Product Introduction of Suction Main Pipe
The suction main pipe is an important pipeline accessory of the suction system at the hydraulic end of the plunger pump. It is usually installed on one side of the suction inlet at the hydraulic end, used to connect the upstream supply pipeline and distribute the working medium entering the main pipe to the corresponding suction channels of each plunger.
For multi-plunger pumps such as three-cylinder and five-cylinder ones, the working chambers of each plunger periodically draw in the medium at a certain phase. The suction main pipe provides a common liquid supply channel for each suction valve through the main pipe cavity and multiple branch interfaces. It is an important connecting component between the external suction pipeline and each suction inlet at the hydraulic end.
The suction main pipe itself does not control the unidirectional flow of the medium. It is the suction valve assembly inside the hydraulic end that truly accomplice the opening and closing of the suction valve. The main task of the suction main pipe is to convey, converge and distribute the medium, and to minimize unnecessary suction resistance and local flow losses as much as possible.
The main function of the intake duct
1. Connect to the external liquid supply system: The inlet of the main suction pipe is matched with the on-site suction pipeline, liquid supply pipeline or corresponding connection components to introduce the medium to be conveyed into the hydraulic end of the plunger pump.
2. Distribution of medium to multiple pump chambers: The main pipe is set up with corresponding branches based on the number of plungers and the structure of the hydraulic end to transport the medium to the inlet areas of each suction valve, providing medium for the suction process in different plunger working chambers.
3. Form a common suction flow channel: Concentrate multiple hydraulic end suction ports into a single main pipe system to reduce the structural complexity caused by separate connections of external pipelines to each suction port.
4. Maintain the connection relationship on the suction side: The positions, center distances and installation directions of the interfaces of each branch of the main pipe should match the structure of the hydraulic end, so that multiple suction ports can be connected and sealed in accordance with the specified positions.
Working principle
When the plunger moves in the direction of expanding the volume of the working chamber, the corresponding pressure in the pump chamber drops. Under the action of the pressure on the suction side, the suction valve opens, and the working medium enters the suction main pipe through the external liquid supply pipeline, and then passes through the corresponding branch and suction channel to enter the pump chamber.
When the plunger enters the compression and discharge stage, the suction valve closes. The plungers of a multi-plunger pump operate continuously in accordance with the specified phase, so the suction main pipe needs to continuously supply liquid to different suction branches.
Therefore, the flow cross-section, branch structure and interface dimensions of the suction main pipe need to be matched with the pump's displacement and the suction system. If the main pipe or the upstream pipeline has insufficient diameter, is severely blocked or has excessive local resistance, it may cause deterioration of the suction conditions and affect the normal liquid filling of the plunger pump.
Structural and interface characteristics
Main pipe: The main common flow channel that constitutes the suction medium, and its inner diameter and internal structure should match the suction flow requirements of the corresponding pump type.
Liquid inlet interface: It is used to connect the external liquid supply pipeline. Specifically, it can adopt flange, flange or other connection forms, and should be determined according to the original equipment interface.
Branch interfaces: Arranged according to the number and position of the suction ports at the hydraulic end, they are respectively connected to the corresponding suction channels. The number of branches cannot be separated from the unified regulations of specific pump types.
Installation connection parts: Between the main pipe and the hydraulic end, flanges, fasteners and corresponding static seals are usually also involved. The specific connection structure should be restored according to the original pump design.
The fit relationship with the suction valve
Although the main suction pipe and the suction valve are both in the plunger pump suction system, their functions are different. The main suction pipe is responsible for transporting and distributing the medium to the intakes of each suction valve. The suction valves open and close based on the pressure difference between the pump chamber and the suction side, controlling the medium to enter the working chamber in one direction.
Therefore, when insufficient suction occurs, in addition to checking the suction valve and spring, it is also necessary to inspect the suction main pipe, upstream pipeline, filter device and connection points for any blockage, air leakage, insufficient diameter or other problems that affect the suction conditions.
Key points for selecting the intake main pipe
The suction main pipe is not a common pipe fitting that can be selected merely based on the "pipe diameter". For the dedicated suction main pipe of plunger pumps, the number of branches, the distance between branch centers, and the interface position with the hydraulic end are particularly important.
For instance, plunger pumps with different numbers of cylinders and different hydraulic end models may not be interchangeable even if the inlet diameters are the same due to differences in the number of branches, center distances, flange sizes or overall lengths.
When making a purchase, it is recommended to focus on confirming the following: pump model, hydraulic end model, inlet diameter, inlet connection form, number of branches, specification of branch interfaces, center distance of each branch, overall size of the main pipe and the original part number.
Common examination areas
When conducting maintenance on the main suction pipe, it is necessary to check whether there is corrosion, erosion, cracks, deformation and internal deposits in the main pipe and branch lines, and pay special attention to inspecting each connection interface and sealing surface.
For the parts connected by flange, the flange sealing surface, bolt holes and the matching sealing parts should be inspected. For parts that adopt the connection form of Ren or other methods, the condition of the connection threads, sealing surfaces and sealing elements should be inspected.
If there is abnormal leakage or a decline in suction performance on the suction side, the connection positions between the main pipe and each branch of the hydraulic end should also be inspected to confirm that there is no seal failure, loose connection or external air entering the suction system.
Installation and Maintenance
Before installing the main suction pipe, the internal flow channel should be cleaned to prevent welding slag, metal shavings, old sealing materials and other foreign objects from entering the suction valve and the pump chamber.
When installing the main pipe, it is necessary to ensure that each branch interface is correctly centered with the suction inlet of the hydraulic end. Do not eliminate obvious pipeline misalignment by forcibly tightening the bolts, as this may cause additional installation stress on the main pipe and the hydraulic end interface.
The multi-interface connection structure should be uniformly tightened in accordance with the requirements of the corresponding equipment, and the flange gasket, sealing ring or other static sealing parts should be correctly installed. The tightening torque and installation sequence should be carried out in accordance with the technical requirements of the specific pump type.
After the equipment is put into operation, it is necessary to check whether there is any leakage at each interface and observe whether the suction state of the plunger pump is normal. Before overhauling the main pipe, the machine should be shut down, depressurized and the relevant pipelines isolated in accordance with the equipment operation procedures.
Procurement Instructions
Juli Petroleum Drilling and Production Equipment Co., Ltd. provides suction main pipe and hydraulic end suction system accessories for plunger pumps. There may be significant differences in the main pipe diameter, the number of branches, the center distance of branches, the inlet interface, the connection method of the hydraulic end and the overall dimensions of the suction main pipes of different pump types. When making a purchase, it is recommended to provide the pump model, hydraulic end model, original part number, interface size, physical sample or technical drawing to accurately verify the product.