1.Pipeline Pig Types

Pipe cleaning can effectively remove impurities inside the pipeline, delay corrosion of the inner wall, reduce friction resistance, reduce oil transportation energy consumption, remove water accumulation in low-lying areas, and prevent accidents. There are many pipeline pig types in use, and their applicable conditions and functions are also different. Therefore, before the pipe cleaning operation, the pipe cleaner should be selected according to the pipeline type, state and cleaning target, so as to achieve the purpose of efficient operation. The commonly used pipeline pig types are as follows:

a. Pigging Ball

The ball is made of elastic material, and the interference is usually 1~2%. It is mainly used for irregularly shaped pipes, such as 90-degree angles, irregular bends and curved pipes. It is usually used to remove liquids, paraffin and accumulated liquid after water pressure tests in pipelines.

b. Foam Pig

Foam brush pigs are used to clean irregular pipes, fittings and valves. They are mainly used to identify obstructions, dry, remove loose dirt and liquid accumulation before running expensive ILI pigs. They can also be coated with polyurethane, attached with steel brushes or silicon carbide to achieve other specific functions.

c. PU Cup Pig

Cup pipe cleaners are mainly cup-shaped or disc-shaped, suitable for pipes with a diameter of less than 36 inches. They can effectively remove liquids in crude oil pipelines and condensed water in natural gas pipelines, and can prevent paraffin accumulation. The hollow space between the disc or cup of the cup pipe cleaner can be filled with chemicals, thereby promoting the protective effect of the chemicals on the pipeline.

d. Bi-di Disk Cup

Bidirectional straight plate pigs are usually disc-shaped and are mainly used in conditions where the pipeline geometry is unclear, because they can pass in both directions and can be reversed when stuck in dents, buckles or other restrictions. They are also commonly used to separate corrosion inhibitors from pipeline products during pipeline cleaning and to clean up accumulated liquid after hydrostatic testing.

2. Pipeline Pig Types selection methods for long-distance natural gas pipelines

In order to ensure the gas transmission efficiency of the long-distance natural gas pipeline during normal operation, it is necessary to carry out timely and effective cleaning of the natural gas pipeline. Especially the hydrogen sulfide corrosion products accumulated in the gas pipeline due to long-term use, condensate water and debris brought into the pipeline to prevent blockage of the gas pipeline and equipment failure.

In order to ensure the stability and safety of the cleaning operation, it is necessary to ensure that the pig can be retracted after it is sent out. Then, it is necessary to adjust the operation process of the pipeline in the operation area according to the actual use of the pipeline network, and control the reasonable operation speed of the pig without affecting the users below. Therefore, it is very important to analyze and discuss the cleaning technology of the long-distance natural gas pipeline.

a. There are three main types of pigs used in long-distance natural gas pipeline cleaning technology:

01 Pipe cleaning balls

They are usually made of rubber materials, with a hollow center and a wall thickness of 3-5 cm. There is also a sealed water injection and exhaust hole on the top of the pipe cleaning ball, and a one-way valve for pressurization at the water injection port. It controls the amount of water in the ball, and thus the interference of the gas pipeline. Pipe cleaning balls can remove liquid and separation media inside the gas pipeline, but their ability to remove lumps is relatively poor.

02 Disk pipe cleaner

The main structure of the straight plate pipeline pipe cleaner is basically similar to that of the leather cup pipe cleaner. The straight plate pipe cleaner is divided into two types: guide plate and sealing plate. It is disc-shaped, and 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 pipeline. This type of pipe cleaner can move in both directions. It has a particularly strong ability to clean up pipeline debris. It is recommended to use a straight plate pipe cleaner before the pipeline is put into production, because if there is a pipeline blockage, this type of pipe cleaner can be used for backblowing operations to remove the pipeline blockage.

03 Cup pipe cleaner

This type of pipe cleaner has a simple structure and is more flexible in installation. The commonly used cups are divided into conical, flat and spherical types according to their shapes; this type of pipe cleaner is composed of a rigid frame and two or more leather cups in front and behind. When it runs in a long-distance pipeline, it can run in a fixed direction, so the cup pipe cleaner can carry instruments and equipment for detecting pipelines.

To ensure that the cup pipe cleaner can easily pass through the large-diameter branch pipe tee, the cups of the front and rear sections of the pipe cleaner must have a shortest spacing limit. Through experimental conclusions and theoretical calculation results, it is determined that the distance between the front and rear cups of the pipe cleaner should be greater than or equal to the pipeline diameter D. The total length of the cup pipe cleaner can be between 1D and 1.5D according to the number of cup sections and the pipeline diameter. The interference of the leather cup lip of the pipe cleaner with the inner diameter of the gas pipeline should be in the range of 2%-5%; there are multiple seals in this pipe cleaner, and the sealing performance is also very good. Its cleaning tool is a steel brush.

b. Pipe cleaning methods and selection methods for long-distance natural gas pipelines

01 Pipe cleaning scheme for waxy crude oil pipelines。

After a certain period of use, waxy crude oil pipelines will deposit on the wall of the gas pipeline. When the wax deposits to a certain thickness, the gas pipeline must be cleaned. This will reduce the cost of gas pipeline operation and increase the transportation volume of the gas pipeline.

When cleaning the pipeline, it is necessary to select a suitable soft pipe cleaner and a mechanical pipe cleaner that can carry a tracker. When cleaning the pipeline, the first step is to use a soft pipe cleaner to understand the specific situation in the pipeline. After ensuring that there are no problems in the pipeline, use a mechanical pipe cleaner to do the cleaning work. The mechanical pipe cleaner can clean the impurities and foreign bodies in the gas pipeline, and can also use its steel brush to remove wax and corrosive rust in the pipeline wall in an all-round way.

02 Pipe cleaning methods for gas pipelines

The gas in the natural gas pipeline usually contains gases such as carbon dioxide and hydrogen sulfide. These gases will combine with water to form hydrates. This leads to the blockage of natural gas pipelines and equipment, posing a hidden threat to the safety of natural gas pipelines. For gas pipelines that are put into operation, traditional pipe cleaners are selected for pipe cleaning operations. For example, bowl pipe cleaners are used for gas pipelines that transport wet gas. Its main job is to remove water from the pipeline. At this time, we must use a straight plate pipe cleaner with very good sealing to remove it. If it is a gas pipeline coming out of a basement or gas field, this pipeline will contain condensate such as light hydrocarbons. We directly use a straight plate pipe cleaner to remove it.

03 Pipe cleaning method for natural gas pipelines with mixed oil, gas and water

In the long-term use of natural gas long-distance pipelines, two-phase flow pipelines will accumulate liquid in the pipeline and corrode the inner wall during long-term operation. These liquids accumulate at the low point of the pipeline, resulting in an increase in the pressure drop of the pipeline, reducing the flow area in the pipeline, and reducing the efficiency of transporting natural gas.

The factors that affect the cleaning effect in two-phase flow pipelines include: the flow rate and pressure drop of the gas-liquid mixture in the gas pipeline; the gas-liquid ratio in the pipeline, the shape of the longitudinal section of the pipeline; the amount of liquid accumulated in the pipeline; the size of the liquid plug capture device; in the offshore pipeline system, the height between the bottom of the riser and the liquid plug capture device. The commonly used cleaning method for two-phase flow pipelines is to use general cleaning balls and cleaning devices, and can also use cleaning devices with bypass for cleaning.

c. The key content of the application of clear pipeline clearance technology of natural gas long -distance pipelines

01 Arrange relevant procedures for clearance work operations

There will be a certain risk for the use of tube clearance technology to clear pipe clearance technology. If the staff is careless to stuck the pipeline clearance in the inside of the gas transmission pipe, the method of cutting the pipeline must be performed to get it to get the way to get it. Clear the tube, so that the gas leakage can be leaked during transportation. During the experience and lessons of the previous work operations of my country’s previous management operations, the staff should do the first step in the process of conducting management operations. The specific situation uses a reasonable method to clear the management operation of the gas transmission pipeline; when the procedures for the clearance of the management work, pay special attention to the step -by -step, and we must not just value the speed.

02 To formulate specific clearing standards for clearing management requirements

There are certain complexity and risks when the clearance work of the natural gas long transmission pipeline. Before conducting the management operation, a detailed plan must be carried out. Detailed standard clearance standards must be formulated for clearing management technology. Staff must carry out first The relevant drawings of the pipeline here are found to clearly understand the detailed parameters and actual situations of the gas transmission pipeline. Then, the staff will formulate a reasonable and detailed management measures and carry out in accordance with the formulated operating procedures, and step by step.

First of all, the clearance personnel use the foam pipe clearance device to conduct a related inspection of the gas transmission pipeline. If there is no serious damage to the pipeline, then the butterfly leather bowl clearance can be used to do it. For more than 20 kg, you can use an aluminum plate with a suitable diameter. If it is inspected, there is no major damage and severe bending in the gas transmission pipeline, and the clearance personnel can use the straight panel clearance in two -way sending. Overall, when the pipeline is cleared, it must be implemented in accordance with the standard procedures formulated, and it must not be overwhelmed.

03 When the natural gas -long infusion pipes conduct the serving operation of the clearance, efficient supervision and management must be implemented

When the setting operation of the clearance work of the natural gas -long transmission pipeline, the staff of the clearance management industry must first do the relevant preparations. Before the pipeline is cleared, the intake valve, the air outlet valve and other parts must be carefully carried out. Maintenance inspection work. In addition, we must also strengthen the drill of clearance technology to prevent sparks from colliding and friction during use; there are also places that need special attention to the clearance balls to retract the cylinder, the operator is It is necessary to use nitrogen for placement in exchange for the pressure difference; and the balance valve must be installed at the different diameter joint of the hairpin. , Make serving operations normally and effective.

3. Conclusion

In addition to the use of the above -mentioned clearance technology, the clearance technology of natural gas long -distance pipelines must continue to track and monitor the work of the tube clearance. Nowadays, my country usually uses the method of tracking device, so it is also necessary to strengthen the work of clearing tube clearance. However, today, with the rapid development of science and technology, many companies are no longer using artificial monitoring methods. They usually use the method of directly installing trackers on the clearance cleaner. They can use the corresponding receiving equipment to track and monitor the work. This can Effectively avoid the disappearance of pipe clearance.

Therefore, the technical operation of clearing pipeline is a very important job. It is of great significance in the operation of the natural gas pipeline before the natural gas pipeline is put into operation. It is a prerequisite for normal transportation and operation of natural gas pipelines. When clearing the pipelines of different types of gas transmission pipes, in order to achieve the requirements of clearing the pipeline, you must choose a reasonable type of tube types and suitable clearance techniques.