How to Replace an Obsolete Random Packing When the Original Brand Is No Longer Available
Industrial packed towers may operate for decades.
When replacement is finally required, the original packing supplier may no longer exist or the original product may have been discontinued.
The maintenance team then faces a common question:
Can another random packing be used as an equivalent replacement?
The answer is often yes, but “equivalent” should not mean merely “same nominal size.”
Start with the Existing Packing Function
The first question is what the original packing was required to achieve.
The replacement may need to preserve:
- mass-transfer performance;
- pressure drop;
- hydraulic capacity;
- corrosion resistance;
- fouling resistance;
- mechanical durability.
The importance of each factor depends on the process.
Nominal Size Is Not Enough
Two random packings labeled 25 mm may have very different:
- specific surface area;
- void fraction;
- geometry;
- bulk density;
- pressure drop.
Therefore, replacing a 25 mm packing with another 25 mm packing does not prove functional equivalence.
Collect Existing Packing Data
If the original datasheet is unavailable, useful information may come from:
- old purchase orders;
- maintenance records;
- photographs;
- physical samples;
- old vendor catalogues.
Measurements can include:
- diameter;
- height;
- wall thickness;
- material;
- piece weight.
Compare Hydraulic Characteristics
If the existing tower has operated successfully, the replacement should ideally provide similar or better hydraulic performance.
Important comparisons include:
- void fraction;
- pressure-drop tendency;
- flooding capacity;
- liquid holdup.
A replacement with substantially higher resistance may cause premature flooding.
Compare Mass-Transfer Characteristics
A packing with much lower effective area may reduce tower performance even if pressure drop improves.
The replacement should therefore be checked against the required separation duty.
This is especially important if the tower already operates near its performance limit.
Material Must Be Verified Separately
Geometry and material are two independent questions.
A geometrically similar packing made from the wrong polymer or metal grade may fail chemically.
Confirm:
- temperature;
- corrosive species;
- solvent exposure;
- material grade.
Support Compatibility Matters
A replacement packing may be smaller or shaped differently from the original.
If the existing support openings are too large, pieces may pass through.
Therefore, the support grid should be checked before changing packing family.
Do Not Promise “100% Equivalent” Without Data
Industrial replacement projects often use words such as:
- equivalent;
- interchangeable;
- alternative.
These should be used carefully.
A technically safer statement is:
“Proposed as a functional replacement subject to hydraulic and process verification.”
This reflects the actual engineering situation.
When a Different Geometry May Be Better
The objective does not always need to be exact duplication.
If the plant wants:
- lower pressure drop;
- higher capacity;
- better fouling resistance;
a newer geometry may be preferable.
But this becomes an upgrade project rather than a simple like-for-like replacement.
Final Engineering Principle
An obsolete packing can often be replaced successfully, but equivalence should be established from function and performance—not product name or nominal size alone.