By Dr. Jeffrey David Rogozinski,
Global Product Director – Fusion-Bonded Epoxy/Pipe, Sherwin-Williams
Protective & Marine
How does an ambitious gas pipeline expansion,
running nearly half the width of Texas, get coated? One spiral weld section of
pipe at a time.
To protect the more than 250 miles of new pipe
added to the Whistler Pipeline in the southwest of the Lone Star State,
applicators got inventive – creating an efficient and resourceful approach that
helped the job flow as smoothly as the energy resources the pipeline now carries
to millions of customers (Figure 1).
More than 18,000 pipes went through the
rigorous coating process at Stupp Coatings’ facility in Baton Rouge, Louisiana.
With a tight deadline of 48 weeks to fully coat and transport the pipes to the
construction site, the coatings team needed to maintain a constant level of
productivity to keep the project on schedule.
Going into the project, pipeline co-owner
WhiteWater Midstream LLC, an Austin, Texas-based midstream oil and gas company
specializing in large infrastructure, knew maximizing efficiencies would be key
as well. To coat and deliver more than 400 pipes a week would only be possible with
the specification of easy-to-apply, fast-curing coatings that required minimal
touchups and enabled rapid handling.
The coatings applied to the pipes needed to be
durable enough to resist damage during installation, as WhiteWater was looking
to streamline the process by eliminating the use of a polymeric protective
wrap. This wrap is typically used to protect the applied coatings from damage
during the backfilling of trenches. Without the use of this external wrap, the
coatings would need to be able to withstand the impact of rocks and debris
falling on the pipes during the backfilling process.
A suitable coating solution emerged – Pipeclad
2060 Moisture Resistant Overcoat (MRO) from Sherwin-Williams Protective &
Marine, which is also an abrasion-resistant overcoat (ARO). This dual-layer
powder system offered the applicator the ability to apply two necessary layers
in tandem – a base anti-corrosion, fusion-bonded epoxy (FBE) layer of Pipeclad 2000
and a damage-resistant Pipeclad 2060 MRO layer.
By applying the top MRO layer coating to the
pipe directly following the base layer, this process did not significantly add
to the overall time of the project. As a result, robust protection against both
corrosion and pipeline damage was achieved within nearly the same time frame
required to simply stave off corrosion.
The strong degree of damage protection provided
by the MRO coating was also needed during pipe storage and transit – and
especially at the application site, where WhiteWater was counting on the coating
possessing the durability to allow backfilling in particularly rocky terrain (Figure
Impact and cold flexibility tests had proven
the MRO coating was up to the challenge. In fact, confidence in these testing results
allowed WhiteWater to forgo the traditional application of polymeric protective
wraps during pipeline installations – a time-consuming and costly process – in
favor of relying on the dual-layer coating system. As a result, WhiteWater
achieved a substantial improvement in the efficiency of the pipeline
What’s more, by spraying the MRO product at
essentially the same time as the FBE layer, a high level of efficiency in
applications was achieved. The applicator also saw a dramatic reduction in
post-application holidays, which are discontinuities in the coating.
Stupp Coatings particularly noticed the
benefit at weld seams on the spiral welded pipe, especially compared to results
from previously used coating systems. This resulted in a reduced need for
coating touchups at the shop and quicker completion and delivery of pipes.
As shown by the results of direct current
voltage gradient inspections conducted after the pipes were welded together and
installed in the field, the MRO coating on the pipes proved to be just as
effective as polymeric protective wraps in protecting against corrosion and
damage, making it an ideal solution for WhiteWater’s pipeline operations.
The Whistler Pipeline is an approximately
450-mile, 42-inch intrastate pipeline that transports natural gas from a
western interconnect with the Waha Header near Coyanosa, Texas, in the Permian
Basin, to an eastern terminus near Agua Dulce, Texas. It also includes an
approximately 80-mile, 36-inch lateral that provides connectivity for gas
processors in the Midland Basin. Providing a direct link to consumers and
markets in South Texas, the venture is a partnership between WhiteWater, MPLX,
WTG and Stonepeak.
Shop technicians sprayed a single layer of the
material to more than 130 miles of pipe (nearly 9,500 pieces) to be installed
in relatively gentle stretch of terrain. When applied onto heated and prepared
pipes, the powdered FBE creates a near-instantaneous barrier coating designed
to deliver long-term corrosion resistance to the below-grade pipeline. When
used in conjunction with cathodic protection (CP) systems, the hard coating
gives protection against impact, abrasion, immersion in chemicals and cathodic
Added protection was needed for the
approximately 120 miles of the pipe (nearly 8,800 pieces) headed for installation
in rockier terrain. Both the base anti-corrosion layer and a damage-resistant
MRO layer was applied to the pipes. The added layer offered exceptional
durability, providing an even higher level of resistance to abrasion, impact,
and general wear and tear than the foundational layer alone (Figure 3).
It also eliminated the need for polymeric wraps.
Choosing a dual-layer coating system was
influenced by the benefits of applying both layers almost simultaneously. Two
booths were set up side by side, one for FBE applications and one for MRO, so
that both coatings could be applied sequentially. The applicator did not have
to endure additional operating expenses as the MRO booth was already an
existing booth for applying ARO coatings.
Applicators first applied the base
anti-corrosion layer to the 76-foot-long pipes and then applied the MRO layer
immediately after. The FBE and MRO coatings chemically react to form covalent
bonds, thereby making a monolithic coating from substrate to surface with a
stratification of properties.
“The first FBE layer is an excellent base coat
because it flows into the substrate really well – it’s not as hard, so it has
better flow characteristics,” said Patrick Shea, president, Stupp Coatings. “Then
you put the MRO crosslinked on top to give it added protection.”
By applying the dual-layer coating system in
quick succession, the coating process was made more efficient as it allowed the
pipes to pass through the coating line at rates comparable to single-layer
application speeds. The entire process – including blasting, applying the
dual-layer coating, curing, quenching to cool the pipe, and inspection – only
took up to 30 minutes per pipe (Figure 4).
“With this amount of pipe, we accelerated
application to each pipe section, to around 14 feet per minute,” said Shea.
“This also allowed us to maximize the protection of both layers. We were very
happy with the quality of the product coming off the line.”
The inspection of the coated pipes revealed
minimal need for touch-ups, allowing for most of the pipes to be quickly moved
to the final stages of completion and delivery. The coatings even successfully
filled in the seams of spiral welded pipes, which are typically difficult to
fully cover during the application process.
One of the key criteria for WhiteWater to
choose the MRO coating solution for the Whistler Pipeline project was its
ability to perform in rocky soil environments without the additional protection
of a polymeric wrap during the backfilling process.
The standard method of pipeline installation
involves digging trenches for miles, laying pipes, welding them together and
covering them with a protective polymeric material before refilling the
trenches with the original soil. But this backfilling process can be harsh on
coatings applied to pipes, particularly in rugged areas. Impacts from rocks and
debris can damage the coating, leaving the steel pipe substrate exposed and
vulnerable to corrosion, which is why polymeric wraps are commonly used.
These wraps provide a protective barrier
around the pipes and help absorb impacts and reduce the likelihood of scratches
and abrasions on the coating surface.
While polymeric wraps can effectively protect
pipes from damage, they are costly and time-consuming to apply in the field.
The wrap is applied manually or with automated tools, leaving overlapped
material around the pipe. This process demands additional labor, extends
installation time and increases overall project costs. These added costs and
delays were the main factor for WhiteWater to explore an alternative way to
safeguard FBE pipeline coatings.
This decision paid off, as the dual-layer
FBE/MRO system allowed for the installation of 120 miles of pipes in a shorter period,
compared to using single-layer, FBE-coated pipe with wraps. Additionally,
WhiteWater was able to cut down on labor and material costs associated with the
use of the wraps.
the equivalent protective strength of wrapped plastic with high-quality coating
materials not only helps us meet many goals at once, but also eliminates an
entire installation step in the field,” said Steve Nelson, vice president of
Major Projects, WhiteWater.
Based on consultations, WhiteWater decided to
evaluate the MRO coating to ensure it could withstand the harshness of native
backfilling and potentially eliminate the need for polymeric wraps during field
installations. Sherwin-Williams created and subjected several coated samples to
thorough testing, using methods outlined by Canadian Standard Association
For example, lab technicians performed impact
testing (Figure 5) to determine the coating’s damage resistance when
being struck by objects. In addition, technicians tested the cold flexibility
of the coating by scoring cold coated samples with a knife, and then bending
them to determine at what bend radius the coatings would crack and flake off (Figure
6). Impact testing was also performed by dropping rocks on coated pipes to
see if the coating would stand up to the impact.
“WhiteWater needed a robust coating that could
bend in the field while being moved in different terrains – and not sustain
damage from backfill,” said Shea. “Extensive lab and field tests showed the
coating system would protect the pipes under these challenging conditions.”
After evaluating the MRO coating and seeing
its exceptional performance, WhiteWater was convinced that it could withstand
the rough conditions of native backfilling, which allowed installers to forgo the
use of polymeric wraps.
Additionally, the MRO coating does not
interfere with the flow of electrons, which means it is compatible with the
pipeline’s backup CP system. Furthermore, the coating’s resistance to moisture
helps prevent water from penetrating the base anti-corrosion layer, resulting
in longer-lasting protection against delamination and cathodic disbondment.
pipeline installation and backfilling operations, installers conducted direct
current voltage gradient inspections to confirm the CP system was operational
and to verify there were no areas with significant spikes that would indicate
coating damage,” said Nelson. “These inspections proved the validity of our
Keeping the project on schedule required a
combination of efficiencies in the shop and on the job site. By using an
innovative, dual-layer coating application method, they were able to increase
production and reduce damage to the pipes.
This resulted in significant cost savings for
backfilling and installation without compromising the integrity of the
pipeline. The durable and flexible coatings used made all this possible and
will continue to protect the pipeline from corrosion and wear for many years,
ensuring the continued flow of energy. P&GJ
Dr. Jeffrey David Rogozinski
is global product director – Fusion-Bonded Epoxy/Pipe for Sherwin-Williams
Protective & Marine. With more than 30 years’ experience in coatings and
academia, he is responsible for developing protective coatings, powder
coatings, resins and additives for the oil and gas, pipeline, and bridge and
highway markets. Rogozinski holds a doctorate in applied science for polymer
and composite chemistry. He can be reached at Jeffrey.Rogozinski@sherwin.com