Preparatory Site Visits Reduce Project Cost and Risk When Planning the Intelligent Pigging of Oil Terminal Wharf PipelinesBy: Geert Bontekoe and Laurie Todd, Quest Integrity
As seen in the Winter 2017 issue of Tanks & Terminals Magazine
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wharf pipelines are often considered "unpiggable.” This can be due to a range
of factors including operating pressure limitations, or that the pipeline was
not designed for intelligent pigging and may have features such as short radius
bends, a lack of pig launcher or receiver, diameter changes or various other
challenges. While new technologies now allow previously
unpiggable wharf pipelines to be accurately and quickly inspected, there are
still many challenges that arise due to operational constraints.
for the inspection of a wharf pipeline, it is important to first understand the
possible inspection methods and all associated challenges. In simple cases it
may be possible to accomplish this by conducting preliminary discussions and collecting
vital information, including drawings and historical pipeline data. More complex projects, however, are typically
characterized by a lack of information and an understanding of possible
inspection methods. In these situations it is recommended that an experienced project
manager conduct a site visit in the early stages of planning for the project.
available ILI tools are often not suitable for the inspection of wharf
pipelines, leaving a much smaller field for consideration. The objective of a pre-inspection
site visit is to gather all available information, including operational
constraints and preferences, so that a safe, efficient and cost-effective
cleaning and inspection procedure can be developed. Experience has shown that the small upfront investment of performing a
preparatory site visit can achieve significant cost savings through the
reduction or elimination of pipeline modifications, pipeline downtime and the
equipment necessary to support the inspection.
A variety of solutions
are available to address problems related to pipeline modifications and
equipment requirements. Some examples include: the use of flexible hoses to
create looped pipeline systems, adjusting tool bypass to suit flow conditions,
or even launching or receiving the ILI tool from a spool piece between valves. In
order to determine which specific methods are appropriate, it is imperative
that a site visit be performed by an expert with specific knowledge of all operating
requirements and available technologies.
This article discusses
the inspection planning and site visit process for wharf pipelines, as well as
the various methods used to mitigate unnecessary inspection project expenditures.
Case studies are presented to illustrate these methods.
only "piggable” pipelines were inspected with ILI tools. The majority of these
tools have been based on MFL technology. Inspections performed with these tools
lengthy launcher and receiver,
gauging pig run with gauge plate at 90 or 95% of pipeline ID,
caliper tool run,
equipment for the ILI tool, and
parameters (minimum pressure and flow rate) that may be difficult to manage in certain
pipelines, however, are not readily piggable with traditional ILI tools for
various reasons including operating pressure limitations or that the system was
never designed for in-line inspection. Most Wharf lines have extra metal
features, like pipe supports, clamps and sleeves. Damage to the coating is
often observed, especially at the weld locations, increasing the chance of
external corrosion in the Heat Affected Zone (HAZ). These features limit the
accuracy of ILI tools based on MFL technology. Fortunately, in recent times, the
introduction of new tool technology is changing the playing field. These truly
innovative tools can cope with challenging operating conditions including the
navigation of tight and mitered bends in low pressure conditions and often eliminate
the need for pipeline modification.
terminal operators are now facing new rules, regulations, safety and
environmental concerns. For instance, a notable amendment of AS/NZ 2885.3 for
Australia and New Zealand was implemented in 2012. This revision recommended
that as part of any Pipeline Integrity Management Plan, the pipeline operator
should consider use of ILI where practicable, taking account of available
inspection technologies. This change has encouraged pipeline operators to assess
all options, including modifications to perform an ILI inspection; only relying
on ECDA, ICDA and/or hydro-testing as a last resort method.
regions, several well publicized incidents have forced operators to focus on the
inspection of wharf pipelines that have previously been neglected from an ILI
perspective. This combination of circumstances has made it both necessary and possible
to inspect the large number of wharf pipelines that had previously been
For the oil
terminal operator, this is both an opportunity and a dilemma. When preparing
for the inspection of a wharf pipeline, the ILI tool selection process now
involves supplying highly specific information about the pipeline; comparing vendor
qualifications and data quality; and potentially making costly modifications to
the pipeline prior to inspection. The implication of this process is also
financially salient, as the total cost of a project can vary considerably from
one inspection technology to the next.
- The total cost
of the project can include:
or temporary pipeline modifications,
of equipment such as pumps, compressors, lifting equipment and frac tanks,
and disposing of the inspection medium,
needed to support the project,
cost of downtime.
can vary depending on the method and supplier of the chosen ILI service. The
selection process has become significantly more difficult and complicated.
of selecting an inspection technology for wharf pipelines are illustrated in
the following case studies.
Case Study A: Inspection of a 14” White Oil
inspection was performed on a 14”, 1-mile long wharf pipeline. The pipeline,
used to transport white oil, had been constructed in 1985 and had not been
pigged since it was commissioned. No traps were present, but a launch valve was
still in place. The pipeline ran from a wharf to a tank farm. Access to the
launch location was through two manways. The first launch location was for
personnel access. The second launch location was located directly above the
launch valve and could be used to lower a small launcher underneath the berth.
At the receiver side there was no mainline valve present, only a flange to
connect to. The maximum pressure allowed was 150 psi. Due to an ever-changing
shipping schedule, scheduling flexibility from the ILI supplier was required. The
pipeline was normally operated by a third party operator; the owner had no
pipeline pigging experience.
initial site visit was performed prior to inspection. During the site visit,
various inspection options were discussed with the owner and 3rdparty operator. A procedure was developed outlining the roles, responsibilities
and materials for each associated party. It was determined that receiver
modification was required in order to allow for future repeat inspection. This
modification would easily allow for the installation of any suitable ILI
receiver, without the need to drain the pipeline. A drawing for the
modification was provided in the procedure (see Figure 1).
before the ILI inspection, the pipeline owner modified the pipeline and
installed the receiver (see Figure 2). The launcher was installed using a small
crane mounted at a truck. Five (5) cleaning runs were completed that afternoon
and the following morning. The pipeline contained a reasonable amount of
sediment brought in by the ships when offloading diesel. Subsequently, the ILI
run was completed successfully. All of the cleaning and ILI inspection pig runs
were carried out using a firewater supply for propulsion. The project was
completed within 2.5 days on site without any incidents or spills.
Figure 1. Drawing of pipeline modification
used to effectively inspect the pipeline.
Figure 2. Real-world application of pipeline
modification design in Figure 1, allowing for the future installation of any
required ILI receiver.
- The ILI vendor was selected based on cost and project management
capabilities. A standard ILI tool could have been used, but would have required
large pig traps. Installation of large pig traps would have required a small
barge, with a great deal of scaffolding under the wharf. At the receiver side,
the client had been contemplating excavating a small part of a hill to make
room for a large trap. These factors increased the overall cost and would have
also increased the risk of an accident or spill due to the increase in work in
a confined space and heavy lifting involved.
- During the site visit, the project manager was able to identify several
options for the client, allowing the operator to select the most convenient
overall solution. One cost saving element was the use of a dock hose as the
bypass line. The dock hose was readily available and could be used on any trap,
from either the current and/or future ILI supplier.
- The cleaning and inspection was completed in 2.5 days. The modifications
took two days to complete. Utilizing the capabilities of all involved parties
and locally available resources, the inspection was executed on time and
Case Study B: Parallel 8” Loading Lines
inspection consisted of two parallel 8”, 4000 ft. loading lines running from a dock
to a tank terminal. One line included a 3-way valve (See Figure 3). These lines
were used for the offloading of various fuel products to the tank farm. The owner
operated several tank farms, but had not previously inspected either of these
loading lines. The initial idea was to inspect each line individually with a
launcher and receiver at both ends, using water as the inspection medium. As this
option would require the use of frac tanks on the dock, a site visit was
organized to explore better options for the client.
the site visit, all viable inspection options were considered. The solution was
to use a dock hose, which was normally used to offload ships, to connect the two
pipelines at the dock (see Figure 4). This method would further reduce the
total work scope for the client.
hours, the two pipelines were cleaned, inspected and handed back to the client.
Figure 3. Three-way valve requiring
logistical consideration prior to inspection.
Figure 4. Two 8” dock hoses used to loop the
pipelines together for inspection, providing the operator with significant cost
savings by avoiding the need to specially fabricate a spool.
- During the site visit, a method was devised that would reduce the total
work load for the client. The ILI inspection was performed in a very short time
- The inspection allowed for minimal dock occupation time. This made
scheduling on a shared dock easier.
- Two pipelines were inspected with minimal work at the shared dock. The installation
of pig traps could also be performed within the client’s terminal, simplifying
and minimizing the work and the risk involved.
inspecting wharf pipelines that historically would not have been inspected or
considered piggable, it is imperative to perform a site visit by an ILI provider
with wharf line inspection experience. The developers of new, innovative ILI
tools are able to provide the best knowledge on potential operational
improvements for an inspection. By utilizing the ILI provider as a consultant
and project manager in this way, it is possible to realize substantial overall
cost savings and risk reduction.