ZECO Valve manufactures a positive shut-off, double block and bleed pigging valve that ranges in size from 2 inches to 20 inches. The pigging valve provides a safe and efficient means of inserting and retrieving pipeline cleaning devices under pressure.
What is Pigging?
Pigging is a word used to describe the action of cleaning a pipeline via the means of a device, that travels through the line, known as a pig. This device, an invention of the oil industry (sometimes referred to as a Pipeline Intervention Gadget), derived its funny name because of the squealing sound the original–composed of straw and wire–made as it traveled through a pipe. Replicating the action of a gun barrel cleaning brush, a pig travels through a pipeline, scrubbing the interior circumference clean of debris as it is carried along by the media flow. Pressure from the media builds behind the snug-fitting pig, and pushes it along through the entire pipeline, providing the pig fits through all of the valves. Therefore, a piggable valve is any valve that allows the free travel of a pig.
Why Pigging in Pipeline?
There are various reasons to pig a pipeline, but the most common is to clear the line of debris. This process ensures that the product running through the line is flowing smoothly and reduces the likelihood of product contamination. There also are major safety advantages to clearing a line, as built-up debris can degrade the integrity of the pipe wall over time.
Smart pigs also are commonly used today to detect various elements about the pipeline. As mentioned earlier, inspection pigs collect information regarding temperature and pressure, corrosion/metal loss, diameter, bends, and curvature to verify pipeline integrity. Cracks, weld defects, surface pitting, and areas of crushing/deformation are often measured through pigging as well.
Because of the variety of environments that pipelines are found in, including underground or underwater, and the construction materials of most pipelines, pigs must record their data internally until it can be retrieved by the user. Retrieving and monitoring where certain data was collected5 is done through surface instruments using audible, magnetic, or gravimetric methods to record where the pig is at various points. The user then uses this information to map out defects to aid repair crews in maintenance.
Some new, “smart” pigs have GPS capabilities that can assist in mapping a pipeline. This helps maintenance crews save time and money by pinpointing exactly where a pipeline is run, instead of having to excavate a large area to reach a specific location in the line.
What is Pigging Valve?
ZECO pigging valves provide a space- and cost-saving substitution for expensive pig launching systems. In addition to its classic use as a shut-off valve, the pigging ball valve functions as a pig launcher or receiver valve. The simple, secure, and fast insertion or removal of pigs takes place through an interlock that is integrated on the side of the pigging valve and that is locked and secured through a bayonet system. An optional bypass in the closed position also allows cleaning operations when the medium flow is not to be interrupted completely. In addition, the pigging valve can be used for separating different products in a pipeline. A 3-step, redundant safety concept, and an entirely metallic sealing shutoff guarantee the highest availability for operation and cleaning of oil, gas, slurry, and water applications. In the standard version, pigging ball valves are designed for a maximum scraper length of 1.4 x the nominal diameter of the pipeline but upon request, ZECO Valve offers special constructions for extended scraper length. Furthermore, ZECO Valve is able to provide 180° pigging valves which can act as launcher and receiver in both directions. This innovative pigging valve concept is already in use as a global standard solution at leading oil companies.
Design of Piggable Valve
- Engineered, manufactured, and tested to API 6D
- Industry Standards: API 6D, ASME B16.34, and API 598
- Meets NACE MR0175-03
- Size range: 2” – 16”
- Pressure Classes: ANSI Classes 150 to 1500
- Standard temperature range: -20 to 300 deg. Fahrenheit
- Special Order range: -50 to 400 deg. Fahrenheit
- Materials: LF2, 316 SS, and Exotic Alloys as required
- Seals: HSN, HNBR, James Walker, Viton, Teflon, Devlon Peek, or as required
Advantages of Pigging Valve
Pigging Valve is engineered and manufactured from the finest materials with advanced equipment and quality craftsmanship. Pipeline pigging valves facilitate asset integrity, mitigate corrosion, and optimize oil and gas production.
Here are a few of our pipeline pigging advantages:
- Forged three-piece body design and construction are superior to castings
- Trunnion-mounted ball extends seat life and promotes ease of operation
- Double block and bleed construction facilitates the launch and receipt of bullet, scraper, and spherical pigs
- Environmentally superior to pigging tees and traps
- Designed for NACE, low-temp, liquid, or gas applications with a standard temperature range of -50ºF to +250ºF (-46ºC to +121ºC)
Pig valve integrity is assured through A350-LF2 low-temperature forged steel construction, while uncompromised quality is secured under ISO 9001:2015 and API 6D certifications.
Launch and Retrieve
Any pipeline utilizing pigging for cleaning must have an entry and exit point for the pig. An entry point is called a launch station–often replacing a section of pipe– while a receiving station, or what’s commonly called a pig catcher, is the exit. Since the incorporation of launch and retrieval tubes requires removing sections of piping, a practical connection type between valves and piping, then, would be flanged. This would be another important consideration when designing or upgrading a pipeline utilizing piggable valves–connections that are not compromised by the removal of the valve.
What makes a Valve Piggable?
Pigging is a word used to describe the action of cleaning a pipeline via the means of a device, that travels through the line, known as a pig. This device, an invention of the oil industry (sometimes referred to as a Pipeline Intervention Gadget), derived its funny name because of the squealing sound the original–composed of straw and wire–made as it traveled through a pipe. Replicating the action of a gun barrel cleaning brush, a pig travels through a pipeline, scrubbing the interior circumference clean of debris as it is carried along by the media flow. Pressure from the media builds behind the snug-fitting pig, and pushes it along through the entire pipeline, providing the pig fits through all of the valves. Therefore, a piggable valve is any valve that allows the free travel of a pig.
Not every valve can do this. The design of some valve types makes it an impossibility. Take, for example, a butterfly valve, which utilizes a rod that runs through the center. It would not be possible to clean it using a pig. In order to work, a pig must have an outward circumference that is practically equal to a pipe’s bore, otherwise, it would be little more than a foreign object in the line, and would prove useless. Because of its size, it could not pass through a butterfly valve, or any other valve using a comparable plug. Nor would it normally be able to pass through a valve using a reduced bore (though multi-diameter pigging is possible with the right equipment, though it is more practical in larger diameter applications).
The valves in a pipeline that will be pigged must be through-conduit, otherwise, the pig will not pass through them. Through-conduit gate valves and ball valves are piggable. In addition, some check valves are piggable. Care should be taken, however, when using smart pigs or pigs with sensors, as the clapper of the check valve can damage the pig unless special design considerations are included. Generally, globe valves, butterfly valves, choke valves and plug valves are not piggable, unless a special pigging method or pig is used. The full bore ball valve lends itself well to the practice of pigging. Because when the valve is open, and the bore of the ball is parallel with the inlet and outlet ports, there is virtually no difference between the bore of the valve and the bore of the line. In this way, not only can the pig pass through the valve unimpeded, it can also clean the bore of the valve, as well as the line.
The process fluid and the type of pipeline largely determine pig type and whether or not pigging a pipeline is necessary. Proper valve selection is essential at the beginning of the pipeline construction process to ensure that pigging is possible if needed.
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