Metal Intalox Saddle / IMTP-Type Replacement: What Must Be Matched Before Ordering?

Metal Intalox Saddle / IMTP-type packing replacement should not be specified only by nominal size, alloy and packed volume. A reliable like-for-like replacement should match the existing saddle geometry, actual dimensions, metal thickness, alloy grade, specific surface area, void fraction, dry bulk density, packing population, dry packing factor and packed-bed volume as closely as practical.

DAIER's representative Metal Intalox Saddle data cover approximately 15–70 mm size classes and show why exact model matching matters.

The series does not obey every intuitive size rule.

For example, moving from approximately 15 to 25 mm:

• packing population decreases sharply;
• specific surface area decreases;
• dry packing factor decreases;

but:

• void fraction decreases slightly;
• dry bulk density actually increases.

Therefore:

A larger metal saddle is not automatically lighter or more open per cubic meter.

For a tower that already performs correctly:

Routine replacement should reproduce the proven metal saddle geometry and physical bed specification as closely as practical.

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1. Direct Answer

Before ordering replacement Metal Intalox Saddle / IMTP-type packing, confirm:

• packing family;
• nominal size;
• actual element dimensions;
• metal thickness;
• alloy grade;
• specific surface area;
• void fraction;
• dry bulk density;
• pieces per cubic meter;
• dry packing factor;
• packed-bed volume;
• tower internal diameter;
• packed height;
• support-grid opening;
• support-grid condition;
• hold-down arrangement where applicable;
• reason for replacement.

For partial top-up:

Matching the existing element becomes especially important because the old and new packing will operate together in the same bed.

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2. Representative Metal Intalox Saddle Data

These values are taken from the catalog data used in DAIER's engineering reference set.

The table immediately shows that:

nominal size, sheet thickness, voidage, bed weight and hydraulic geometry must be evaluated separately.

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3. First Decide: Replacement or Retrofit?

Routine Replacement

The existing metal saddle bed already:

• meets process duty;
• has acceptable pressure drop;
• operates reliably;
• has acceptable corrosion life.

The objective is simply to restore the original tower.

Normally preserve:

• packing family;
• size;
• alloy;
• thickness;
• geometry;
• packed height;
• comparable physical properties.

Retrofit

The project intentionally wants to alter:

• capacity;
• pressure-drop position;
• mass-transfer area;
• corrosion resistance;
• fouling tolerance;
• packed-bed weight.

Then size, alloy or packing family may change.

That becomes:

an engineering retrofit rather than ordinary replacement.

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4. “50 mm SS316L Metal Intalox Saddle” Is Still Incomplete

A buyer may specify:

SS316L Metal Intalox Saddle, 50 mm, 20 m³.

This is a useful starting point.

But the representative 50 mm-class model is approximately:

• 48.5 × 28.6 × 0.5 mm;
• 97 m²/m³ surface area;
• 97.9% void fraction;
• 169 kg/m³ bulk density;
• 15,550 pcs/m³;
• 103.9 m⁻¹ dry packing factor. 

If another supplier's proposed 50 mm saddle differs substantially from those physical properties:

do not automatically treat it as like-for-like.

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5. Actual Dimensions Matter More Than the Rounded Size Label

Notice the catalog size labels and physical dimensions:

15 mm class

Actual main dimension:

16.5 mm

25 mm class

25.9 mm

40 mm class

35.4 mm

50 mm class

48.5 mm

60 mm class

67 mm

70 mm class

76.5 mm.

Therefore:

commercial nominal size and measured element dimension are not always identical.

This is particularly important when reverse-engineering old packing.

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6. Do Not Reject a Replacement Just Because Caliper Size Does Not Equal the Nominal Label

An old packing may be called:

40 mm Metal Intalox Saddle

while its measured principal dimension is around:

35.4 mm.

Likewise a nominal 70 mm-class element may measure roughly:

76.5 mm.

Therefore old packing identification should combine:

• catalog family;
• dimensions;
• thickness;
• geometry;
• physical data.

Do not use only:

one ruler measurement.

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7. Metal Thickness Is a Core Procurement Parameter

Representative metal thickness increases from:

• 15 mm — 0.3 mm;
• 25 mm — 0.4 mm;
• 40 mm — 0.4 mm;
• 50 mm — 0.5 mm;
• 60 mm — 0.5 mm;
• 70 mm — 0.5 mm. 

Thickness affects:

• metal consumption;
• mechanical stiffness;
• element durability;
• dry bulk density;
• quotation price.

Therefore:

same alloy + same nominal size does not automatically mean the same product.

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8. Why Two Supplier Prices Can Differ So Much

Suppose two suppliers quote:

50 mm SS316L Metal Saddle Packing.

One offers:

• 0.5 mm construction.

Another offers:

• a materially thinner geometry.

Their quotations may differ because they contain different:

kg of stainless steel per cubic meter.

Before concluding that one supplier is cheaper:

normalize the physical specification.

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9. 15 → 25 mm Produces a Counterintuitive Result

At 15 mm:

• 275 m²/m³;
• 96.7% void;
• 263 kg/m³;
• 324,110 pcs/m³;
• 304.9 m⁻¹.

At 25 mm:

• 199 m²/m³;
• 96.6% void;
• 266 kg/m³;
• 127,180 pcs/m³;
• 221.0 m⁻¹.

The packing becomes larger and the number of elements falls dramatically.

Yet:

dry bulk density increases.

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10. Packing Count Falls by About 61%

From 15 to 25 mm:

324,110 → 127,180 pcs/m³.

That is roughly:

61% fewer individual saddle elements.

Yet dry bulk density changes:

263 → 266 kg/m³.

So:

far fewer pieces do not necessarily mean less metal per cubic meter.

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11. Thickness Helps Explain the Weight Reversal

The representative thickness changes:

0.3 → 0.4 mm.

Therefore each larger 25 mm-class saddle contains more metal.

This is an important replacement lesson:

packing population and sheet thickness must be considered together.

Neither parameter alone predicts bed weight.

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12. Void Fraction Also Falls Slightly

The 15 → 25 mm transition changes:

96.7% → 96.6%.

The difference is small, but the direction matters.

The larger element is not automatically:

more void.

Therefore:

larger metal saddle = higher voidage

is not a valid universal rule.

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13. Surface Area Falls About 28%

Specific surface area changes:

275 → 199 m²/m³.

This is approximately:

28% less geometric area.

At the same time packing factor falls:

304.9 → 221.0 m⁻¹.

So the size increase trades:

contacting-area density for a lower dry-packing-factor position.

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14. 25 → 40 mm Behaves More Conventionally

At 25 mm:

• 199 m²/m³;
• 96.6% void;
• 266 kg/m³;
• 127,180 pcs/m³;
• 221.0 m⁻¹.

At 40 mm:

• 151 m²/m³;
• 97.4% void;
• 203 kg/m³;
• 51,180 pcs/m³;
• 163.2 m⁻¹.

The larger model provides:

• less area;
• higher voidage;
• lower bulk density;
• fewer elements;
• lower packing factor.

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15. Surface Area Falls About 24%

The transition:

199 → 151 m²/m³

reduces area by approximately:

24%.

This is large enough that a 40 mm model should not be substituted into a proven 25 mm bed without considering process duty.

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16. Dry Bed Weight Falls Significantly

Bulk density:

25 mm

266 kg/m³.

40 mm

203 kg/m³.

Difference:

63 kg/m³.

For a 20 m³ bed:

25 mm

5,320 kg.

40 mm

4,060 kg.

Difference:

approximately 1.26 tonnes.

This can be mechanically significant.

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17. 40 → 50 mm Produces a Strong Hydraulic-Area Trade-Off

At 40 mm:

• 151 m²/m³;
• 97.4% void;
• 203 kg/m³;
• 51,180 pcs/m³;
• 163.2 m⁻¹.

At 50 mm:

• 97 m²/m³;
• 97.9% void;
• 169 kg/m³;
• 15,550 pcs/m³;
• 103.9 m⁻¹.

This is not a minor size change.

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18. Surface Area Falls About 36%

The reduction is:

151 → 97 m²/m³.

That is approximately:

36% less geometric surface area.

So if an existing 40 mm saddle bed was selected because of:

• high contacting-area requirements;

moving to 50 mm may materially change process capability.

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19. Packing Factor Also Falls About 36%

Dry packing factor changes:

163.2 → 103.9 m⁻¹.

That is also approximately:

36% lower.

So the 40 → 50 mm transition represents a particularly clear trade-off:

much less area + much lower dry packing factor.

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20. Packing Factor Is Not Actual Pressure Drop

A 36% reduction in dry packing factor does not establish:

36% lower tower pressure drop.

Actual pressure drop depends on:

• vapor/gas velocity;
• liquid loading;
• fluid density;
• viscosity;
• packed height;
• tower diameter.

Packing factor should be treated as:

a geometry/hydraulic characterization parameter.

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21. Packing Population Drops by About 70%

From 40 to 50 mm:

51,180 → 15,550 pcs/m³.

That is roughly:

70% fewer packing elements.

Yet surface area falls by only about:

36%.

Again:

pieces/m³ are not a surface-area metric.

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22. 50 → 60 mm Is a Much Smaller Step

Compare:

50 mm

97 m²/m³97.9% void169 kg/m³15,550 pcs/m³103.9 m⁻¹.

60 mm

84 m²/m³98.2% void145 kg/m³9,000 pcs/m³88.4 m⁻¹.

Changes are much more moderate.

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23. Surface Area Falls About 13%

The change:

97 → 84 m²/m³

is approximately:

13% lower.

Packing factor falls:

103.9 → 88.4 m⁻¹

or approximately:

15%.

This makes 50 and 60 mm more closely positioned than:

• 40 and 50 mm.

But they are still not like-for-like.

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24. 60 → 70 mm Creates Another Significant Step

At 60 mm:

• 84 m²/m³;
• 98.2% void;
• 145 kg/m³;
• 9,000 pcs/m³;
• 88.4 m⁻¹.

At 70 mm:

• 61 m²/m³;
• 98.7% void;
• 106 kg/m³;
• 4,690 pcs/m³;
• 63.5 m⁻¹.

Here the larger saddle becomes:

• significantly lower in area;
• more void;
• lighter;
• lower in dry packing factor.

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25. Surface Area Falls About 27%

From:

84 → 61 m²/m³.

So changing 60 → 70 mm reduces geometric area by roughly:

27%.

At the same time packing factor falls by roughly:

28%.

This is again a significant geometry conversion.

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26. Large-Size Bed Weight Also Falls Strongly

Bulk density:

60 mm

145 kg/m³.

70 mm

106 kg/m³.

Difference:

39 kg/m³.

For a 30 m³ bed:

60 mm

4,350 kg.

70 mm

3,180 kg.

Difference:

approximately 1.17 tonnes.

That may be relevant in existing tower retrofits.

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27. Do Not Select the Largest Size Only for Low Packing Factor

The 70 mm-class model has the lowest verified dry packing factor in this series:

63.5 m⁻¹.

But it also has the lowest surface area:

61 m²/m³.

Therefore the right question is not:

Which size has the lowest packing factor?

It is:

Which size provides an acceptable balance of contacting area, hydraulics and tower-diameter suitability?

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28. Tower Diameter Must Be Checked Before Using Large Saddle Packing

As the saddle becomes large relative to tower ID:

• wall effects become more important;
• fewer elements span the cross-section.

Therefore large 60 or 70 mm-class saddle packing should not be selected solely from:

• low factor;
• high voidage.

Confirm:

tower internal diameter first.

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29. Alloy Grade Must Be Matched Separately

Metal saddle geometry does not determine corrosion resistance.

The existing packing may use:

• SS304;
• SS316L;
• another suitable alloy.

Material selection depends on:

• chemical species;
• concentration;
• temperature;
• chlorides;
• corrosion mechanism.

A geometrically equivalent product in the wrong alloy is:

not an equivalent replacement.

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30. Material Certificate Does Not Prove Geometry

A certificate can confirm:

stainless-steel chemistry.

It cannot confirm:

• dimensions;
• sheet thickness;
• surface area;
• void fraction;
• packing factor.

Replacement procurement therefore has two separate questions:

Is the material correct?

and

Is the packing geometry correct?

Both must be answered.

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31. Replacement Due to Corrosion Requires Root-Cause Review

If old saddle elements show:

• pitting;
• perforation;
• severe thinning;
• cracking related to corrosion;

do not automatically reorder the same alloy.

Review:

• process composition;
• chloride level;
• temperature;
• cleaning chemistry.

If the alloy is the problem:

perfect geometric matching alone will not solve the failure.

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32. Replacement Due to Deformation Requires Thickness Review

If existing saddles are:

• crushed;
• flattened;
• permanently bent;

investigate:

• original metal thickness;
• installation method;
• mechanical loading;
• support condition.

Do not select a thinner replacement simply because:

it is cheaper.

A thickness reduction changes both:

• mechanical behavior;
• physical bed specification.

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33. Be Careful Measuring Corroded Old Packing

If the original sheet was:

0.5 mm

but corrosion has removed material, field measurement may show:

0.35–0.4 mm.

That does not prove the original specification was thinner.

For reverse engineering, use:

• least-damaged elements;
• old drawings;
• purchase records;
• original datasheets

where available.

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34. Partial Top-Up Should Stay Close to the Existing Packing

If the project only needs:

• 0.5 m³;
• 1 m³;
• several m³

of topping-up material, generally match:

• size;
• alloy;
• thickness;
• saddle geometry.

Do not introduce a new size simply because it is in stock.

Top-up is normally:

maintenance—not optimization.

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35. Do Not Accidentally Mix 40 and 50 mm Saddles

The two models differ strongly in:

• surface area;
• packing population;
• bulk density;
• packing factor.

An accidental mixed bed can create:

• segregation;
• non-uniform local packing structure.

If multiple sizes are intentionally used:

the arrangement should be engineered deliberately.

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36. Packed Volume Should Be the Main Order Quantity

For a cylindrical tower:

V = πD²/4 × H

where:

• D = internal diameter;
• H = packed height.

Once volume is known, theoretical clean packing mass can be checked with:

V × catalog bulk density.

This is much more reliable than ordering solely from the old tower's removed weight.

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37. Removed Packing Weight May Be Misleading

Old metal packing can contain:

• retained liquid;
• scale;
• crystals;
• corrosion products;
• process solids.

Therefore:

field weight is not necessarily clean dry packing weight.

Reconstruct the requirement from:

• tower ID;
• packed height;
• verified bulk density.

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38. Support Grid Compatibility Must Be Checked

For a true like-for-like replacement, support retention may already be proven.

Still inspect:

• corrosion;
• deformation;
• support beams;
• blocked areas.

If packing size changes, also check:

• grid opening;
• smallest element dimension;
• packing retention.

Changing random packing can therefore affect:

tower internals as well as packing.

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39. Hold-Down or Bed Limiter Should Be Inspected

Depending on tower orientation and operating gas velocity, an upper packing restraint may be installed.

Its role is:

to restrain excessive packing movement.

It should not be designed to:

compress the random packing bed.

A replacement shutdown is a good opportunity to inspect this component.

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40. Existing Packed Height Should Normally Remain for Routine Replacement

If a 50 mm Metal Intalox Saddle bed already performs correctly:

same size + comparable geometry + same packed height

generally introduces less uncertainty.

If changing to:

• 40 mm;
• 60 mm;
• Pall Ring;
• Nutter Ring;
• another geometry,

the old packed height should not automatically be assumed suitable.

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41. Keep Old Packing Samples When Documentation Is Missing

Retain several intact elements and record:

• main dimensions;
• saddle height;
• metal thickness;
• visible geometry.

Photograph:

• front;
• side;
• top.

If alloy identity is uncertain, appropriate material verification may also be required.

One sample alone may be:

• deformed;
• corroded;
• unrepresentative.

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42. Supplier Quotations Should Be Technically Normalized

Use a comparison such as:

Only then compare:

USD/m³.

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43. Compare kg/m³ as Well as Price

For metal packing, a lower quotation can sometimes reflect:

• thinner construction;
• lower metal consumption;
• different geometry.

Therefore compare:

alloy + thickness + kg/m³ + physical specification + price.

A lower-metal-content option may still be suitable.

But it should be:

consciously approved—not mistaken for the same packing at a lower price.

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44. A Replacement RFQ Should Include the Reason for Replacement

This field is often overlooked.

Examples:

Normal service-life replacement

Match the old specification.

Corrosion

Review alloy.

Deformation

Review thickness and mechanical condition.

Excessive pressure drop

Review actual hydraulics.

Fouling

Review deposits, size and distribution.

Process capacity increase

Treat as retrofit.

The reason for replacement determines:

whether preserving or changing the old packing is the right objective.

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Metal Intalox Saddle Replacement Checklist

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45. Quick Replacement Logic

Existing Metal Intalox Saddle bed works correctly

Specify:

same packing family + same alloy + same size + same thickness + closely matched physical data.

Existing elements are corroded

Review:

chemistry + temperature + alloy selection.

Existing elements are deformed

Review:

sheet thickness + support + mechanical handling.

Existing pressure drop is too high

Do not simply choose the largest available saddle.

Review:

tower ID + required contacting area + gas/liquid loads + allowable ΔP.

Supplier proposes Pall Ring, Nutter Ring or another packing

Treat it as:

a packing-family retrofit.

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Common Replacement Mistakes

Ordering Only “50 mm SS316L Metal Intalox Saddle”

Actual dimensions and thickness are still missing.

Assuming Nominal Size Equals Measured Diameter

The catalog size class and physical dimensions may differ.

Assuming Larger Saddle Always Has Higher Voidage

15→25 mm decreases slightly from 96.7% to 96.6%.

Assuming Larger Saddle Always Has Lower Bulk Density

15→25 mm increases from 263 to 266 kg/m³.

Assuming Fewer Elements Means Less Metal

The 15→25 mm count falls by about 61%, yet bulk density increases.

Ignoring Metal Thickness

The same transition increases thickness from 0.3 to 0.4 mm.

Selecting the Largest Size Only Because Packing Factor Is Lower

Geometric surface area also falls substantially.

Treating Packing Factor as Actual Pressure Drop

Real operating conditions are required.

Measuring Corroded Thickness as Original Thickness

Metal loss can distort the result.

Changing Packing Size During a Routine Top-Up

This creates an unintended mixed bed.

Comparing Price Before Normalizing Physical Specification

The quotations may not represent the same packed bed.

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Frequently Asked Questions

What must be matched when replacing Metal Intalox Saddle?

Match the alloy, nominal size, actual saddle dimensions, sheet thickness, surface area, void fraction, dry bulk density, packing population and dry packing factor as closely as practical.

What size range is represented in the catalog data used here?

Approximately:

15, 25, 40, 50, 60 and 70 mm classes.

What is the 25 mm specification?

Approximately:

• 25.9 × 12.6 × 0.4 mm;
• 199 m²/m³;
• 96.6% void;
• 266 kg/m³;
• 127,180 pcs/m³;
• 221.0 m⁻¹.

What is unusual about 15 vs 25 mm?

Despite the larger size and much lower packing population, the 25 mm model is slightly heavier per cubic meter:

266 vs 263 kg/m³

and slightly lower in void fraction:

96.6% vs 96.7%.

Why?

One contributing specification change is sheet thickness:

0.3 → 0.4 mm.

What is the 40 mm-class specification?

Approximately:

• 35.4 × 18.8 × 0.4 mm;
• 151 m²/m³;
• 97.4% void;
• 203 kg/m³;
• 51,180 pcs/m³;
• 163.2 m⁻¹.

What is the 50 mm-class specification?

Approximately:

• 48.5 × 28.6 × 0.5 mm;
• 97 m²/m³;
• 97.9% void;
• 169 kg/m³;
• 15,550 pcs/m³;
• 103.9 m⁻¹.

What is the 60 mm-class specification?

Approximately:

• 67 × 37 × 0.5 mm;
• 84 m²/m³;
• 98.2% void;
• 145 kg/m³;
• 9,000 pcs/m³;
• 88.4 m⁻¹.

What is the 70 mm-class specification?

Approximately:

• 76.5 × 42.5 × 0.5 mm;
• 61 m²/m³;
• 98.7% void;
• 106 kg/m³;
• 4,690 pcs/m³;
• 63.5 m⁻¹.

Can 50 mm directly replace 40 mm Metal Intalox Saddle?

Do not treat that as like-for-like. Surface area falls from approximately 151 to 97 m²/m³, while dry packing factor also falls substantially.

Can Metal Pall Ring directly replace Metal Intalox Saddle?

It can be evaluated as an alternative packing geometry, but that is a retrofit rather than routine replacement.

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Selection Takeaway

Metal Intalox Saddle / IMTP-type replacement requires exact geometry and thickness matching because nominal size does not reliably predict void fraction, dry bed weight or hydraulic position.

Representative catalog data show:

15 mm class → 16.5 × 10.6 × 0.3 mm / 275 m²/m³ / 96.7% void / 263 kg/m³ / 324,110 pcs/m³ / 304.9 m⁻¹

25 mm class → 25.9 × 12.6 × 0.4 mm / 199 m²/m³ / 96.6% void / 266 kg/m³ / 127,180 pcs/m³ / 221.0 m⁻¹

40 mm class → 35.4 × 18.8 × 0.4 mm / 151 m²/m³ / 97.4% void / 203 kg/m³ / 51,180 pcs/m³ / 163.2 m⁻¹

50 mm class → 48.5 × 28.6 × 0.5 mm / 97 m²/m³ / 97.9% void / 169 kg/m³ / 15,550 pcs/m³ / 103.9 m⁻¹

60 mm class → 67 × 37 × 0.5 mm / 84 m²/m³ / 98.2% void / 145 kg/m³ / 9,000 pcs/m³ / 88.4 m⁻¹

70 mm class → 76.5 × 42.5 × 0.5 mm / 61 m²/m³ / 98.7% void / 106 kg/m³ / 4,690 pcs/m³ / 63.5 m⁻¹.

The 15 → 25 mm transition is particularly important:

• size increases;
• packing population falls by about 61%;
• dry packing factor falls substantially;

yet:

• void fraction decreases slightly;
• dry bulk density rises;
• sheet thickness increases.

Therefore:

neither nominal size nor packing population can be used to infer bed weight or openness.

The correct replacement workflow is:

Identify Existing Metal Saddle → Confirm Alloy → Measure Actual Geometry → Measure / Verify Thickness → Match Surface Area / Voidage / Bulk Density / Packing Population / Packing Factor → Confirm Tower ID and Packed Height → Inspect Support / Hold-Down → Review Corrosion or Deformation → Calculate Required Packed Volume → Normalize Supplier Quotations → Decide Like-for-Like vs Retrofit

The key principle is:

For routine Metal Intalox Saddle / IMTP-type replacement, reproduce the proven alloy, saddle geometry, sheet thickness and packed-bed properties as closely as practical. If size, thickness, alloy or packing family changes materially, treat the proposal as an engineering retrofit rather than a purchasing substitution.