How to Replace Tower Packing When the Original Drawings and Packing Specification Are Missing

Older process towers often remain in operation long after the original design documents have disappeared.

When the packing finally needs replacement, the maintenance team may know only that:

• the tower has been operating for many years;
• the existing packing is damaged or fouled;
• no reliable packing specification can be found.

The supplier is then asked to provide a replacement.

Without drawings or historical records, the project becomes a controlled reverse-engineering exercise.

Do Not Identify Packing from One Photograph Alone

A photograph can help determine the general packing family.

However, visual similarity is not enough to confirm:

• exact size;
• material grade;
• wall thickness;
• bulk density;
• hydraulic behavior.

Several manufacturers may produce geometrically similar packing with different dimensions.

Physical measurements are preferable.

Measure Actual Samples

If possible, remove several representative pieces and record:

• overall diameter or width;
• height;
• wall thickness;
• material;
• approximate mass.

For old or deformed packing, measure more than one piece.

Do not assume a damaged sample still represents the original dimensions perfectly.

Confirm Tower Diameter

Even if the original packing is identified, tower diameter is essential.

It helps evaluate whether the existing packing size was appropriate and whether a different size could be considered.

The tower internal diameter should be measured or verified from equipment records.

Determine the Existing Bed Height

Replacement quantity depends on actual packed height.

During shutdown, measure:

• support elevation;
• top of packing;
• number of beds;
• bed depth.

Do not rely only on the volume of material removed because old packing may contain:

• deposits;
• broken pieces;
• retained liquid;
• foreign material.

Inspect the Support Plate

If documentation is missing, the support plate provides important clues.

Record:

• opening size;
• beam arrangement;
• material;
• corrosion condition;
• deformation.

A new packing should be compatible with the existing support openings.

Otherwise, smaller pieces may fall through.

Review the Distributor Before Reusing It

The old packing may not be the only component that requires attention.

An existing distributor should be checked for:

• blockage;
• corrosion;
• damaged holes;
• poor levelness;
• mechanical deterioration.

Replacing the packing while leaving a badly damaged distributor can produce disappointing performance.

Identify the Actual Process Conditions

Historical tower design conditions may no longer represent current operation.

Ask for:

• present gas flow;
• present liquid flow;
• current temperature;
• pressure;
• process composition;
• required outlet performance.

Many plants increase throughput over time.

The original packing may therefore no longer be optimal.

Decide Whether the Goal Is “Like-for-Like” or “Upgrade”

These are different projects.

Like-for-like replacement

The objective is to reproduce the existing system as closely as possible.

This may be appropriate when the tower has performed satisfactorily for years.

Performance upgrade

The objective may include:

• more capacity;
• lower pressure drop;
• greater fouling resistance;
• improved corrosion resistance.

This requires additional engineering verification.

The supplier should not quietly substitute a different packing geometry without clarifying the project objective.

Material Identification May Require Testing

If the original material grade is uncertain, visual appearance is insufficient.

For metallic packing, material verification may be required.

For plastics or ceramics, historical process chemistry can help narrow the likely material but may not prove the exact grade.

Record Everything During Shutdown

When old towers are opened, the opportunity for inspection may be limited.

Useful records include:

• photographs;
• measurements;
• packing samples;
• support drawings;
• distributor dimensions;
• manway size.

This information can become the new equipment record for future maintenance.

Prepare a Replacement Data Sheet

Before ordering the new packing, summarize:

• tower diameter;
• packed height;
• packing family;
• nominal size;
• material;
• quantity;
• support details;
• process conditions;
• installation access.

Even a simple replacement data sheet dramatically reduces procurement risk.

Final Engineering Principle

When original drawings are missing, the safest approach is not to guess the previous design.

Reconstruct the critical mechanical and process information from field measurements, samples, operating data, and internal inspection.