Pipeline Pigging Pig

Long-term use of natural gas pipelines. In this process, we also need to carry out pigging work. This operating technology allows us to clearly understand the real situation inside the pipeline. If the internal pipeline is found to be defective, it can also be repaired and maintained in time. It can also reduce the cost of the pipeline. The pigging technology we are using now can accurately obtain relevant data and information. We conduct baseline evaluations of gas pipelines. This provides a reference for the overall assessment. Strengthen the overall protection level of gas pipelines. This ensures the long-term safe operation of the pipeline.

Description

Long-term use of natural gas pipelines. In this process, we also need to carry out pigging work. This operating technology allows us to clearly understand the real situation inside the pipeline. If the internal pipeline is found to be defective, it can also be repaired and maintained in time. It can also reduce the cost of the pipeline. The pigging technology we are using now can accurately obtain relevant data and information. We conduct baseline evaluations of gas pipelines. This provides a reference for the overall assessment. Strengthen the overall protection level of gas pipelines. This ensures the long-term safe operation of the pipeline.

Moreover, it avoids gas leakage due to corrosion and perforation of the pipeline. In this regard, we focus on the types of pigs used in pipelines. Which pigging measures should be selected in terms of pipeline pigging technology? And the key content involved in pigging technology for long-distance pipelines. These provide references for the pigging technology of long-distance natural gas pipelines.

Pipeline Pigging Pig

Pigs for Pipeline Cleaning

We ensure the gas transmission efficiency of long-distance natural gas pipelines during normal operation. Therefore, it is necessary to carry out timely and effective pigging work on natural gas pipelines. In particular, the corrosion products of hydrogen sulfide accumulated in the gas pipeline due to long-term use. There is also condensate water and debris brought into the pipeline. In order to prevent blockage of gas pipelines and equipment failures. Then it is necessary to carry out regular pigging work on the pipeline.

In order to ensure the stability and safety of the pigging operation, ensure that the pigging device can be recovered after it is issued. Then, it is necessary to adjust the operation process of the pipeline in the operation area according to the actual application of the pipeline network. without affecting the users below. To control the reasonable operating speed of the pig. Therefore, it plays a very important role in the analysis and discussion of pigging technology for long-distance natural gas pipelines.

1. In the pigging technology of long-distance natural gas pipelines, there are three types of pigs mainly used

(1) Pigging Ball

Usually, the main material of pigging balls used in gas pipelines is rubber material. It’s empty in the middle. Tube wall thickness is in the range of 3-5 cm. There is also a sealed water injection vent on the upper part of the pigging ball. There is also a one-way valve for pressurization at the water injection port. It has the function of controlling the amount of water in the ball. This also controls the interference of the gas pipeline. The pigging ball has the function of removing the liquid inside the gas pipeline and separating the medium. But it is relatively poor in its ability to remove lumps.

(2) Mechanical pig

The main structure of the straight pipe pig is basically similar to that of the leather bowl pig. The straight plate pig is divided into two types: guide plate and a sealing plate. Its shape is a disc. The diameter of the guide plate is slightly smaller than the inner diameter of the gas pipeline. The sealing plate should have a certain degree of interference compared with the inner diameter of the gas pipe. This pig is capable of bidirectional movement. It has a particularly strong ability to clean up pipe debris. It is recommended to use a straight plate pig before the pipeline is put into production. Because if there is a pipe blockage. We can use this pig for backflushing. This thereby unblocks the pipe.

(3) Cup pig

Solid Cast Pigs

 

This type of pig has a simple structure. It is also more flexible in terms of installation. The leather bowls we usually use are divided into cones, planes, and spheres according to their shapes. This pig has a rigid frame and two or more leather cups in the front and rear. When it runs in a long-distance pipeline, it can run in a fixed direction. Therefore, the leather cup pig can carry the instruments and equipment for testing the pipeline. In order to ensure that the leather bowl pig can easily pass through the large diameter branch pipe tee. Therefore, the leather cups of the two sections before and after the pig should have the shortest interval limit. Through experimental conclusions and theoretical calculation results.

We have determined that the distance between the front and rear leather cups of the pig should be greater than or equal to its pipe diameter D. The total length of the leather cup pig should be between 1D and 1.5D according to the number of leather cup sections and the diameter of the pipe. The interference between the lip of the leather cup of the pig and the inner diameter of the gas pipeline should be in the range of 2%-5%. There are multiple seals in this pig. And the sealing performance is also very good. Its cleaning tool is a steel brush.

2. Pigging methods and selection methods for the use of long-distance natural gas pipelines

(1) Pigging scheme for waxy crude oil pipelines

Use waxy crude oil lines after a certain period of use. At this time, the oil wax will be deposited in the wall of the gas pipeline. When the oil wax is deposited to a certain thickness, the gas pipeline must be pigged. This can reduce the expenditure of gas pipelines in operation. Increase the capacity of gas pipelines. When carrying out wax cleaning and pigging operations on pipelines. We need to choose suitable soft pigs and mechanical pigs that can carry trackers. During pigging operations.

The first step is to use a soft pig to understand the specific conditions in the pipeline. After making sure there is no problem in the pipeline. We then use mechanical pigs to do the pigging work. The mechanical pig can carry out pig treatment for impurities and foreign matter in the gas pipeline. This also enables all-around removal with its steel brush. Or wax precipitation and corrosion rust in the pipe wall.

(2) Pigging methods for gas pipeline applications

Gases in natural gas pipelines usually contain gases such as carbon dioxide and hydrogen sulfide. All of these gases combine with water to form hydrates. This leads to the blockage of natural gas pipelines and equipment. At the same time, it poses a hidden threat to the safety of natural gas pipelines, for putting the gas pipeline into operation. We will choose traditional pigs for pigging operations. For example, the use of leather bowl pigs is aimed at the gas pipelines that transport moisture. Its main job is to remove water from the pipeline. At this time, we need to use a straight plate pig with a very good sealing performance to remove it. If it is a gas pipeline from a basement or a gas field. That kind of pipeline will contain condensate such as light hydrocarbons. We directly use straight plate pigs for removal.

(3) Pigging method of natural gas pipeline for mixed transportation of oil and water

In the long-term use of natural gas pipelines. When the two-phase flow pipeline runs for a long time, there will be liquid accumulation in the pipeline and corrosion of the inner wall. These liquids accumulate at low points in the line. This results in an increased pressure drop across the line. At the same time, the flow area in the pipeline is reduced.

The factors that affect the pigging effect in the pipeline of two-phase flow are:
The flow rate and pressure drop that a gas-liquid mixture is allowed to pass through in a gas pipeline. The gas-liquid ratio in the pipeline, and the shape of the pipeline longitudinal section. The amount of liquid accumulated in the line. The size of the plug-trapping instrument. In offshore pipeline systems, the height between the bottom of the riser and the liquid plug trapping instrument. The pigging method commonly used in pipelines for two-phase flow is to use general pigging balls and pigs for processing. In addition, we can also use pigs with bypass for pigging.

3. Key Contents of Pigging Technology Applied in Long-distance Natural Gas Transmission Pipelines

(1) Relevant procedures for arranging pigging operations

There are certain risks when pigging technology is for long-distance natural gas pipelines. If the staff is careless, the pig is stuck inside the gas pipeline. Then it is necessary to cut the pipeline to take out the pig. In this way, it is easy to cause gas leakage in the gas pipeline during transportation. Draw lessons from previous pigging operations in my country. The staff is in the process of pigging. The first step we should do is to use the straight plate pig to explore and detect. First, let’s understand what’s going on inside the gas pipeline. Then, according to the specific situation, a reasonable method is used to carry out the pigging operation of the gas pipeline. When carrying out the procedures of the pigging work, special attention should be paid to the step-by-step process. In other words, it’s not just about speed.

(2) Formulate specific pigging standards for pigging requirements

There are certain complexities and risks in the pigging work of long-distance natural gas pipelines. Careful planning must be done prior to pigging operations. Detailed pigging standards should be formulated for pigging technology. The staff must first search for the relevant drawings and data of the pipeline here. This can facilitate a clear understanding of the detailed parameters and actual conditions of this gas pipeline. Then, the staff will formulate a reasonable and detailed pigging measures plan. Carry out in accordance with the established operating procedures, step by step.

First, the pigs use foam pigs to conduct relevant inspections on the gas pipelines. If there is no serious damage to the pipeline, it can be treated with a butterfly-shaped leather cup pig. For example, the debris in the pipe wall does not exceed 20 kg. Then we can use an aluminum plate of suitable diameter to deal with it. If after inspection, there is no major damage or serious bending of the gas pipeline. Then the piggers can use the straight plate pigs for two-way transmission. In general, pipeline pigging must be carried out in accordance with established standard procedures. And don’t be too hasty.

(3) The pigging operation of the long-distance natural gas pipeline

To implement efficient supervision and management. Therefore, when carrying out the teeing operation of the pigging work of the natural gas long-distance pipeline. The pigging operators must do the relevant preparations first. Before pigging the pipeline, all parts such as the intake valve and the exhaust valve should be carefully maintained and inspected. In addition, it is necessary to strengthen the drill of pigging technology. This is to prevent sparks from occurring due to collision, friction, etc. during use. There are also places that require special attention.

When the pigging ball is recovered into the cylinder, the operator must replace it with nitrogen to reduce its pressure difference. There is also a balance valve installed at the reducing joint of the ball cylinder. during a slow boost. First, open the inlet and outlet valves of the ball cylinder in sequence. Then close its balancing valve. Finally, the service operation can be carried out normally and effectively.

4. Summary

In addition to the pigging technology mentioned above, the pigging technology of the long-distance natural gas pipeline. We also continue to track and monitor pigs. Many companies use corresponding receiving equipment for tracking and monitoring work. This can effectively avoid the situation where the pig is missing. Therefore, pigging technical operations is vital to work. It is of great significance whether before the long-distance natural gas pipeline is put into production or during the operation of the natural gas pipeline. It is the premise guarantee for the normal transmission and operation of natural gas pipelines. When pigging different types of gas pipelines. If you want to achieve the requirements of pigging. Then we must choose a reasonable type of pig and suitable pig technology.

So if you want to know more about Pipe Pig please contact our professionals to answer them for you.

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