How Does Covalence Waterwrap Protect Water Pipeline Field Joints Against Corrosion?
Large-diameter steel water pipelines are designed to provide decades of reliable service. These pipelines transport drinking water, raw water, and other water supplies across cities, counties, and entire regions.
Protecting the exterior steel surface against corrosion is an important part of achieving that service life.
Most steel water transmission pipelines arrive at the construction site with a factory-applied external coating. However, the pipe ends are typically left uncoated so the individual pipe sections can be welded together.
Once the pipe sections are joined, the exposed steel at the field weld must be protected.
Covalence Waterwrap is a heat-shrinkable, two-layer corrosion protection system specifically designed for field joints on large-diameter buried steel water pipelines.
Unlike ordinary wrapping tape, Waterwrap combines a specially formulated adhesive sealant with a thick, heat-shrinkable polyethylene backing.
When properly installed, the two layers work together to provide corrosion protection, moisture resistance, and mechanical durability.
Why Do Steel Water Pipeline Field Joints Need Protection?
Steel water transmission pipelines are often factory coated with protective external coatings such as polyurethane, polyethylene, fusion-bonded epoxy, or other specified coating systems.
These factory-applied coatings protect the pipe body against contact with the surrounding soil environment.
However, field welding requires access to bare steel at the ends of adjoining pipe sections.
After welding, the field joint creates an area where the factory-applied coating is interrupted.
If this area is left unprotected, moisture and other substances in the surrounding soil can contact the steel.
Over time, this exposure can contribute to external corrosion.
A field joint coating must therefore accomplish two important objectives:
Protect the exposed steel surrounding the weld.
Overlap and integrate with the existing factory-applied pipeline coating.
Waterwrap is designed to provide this protection through a heat-shrinkable sleeve system.
What Is Covalence Waterwrap?
Covalence Waterwrap is a wraparound heat-shrink sleeve designed for corrosion protection of field girth welds in water distribution and transmission pipelines.
It is supplied as a ready-to-fit assembly that is positioned around the pipe and heated during installation.
The system consists of two primary layers:
First layer: Visco-elastic, low-preheat adhesive sealant
This material contacts the prepared steel and adjacent factory coating, forming the primary corrosion protection seal.
Second layer: Radiation-crosslinked, high-density polyethylene backing
This thick outer layer shrinks when heated and provides mechanical protection against external damage.
The two layers are designed to work together.
The adhesive establishes intimate contact with the pipeline surface, while the heat-shrink backing provides compression and a durable external barrier.
How Does the Waterwrap Adhesive Protect Against Corrosion?
The adhesive is one of the most important components of the Waterwrap system.
Waterwrap uses a specially formulated visco-elastic sealant designed to conform to the pipe surface during installation.
When the sleeve is heated, the adhesive softens and flows into surface irregularities.
These may include minor variations in the steel surface, transitions between bare steel and factory-applied coating, and the contours surrounding the weld.
As the sleeve shrinks, the backing presses the adhesive against the pipe.
This helps establish continuous contact with the substrate.
The resulting adhesive barrier is designed to restrict the movement of moisture and other corrosion-promoting substances toward the steel.
The combination of adhesive flow and backing recovery is central to how Waterwrap protects a field joint.
Why Does Waterwrap Use a Heat-Shrinkable Backing?
The outer layer of Waterwrap is manufactured from radiation-crosslinked high-density polyethylene.
Radiation crosslinking allows the polymer to retain a recoverable shape.
During manufacturing, the backing is expanded into its supplied dimensions.
When sufficient heat is applied during installation, the backing attempts to recover toward its original dimensions.
This creates the shrinking action.
As the backing contracts around the pipeline, it presses the adhesive against the prepared surface.
This provides several important functions:
Helps eliminate trapped air beneath the sleeve
Encourages the adhesive to fill small surface irregularities
Produces a tight fit around the pipe
Provides resistance to moisture penetration
Helps protect the corrosion barrier against impact and mechanical damage
The backing is therefore much more than a protective plastic covering.
It is an active component of the installation process.
Why Is Waterwrap Particularly Useful on Large-Diameter Water Pipelines?
Large-diameter steel water pipelines present several practical installation challenges.
A pipeline may be several feet in diameter, making surface preparation, heating, and coating application more demanding than on smaller pipes.
Waterwrap was developed with these applications in mind.
Its heat-shrink construction allows the sleeve to be wrapped around the circumference of the pipe and recovered into position.
This eliminates the need to slide a tubular sleeve over the end of the pipe before welding.
Waterwrap is suitable for a range of large-diameter pipeline applications, subject to the selected product dimensions and installation requirements.
It can also be used for certain bare replacement pipe sections and large-radius bends.
For water transmission contractors, this versatility can be useful when working with different joint configurations along the same project.
What Is the Minimum Preheat Temperature for Waterwrap?
One of Waterwrap's distinguishing characteristics is its low-preheat adhesive system.
According to the Covalence Waterwrap product data sheet, the minimum specified preheat temperature is:
20°C (68°F).
This is substantially lower than the preheat required by many other heat-shrink sleeve products.
The lower preheat requirement can be especially useful when working with large-diameter steel water pipelines.
Heating a large steel pipe to an elevated temperature requires time and energy.
A lower preheat requirement can simplify the installation process.
However, contractors should not confuse the minimum preheat temperature with the amount of heat required to recover the sleeve.
Waterwrap still requires sufficient controlled heating to shrink the backing and activate the adhesive.
The manufacturer's complete application instructions must be followed.
What Are Waterwrap's Permanent Change Indicators?
Covalence Waterwrap incorporates Permanent Change Indicator technology, commonly referred to as PCI.
These indicators provide installers and inspectors with a visual way to evaluate the heating process.
Waterwrap's published product information identifies two PCI functions:
Underheat indication
This helps identify areas that may not have received sufficient installation heat.
Overheat indication
This helps identify areas that may have been exposed to excessive heating.
These features are particularly valuable on large-diameter field joints, where achieving consistent heating around the entire circumference can be challenging.
The indicators provide an additional inspection tool during and after installation.
However, PCI does not replace proper surface preparation, temperature verification, adhesion requirements, or other specified quality control procedures.
How Is Covalence Waterwrap Installed?
Although installation requirements can vary by product configuration and project specification, the general process involves several stages.
Step 1: Prepare the Steel Surface
The exposed steel and adjacent coating must be cleaned and prepared according to the manufacturer's instructions.
The Waterwrap product data sheet identifies SP2 or SP3 as recommended preparation methods, referencing AWWA C216.
These correspond to hand-tool or power-tool cleaning procedures.
The surface must also be dry and free of contamination that could interfere with adhesion.
Step 2: Inspect the Weld and Coating Transition
The contractor should examine the field weld and the transition between the exposed steel and the factory coating.
Sharp edges, excessive weld reinforcement, and abrupt transitions can interfere with sleeve conformity.
Where required, an approved filler material is used to create a smoother profile.
Step 3: Apply Filler Where Required
The Waterwrap data sheet identifies Covalence 939-HT filler for certain weld configurations.
Specifically, the manufacturer requires 939-HT when the step-down at the weld bead is 1/4 inch or greater.
The filler helps smooth the transition and reduce the possibility of voids beneath the sleeve.
Step 4: Preheat the Joint
The prepared pipe surface is heated according to the installation instructions.
For standard Waterwrap, the published minimum preheat temperature is 68°F (20°C).
The required temperature must be verified using the appropriate method.
Step 5: Position the Waterwrap Sleeve
The sleeve is centered over the field joint and positioned to provide the required coverage of exposed steel and adjacent factory coating.
The wraparound configuration allows the installer to place the sleeve around an already assembled pipeline.
The sleeve is secured using the specified closure arrangement.
Step 6: Apply Heat and Shrink the Sleeve
Heat is applied in the prescribed sequence.
As the polyethylene backing recovers, it contracts around the pipe.
At the same time, the adhesive softens and conforms to the steel and adjacent coating.
The installer must achieve uniform recovery around the complete circumference.
Step 7: Inspect the Completed Installation
The finished sleeve should be examined for proper recovery, adhesion, coating coverage, and other specified acceptance criteria.
The PCI indicators provide additional visual evidence of the heating process.
Any required holiday testing or other quality control checks should be performed according to the project specification.
Does Waterwrap Require a Primer?
Waterwrap is designed as a two-layer heat-shrink sleeve system with a low-preheat adhesive.
It is generally installed directly over the properly prepared and preheated substrate without a separate liquid epoxy primer.
This distinguishes it from certain three-layer heat-shrink sleeve systems that incorporate a liquid epoxy component.
Eliminating a separate epoxy priming and curing operation can simplify field installation.
However, the contractor must still follow the exact product instructions and project specification.
What Factory-Applied Pipe Coatings Are Compatible With Waterwrap?
The manufacturer's product data sheet identifies compatibility with several common external pipeline coating types, including:
Polyethylene (PE)
Polyurethane (PU)
Fusion-bonded epoxy (FBE)
Polypropylene (PP)
Coal tar
Tape coatings
Asphalt coatings
This is important because municipal and industrial water transmission projects may use different factory coating systems.
The field joint coating must be suitable for the coating already present on the pipe.
Compatibility should be confirmed for the particular project, especially where unusual coatings, repairs, or operating conditions are involved.
What Is the Maximum Operating Temperature for Waterwrap?
According to the manufacturer's product selection information, standard Covalence Waterwrap has a maximum operating temperature of:
50°C (122°F).
This makes the product appropriate for many buried water transmission and distribution applications operating within its specified temperature range.
It should not automatically be substituted for higher-temperature pipeline sleeve systems.
Different Covalence products have different adhesive formulations, backing constructions, and operating temperature limits.
Selecting the correct sleeve is essential.
Does Waterwrap Meet AWWA C216?
The Waterwrap product data sheet identifies performance in accordance with AWWA C216, the American Water Works Association standard addressing heat-shrinkable cross-linked polyolefin coatings for the exterior of special sections, connections, and fittings on steel water pipelines.
This is particularly relevant for municipal water transmission projects.
Engineers and pipeline owners frequently reference AWWA standards when preparing coating specifications.
Contractors should confirm the edition of the standard and any additional project-specific requirements before selecting materials.
What Is Waterwrap-WAB?
Some large-diameter steel water pipelines use a construction method known as Weld-After-Backfill (WAB).
In this method, pipe sections are positioned and backfilled before the final internal welding operation is completed.
The procedure can create unusual demands on the field joint coating.
Covalence offers a Waterwrap-WAB configuration designed for this type of application.
The product uses the same general two-layer corrosion protection concept and is specifically identified by the manufacturer for large-diameter steel water pipe projects using internal welding and Weld-After-Backfill procedures.
Waterwrap-WAB should be selected and installed according to its own product data sheet and project requirements.
How Does Waterwrap Compare With Ordinary Pipeline Tape?
Both tape coatings and heat-shrink sleeves can be used to protect pipeline surfaces.
However, the installation mechanisms are different.
Ordinary cold-applied pipeline tape relies primarily on adhesive contact and wrapping tension.
Waterwrap uses a heat-recoverable backing that actively contracts around the joint during installation.
This shrinking action presses the adhesive into contact with the steel and adjoining factory coating.
Waterwrap also incorporates PCI technology to assist with evaluating the heating process.
These differences can be particularly useful on large-diameter field joints.
The most appropriate system ultimately depends on the project specification, installation conditions, and required coating performance.
Why Is Proper Waterwrap Installation Important?
Even a well-engineered heat-shrink sleeve can fail to provide the intended protection if it is installed incorrectly.
Potential installation problems include:
Insufficient surface preparation: Contamination or loose material can interfere with adhesion.
Inadequate preheat: The adhesive may not develop the intended contact with the substrate.
Uneven heating: Portions of the sleeve may not recover properly.
Excessive heating: Overheating can damage the backing or adhesive system.
Improper sleeve positioning: Insufficient coverage of the adjacent factory coating can compromise the joint.
Unfilled irregularities: Abrupt transitions or weld profiles can create areas of poor contact.
The purpose of following the manufacturer's installation instructions is to avoid these problems before the pipeline is placed into service.
Selecting Waterwrap for Your Next Water Pipeline Project
When evaluating Covalence Waterwrap, contractors should identify the following project details:
Pipe outside diameter
Number of field joints
Width of the uncoated field joint area
Type and thickness of factory-applied coating
Field weld configuration
Maximum operating temperature
Installation and ambient conditions
Applicable AWWA and project specifications
Whether Weld-After-Backfill construction will be used
These details help determine the appropriate Waterwrap configuration, sleeve dimensions, and material quantities.
Covalence Waterwrap From Joint Specialists Inc.
Joint Specialists Inc. supplies Covalence heat-shrinkable corrosion protection products for pipeline construction and rehabilitation projects.
JSI has extensive experience with Covalence products, including heat-shrink sleeves for large-diameter steel water transmission pipelines.
Whether your project involves conventional field joints, replacement pipe sections, or Weld-After-Backfill construction, we can assist with product inquiries and material quotations.
For more information about Covalence Waterwrap, contact:
Steve Simpson
Joint Specialists Inc.
Phone: 936-321-3333
Email: steve@jsicoatings.com
When requesting a quotation, please provide the pipe diameter, number of joints, factory coating type, and any applicable project specifications.
We welcome the opportunity to assist with your next water transmission pipeline project.
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