How Does STOPAQ Visco-Elastic Coating Work?

How Does STOPAQ Visco-Elastic Pipeline Coating Work?

Most pipeline corrosion protection systems are designed to create a barrier between steel and the surrounding environment. However, the way that barrier is formed can vary considerably.

Traditional liquid epoxy coatings develop their protective properties through a chemical curing process. Heat-shrinkable sleeves rely on a combination of polymer backing, adhesive, and controlled heating during installation.

STOPAQ takes a different approach. Its corrosion protection technology is based on visco-elastic polyisobutene (PIB), a material that remains flexible, conformable, and capable of controlled cold flow throughout its service life.

Understanding this difference helps explain why STOPAQ is used for pipeline field joints, rehabilitation projects, tank foundations, soil-to-air transitions, and other difficult corrosion protection applications.

What Is a Visco-Elastic Coating?

The term visco-elastic describes a material that exhibits both viscous and elastic behavior.

In practical terms, STOPAQ's visco-elastic compounds can deform and conform to irregular surfaces without curing into a conventional rigid film.

This matters because steel surfaces are rarely perfectly smooth.

Pipeline welds, pits, coating transitions, fittings, and other irregular geometries can create challenges for corrosion protection materials.

A coating must establish intimate contact with the surface to minimize pathways for moisture and other corrosive substances.

STOPAQ's controlled cold-flow characteristics help the material conform to these irregularities.

What Is Polyisobutene (PIB)?

Polyisobutene is a polymer used as the foundation of STOPAQ's visco-elastic corrosion prevention technology.

For example, STOPAQ Wrappingband CZH is manufactured using a non-crystalline, non-crosslinked, fully amorphous polyisobutene compound.

These characteristics are important.

Because the material is not crosslinked into a rigid structure, it retains its viscous behavior within its specified operating conditions.

The compound does not require a chemical curing reaction after installation.

Instead, it is designed to maintain contact with the substrate while providing resistance to water and gas penetration.

How Does STOPAQ Cold Flow Work?

Cold flow is one of STOPAQ's most important characteristics.

It refers to the ability of the visco-elastic compound to deform gradually and flow into surface irregularities without needing to be melted or chemically cured.

Consider a steel pipeline with small pits or an irregular weld transition.

A rigid coating may require additional preparation or filling to establish a suitable coating profile.

A STOPAQ visco-elastic compound can conform to many of these irregularities through its controlled flow behavior.

This helps establish continuous contact between the coating and the substrate.

Cold flow does not mean the material behaves like a liquid that simply runs off the pipe. The compound is formulated to retain its position and function within its specified service conditions and with the required supporting coating components.

What Does Self-Healing Mean?

STOPAQ is often described as a self-healing corrosion protection system.

That description has a specific technical meaning.

Because the visco-elastic compound does not cure into a rigid film, it can flow into certain small discontinuities in the coating.

For example, STOPAQ's published Wrappingband CZH technical data describes testing in which an artificial 6 mm (approximately 1/4-inch) defect in the complete coating system self-healed within 24 hours at 23°C (73°F).

That is a measurable example of the material's behavior under defined test conditions.

It does not mean that STOPAQ can automatically repair every type of damage.

Large areas of missing coating, damaged outerwraps, or unsuitable service conditions may still require inspection and repair.

How Does STOPAQ Prevent Corrosion?

External corrosion of steel requires an environment that supports electrochemical reactions.

Moisture and oxygen are important contributors to many corrosion processes.

STOPAQ's PIB-based material is designed to create a low-permeability barrier that limits the movement of water and gases toward the steel.

Its ability to conform closely to surface irregularities is another important part of the protection mechanism.

The objective is to maintain a continuous protective barrier without relying on the development of a conventional rigid coating film.

This makes STOPAQ fundamentally different from many traditional coating technologies.

Why Doesn't STOPAQ Need to Cure?

Many industrial coating systems require a curing period before they achieve their intended properties.

For two-component epoxies, the process involves a chemical reaction between the components.

STOPAQ Wrappingband products such as CZH are supplied as prefabricated, cold-applied materials.

The visco-elastic compound does not undergo a conventional chemical cure after application.

This eliminates the need to wait for that type of curing reaction.

However, a complete STOPAQ system may still require additional installation steps, outer protection materials, and inspection before the asset is returned to service.

Why Does STOPAQ Need an Outerwrap?

This is an important distinction when evaluating STOPAQ systems.

The visco-elastic material provides the primary corrosion prevention barrier, while the specified outerwrap provides mechanical protection and helps support the coating system.

For example, STOPAQ Wrappingband CZH requires an additional protective outer layer.

Depending on the application, this may involve STOPAQ Outerwrap or High Impact Shield.

The outer layer helps protect the underlying visco-elastic compound against impact, indentation, and other mechanical stresses.

For more demanding conditions, additional protection such as STOPAQ Outerglass Shield may be specified.

The correct combination depends on the product, application, and operating environment.

Can STOPAQ Be Applied Without Sandblasting?

Certain STOPAQ systems offer less demanding surface preparation requirements than coatings that require abrasive blast cleaning.

For example, the manufacturer's Wrappingband CZH data sheet identifies wire brushing to ISO 8501-1 St 2 as an acceptable preparation method for the stated application conditions.

This can be particularly useful during maintenance and rehabilitation work where abrasive blasting may be difficult or expensive.

However, this does not mean surface preparation can be ignored.

Loose corrosion products, contamination, and other unsuitable surface conditions must still be addressed according to the specific product instructions.

Different STOPAQ products may have different preparation requirements.

Can STOPAQ Be Applied to Wet Steel?

Some STOPAQ products are specifically designed for wet or submerged applications.

STOPAQ Wrappingband WSH is an example.

It is intended for applications involving wet or submerged tubular structures, including certain offshore, splash-zone, and submerged pipeline conditions.

Other STOPAQ products are intended for dry substrate applications.

Therefore, it is important not to assume that every STOPAQ Wrappingband can be installed on wet steel.

Product selection must account for the actual environmental conditions.

Where Is STOPAQ Visco-Elastic Technology Used?

STOPAQ corrosion protection systems can be used in a variety of industrial applications.

Pipeline Field Joints

STOPAQ Wrappingband systems can provide corrosion protection around welds and approved coating transitions.

Pipeline Rehabilitation

The conformable material can be useful on existing pipelines where surface geometry and access conditions make conventional coating application challenging.

Soil-to-Air Transitions

Pipeline locations transitioning from buried to aboveground service can experience challenging environmental conditions. Suitable STOPAQ systems can be considered for these applications.

Tank Chimes

STOPAQ materials can be used as part of a system to seal and protect the perimeter of aboveground storage tanks against moisture intrusion.

Offshore and Splash-Zone Structures

Specialized STOPAQ products, including Wrappingband WSH, are designed for certain wet and submerged applications.

Industrial Piping and Equipment

STOPAQ systems can also be considered for industrial piping, fittings, and other steel structures requiring corrosion protection.

Are All STOPAQ Wrappingbands the Same?

No. The STOPAQ product family includes multiple formulations designed for different applications and operating conditions.

Examples include:

• STOPAQ Wrappingband EZ

• STOPAQ Wrappingband CZH

• STOPAQ Wrappingband CZHT

• STOPAQ Wrappingband WSH

These products should not be treated as interchangeable.

Operating temperature, substrate condition, installation environment, required mechanical protection, and project specifications must all be considered.

For example, WSH is specifically intended for wet or submerged applications, while other products have different application requirements.

Why Consider STOPAQ Instead of a Conventional Coating?

STOPAQ's most significant difference is its underlying technology.

Rather than depending on a conventional rigid cured film, it uses a visco-elastic compound designed to remain conformable.

This provides several potential advantages in suitable applications:

• Close conformity to irregular steel surfaces

• Controlled cold flow

• Self-healing of certain small coating defects

• Low permeability to water and gases

• No conventional chemical curing requirement

• Surface preparation options that can simplify certain rehabilitation projects

These characteristics do not make STOPAQ the best choice for every application.

The correct coating system must still meet the operating conditions, installation requirements, and project specifications.

STOPAQ Corrosion Protection Products From Joint Specialists Inc.

Joint Specialists Inc. supplies STOPAQ corrosion prevention materials for pipeline construction, rehabilitation, and industrial maintenance projects.

JSI can assist with product selection discussions, material requirements, and quotations for STOPAQ Wrappingband products and associated system components.

If you are evaluating STOPAQ for a pipeline, tank, or industrial corrosion protection application, contact:

Steve Simpson
Joint Specialists Inc.
Phone: 936-321-3333
Email: steve@jsicoatings.com

Please include the application, operating temperature, substrate condition, pipe diameter or equipment dimensions, and any applicable coating specifications.

This information will help us identify the appropriate STOPAQ products for your project.