Packing Support Design in Brick-Lined and Rubber-Lined Towers

Packing supports in brick-lined or rubber-lined towers require a different design approach from supports installed directly against a bare metal shell.

The corrosion-resistant lining protects the vessel but is usually not intended to carry concentrated structural loads. It may also be damaged by field welding, sharp support edges, excessive clamping force or differential thermal movement.

The packing load must be transferred safely to the vessel structure without breaking the continuity of the corrosion barrier.

Do Not Treat the Lining as a Structural Support

Acid-resistant brick, mortar and rubber lining perform important protective functions, but they should not automatically be treated as extensions of the steel shell.

A support beam placed directly on brickwork can create high local compression. The brick may crack, the mortar joint may fail or the lining may separate from the shell.

Rubber lining presents a different problem. It can deform under sustained bearing pressure and may be cut by sharp metal edges. A support resting on the rubber can move as the lining compresses, leaving the grid uneven.

The support load should therefore pass into engineered structural attachments connected to the vessel shell or another verified load-bearing structure.

Design the Load Path Before Applying the Lining

The best time to determine support locations is during vessel mechanical design, before lining installation begins.

Possible load-transfer arrangements include:

Shell-mounted support rings

Welded clips or brackets

Supported internal frames

Flanged internal connections

Engineered ledges with corrosion protection

Nozzle-supported structures where mechanically justified

The exact arrangement depends on tower diameter, lining system, process chemistry, temperature and packed-bed load.

Attachments that require shell welding should normally be installed, inspected and tested before rubber or brick lining is applied. Later welding can burn rubber, damage bonding layers, crack brickwork or create an unprotected heat-affected area.

Maintain the Corrosion Barrier Around Attachments

A structural attachment passing through or interrupting the lining creates a potential corrosion path.

The detail must define:

How the lining terminates around the attachment

Which metal surfaces remain exposed

Whether exposed parts require alloy construction or coating

How joints and penetrations are sealed

Whether crevices can retain corrosive liquid

How the area can be inspected and repaired

Simply covering part of a carbon-steel bracket with mortar is not always sufficient. Liquid can enter through a crack or unsealed boundary and attack the concealed steel.

The lining supplier, vessel designer and internals supplier should approve the interface detail together.

Special Concerns in Brick-Lined Towers

Brick-lined towers have a hard but relatively brittle internal surface. Actual finished dimensions may differ from the original steel-shell dimensions because of brick thickness, mortar joints and installation tolerances.

Support design should account for:

Variation in finished internal diameter

Uneven brick courses near support elevations

Fragile edges around openings

Limited permission for field cutting or grinding

Difficulty obtaining a flat bearing surface

Repair requirements if brickwork is damaged

A support member should not be forced into place by hammering against the brick lining. Nor should brick be removed without an approved repair procedure.

Field measurement after lining completion is often necessary for removable grid sections and perimeter components.

Special Concerns in Rubber-Lined Towers

Rubber lining is continuous and flexible, but it is vulnerable to puncture, cutting and heat.

Metal support components should not have sharp corners or burrs where they can contact the lining. During installation, temporary padding may be required to prevent beams from scraping the wall as they pass through the manway.

Fasteners and clamps must be positioned so tightening does not pinch or tear the rubber. If a component moves during thermal cycling, its edge should not rub repeatedly against the lining.

Hot work restrictions must be explicit. Even welding some distance from the visible lining can overheat the bond layer or create hidden damage.

After installation, the lining around structural attachments should be inspected using the method appropriate for that lining system.

Allow for Differential Thermal Movement

The vessel shell, support structure, packing and lining may have different thermal expansion behavior.

A support that fits tightly at ambient temperature can expand against the wall during operation. Excessive restraint may:

Crack brick lining

Shear mortar joints

Abrade rubber lining

Distort support panels

Overload attachment clips

Close necessary hydraulic clearances

The system should have a defined fixed point and controlled movement where required. Expansion clearance must not be improvised by leaving uncontrolled gaps that allow the packing to bypass the support.

Material selection and operating temperature should be considered together.

Measure the Finished Tower, Not Only the Steel Drawing

The original vessel drawing usually gives the steel-shell internal diameter. After lining, the usable diameter is smaller and may be less uniform.

Important field measurements include:

Finished diameter at several directions

Diameter at multiple elevations

Support attachment locations

Manway clear opening

Lining thickness near brackets

Local protrusions and repairs

Elevation and levelness of support points

These measurements determine whether beam sections can enter the vessel and whether grid panels will seat without contacting the lining.

A field-adjustable design may be useful, but adjustment should not require uncontrolled cutting inside the tower.

Segment the Support for Safe Installation

Lined towers often impose tighter installation restrictions. Support beams and panels must pass through the manway without dragging across the lining.

The segmentation plan should define:

Maximum transport size through the manway

Safe lifting points

Installation order

Temporary lining protection

Match marks for each section

Accessible connection locations

Removal method for future maintenance

Loose components should be controlled carefully. A dropped beam or fastener can damage the lining even if the support itself remains intact.

Prevent Hidden Liquid Traps

Support brackets and lining transitions can create pockets where corrosive liquid collects.

The design should avoid closed crevices and undrainable ledges. Where a pocket cannot be eliminated, compatible drainage and sealing provisions should be evaluated.

The hydraulic design must also prevent the packing support from forcing liquid toward an unprotected attachment. Corrosion protection should cover the real wetting pattern, not only the region expected under normal flow.

Inspection Before Packing Installation

Before the support grid is covered, inspectors should confirm:

Correct support elevation and levelness

Complete seating of beams and panels

No direct damaging contact with the lining

Required thermal clearances

Smooth edges and protected handling surfaces

Integrity of sealed lining transitions

Material identification of exposed parts

Removal of installation debris

Completion of lining repairs and testing

Photographic records are particularly valuable because these areas become inaccessible after packing is loaded.