unless specifically designed for throttling.

Position Indicators

4. Maintenance Schedule

Monthly Inspection

• Check for external leakage.
• Verify smooth plug rotation.
• Inspect fasteners and operating mechanism.
• Check flange joints.

Quarterly Inspection

• Inspect plug sealing surfaces.
• Check lubrication condition (where applicable).
• Examine gearbox or lever assembly.
• Verify coating condition.

Annual Inspection

• Inspect plug and body seating surfaces.
• Examine bearings and bushings.
• Check stem condition.
• Replace worn seals and gaskets.
• Conduct pressure and leakage testing.

Recommended Spare Parts

• Plug Assembly
• Stem
• Bearings
• Bushings
• O-Rings
• Gaskets
• Fasteners
• Gearbox Components

5. Warranty Coverage

Warranty Exclusions

Warranty does not cover:

• Improper installation.
• Operation beyond rated pressure or temperature limits.
• Corrosion caused by incompatible media.
• Mechanical damage.
• Unauthorized modifications.
• Improper lubrication practices.
• Normal wear and tear.

6. Expected Service Life

Factors Affecting Service Life

• Fluid Characteristics
• Operating Pressure
• Temperature Conditions
• Frequency of Operation
• Corrosion Exposure
• Maintenance Practices

Regular maintenance significantly extends valve life.

7. Customer Responsibilities

The customer shall:

• Ensure proper installation.
• Operate within specified limits.
• Maintain inspection and maintenance records.
• Conduct scheduled maintenance.
• Protect valves from external damage.
• Follow lubrication recommendations.
• Report abnormalities promptly.

Failure to comply may affect warranty eligibility.

8. Warranty Claim Procedure

Step 1 – Claim Submission

Provide:

• Purchase Order Number
• Invoice Copy
• Valve Identification Details
• Installation Date
• Description of Defect
• Photographs of Valve and Installation

Step 2 – Technical Evaluation

The submitted information will be reviewed to determine:

• Installation compliance
• Operating conditions
• Maintenance history
• Warranty applicability

Step 3 – Inspection

Where required:

• Site inspection may be conducted.
• Valve may be requested for detailed examination.

Step 4 – Resolution

Based on technical findings:

• Repair
• Component Replacement
• Valve Replacement
• Technical Recommendations

will be provided according to warranty terms.

Safety Precautions

• Depressurize and drain the system before maintenance.
• Never dismantle the valve under pressure.
• Wear appropriate PPE during servicing.
• Follow all plant safety procedures.
• Use approved lifting methods for large-size valves.

Document Retention

Maintain installation records, maintenance logs, inspection reports, pressure test records, and warranty documentation throughout the service life of the valve for operational reference and warranty support.