Nowadays there is global use of pipelines for safe transportation of various liquids and gases over long distances. And there is a need to maintain all these pipelines in economically effective operation during decades.
The primary objective is to clean the inner cavity of pipelines from various deposits, which hinder the pumping of fluid or gas. Also it is necessary periodically clean pipelines to remove scale, rust and other debris, which for various reasons fall into it or remain inside after construction.
Regular cleaning of pipelines is economically justified, since it allows significantly reduce the cost of the product pumping. Variety of cleaning and batching in-line PIGs are run through a pipeline with the flow of liquid or gas. The cleaning of pipeline internal walls is made by polyurethane discs and cuffs as well as by brushes made of metallic wires and also by magnets. The sediments and dirt are removed from the pipeline into receiving chamber for proper disposal later.
The design of utility PIGs must ensure their safe passage (without stops and jams) along the entire length of the pipeline from the launching chamber to receiving chamber. And since each pipeline has its own structural features and defects of construction, so PIGs of different design are used.
Mechanical designers of APRODIT Ltd. used to divide all the designs of PIGs into two series based on their ability to pass without jams and damage through different narrowings and obstructions in the pipeline.
USO line PIGs are designed to pass narrowings in a pipeline up to 85% of Dout and 90 degrees bends with the bending radius R = 1.5D
CKT line PIG can run through constrictions up to 70% (in some designs to 65% or even 60%) of Dout and 90 degrees turns with the bending radius R = 1.5D
The PIGs of SKT series have body of smaller diameter and they are equipped with more flexible cleaning and sealing elements (disks, cuffs). It allows for SKT PIG to pass through bigger restrictions in a pipeline. However it somewhat reduces cleaning capacities of SKT line PIGs compared with USO. So several runs of SKT PIG can be required to achieve desired pipeline cleaning quality.
Since PIGs of USO line are not required to pass through significant narrowing of a pipeline, so they have a larger body diameter and are equipped with tougher cleaning elements. It allows to make a better cleaning of the pipeline in a single pass.
Specialists of the companies operating pipelines have different preferences and different demands to the optimal in-line PIG for the particular pipeline and the specific tasks that the PIG has to perform. Designers in APRODIT Ltd. strive to offer designs of PIGs, which can be adapted and customized to different requirements of different customers, while preserving the simplicity, reliability and maintainability at low costs and short deadlines of manufacturing.
We came to a conclusion that for various diameters and for optimum price vs. technical characteristics the PIGs ought to have different design of the housing (body).
For main trunk oil and gas pipelines with a nominal diameter 24" (600 mm) or more, we offer in-line PIGs with metal welded hull (a shell with flanges). Cleaning and supporting disks or cuffs made of PU are fixed between the metal flanges of the PIG by bolts.
For "medium" pipelines with diameters 8" to 22" (DN 200 .... 500 mm) the best design is the PIG body assembled from hard polyurethane bushings tightened by multiple metal pins. Hull bushings are made of polyurethane with hardness 95 units of Shore A scale or harder. Replaceable cleaning discs or cuffs made of more flexible and wear-resistant polyurethane are clamped between the body bushings the same way as on the PIGs with a metal housing. For these diameters the PIG body made of polyurethane bushings is lighter. And at the same time this design eliminates the risk of damage to the valves.
For the infield, "small" diameter pipelines the optimal design seems to be all-polyurethane solid-cast PIGs. When the cleaning elements of such PIG wear off then simply replace it with inexpensive new one. Indeed the replacement of individual polyurethane discs or cuffs on small PIGs is tedious and don't save big budgets.
When analyzing the advantages and disadvantages of the various PIG designs it worth to remember that the ability of the PIG to clean the inner cavity of the pipe is determined by the quality of the polyurethane, of which the cleaning elements (disks and cuffs) are made. Also the force which the edge of the cleaning element is pressed against the inner surface of the pipeline plays a role. The body of the PIG serves only for fixing and holding of the cleaning elements and transmitter. For cleaning performance the design of PIG's body shows little effect.
While designing a PIG the specialists of APRODIT Ltd. assume that the costs of search and retrieval of a stuck PIG without low-frequency transmitter will many times exceed the cost of the transmitter. That is why all our PIGs have cavities for installation of the low-frequency transmitter. Its installation in a PIG is simple and always can be done by specialists of the pipeline operating organization.
Wide range of overall dimensions for certified transmitters of PNT series allows them to be installed in any PIG, in-line scraper or smart inspection in-line tool of any diameter. Along with different PIGs and transmitters, we also offer a wide range of other devices used during in-line inspections and pigging of pipelines such as: low-frequency receivers NPR, acoustic amplifiers LKA, temperature and pressure loggers RDT., in-line form-measuring multi-channel geometry PIG of PVM line.
For many, both standard and specific tasks related to pigging or inspection of pipelines we already have ready-made solutions. Even if you have not found on our website a description of an equipment that your organization need to solve a specific problem related to cleaning or inspection of the pipeline, you can write to APRODIT via email@example.com
Our specialists will answer in short time and will try to propose a solution for your problem.
Manufacturer: APRODIT Ltd.
140402, Russia, Moscow region, Kolomna, Okskiy prospect 40.
Have a question? Please contact us by phone +7 (916) 674-82-59 (English) or by e-mail firstname.lastname@example.org