Why Cleaning and CIP Conditions Must Be Included in Tower-Packing Material Selection

A packing material may be fully compatible with the normal process and still fail during maintenance.

The reason is simple:

cleaning conditions can be more aggressive than operating conditions.

Industrial towers may be cleaned using:

• alkaline solutions;
• acidic solutions;
• oxidizing chemicals;
• hot water;
• steam;
• solvents.

These conditions should be part of material selection from the beginning.

Normal Process Chemistry Is Only One Exposure Case

Suppose a packed tower normally handles an acidic gas at moderate temperature.

A PP packing may be suitable.

However, if maintenance procedures use:

• high-temperature cleaning;
• strong oxidizer;
• incompatible solvent;

the material may be damaged even though normal service is safe.

Cleaning Temperature Can Be the Controlling Limit

Plastic packing is particularly sensitive to temperature.

A tower operating at 50°C may later be cleaned with much hotter fluid.

If the cleaning temperature exceeds the allowable range, possible consequences include:

• deformation;
• loss of stiffness;
• dimensional change.

Therefore, the maximum temperature should include maintenance events.

Ceramic Can Handle Heat but Not Every Chemical Equally

Ceramic packing offers high-temperature resistance.

But different ceramic formulations can have different resistance to:

• acid;
• alkali.

A cleaning procedure that alternates acidic and alkaline washing should therefore be checked against the actual ceramic grade.

Metals Also Require Cleaning Review

Stainless steel may perform well during normal operation but experience problems under:

• concentrated chloride exposure;
• aggressive cleaning chemistry;
• stagnant conditions.

Material compatibility tables should therefore include both process and maintenance chemistry.

Internals Beyond the Packing Must Be Checked

Cleaning fluid contacts more than the packing.

It may also reach:

• distributor;
• support grid;
• demister;
• fasteners;
• gaskets.

A system is only as resistant as its weakest component.

Steam Cleaning Requires Special Attention

Even if chemical compatibility is acceptable, steam introduces high temperature.

Some plastic internals that are perfectly suitable during normal operation may not tolerate direct steam exposure.

Cleaning Method Can Influence Design

If frequent washdown is expected, engineers may want:

• flushing connections;
• accessible distributor openings;
• drainage paths;
• removable sections.

Maintenance philosophy can therefore influence tower-internal design.

Ask About Cleaning Before Finalizing Material

Useful questions include:

• What cleaning chemical is used?
• At what concentration?
• At what temperature?
• For how long?
• How often?
• Is steam used?
• Is the tower completely drained afterward?

These questions are often missed in the initial RFQ.

A Material Datasheet Is Not Enough Without the Exposure Case

A statement such as:

PP is chemically resistant to this process.

is incomplete if the cleaning procedure is unknown.

Material approval should cover the complete lifecycle exposure.

Final Engineering Principle

Packing material should survive not only production but also the methods used to keep the tower operational.

Maintenance chemistry and cleaning temperature belong in the design basis.