MANUAL OF WIDE TYPE STRAINERS

1. Introduction

Scope

This manual provides guidelines for the installation, operation, maintenance, inspection, warranty coverage, and service procedures for Wide Type Strainers used in water, wastewater, and industrial piping systems.

Applications

Wide Type Strainers are mechanical filtration devices with a large screen area relative to the pipe bore, which gives a low pressure drop and long intervals between cleaning. They are commonly used in:

• Water Transmission Pipelines
• Water Distribution Networks
• Pumping Stations
• Water Treatment Plants
• Sewage Treatment Plants
• Irrigation Systems
• Industrial Process Pipelines
• Fire Protection Systems

Purpose

The primary function of a Wide Type Strainer is to retain solids and debris carried by the fluid and so prevent damage to:

• Pumps and Impellers
• Control Valves and Pressure Reducing Valves
• Flow Meters
• Heat Exchangers
• Nozzles and Spray Systems
• Downstream Process Equipment

2. Installation Guidelines

Pre-Installation Inspection

Before installation:

• Verify strainer size, pressure rating, screen perforation or mesh size, and material specifications.
• Inspect the body, cover, and screen for transportation damage.
• Confirm the screen is undamaged, correctly seated, and free from blockage.
• Remove all protective covers and packaging materials.

Pipeline Preparation

• Clean and flush the pipeline before installation.
• Remove debris, welding slag, stones, rust, and foreign particles.
• Ensure proper pipeline alignment and that flanges are parallel.

Installation Position

• Install with the flow direction arrow matching the actual direction of flow.
• Install upstream of the equipment to be protected.
• Mount in a horizontal line with the screen chamber below the horizontal centreline so that collected solids settle away from the flow.
• Provide isolation valves on both sides, and a bypass where uninterrupted service is required.

Clearance and Access

• Provide clearance in line with the cover for full withdrawal of the screen.
• Provide a drain connection with a valve at the lowest point.
• Provide pressure gauge tappings upstream and downstream to monitor the differential pressure.
• Support the strainer independently; do not let it carry pipeline loads.

Installation Precautions

• Do not use the strainer as a pipe anchor.
• Tighten cover and flange bolts evenly in a diagonal sequence.
• Replace the cover gasket whenever the cover is removed.
• Do not commission the system without the screen in place.

3. Operation Instructions

Initial Startup

1. Confirm the screen is correctly installed and the cover is fully tightened.
2. Open the isolation valves slowly and fill the line.
3. Vent trapped air where a vent connection is provided.
4. Check the body, cover, and drain connection for leakage.
5. Record the clean differential pressure as the reference for future cleaning.

Normal Operation

During operation:

• Fluid passes through the screen and solids are retained inside the screen chamber.
• Differential pressure across the strainer rises as the screen loads with debris.
• A rising differential pressure is the indication that cleaning is due.
• Cleaning requires the strainer to be isolated and depressurised unless a blow-down arrangement is provided.

Operating Precautions

• Monitor the differential pressure regularly, especially during commissioning when debris loading is highest.
• Do not allow the screen to block completely; a collapsed screen passes debris downstream.
• Operate within rated pressure and temperature limits.
• Never open the cover while the line is pressurised.
• Do not run the system with a damaged or omitted screen.

4. Maintenance Schedule

Monthly Inspection

• Record the differential pressure across the strainer.
• Inspect the body, cover joint, and drain valve for leakage.
• Operate the drain valve to remove settled solids where a blow-down is fitted.

Quarterly Inspection

• Isolate, depressurise, and drain the strainer.
• Remove and clean the screen.
• Inspect the screen for distortion, perforation damage, or corrosion.
• Clean the body cavity of accumulated solids.
• Replace the cover gasket and refit the cover.
• Inspect external coating for corrosion.

Annual Inspection

• Carry out a detailed inspection of the body, cover, and screen seating surfaces.
• Replace the screen if distorted, perforated, or heavily corroded.
• Replace gaskets, O-rings, and the drain plug seal.
• Check fasteners and replace any that are corroded.
• Re-record the clean differential pressure after reassembly.
• Record all findings in the maintenance log.

Recommended Spare Parts

• Screen Element
• Cover Gasket
• O-Rings
• Drain Plug / Drain Valve
• Cover Fasteners
• Body Gasket Set

5. Warranty Coverage

Warranty Exclusions

Warranty shall not cover:

• Damage caused by clogged screens.
• Improper installation.
• Corrosion due to incompatible media.
• Mechanical damage during maintenance.
• Operation beyond rated conditions.
• Unauthorized modifications.
• Normal wear and tear.

6. Expected Service Life

Factors Affecting Service Life

• Fluid Cleanliness
• Solids Loading
• Pressure Conditions
• Temperature Conditions
• Maintenance Frequency
• Corrosion Exposure
• Operating Environment

Routine cleaning significantly extends screen and strainer life.

7. Customer Responsibilities

The customer shall:

• Ensure proper installation as per this manual.
• Monitor differential pressure and clean the screen before it blocks.
• Operate within rated limits.
• Use the correct screen perforation or mesh size for the duty.
• Conduct routine inspections.
• Maintain installation, cleaning, and maintenance records.
• Use approved spare parts.
• Report abnormalities promptly.

Failure to comply may affect warranty eligibility.

8. Warranty Claim Procedure

Step 1 – Claim Submission

Provide:

• Purchase Order Number
• Invoice Copy
• Strainer Identification Details
• Installation Date
• Operating Conditions
• Cleaning Records
• Description of Defect
• Photographs of 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 necessary:

• Site inspection may be conducted.
• Strainer may be requested for factory examination.

Step 4 – Resolution

Based on technical findings, one of the following may be provided:

• Repair
• Component Replacement
• Strainer Replacement
• Technical Recommendations

Safety Precautions

• Isolate, depressurize, and drain the strainer before removing the cover.
• Never loosen cover bolts while the line is under pressure.
• Take care with hot fluids and with media that may be hazardous when the cover is opened.
• Wear appropriate PPE during servicing.
• Follow all site safety regulations.
• Use approved lifting methods for large-size strainers and covers.

Document Retention

Maintain installation records, maintenance logs, cleaning schedules, inspection reports, and warranty documentation throughout the service life of the Wide Type Strainer for operational reference and warranty support.