Hydrocarbon Processing - December 2020 - 18

Executive Viewpoint
in process plants to regulate flows. These
critical assets cannot be maintained in a
reactive manner as unplanned failures can

rective actions needed to remedy the issue.
Algorithms are continually updated as new
leading indicators are identified through

Digital transformation is most effectively
implemented one step at a time by focusing on
operational issues at the plant level.
cause serious safety-related incidents, including those related to occupational safety, loss of containment and process safety.
Remote monitoring of control valves
enables prediction of problems before
they occur, allowing issues to be addressed
proactively. Valve diagnostics begin with
data collection, facilitated by digital valve
controllers, which provide extensive information for use by asset management, distributed control and other host systems.
Offline diagnostic testing characterizes nominal performance, creating a
valve signature based on high-resolution
samples of actuator pressure and travel.
Once the signature is created, online diagnostics collect information from the valve
while in operation, utilizing established
thresholds to indicate when valve performance is being compromised.
Subject matter experts (SMEs) review
these and other data to identify problems, often utilizing data interpretation
tools powered by anomaly detection algorithms. SME knowledge and expertise
are applied to determine if a problem has
occurred or is predicted, and to direct cor-

FIG. 1. The acoustic monitoring device
shown in the upper right of this diagram
detects vibrations and uses these readings
to determine valve position.

DECEMBER 2020 | HydrocarbonProcessing.com

analysts' findings, and via artificial intelligence and machine-learning algorithms.
SMEs provide remote assistance services to empower local technicians via
mobile device connectivity, allowing
them to securely share their field of view
with SMEs through augmented reality
software. A specific valve installation can
be automatically identified, along with its
maintenance history and repair instructions. Step-by-step instructions overlaid
in the user's application serve to support
installation, calibration or repair actions.
Pressure relief valve (PRV) monitoring. PRVs activate only in an emergency

but must perform when needed. Failure
to activate can cause pressure to increase
to dangerous levels, eventually resulting
in ruptures to pipes or vessels. This loss
of containment spews process media into
the plant, possibly resulting in a fire or explosion. More commonly, PRVs operate
as designed to relieve pressure, but often
do not seal correctly after conditions return to normal, resulting in continuous
emissions to the environment.
Acoustic monitoring devices equipped
with wired or WirelessHART transmitters
can be mounted directly to pipes adjacent to PRVs to verify correct operation
(FIG. 1). These devices sense vibrations
in the discharge pipe due to turbulences
generated by fluid flowing through the
valve and transmitted directly through
the pipe wall. Vibrations are analyzed by
the device to determine valve position,
with this data sent to host systems either
locally via wired or wireless networks, or
remotely via the internet.
PRVs are designed to open once a preset pressure value is reached. If the process
recovers and system pressure returns to
normal, or if operators reduce pressure
sufficiently, then the PRV should close
again automatically. If everything is working correctly, it will seal, and the mechani-

cal vibration will cease. Data from the
acoustic transmitter can verify the action,
reporting the time the discharge began
and ended, while giving some approximate indication of how serious the discharge was based on
the amplitude of the sound.
However, sometimes things
go wrong and a small particle of
debris from the process can lodge
on the valve seat, causing leakage.
Like a full overpressure-driven
release, small leakages also generate turbulence inside the discharge pipe, causing mechanical vibration detectable by
the acoustic transmitter. The importance
of detecting leakage as soon as it starts is
driven by a compounding effect over time.
A 0.1% leakage, if left unaddressed for 1 yr,
equals a full release from a PRV for 6 hr.
monitoring. A typical
250,000-bpd refinery can save $5 MM/yr-
$12 MM/yr by using a digital transformation solution to monitor metal thickness
in real-time. This solution requires full
implementation costs of approximately $2
MM, resulting in a quick return on investment. Like most digital transformation
initiatives, metal thickness monitoring can
start small with the highest risk and most
critical assets, such as pipes with a history
of corrosion-related failure.
Quantifiable savings can be obtained
through better feedstock selection to avoid
the most corrosive fluids, improved use of
inhibitors to reduce corrosion, and proactive maintenance. Other benefits include
a safer working environment with fewer
emissions as leaks can be predicted, before
they occur, by monitoring metal thickness.
Measurements are made using nonintrusive wireless sensors, with collected
data sent to a host system running software specifically designed to analyze metal thickness data. The software's sophisticated visualization and analytical tools
reduce the time needed for data analysis
and interpretation.

Corrosion

Let the journey begin. Digital transformation is most effectively implemented one step at a time by focusing
on operational issues at the plant level.
Once improvements are made to resolve
one issue, the next item on the list can be
addressed, eventually resulting in substantial operational improvements as one
success leads to another.

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Hydrocarbon Processing - December 2020

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