Automatic Pig Valve Launchers Enable Simplified Pigging Automation for Remote Pipelines
N. AINSWORTH, Argus, Edmonton, Alberta, Canada
(P&GJ) — Pigging is a foundational integrity operating practice used to remove debris, support flow assurance, and enable gauging and inline inspection (ILI) on pipelines.¹² Often, these operations are conducted using launcher/receiver stations that require direct intervention for each operation.¹ In many cases, these stations are fully capable of maintaining the operator's integrity programs. However, in situations where the line requires frequent pigging to ensure its integrity—in locations with tricky access, or when various safety and emissions targets need to be met—direct human intervention for every operation can become a significant burden.³ In these situations, automatic launchers become a viable solution supporting operators by addressing the logistical, cost and regulatory challenges associated with these operating conditions.⁴
Automated launcher systems enable operators to preload multiple pigs and launch them at defined intervals using remote actuation.⁵ These features reduce the number of site visits required for a pigging program.⁵ However, many automated launcher concepts (including carousel, sphere and subsea launchers) can have very complex designs and functional requirements.³–⁵ The increased complexity may leave systems open to more opportunities for failure.⁶
Now, while many automated systems are complex, that is not universal. One of the simplest, most reliable yet perhaps lesser-known concepts for automating pigging is the automatic pigging valve (APV) launcher, also known as multi-pig launchers.⁶ This article will review the design concept of APVs, how they operate, their strengths and weaknesses, and the applications in which they can provide the most value to operators.
Design and operation concept. To oversimplify, the APV launcher is a pigging valve with a vertical cylindrical chamber mounted on top.⁶ The chamber houses multiple pigs (sometimes up to 11) and, unlike many inland automatic launchers that are horizontal or inclined, the APV is perfectly vertical.³⁶ The pig valve portion is directly connected to the line, and an actuation unit is typically connected to its front face.⁷ For simplicity, the following components are key to the concept of the launchers' design:
- Pigging valve: A trunnion-mounted, quarter-turn ball valve configured for top entry pig loading.⁷ Pigs drop down from the barrel into its cavity when the valve is turned to its closed position and then are released into the line when turned again to its open position.⁷
- Vertical barrel/chamber: A vessel that rests on top of the pig valve and stores the pigs and follower weight.⁷
- Follower weight: A weight that rests above the pig stack. The follower weight supports staging by placing downward force on the pigs.⁷
- Actuation: While not an inherently essential component to the general station's function, an actuator usually also accompanies the design and provides it with automation.⁶⁷
In addition to these elements, platforms and scaffolds are commonly incorporated into the design to allow operators to access the entry point at the top of the barrel.
Operating concept. The conceptual process of how an APV launcher works is to move pigs down the barrel and into the valve cavity individually, using gravity and the pressure from the follower weight.⁶ Each time the valve rotates from the open to the closed position against the flow of the mainline, a pig will fall into the valve's empty cavity.⁶ When the valve rotates back to the open position, the pig will be pushed out of the launcher and into the pipeline from the mainlines' flow, emptying the ball valve's cavity.⁶ This repeats until all pigs stored in the barrel have been launched.⁶ Exact procedures will vary based on station design, safety features and other requirements; however, the sequence can generally be summarized as follows:
- Isolation and depressurization (for reload): The valve is rotated to the closed position, and the barrel is depressurized to a verified safe condition for opening. Drain posts are used to remove residual liquids as required by the service's condition.⁷
- Load and secure: The entry cap is opened, the pig weight is removed and pigs are loaded nose-first. The weight is placed back on top of the pig stack and the entry cap is closed and secured.⁷
- Pressurize and launch: Vents and drain ports are closed, the barrel cavity is pressure equalized to line conditions, and the actuator cycles the valve to release the pig into the pipeline.⁷
- Relaunch (no loading required): To launch the next pig, the actuator returns the valve to the closed/staging position, where the next pig will advance by moving into the valve’s cavity. The actuator then opens the valve again to launch the pig, and the system repeats until the barrel is exhausted and requires reloading.⁷
Why vertical? Because they are perfectly vertical, APVs do not fight gravity; they use it to support the movement of pigs through the launch process. Other launchers often use indexing pins or rotating carousels to position the next pig. These approaches often rely on hydraulic or pneumatic controls and substantial additional support systems to move the pigs into position.³–⁵ Increased complexity creates more areas where the launcher can fail and a greater maintenance burden to keep the station running as intended.⁸ By using gravity rather than fighting it, the automatic pig valve launcher does not require a complex mechanism: it only requires a weight and a valve, lowering these risks and potential failure points.⁷
As the author’s company’s VP of Innovation and Technology, Jason Weiss, stated in an internal interview, “We want to keep the operation of multiple pig launchers simple—use gravity to our advantage—(so) we do not need complex mechanisms prone to failure.”
Practical limitations. There are limitations to the launcher primarily related to its pig-type capabilities. Automatic pig valve launchers require the pigs they send to be sized so they fit into the cavity of the valve's ball.⁷ That can limit the launcher's ability to use certain pigging tools, such as ILI equipment. As such, APVs are usually limited to maintenance pigs.⁶ However, there are some common workarounds to this limitation.
Commonly, operators will use an automatic pig valve with a barrel trap downstream. This hybrid approach uses the APVs for maintenance operations. When other operations (e.g., inspections) are required, the barrel is used. Because APVs are hollow balls, the launcher will not cause any obstruction between the barrel trap and the rest of the line.⁷ By combining these traps, operators gain the benefits of automation without sacrificing the versatility in tool use.⁷
FREQUENT APPLICATIONS
APVs are usually used in operating situations that involve the significant logistical, cost, emissions or safety concerns associated with pigging.⁴ In these situations, APVs provide the greatest value by helping operating companies consolidate multiple loading operations into a single operation. This reduces the number of direct interventions needed at the site by workers, lowering operating expenditures (OPEX), greenhouse gas (GHG) emissions, and schedule risk, and increasing safety.⁴ The following section outlines some of the most common operations where these challenges arise.
High-frequent sweeping and debris control. One of the most common applications of APVs is their use on lines that require high-frequency pigging. Some pipelines, such as lines carrying hydrocarbon-rich gas or waxy crudes, are prone to rapid wax and liquid build-up.⁹¹⁰ These lines require frequent and consistent pigging to maintain flow assurance and integrity.⁹¹⁰ With manual launchers, operators must mobilize crews to the site each time pigging is needed to meet the integrity program's schedule.⁹¹⁰ The more frequently these lines need sweeping and debris removal, the more OPEX begins to mount from these repeated crew mobilizations.
In these circumstances, an APV launcher can be a more practical solution than repeated crew operations.⁴ The consolidation of automation operations allows operators to significantly reduce the cost burden of maintaining these pipelines while ensuring better integrity program schedule assurance.
Remote and challenging access. Some stations can be very challenging to access. Sometimes this is due to the line's remoteness; other times, it is simply due to the terrain and difficulty of accessing the station.³⁴ Both situations lead to similar challenges that pipelines requiring high-frequency pigging face when using manual launchers. The cost of crew mobilization can quickly get out of hand, and maintaining the integrity of the program's schedule can become difficult.³ As such, in these circumstances, APV launchers may be utilized in place of manual traps. Remote launch capabilities with their automation reduce the frequency operators need to make the trip to the site.⁴
Lines with emissions and safety concerns. The last common application for APVs is in sites where operators are working under tight emissions regulations and/or heavy safety expectations. APV launchers reduce the number of times personnel must physically interact with the equipment, lowering the travel requirements and exposure associated with repeated site visits.⁶ In addition, because reload cycles occur less frequently, automatic launching reduces the number of venting events during depressurization, supporting emissions-reduction initiatives.⁶ Why is this significant to emissions and safety considerations?
Safety-wise, traveling and depressurization are consistently cited as two of the highest-risk components of an operator's job. Energy Safe Canada reports that 40% of occupational fatalities in oil and gas are due to transportation accidents, while the National Energy Board notes that depressurization events pose significant hazards to operators due to the threat of projectiles and potentially toxic or flammable gases.¹¹¹² Emissions-wise, decompression and travel also contribute to GHG emissions, with the degree depending on the distance, launcher cavity volume, line pressure and other operational circumstances.¹⁶ As the design of the APV launchers directly addresses both these concerns, when safety risk and/or emissions reduction are prioritized by operations, these tools are often implemented.
Takeaways. APV launchers solve a specific but recurring operational problem: how can we sustain our pipeline integrity program with pigging when the required frequency or line accessibility creates unsustainable logistical, emissions, safety and/or operating costs.¹⁴–¹⁶ By using actuation and housing multiple pigs, APV launchers enable multiple pigging runs to be consolidated into one loading and allow remote launching. Among APV launchers, the automatic pig valve is a simple, reliable approach that uses gravity to support the launching mechanism. While the design is not intended to replace conventional barrel traps in all cases, for remote assets, programs under emissions and safety scrutiny, and lines with build-up that require high-frequency pigging to maintain, the APV launcher offers a pragmatic pathway to operational excellence.
About the author
NICOLAAS AINSWORTH is the Marketing Manager at Argus, where he leads marketing, market research and commercial strategy development for advanced pigging solutions. His work focuses on identifying market opportunities, shaping go-to-market approaches and translating complex technical solutions into clear commercial value for pipeline operators. Ainsworth works across research, strategy and marketing management to support the successful positioning of innovations such as APV launchers.
LITERATURE CITED
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