Pingxiang Daier Separation Tech Aug 29, 2026

Can Ceramic Pall Rings Be Replaced with Metal Pall Rings in an Existing Tower?

Ceramic Pall Rings can sometimes be replaced with Metal Pall Rings in an existing tower, but the change should not be treated as a direct material substitution simply because the nominal packing size is the same. A 50 mm Ceramic Pall Ring and a 50 mm Metal Pall Ring can have different geometry, specific surface area, void fraction, bulk density and hydraulic characteristics.

Before conversion, the existing tower should be reviewed for:

process chemistry;
temperature;
existing packing size;
actual packed height;
gas and liquid loads;
pressure-drop requirement;
support-grid compatibility;
liquid distribution;
reason for replacing the ceramic packing.

The key retrofit question is:

Will the proposed Metal Pall Ring maintain the required process performance and hydraulic operating margin while remaining compatible with the process chemistry?

The correct replacement sequence is:

Identify Existing Bed → Confirm Why It Is Being Replaced → Verify Metal Compatibility → Compare Packing Geometry → Review Hydraulics → Check Packed Height → Check Tower Internals → Approve Replacement

1. Same Nominal Size Does Not Mean Equivalent Packing

One of the most common replacement assumptions is:

Existing packing = 50 mm Ceramic Pall RingNew packing = 50 mm Metal Pall RingTherefore the replacement is equivalent.

That conclusion is not reliable.

Nominal size identifies the approximate packing dimension.

It does not guarantee identical:

wall structure;
internal tabs;
openings;
surface area;
void fraction;
packing factor;
bulk density.

The material change often comes with a geometry change as well.

Therefore:

50 mm ceramic and 50 mm metal should be treated as two different packing products until their technical data are compared.

2. Why Would a Plant Consider Replacing Ceramic Pall Rings with Metal Pall Rings?

Typical reasons may include:

excessive ceramic breakage;
difficult handling during maintenance;
desire to reduce packed-bed weight;
need for greater hydraulic openness;
planned throughput increase;
changes in operating conditions;
limited availability of the original ceramic product;
preference for a stainless-steel packing specification.

These are valid reasons to investigate the conversion.

But none automatically proves that Metal Pall Ring is the correct replacement.

3. First Determine Why the Existing Ceramic Packing Is Being Replaced

The replacement decision should begin with the failure or operational problem.

Ask:

What exactly is wrong with the current ceramic bed?

Possible answers include:

packing is broken;
pressure drop is too high;
tower capacity is insufficient;
fouling is severe;
corrosion conditions have changed;
maintenance handling is difficult;
original packing has simply reached end of life.

Each reason leads to a different replacement decision.

4. Ceramic Breakage Does Not Automatically Mean Metal Is Required

If the ceramic packing is heavily broken, identify why.

Possible causes include:

excessive installation drop height;
maintenance impact;
poor support condition;
abnormal tower vibration;
thermal shock;
severe operating events.

Metal packing may be mechanically more tolerant of impact, but replacing the packing without correcting the underlying problem can leave the tower with another unresolved failure mechanism.

5. High Pressure Drop Does Not Automatically Mean “Change Ceramic to Metal”

Pressure drop can result from:

packing geometry;
small packing size;
excessive gas velocity;
high liquid loading;
fouling;
broken ceramic fragments;
poor distribution.

Metal Pall Ring may provide a more open geometry in some cases.

But the correct question is:

Is the existing pressure-drop problem caused by the ceramic material, or by the current packed-bed design and operating condition?

Material alone is rarely enough to answer that question.

6. Chemical Compatibility Must Be Rechecked from the Beginning

This is one of the most important retrofit checks.

A process that is compatible with ceramic may not be compatible with:

SS304;
SS316L;
another metal alloy.

Ceramic may originally have been selected because the tower handles a highly corrosive stream.

Changing the packing material can therefore solve a mechanical problem while creating a corrosion problem.

7. Ceramic Compatibility Does Not Prove SS316L Compatibility

A common shortcut is:

Ceramic works in the chemical, so SS316L should also work.

That is not valid.

SS316L provides good corrosion resistance in many industrial environments, but it is not universally resistant to:

strong acids;
chloride-containing environments;
aggressive oxidizing conditions;
unusual chemical mixtures.

The metal grade should be selected from the actual chemistry.

8. Check the Complete Process Chemistry

Before proposing Metal Pall Rings, confirm:

chemical species;
concentrations;
operating temperature;
gas composition;
liquid composition;
chlorides where relevant;
contaminants;
cleaning chemicals;
upset conditions.

Do not select stainless steel using only:

pH;
the main chemical name.

Material compatibility is application-specific.

9. The Existing Ceramic Material May Reveal Why Metal Was Avoided Originally

If the original tower was deliberately designed with ceramic packing, ask:

Why was ceramic selected in the first place?

Possible reasons include:

high operating temperature;
acid resistance;
metal-corrosion concerns;
historical plant experience.

Understanding the original design basis can prevent an inappropriate material conversion.

10. Metal May Become Suitable If the Process Has Changed

The opposite can also happen.

The process may now operate under:

lower temperature;
different chemistry;
reduced corrosiveness.

If the original reason for ceramic no longer exists, Metal Pall Ring may become a reasonable retrofit candidate.

Existing material should therefore be treated as historical evidence, not an unchangeable rule.

11. Bulk Density Should Be Compared

Ceramic and Metal Pall Rings can have very different bulk densities.

This affects:

total dry bed weight;
support load;
freight;
installation handling.

In many cases, switching from ceramic packing to an open thin-wall metal design may reduce bed weight.

But this should be confirmed using the actual:

kg/m³

of both products.

Do not rely on material names alone.

12. Lower Packing Weight Can Be an Important Retrofit Advantage

If the Metal Pall Ring bed is significantly lighter, the conversion may reduce load on:

packing support grid;
support beams;
tower support ring.

This can be attractive in older towers where structural margin is limited.

However:

A lighter bed does not automatically mean better process performance.

Mechanical advantage and separation performance must both be evaluated.

13. Existing Support Capacity Should Still Be Checked

Even if the new Metal Pall Ring is lighter, inspect the existing support system.

Look for:

corrosion;
deformation;
damaged beams;
blocked openings;
broken ceramic fragments.

An old support grid may need repair regardless of the new packing weight.

Packing replacement is a useful opportunity to inspect the internals that normally remain hidden beneath the bed.

14. Support-Grid Opening Size Must Be Compatible

Suppose both products are sold as:

50 mm Pall Ring

Their actual geometry may still differ.

The new metal packing should not:

pass through support openings;
become trapped in openings;
create unstable seating.

Confirm:

actual packing dimensions;
support-grid opening size;
retaining arrangement.

This is especially important when changing packing size at the same time as material.

15. The Bed Limiter or Hold-Down Arrangement Should Be Reviewed

Ceramic and metal packings may have different:

weight;
movement behavior;
mechanical resilience.

Therefore, the existing top restraint should be checked.

A hold-down device should prevent undesirable bed movement where required.

It should not unnecessarily compress the random packing bed.

16. Specific Surface Area May Change

Even with the same nominal size, ceramic and metal Pall Rings can provide different:

geometric surface areas;
usable surface structures.

This can affect mass-transfer potential.

Therefore, replacing:

50 mm Ceramic Pall Ring

with:

50 mm Metal Pall Ring

does not automatically preserve the same:

absorption performance;
stripping performance;
separation performance.

Compare actual product data.

17. Void Fraction May Change

Metal Pall Rings are often manufactured from relatively thin sheet with open windows.

Depending on the design, they may provide a highly open bed.

Ceramic Pall Ring geometry can be substantially different because ceramic manufacturing requires a different structural form.

Therefore, the replacement can change:

bed openness;
gas-flow paths;
liquid drainage.

That can influence hydraulic behavior.

18. Pressure Drop May Change

A metal replacement may reduce pressure-drop tendency if the selected product provides a more open geometry.

But this should be stated carefully:

Metal Pall Ring does not automatically have a guaranteed lower operating pressure drop simply because it is metal.

Actual pressure drop depends on:

packing design;
packing size;
gas load;
liquid load;
fluid properties;
packed height.

The retrofit requires hydraulic evaluation.

19. Capacity May Change

A more open packing can potentially provide greater hydraulic capacity.

This may be useful when the plant wants to:

increase throughput;
recover operating margin;
reduce approach to flooding.

However, higher capacity may come with a different mass-transfer trade-off.

Therefore:

Capacity improvement should not be evaluated independently from process performance.

20. Flooding Margin Should Be Re-Evaluated

Changing packing changes the hydraulic characteristics of the bed.

Therefore, the previous operating margin cannot simply be assumed to remain unchanged.

The new packing should be evaluated against:

normal gas load;
maximum gas load;
liquid circulation;
expected turndown and peak operation.

The detailed calculation belongs to project-specific hydraulic evaluation rather than simple product substitution.

21. Liquid Holdup Can Also Change

Different random packing geometries can retain different amounts of liquid during operation.

Liquid holdup can influence:

hydraulic resistance;
bed weight;
process response.

Therefore, dry-product comparisons alone do not describe the complete operating bed.

22. Same Packed Height Does Not Guarantee Same Process Performance

This is one of the most important retrofit principles.

Suppose the existing tower has:

3,000 mm ceramic packing height

and the plant installs:

3,000 mm Metal Pall Ring.

That does not automatically mean the tower will provide the same:

absorption;
stripping;
distillation

performance.

The new product may have different mass-transfer characteristics.

Therefore:

Same tower + same bed height + same nominal size does not guarantee equivalent duty.

23. Packed Height May Need to Be Reconfirmed

If the Metal Pall Ring provides different effective contacting performance, engineers may need to assess whether the existing packed height remains sufficient.

Possible outcomes include:

same height remains acceptable;
less height could theoretically be required;
more height may be required;
another packing geometry may be preferable.

Do not change bed height solely from generic product claims.

24. Do Not Assume Metal Is Always More Efficient

Metal construction allows thin-wall, open packing designs.

That can be advantageous.

But “metal” itself does not create mass-transfer efficiency.

Actual performance still depends on:

geometry;
size;
wetting;
liquid distribution;
process conditions.

A poorly selected Metal Pall Ring can still perform worse than a correctly selected ceramic bed.

25. Liquid Distributor Suitability Should Be Reviewed

Changing packing material does not automatically require a new liquid distributor.

However, the distributor should be reviewed if:

packing size changes;
bed configuration changes;
liquid-load range changes;
the original tower already has maldistribution problems.

The goal is to verify that the new packing will receive reasonably uniform liquid distribution.

26. A Packing Upgrade Cannot Fix a Bad Distributor by Itself

If the existing tower suffers from:

poor irrigation;
dry zones;
wall flow;

simply changing Ceramic Pall Rings to Metal Pall Rings may not solve the underlying problem.

The new packing may still be poorly utilized.

Therefore:

Packing retrofit and liquid-distribution condition should be evaluated together.

27. Gas Distribution May Also Matter

In larger or more demanding towers, non-uniform gas entry can affect bed utilization.

If the old tower already shows:

channeling;
uneven pressure drop;
localized damage;

the inlet and lower internals should also be reviewed during the retrofit.

A more advanced packing cannot fully compensate for severe gas maldistribution.

28. Fouling Behavior May Change

The more open geometry of some Metal Pall Rings may improve tolerance to:

deposits;
solids;
scale.

However, metal packing is not fouling-proof.

If the process strongly generates deposits, consider:

packing size;
opening size;
cleaning strategy;
solids control.

The correct retrofit may involve more than changing the packing material.

29. Broken Ceramic Fragments Should Be Completely Removed

When old ceramic packing has fractured, small pieces can accumulate:

on the support grid;
inside support openings;
in lower internals.

Before installing the new metal bed, the tower should be cleaned and inspected.

Leaving old fragments underneath a new open packing bed can restrict:

gas flow;
liquid drainage.

30. Do Not Simply Pour Metal Packing on Top of Remaining Ceramic Fragments

A partial uncontrolled bed can create:

uneven density;
irregular hydraulic resistance;
poor flow distribution.

If the conversion is intended as a complete replacement, the old ceramic bed should normally be removed according to the approved maintenance plan before installing the new product.

31. Partial Replacement Requires a Defined Engineering Reason

Some projects may intentionally retain one packing section and replace another.

For example:

lower ceramic bed remains;
upper bed changes to metal.

This can be technically possible if the tower has separate defined beds.

But the interface should be supported by appropriate:

support;
collection;
redistribution

where required.

This is different from casually mixing old ceramic and new metal packing.

32. Ceramic and Metal Pall Rings Should Not Be Randomly Mixed

Uncontrolled mixing is not a reliable way to obtain:

“the chemical resistance of ceramic plus the efficiency of metal.”

Different:

weights;
geometries;
sizes

can create an unpredictable bed structure.

For a retrofit, each bed should have a defined product specification.

33. Existing Tower Diameter Must Be Included in the Evaluation

Packing size should be appropriate for:

tower internal diameter.

If the retrofit also changes nominal packing size, wall effects and bed structure can change.

For example, switching from:

smaller ceramic packing

to:

substantially larger metal packing

may improve hydraulic openness but may be inappropriate in a relatively small column.

34. Replacement Quantity Should Be Based on Actual Bed Volume

If the tower geometry and bed height remain unchanged, the required packing volume is approximately determined by:

Tower Cross-Sectional Area × Packed Height

The new packing should therefore normally be purchased on a volume basis.

Do not order the same kilograms of Metal Pall Ring as the old ceramic packing.

Their bulk densities can be very different.

35. Same Weight Would Usually Produce the Wrong Bed Volume

Suppose the old ceramic bed weighed several tonnes.

If Metal Pall Rings have a lower bulk density, purchasing the same weight could provide substantially more packing volume than the tower requires.

Therefore:

Replacement quantity should begin with m³, not old packing weight.

Weight is then estimated from the new product's bulk density.

36. Freight Can Change Significantly

A lighter metal bed can reduce shipment weight relative to some ceramic alternatives.

However, metal packing also needs appropriate:

packaging;
volume planning;
corrosion protection where relevant.

Final freight should be calculated from actual:

package volume;
gross weight.

37. Handling May Become Easier

Metal Pall Rings are generally less brittle than ceramic random packing.

This can make:

transport;
unloading;
installation;
maintenance

less sensitive to impact breakage.

That can be a practical reason to consider conversion in towers that require repeated maintenance.

But mechanical convenience must not override chemical compatibility.

38. Metal Packing Can Deform Instead of Fracture

Ceramic and metal have different failure behavior.

Ceramic tends to be brittle.

Thin metal packing may instead:

bend;
crush;
deform

under excessive mechanical load.

Therefore:

Replacing brittle failure with deformable material does not eliminate mechanical design requirements.

The bed should still be protected from abnormal compression.

39. Metal Grade Must Be Defined

Do not specify only:

Metal Pall Ring

for a corrosion-sensitive retrofit.

Specify the intended material, such as:

SS304;
SS316L;
another approved alloy.

The appropriate grade should be determined before quotation comparison.

40. SS304 and SS316L Are Not Interchangeable Material Labels

If the project requires SS316L, an SS304 quotation is not a direct equivalent.

Conversely, if SS304 is fully compatible, using SS316L may add cost without improving the process hydraulics.

Material grade should be justified by:

chemistry;
service-life requirement.

41. Material Documentation May Need to Be Updated

A ceramic packing specification and a stainless-steel packing specification require different documentation.

Depending on the project, the retrofit RFQ may request:

material grade;
material certificate;
certificate of conformity;
PMI where justified.

Requirements should be established before production.

42. Existing Ceramic Specifications Are Still Valuable

Before requesting a replacement quotation, collect:

old packing datasheet;
purchase record;
tower drawing;
bed height;
old ceramic size;
bulk density if available;
operating history.

This gives the supplier or engineer a real comparison basis.

“Please replace our ceramic packing with metal packing” is not enough information for a serious retrofit review.

43. Photos of the Removed Packing Can Be Useful

Photographs can help show:

exact packing geometry;
breakage;
fouling;
scale;
corrosion of supports.

If the original product name is unknown, dimensions and photos can help identify the existing packing family.

However, photos cannot replace operating data.

44. Measure the Actual Existing Packing

Older plant documentation is not always accurate.

During shutdown, it may be useful to confirm:

approximate diameter;
height;
geometry;
condition.

This can prevent a replacement quotation from being based on an incorrect historical description.

45. Retrofit Should Not Be Driven Only by Unit Price

Suppose Metal Pall Ring costs more per cubic meter than the existing ceramic product.

That does not automatically make it a worse option.

Potential lifecycle factors include:

reduced breakage;
easier maintenance;
lower bed weight;
hydraulic performance;
expected service life.

Conversely, a cheaper metal option that corrodes rapidly can be far more expensive in operation.

46. Compare Lifecycle Cost

A meaningful retrofit comparison can include:

Packing Cost

Freight

Installation

Support Modifications

Operating Energy

Maintenance

Expected Replacement Interval

The cheapest packing at purchase is not necessarily the lowest-cost packing over the tower lifecycle.

47. When Metal Pall Ring May Be a Strong Retrofit Candidate

Metal Pall Ring deserves stronger consideration when:

process chemistry is compatible with the selected alloy;
existing ceramic suffers repeated mechanical breakage;
reduced bed weight is valuable;
increased hydraulic openness is desired;
maintenance handling needs improvement;
existing tower geometry can accommodate the proposed packing.

These conditions make the conversion worth engineering evaluation.

48. When the Existing Ceramic Pall Ring Should Probably Be Retained

Ceramic may remain the stronger candidate when:

process chemistry is highly corrosive to practical metal options;
high temperature favors ceramic;
existing ceramic bed performs reliably;
the only motivation for replacement is a minor initial-price difference.

Do not remove a technically successful ceramic packing simply because another material is available.

49. When Another Packing Type Should Be Evaluated Instead

Sometimes neither:

existing Ceramic Pall Ring;
proposed Metal Pall Ring

is the best answer.

If the real project problem is:

very low pressure-drop requirement;
demanding separation efficiency;
severe fouling;
extreme corrosion;

other options may deserve consideration, including:

another random packing geometry;
structured packing;
plastic packing;
specialty alloy packing;
another ceramic geometry.

Retrofit work should solve the real constraint rather than force a predetermined material change.

50. Ceramic-to-Metal Retrofit Decision Table

Retrofit Question

Why It Matters

Is the process compatible with the proposed metal alloy?

Prevents corrosion-driven replacement failure

Is the nominal size the same?

Useful starting point, but not proof of equivalence

Are surface area and geometry equivalent?

Affects mass-transfer potential

Is void fraction different?

May affect hydraulic behavior

Is bulk density different?

Changes bed and support load

Will pressure drop change?

Affects operating margin

Is existing packed height still adequate?

Same height may not provide same duty

Is the support grid compatible?

Prevents packing retention problems

Is liquid distribution adequate?

New packing still needs proper irrigation

Why did the old ceramic bed fail?

Prevents repeating the real root cause

51. Common Mistake 1: “Same 50 mm Size Means Direct Replacement”

False.

Nominal size alone does not define hydraulic or mass-transfer equivalence.

52. Common Mistake 2: “SS316L Is Safe Wherever Ceramic Was Used”

False.

Chemical compatibility must be independently verified.

53. Common Mistake 3: “Metal Always Has Lower Pressure Drop”

Not universally.

Actual geometry and operating conditions determine pressure drop.

54. Common Mistake 4: “Same Bed Height Means Same Efficiency”

Not necessarily.

Changing packing changes the mass-transfer characteristics of the bed.

55. Common Mistake 5: Ordering the Same Weight as the Old Ceramic Packing

Replacement quantity should normally be based on required packed volume.

56. Common Mistake 6: Ignoring the Support Grid

Different packing dimensions or geometry may require changes to the retaining/support arrangement.

57. Common Mistake 7: Changing Packing Without Inspecting the Distributor

If poor distribution caused the old tower problem, new packing alone may not fix it.

58. Common Mistake 8: Replacing Ceramic Because It Is Broken Without Finding Out Why

Installation, support, vibration or thermal shock may be the real root cause.

59. What Information Should Be Provided for a Ceramic-to-Metal Replacement RFQ?

Existing Packing

Provide:

product type;
material;
nominal size;
actual dimensions if known;
old datasheet if available.

Tower Geometry

Provide:

tower internal diameter;
current packed height;
number of packed beds.

Process Chemistry

Provide:

gas composition;
liquid composition;
concentrations;
contaminants;
chlorides where relevant.

Operating Conditions

Provide:

gas flow;
liquid flow;
pressure;
normal temperature;
maximum temperature.

Existing Performance

Provide:

current pressure drop if available;
process performance;
known capacity limitation.

Replacement Reason

Explain whether the main problem is:

breakage;
corrosion;
fouling;
pressure drop;
capacity;
maintenance.

Tower Internals

Provide information about:

support grid;
hold-down/bed limiter;
liquid distributor;
redistributor where present.

This information allows the proposed Metal Pall Ring to be evaluated as an actual retrofit rather than a simple product substitution.

For projects where hydraulic performance must be screened after the packing change, operating data can also be evaluated separately through the DAIER Tower Packing Engineering Assistant:

https://www.pxdaier.com/tower-packing-engineering-assistant.html

Frequently Asked Questions

Can 50 mm Ceramic Pall Rings be directly replaced with 50 mm Metal Pall Rings?

Not automatically.

The nominal size may be similar, but geometry, surface area, void fraction, bulk density and hydraulic behavior can differ.

Will Metal Pall Rings reduce pressure drop compared with ceramic packing?

They may in some cases if the proposed metal geometry is more open, but actual pressure drop must be evaluated using the specific packing and operating loads.

Will Metal Pall Rings improve tower efficiency?

Not simply because they are metal.

Efficiency depends on packing geometry, size, wetting, distribution and process conditions.

Can SS316L Pall Rings replace ceramic packing in acid service?

Possibly, but only if SS316L is compatible with the specific acid, concentration, temperature and contaminants.

Ceramic compatibility does not prove SS316L compatibility.

Do I need to change packed height?

Maybe.

The existing height should be reviewed because the new packing may have different mass-transfer performance.

Do I need to change the support grid?

Not necessarily.

But the support opening, structural condition and compatibility with the new packing dimensions should be checked.

Do I need a new liquid distributor?

Not automatically.

The existing distributor may remain suitable, but its condition and performance should be reviewed during the retrofit.

Can ceramic and metal Pall Rings be mixed in one packed bed?

Uncontrolled mixing is generally not recommended because it creates an undefined bed structure.

Should I order the same kilograms of metal packing as the old ceramic packing?

No.

Determine the required packed volume first because ceramic and metal Pall Rings may have very different bulk densities.

What is the most important information for a replacement quotation?

At minimum, provide:

existing packing;
tower diameter;
packed height;
chemistry;
temperature;
gas/liquid loads;
reason for replacement.

Replacement Takeaway

Ceramic Pall Rings can be replaced with Metal Pall Rings in some existing towers, but the conversion is an engineering retrofit—not a simple material swap.

The correct decision path is:

Why Is the Ceramic Bed Being Replaced?

↓

Can the Proposed Metal Alloy Survive the Chemistry?

↓

How Do the Two Packing Geometries Compare?

↓

Will Hydraulic Performance Change?

↓

Will Existing Packed Height Still Meet the Process Duty?

↓

Are the Support Grid and Distribution Internals Compatible?

↓

Does the Retrofit Create a Better Lifecycle Result?

The most important rule is:

Same nominal packing size does not mean equivalent packed-bed performance.

Before changing from Ceramic Pall Rings to Metal Pall Rings, compare the actual product data and evaluate the existing tower under its real operating conditions.