AirSprayTech Academy Certificate Program

Secondary Containment Coating Systems for Industrial Contractors

Article 15 of 24

Coves, Joints, Drains, Penetrations, and Terminations

Containment systems rarely fail in the middle of an open floor. Failures usually begin where the lining changes direction, meets another material, crosses a joint, surrounds a penetration, or terminates at an edge. These details must be designed, installed, and inspected as carefully as the main lining.

Learning Objectives

After completing this article, you should be able to:

• Explain why containment details experience concentrated stress and chemical exposure.
• Distinguish dormant cracks, control joints, construction joints, and expansion joints.
• Understand the purpose of coves at wall-to-floor transitions.
• Recognize proper approaches to drains, pipes, equipment bases, anchors, and other penetrations.
• Identify the purpose of reglets, chases, mechanical terminations, and compatible sealants.
• Document and inspect critical details before they are covered by succeeding layers.

Open Areas Are Usually the Easy Part

Large horizontal and vertical surfaces allow the applicator to maintain a consistent application angle, overlap, coverage rate, and film thickness. Details interrupt that consistency. They create changes in geometry, material, movement, accessibility, drainage, and film thickness.

At these locations, a lining may be stretched, compressed, thinned, bridged, punctured, poorly bonded, or exposed along an unsealed edge. Liquid can enter a small defect and travel beneath an otherwise sound system.

Detail work should therefore be planned before production application begins. The crew should have approved drawings, compatible materials, and a defined installation sequence for every transition and penetration.

Do Not Design Critical Details in the Field

The applicator should not be expected to invent a joint, drain, or penetration detail after the project has begun. Different lining systems accommodate movement, chemical exposure, temperature, and substrate changes differently.

Project drawings or approved manufacturer details should identify:

• Surface preparation
• Cove dimensions
• Reinforcement type and width
• Required overlap
• Sealant and backing material
• Bond-breaker location
• Termination height and method
• Mechanical anchorage or clamping
• Inspection and testing requirements

If a required detail is missing or conflicts with field conditions, stop and obtain written clarification before covering the area.

Wall-to-Floor Transitions

A sharp 90-degree inside corner is difficult to coat uniformly. Liquid material can pull away from the corner, fiberglass can bridge it, spray equipment can leave a thin shadowed area, and stress can concentrate along the intersection.

A cove creates a smooth, curved transition between the floor and wall. The cove allows coatings, membranes, or reinforcement to continue through the change in plane with less bridging and more uniform thickness.

Cove material must be compatible with the substrate and lining system. It may be formed from resin mortar, polymer-modified repair material, elastomeric compound, or another manufacturer-approved product.

The cove should be solid, fully bonded, smoothly finished, and free of cracks, voids, sharp edges, and feathered weak margins. Cove radius and height should follow the approved detail.

Do Not Build a Cove over Contamination

Wall-to-floor intersections frequently collect chemicals, oil, water, dirt, failed sealant, and previous coating material. These contaminants must be removed before a new cove is installed.

The contractor should prepare both the floor and wall surfaces far enough beyond the intended cove to provide a clean, sound bonding area. Weak concrete, loose mortar, corrosion, and hidden voids must be corrected.

A well-shaped cove bonded to contaminated or unsound material is still a failed detail.

Understand the Type of Joint

Every visible line in concrete should not receive the same treatment. Before preparing or filling a joint, identify its purpose and expected movement.

• Construction joint: A location where separate concrete placements meet. It may or may not experience movement.
• Control or contraction joint: A planned weakened location intended to control where concrete shrinkage cracking occurs.
• Isolation joint: Separates a slab from a column, wall, equipment foundation, or another structural element.
• Expansion joint: Designed to accommodate movement caused by thermal change, structural movement, settlement, vibration, or other forces.
• Dormant crack: A crack that is not expected to experience significant future movement.
• Active crack: A crack that continues to open, close, shear, or otherwise move.

Do Not Rigidly Coat a Moving Joint

Filling an expansion or active joint with rigid mortar and coating across it can transfer movement directly into the lining. The system may crack, tear, or delaminate along the joint.

Moving joints normally require a flexible detail designed for the expected movement. Possible components include:

• Flexible chemical-resistant sealant
• Compatible backer rod
• Bond-breaker tape
• Reinforced flexible membrane
• Looped or bellows-type membrane detail
• Prefabricated joint system
• Mechanical clamping or termination

The detail must accommodate movement while preserving containment continuity. Elongation data from an unbonded laboratory specimen should not be used by itself to determine joint capability.

Sealant Compatibility

The sealant must be compatible with the contained chemicals, lining system, substrates, primer, temperature, movement, and cleaning procedures. A common construction sealant may not be suitable for chemical containment.

Verify:

• Chemical resistance to the expected exposure
• Movement capability
• Adhesion to both joint faces
• Required joint primer
• Backer-rod compatibility
• Joint width-to-depth requirements
• Cure time before chemical service
• Compatibility with adjacent coating or membrane

Three-sided adhesion can restrict proper sealant movement. Backer rod or bond-breaker tape may be used to create the intended two-sided bond when required by the detail.

Crack Treatment

Before repairing a crack, determine its width, depth, direction, contamination, moisture condition, and movement history. Look for changes in elevation or out-of-plane displacement that may indicate structural movement.

A dormant crack may be routed, cleaned, filled, and reinforced using materials approved for the lining system. The repaired area should be smooth enough to avoid bridging and thick enough to support the required lining build.

An active crack requires a detail capable of movement. Simply filling it with rigid epoxy can cause the crack to reappear beside or through the repair.

Cracks showing significant movement, water flow, settlement, structural distress, or unexplained recurrence should be referred to the owner or qualified engineer.

Drains and Sumps

Drains and sumps are natural collection points for chemicals, wash water, sediment, and debris. They often experience longer exposure than the surrounding floor and may be subjected to cleaning tools, pumps, hoses, and mechanical damage.

Determine whether the drain is intended to remain open, remain normally closed, or connect to a controlled collection system. The lining should not be terminated at the drain without a defined seal or mechanical connection.

Drain details may include:

• Prepared and profiled drain flange
• Reinforcement carried onto the flange
• A recessed termination or reglet
• Compatible sealant
• Mechanical clamping ring
• Lining continued into a compatible drain body

Ponding around a drain can increase exposure and conceal defects. Verify slope, drain elevation, lining thickness, and continuity before acceptance.

Pipe Penetrations

Pipes entering or passing through containment walls and floors create interfaces between different materials. The pipe and surrounding concrete may move at different rates because of temperature, vibration, pressure, settlement, or equipment operation.

The penetration should be accessible for surface preparation. Rust, mill scale, oil, insulation adhesive, old sealant, and process contamination must be removed from the bonding area.

A typical detail may use a formed cove, reinforced collar, flexible sealant, bond breaker, termination band, clamp, or mechanical boot. The lining should not end as a thin feathered edge against an unprepared pipe.

Hot pipes, vibrating pipes, and pipes carrying aggressive chemicals require special attention. Confirm that the detail can tolerate both the external spill exposure and the pipe’s operating temperature.

Equipment Bases, Columns, and Anchor Bolts

Equipment bases and columns interrupt the containment surface and create difficult inside corners. Vibration, washdown, maintenance activity, and chemical accumulation can place additional stress on the lining.

The detail should establish whether the lining:

• Terminates at the equipment base
• Continues over the base
• Turns up a curb surrounding the equipment
• Uses a flexible isolation joint
• Requires a reglet, sealant, flashing, or mechanical termination

Anchor bolts, plates, grout edges, and shims must be considered. Coating around a bolt without sealing its interface may leave a direct leakage path.

Do not coat moving machinery surfaces, removable components, adjustment points, bearings, grounding connections, or identification plates unless specifically directed.

Embedded Steel and Dissimilar Materials

A lining may transition from concrete to carbon steel, stainless steel, galvanized steel, fiberglass-reinforced plastic, plastic pipe, grout, sealant, or another material. Each substrate may require a different preparation method.

Dissimilar materials may expand, contract, vibrate, or absorb moisture differently. A rigid coating applied continuously across the interface can crack or separate.

The approved detail should identify surface preparation for each material, the required overlap, any flexible transition layer, primer compatibility, and how the edge will be sealed.

Vertical Terminations

Containment linings commonly turn up walls, curbs, columns, or equipment pads. The top edge should not be left as an exposed feathered termination where liquid can enter behind the system.

Termination methods may include:

• Cut reglet or chase
• Recessed termination
• Compatible sealant bead
• Termination bar
• Metal flashing or counterflashing
• Reinforced transition into another approved system

The termination height should be based on the containment design and maximum required liquid level, with allowance for waves, cleanup, and operational conditions.

Detail Installation Sequence

1. Confirm the approved detail and actual field dimensions.
2. Inspect the substrate for movement, damage, contamination, and moisture.
3. Remove failed material and prepare every bonding surface.
4. Complete required concrete, steel, weld, crack, and joint repairs.
5. Form coves, recesses, chases, and transitions as specified.
6. Apply the required primer or bonding layer.
7. Install sealant, reinforcement, membrane, or laminate in the specified sequence.
8. Maintain required overlap, thickness, and termination dimensions.
9. Inspect the detail before applying materials that will conceal it.
10. Complete the general lining and final topcoat.
11. Inspect, holiday test when specified, repair, and retest.
12. Photograph and document the completed detail.

Inspection of Critical Details

Critical details should be inspected at several stages. Waiting until the finished topcoat is applied may conceal inadequate preparation, dry reinforcement, missing sealant, insufficient overlap, or unsupported bridging.

Inspection should confirm:

• Correct detail and materials
• Sound, clean, properly prepared substrate
• Cove radius, termination height, and joint dimensions
• Required primer and recoat condition
• Sealant depth, backing, and adhesion
• Reinforcement width, saturation, and overlap
• Continuous coating or membrane thickness
• No voids, pinholes, bridging, cracks, or exposed edges
• Complete cure before testing or service
• Accepted repairs and successful retesting

Photographic Documentation

Photograph details before they are concealed. Images should show location, scale, surface preparation, reinforcement, overlap, sealant, termination, and the completed condition.

Use consistent location names that correspond with drawings and inspection reports. For example, “north wall pipe penetration P-4” is more useful than “pipe detail.”

Good photographic records protect the owner and contractor by showing how critical details were constructed before they disappeared beneath the finished system.

Common Detailing Failures

• Bridged inside corner: The lining spans the corner without support, leaving a hidden void.
• Rigidly coated movement joint: Structural movement cracks or tears the lining.
• Unsealed termination: Liquid enters behind the exposed edge of the system.
• Incompatible sealant: The sealant swells, softens, loses adhesion, or is attacked by the chemical.
• Poor drain connection: Liquid travels beneath the lining at the drain flange or body.
• Pipe-interface failure: Differential movement separates the lining from the penetration.
• Thin film at geometry changes: The coating pulls away from edges or receives inadequate spray coverage.
• Unprepared dissimilar material: The system bonds to concrete but releases from adjacent metal, plastic, grout, or sealant.

Field Quality-Control Checklist

• Approved detail exists for every transition and penetration.
• Joint type and expected movement have been identified.
• All bonding surfaces are accessible and properly prepared.
• Coves are solid, smooth, and correctly dimensioned.
• Active joints have not been rigidly filled or coated.
• Sealants are chemically and mechanically compatible.
• Backer rod and bond breakers are correctly installed.
• Drains and sumps have secure, continuous terminations.
• Pipe penetrations allow for the required movement.
• Equipment bases and anchor points are completely detailed.
• Dissimilar-material transitions use approved preparation and overlap.
• Vertical terminations are sealed or mechanically secured.
• No bridging, voids, exposed edges, pinholes, or thin areas remain.
• Concealed work has been photographed and documented.
• Final testing and repair retesting are complete.

Technical References

Use the editions identified in the contract documents and verify current designations before incorporating standards into a proposal, submittal, quality-control plan, or work procedure.

• AMPP — Design, Installation, and Maintenance of Coating Systems for Concrete Used in Secondary Containment
• AMPP — Coatings and Linings over Concrete for Chemical Immersion and Containment Service
• ASTM C920 — Elastomeric Joint Sealants
• ASTM C1193 — Use of Joint Sealants
• ASTM C881/C881M — Epoxy-Resin Bonding Systems for Concrete
• ASTM C822 — Terminology Relating to Concrete Joint Sealants
• ICRI Technical Guideline No. 310.2R: Selecting and Specifying Concrete Surface Preparation for Sealers, Coatings, Polymer Overlays, and Concrete Repair.
• AMPP SP0188: Discontinuity holiday testing of protective coatings and linings.
• Manufacturer documentation: Current technical data sheets, safety data sheets, joint and penetration drawings, chemical-resistance guides, sealant instructions, repair procedures, and written project-specific recommendations.

Key Takeaways

• Containment failures frequently begin at details rather than open surfaces.
• Critical details should be designed before field application begins.
• Coves reduce stress and application difficulty at wall-to-floor transitions.
• Every joint must be identified before deciding how to treat it.
• Moving joints should not be rigidly filled and coated.
• Sealants must resist both movement and the expected chemical exposure.
• Drains, pipes, equipment bases, and terminations require continuous sealed connections.
• Dissimilar materials may require separate preparation and flexible transitions.
• Inspect and photograph critical work before it is concealed.
• A detail is not complete until it has passed final inspection and testing.

Professional responsibility: This article provides foundational educational information and is not a substitute for the project specification, engineering direction, structural evaluation, regulatory requirements, or the lining manufacturer’s current written instructions. Always obtain approved details for joints, drains, penetrations, transitions, coves, and terminations. Review current technical data sheets, safety data sheets, chemical-resistance information, application instructions, and site-safety requirements before beginning work.

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