How to Specify Corrugation Geometry in Structured Packing Procurement

Corrugation geometry is one of the defining characteristics of structured packing.

Yet many purchase specifications identify only:

• packing type;
• nominal surface area;
• material.

That can leave a critical part of the packing construction uncontrolled.

For engineering procurement, corrugation geometry should be treated as part of the approved packing identity.

What Is Corrugation Geometry?

Structured packing sheets are formed into repeated corrugated channels.

Important geometric characteristics may include:

• corrugation height;
• corrugation pitch;
• channel width;
• corrugation angle;
• sheet thickness.

Together, these characteristics influence the internal flow passages through the packed bed.

Changing them can change the packing's hydraulic behavior.

Why Procurement Should Care

A supplier may manufacture a packing with the same nominal surface area but a different corrugation pattern.

The resulting product can still look similar from outside.

However, gas and liquid flow paths may not be identical.

For new designs, this can be acceptable if the supplier's packing is independently approved through process design.

For replacement service, uncontrolled changes may be unacceptable.

Corrugation Angle Needs Clear Wording

The corrugation angle is commonly described relative to the horizontal or vertical plane.

That creates a potential source of confusion.

For example, one party may say 45° from horizontal while another interprets the same geometry from vertical.

The procurement drawing should therefore show the reference direction rather than relying on a number alone.

A simple sketch can prevent a major manufacturing misunderstanding.

Define Critical Dimensions, Not Every Feature

A specification does not need to become a complete tooling drawing.

The objective is to identify the dimensions that preserve the approved geometry.

Typical controlled parameters might include:

• corrugation height;
• corrugation pitch;
• angle;
• sheet thickness.

Secondary forming details may remain under the manufacturer's control.

This balances technical control with practical manufacturing freedom.

Tolerance Must Be Realistic

Corrugated sheets are formed from thin metal or plastic material.

Some variation is inevitable.

The purchase specification should therefore define realistic dimensional tolerances where necessary.

Overly tight tolerances can increase cost without improving tower performance.

Too-loose requirements, on the other hand, may allow significant geometry changes.

The correct tolerance should reflect the manufacturing method and the engineering sensitivity of the project.

Compare Supplier Drawings Before Approval

When multiple suppliers quote a structured packing project, technical bid evaluation should include drawings rather than catalog names alone.

The buyer should compare:

• channel geometry;
• sheet thickness;
• surface features;
• perforations;
• element construction.

This is especially important when the offered product is described as “equivalent.”

Equivalent should mean technically reviewed, not simply commercially similar.

Production Inspection

Corrugation geometry can be checked during production using:

• dimensional measurement;
• templates;
• approved drawings;
• sample comparison.

For large projects, pre-production approval of a sample or drawing can reduce later disputes.

The final inspection does not need to re-engineer the packing.

It needs to confirm that production remains consistent with the approved construction.

Control Geometry Changes

A useful purchase requirement is:

Supplier shall not modify approved corrugation geometry without purchaser approval.

This is particularly valuable for repeat orders.

Tooling changes or manufacturing optimization can otherwise alter the product while the commercial designation remains unchanged.

Avoid Using Corrugation Geometry as a Stand-Alone Performance Guarantee

Like surface area, geometry supports hydraulic performance but does not independently guarantee tower performance.

Actual performance also depends on:

• liquid distribution;
• gas and liquid loads;
• fluid properties;
• tower condition;
• installation.

Therefore, geometry should be controlled as a product characteristic, while process guarantees should be handled separately.

Engineering Takeaway

Corrugation geometry is one of the key physical characteristics that defines structured packing.

Procurement teams should control the dimensions that preserve the approved design, use drawings to eliminate angle ambiguity, and require technical approval for significant geometry changes.