How to Install Demister Pad Properly and Quickly

Introduction

In chemical, petrochemical, and gas processing industries, demister pads (also known as mist eliminators or wire mesh demisters) play a vital role in removing liquid droplets from vapor streams. A well-installed demister pad improves process efficiency, reduces product loss, and protects downstream equipment.

This guide covers how to install a demister pad properly and quickly, ensuring optimal performance and longevity. We also provide practical tips, tools needed, and common mistakes to avoid.

What Is a Demister Pad?

A demister pad is typically made of knitted wire mesh and is installed inside process vessels such as columns or scrubbers. Its function is to capture entrained droplets from gas or vapor streams before they exit the vessel.

Main components of a demister pad installation:

• Wire mesh element (pad)

• Grid/support frame

• Fastening mechanisms (bolts, clamps, etc.)

• Vessel housing

Why Proper Installation Matters

Improper installation can lead to:

• Reduced separation efficiency

• Higher pressure drop

• Mesh dislocation or damage

• Premature replacement

• Unnecessary shutdowns

A correct and quick installation process helps avoid these issues and ensures that the demister performs its intended function efficiently.

Tools and Materials Needed

Before starting the installation, gather the following:

• Demister pad (custom-sized or standard)

• Support grid or tray (if required)

• Fastening bolts or clamps

• Lifting equipment (for large demisters)

• Gasket or sealing tape

• Wrench, screwdriver, and torque tools

• Safety equipment (gloves, helmet, harness, etc.)

Step-by-Step Guide: How to Install a Demister Pad

Step 1: Preparation and Safety Check

Keywords: demister installation preparation, safety

• Review the vessel drawing and demister specifications.

• Ensure the vessel is depressurized, ventilated, and clean.

• Inspect access space for tools and lifting.

• Check demister dimensions against the vessel internal diameter.

• Verify orientation: some demisters are directional.

Tip: Always follow the facility’s confined space entry protocol.

Step 2: Inspect the Demister Pad and Grid

Before placement:

• Inspect the knitted wire mesh for physical damage or deformation.

• Check welds on the support grid or frame.

• Ensure there is no corrosion or contamination on the pad.

If using a multi-piece pad, check that all segments are present and match the numbering or layout diagram.

Step 3: Install Support Grid (If Required)

Keywords: demister support grid, mesh tray installation

Some vessel designs require a support grid to hold the demister pad.

• Lower the support grid into position through the manhole.

• Align it horizontally with the vessel’s mounting brackets.

• Bolt or clamp it securely into place.

• Ensure it is level and free of obstructions.

Step 4: Position the Demister Pad

Keywords: demister pad placement, wire mesh demister installation

• Carefully lift the demister pad using ropes or hoists (for heavy units).

• Insert the pad through the manhole.

• Place the pad flat on the support grid or vessel seating ring.

For multi-section demister pads:

• Install section by section, aligning edges precisely.

• Ensure no gaps exist between segments.

• Use tie wires or clips to join adjacent segments if specified.

Step 5: Secure the Pad

Keywords: securing demister pad, clamp mesh pad

• Fasten the pad using the recommended clamping system or retainer bars.

• Avoid overtightening, which may deform the mesh.

• If a top grid is used, align and bolt it down evenly across the pad.

Step 6: Install Gasket or Sealing Ring (if required)

Some designs require a sealing gasket to prevent bypass.

• Install a rubber or PTFE gasket around the pad's circumference.

• Ensure it fits snugly between the pad and vessel wall.

• Avoid compression gaps.

Step 7: Final Inspection

Keywords: demister installation inspection, final check

• Double-check alignment and leveling.

• Make sure there is no loose mesh, bolt, or foreign object.

• Rotate the vessel if needed to inspect all sides.

• Take photos for documentation.

Tips to Install Quickly Without Compromising Quality

• Use modular demister pads for easier handling in tight spaces.

• Pre-label multi-piece pads for faster assembly.

• Use trained personnel for rigging and alignment.

• Maintain clear communication between lifting and installation teams.

• Prepare all tools and materials in advance at the job site.

Common Mistakes to Avoid

Once installed, your demister pad requires minimal maintenance. However, schedule periodic inspections for:

• Pressure drop monitoring

• Contamination or fouling

• Mechanical damage

Replace the pad if:

• Separation efficiency declines

• Visible deformation occurs

• Mesh becomes clogged or corroded

Case Study: 3-Hour Demister Pad Installation for a 2.5m Vessel

Location: Petrochemical plant, Indonesia
Challenge: Replace an old wire mesh demister pad during routine shutdown.
Solution:

• Prepared custom 3-piece modular pad.

• Used magnetic retainer clips for fast locking.

• Trained 3-person team finished full removal and installation in under 3 hours.

Result: Improved gas-liquid separation, reduced pressure drop by 18%.

Frequently Asked Questions

Can I reuse an old demister pad?

Not recommended unless it passes full inspection and cleaning. Deformed or corroded mesh won’t perform well.

How long does installation usually take?

1–6 hours depending on vessel size, access, number of pieces, and team experience.

What materials are best for demister pads?

• SS304 / SS316: Standard for corrosion resistance

• Monel, Hastelloy, PTFE: For aggressive chemical environments

Conclusion

Installing a demister pad properly and quickly requires good preparation, the right tools, and attention to detail. Following the step-by-step guide above ensures optimal performance and longevity of your demister system.

Remember: the investment in careful installation pays off through better efficiency, lower operating costs, and longer equipment life.