In pipeline transportation, Piping Pig is pipeline detection. It is generally known as the practice hog or scraper of the device. At the same time, it can perform various maintenance operations. This is done without stopping the flow of products in the pipeline.
These operations include but are not limited to cleaning and inspecting pipes. This is where the pig is inserted into the “pig launcher”. (or “launch station”) – that is, a super-section in the pipeline. This is accomplished by reducing it to its normal diameter. The launch station is then closed and the pressure-driven flow of product in the pipeline is used to propel the pig down the pipeline. until it reaches the receiving trap – the “pig trap” (or “receiving station”).
Cup Piping Pig
-40 Deg.C ~ +120 Deg.C
2 inches ~ 60 inches
There are many pigs commonly used in long-distance natural gas pipelines. For example, pigging balls, polyurethane foam pigs, mechanical pigs, caliper pigs, and smart pigs (magnetic flux leakage detection pigs). and isolation pigs for reducing oil contamination in sequential transfers. The specific classification of cleaners is as follows:
1. Pigging ball
The pigging ball is made of neoprene. Hollow, the wall thickness is 10% of the pipe diameter (30~95mm). It controls the amount of water injected through the one-way valve of the water injection vent hole on the pigging ball. In this way, the interference of the pigging ball is controlled. The pigging ball is mainly used to remove the fluid in the pipe and the separation medium. It includes the isolation of different oil products in the sequential delivery of oil products. There is also the removal of air in the pipe during the hydrostatic test of the pipe.
The disadvantage of the pigging ball is that it has poor ability to remove lumps and dust. For example, the diameter of the branch pipeline is greater than 1/2 of the diameter of the trunk pipeline. Or use an equal diameter tee. At the same time, it does not have a protective bar, which is easy to cause ball jamming.
The length of the polyurethane foam pig is 1.75 to 2 times the diameter of the pipe. Its interference is generally 25mm or 5% to 10% of the pipe diameter. This has high elasticity, toughness and certain wear resistance. At the same time, its deformation exceeds 50%. The foam pig has a strong passing ability and is easy to pass through the bend. It can be passed through even if a jam occurs due to its high deformation performance. Or the operator increases the pressure to make it rupture and remove the blocked pipe by itself. Therefore, it will not cause a pressurization accident. The foam debris of the foam pig does not cause any damage to the inner wall of the pipeline. So it is suitable for cleaning pipes with inner wall coating.
The disadvantage is that the ability to remove debris is average. The product is mainly used for pipeline water absorption and cleaning. It is single-use only and has a shorter running distance.
The mechanical pig can not only remove liquid accumulated in the pipe, but also remove solid impurities. It can also install steel brushes and scrapers to enhance the pigging effect as needed. The mechanical pig has a long service life and can generally run for 800~1000km. And operators can install tracking devices, caliper plates, magnets, and more. The disadvantage is that the passability is slightly poor, and it is not suitable for multi-elbows, valves and pipes with large deformation. The mechanical pigs used in domestic pipelines are mainly dish-shaped leather bowl pigs and two-way straight plate pigs. The interference of the disc-shaped cup cleaner is generally 3% to 5% of the pipe diameter. Its passing capacity is better than that of two-way straight pigs. The leather bowl pig runs in a fixed direction in the pipeline.
Therefore, this product is mainly used to remove liquid, dust and other dirt in the pipeline. The cleaning ability of the two-way straight plate pig is better than that of the cup pig. In particular, it can effectively remove suspended dirt in the pipeline. Compared with the dish type cup, the wear is faster and the running distance is shorter. There is better pigging efficiency in short-distance pipe sections. The straight pipe pig can move in both directions. When the pipeline is put into production or the pipeline is not cleaned for a long time, if it is blocked, it can be blown back to remove the blockage.
Caliper pigs measure parameters such as pipe geometry, ovality, roughness and weld penetration. These provide raw base data on the condition of the pipeline. This also provides the basis for pipeline maintenance and pigging. The diameter of the caliper pig is about 60% of the pipe diameter. The flexibility of the cup is good, and it can pass through 15% of the shrinkage cavity. The key technologies of the caliper pig are speed control, detection accuracy, reliability, and post-data processing and analysis. Before intelligent pigging (in-pipeline detection), the caliper pig should be launched first. Then determine the internal condition of the pipeline. Finally, check the passing capacity of the pipeline.
Application of Piping Pig
In the petroleum industry, pipe pigs have been used to clean large diameter pipelines for many years. Today, however, as plant operators seek to increase efficiency and reduce costs. So smaller diameter pigging systems are increasingly being used in many continuous and batch processing plants.
Pigging can be used for almost any part of the transfer process between mixing, storage or filling systems. Pigging systems have been installed in industries that handle a variety of products such as lubricants, paints, chemicals, cosmetics, cosmetics and food.
Pipe pigs are used for lubricating oil or paint mixing to clean pipes to avoid cross-contamination. and empty the pipes into product tanks (or sometimes send components back to storage tanks). Typically pigging is performed at the beginning and end of each batch. But sometimes it does it in the middle of the batch. For example when producing premixes that will be used as intermediate components.
Pipe pigs are also used in oil and gas pipelines to clean the pipeline. There are also “smart pigs” used to check pipelines for leaks, which can be explosive and dangerous to the environment. They usually do not interrupt production, but some products may be lost when pigs are extracted. They can also be used to separate different products in multi-product pipelines.
If there are butterfly valves or shrinking ball valves in the pipeline, the pipeline cannot be pigged. Full bore (or full-bore) ball valves don’t cause any problems. Because the inner diameter of the ball opening is the same as the inner diameter of the pipe.
Advantages in a production environment
Product and Time Savings
A major advantage of multi-product pipelines with piggable systems is the potential for product savings. At the end of each product transfer, the pig can be used to remove the contents of the entire production line. Forward to the sink point, or backward to the source tank. It does not require extensive line flushing.
Without the need to flush the lines, the pigs offer the added benefit of faster and more reliable product changeovers. Product sampling at the point of receipt with a pig is faster. Because the interface between products is very clear. The old method of checking every once in a while to make sure a product meets specifications takes much longer. Pigging can also be fully operated by a programmable logic controller (PLC).
Pigging plays an important role in reducing the environmental impact of batch operations. Traditionally, the best way a batch operator can ensure the complete removal of the product from a line is to flush the line with a cleaning agent such as water or solvent, or even the next product. The cleaning agent must then be subjected to wastewater treatment or solvent recovery. If the product is used to clean up a production line, the contaminated portion of the product must be downgraded or dumped. Due to the very precise interface produced by modern pigging systems. All these problems can now be eliminated.
The pigging system is designed so that the pigs are loaded into the launcher. The launcher is then pressurized to launch the pig through the injection line and into the pipeline. In some cases, pigs are removed from the pipeline by receivers at the end of each run. All systems must allow pigs to be received at the launcher. A blockage in the pipe may require the pig to be pushed back into the launcher. Many systems are designed to pig the pipeline in either direction.
Push the pig with gas or liquid. If propelled by gas, some systems can be adjusted at the inlet to ensure a constant velocity of the pig regardless of the flow pressure. The pig must be removed. Because many pigs are rented. So the pigs wear out and have to be replaced. And cleaning (and other) pigs push the contaminants out of the pipes. Such as wax, foreign matter, hydrate, etc. Operators must remove these contaminants from the pipeline. There are inherent risks in opening the barrel to atmospheric pressure. Care must therefore be taken to ensure that the barrel is depressurized prior to opening it. If the bucket is not fully depressurized, the pig may pop out of the bucket when standing in front of an open pig door. The operator could be seriously injured.
There have been pipe pigs accidentally shot off the end of pipes without a suitable pig receiver. And it went through a house 500 feet away. When the product goes sour, the drum should be emptied to a flare system that burns the sour gas. Operators should wear self-contained breathing apparatus when working on acidic systems.
Some pigging systems use Piping Pig. Pipelines are opened only occasionally to check the condition of the pigs. Other times, pigs shuttle up and down the pipeline at the end of each transfer. Pipelines are never opened during process operation. These systems are not standard.