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Requirements for the horizontal pipeline prior to vertical pumping with a truck-mounted concrete pump
Release time:
2026-09-08
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Summary:
In vertical concrete pumping operations, the horizontal pipeline is not a dispensable transition section but an essential component of the vertical pumping system. Its installation requirements are primarily based on two national standards: JGJ/T 10-2011 “Technical Code for Concrete Pumping Construction” and GB 50666-2011 “Code for Construction of Concrete Structures.”
I. The Necessity of Installing Horizontal Pipes: Balancing Backflow Pressure
When pumping vertically upward, during the concrete pump’s valve reversal to draw in concrete or when pumping is stopped, the weight of the concrete in the vertical pipe generates a backflow pressure—referred to as “back pressure”—on the pump. The greater the height of the vertical run, the larger this backflow pressure becomes. Such backflow pressure reduces the pump’s volumetric efficiency, diminishes its delivery rate, and can lead to concrete segregation or even blockages. In horizontal runs, friction between the concrete mix and the pipe wall helps counteract this backflow pressure, preventing the concrete from flowing backward under its own weight. Without a sufficiently long horizontal section to provide adequate cushioning, the entire weight of the concrete column in the vertical pipe would be borne directly by the pumping system, increasing pumping resistance and potentially causing concrete to flow backward during pauses, leading to segregation within the distribution valve and significantly raising the risk of pipe blockage upon restart.
II. Minimum Length Requirements for Horizontal Pipes
With regard to the minimum length of horizontal pipelines, the current codes prescribe two concurrently applicable criteria, which should be selected based on the specific operating conditions.
20-meter standard. This requirement is primarily derived from various safety technical briefings and operational specifications: vertical pumping pipelines shall not be directly connected to the pump’s discharge outlet; instead, a horizontal pipeline at least 20 meters long must be installed at the upstream end of the vertical pipe, with a check valve fitted near the pump on the horizontal section. This standard applies to medium‑height vertical pumping in conventional construction and municipal engineering projects, offering simple operation and ease of on‑site implementation.
Equivalent length criterion. JGJ/T 10-2011 and GB 50666-2011 explicitly stipulate that, when conveying concrete vertically, the total equivalent length of straight and bent sections of the horizontal delivery pipeline on the ground should not be less than 20% of the vertical delivery height, nor less than 15 m. This standard more precisely links horizontal buffering capacity to the vertical delivery height, quantifying buffering capability as the sum of the equivalent lengths of horizontal pipe and bends. The equivalent length of horizontal pipe is taken as its actual length (with a coefficient of 1.0), while each 90° bend contributes approximately 0.10, and each 45° bend about 0.05; the total equivalent length of straight and bent sections of horizontal pipe is calculated by sequentially adding these values.
In practical applications, if the required length calculated according to the converted‑length criterion is less than 20 m, the requirement of not less than 20 m must still be met. In engineering practice, the two standards may be applied in combination to ensure adequate horizontal buffering capacity.
III. Arrangement of the Check Valve and Conical Tube
A check valve (one-way valve) must be installed near the pump on the horizontal pipeline. Its function is to close automatically when the pump stops, thereby preventing backpressure surges from the concrete column in the vertical pipe from impacting the pumping system and ensuring that concrete does not flow backward into the hopper. At the discharge outlet of a truck-mounted pump, a conical transition piece should be fitted downstream of the “Y”‑shaped pipe to provide a smooth transition from the pump outlet diameter to the delivery hose diameter, thus minimizing pressure spikes.
IV. Support and Fixing of Vertical Pipelines
Both vertical and horizontal pumping pipelines shall be secured with supports and firmly connected to the structure; support spacing shall be increased at pipeline bends. On walls and columns, each pipe section must have no fewer than one fixing point, and all openings in floor slabs shall be properly anchored. The bent pipe at the lower end of a vertical line shall not serve as a support for the upper piping; steel supports should be provided to bear the weight of the vertical pipe. Pumping pipelines and their supports must never be directly attached to scaffolding or formwork to prevent safety hazards. For horizontal straight runs, a conversion factor of 0.10 applies for every 20 m; for vertical runs, a conversion factor of 0.10 applies for every 5 m—these factors are used in calculating pipeline pressure losses but should not be confused with the minimum‑length requirements for horizontal piping.
V. Supplementary Requirements for the Installation of Horizontal Pipelines
Horizontal pumping pipelines should be laid in straight runs, with the number of bends and flexible hoses kept to a minimum. During hot weather, cover the pipeline with wet burlap or straw bags and apply water to cool it, preventing high‑temperature dehydration of the concrete inside the pipe that could lead to blockages. Before pumping, first convey cement mortar to lubricate the pump and pipeline, then begin concrete delivery—starting slowly and gradually accelerating until the system is running smoothly, at which point operation can proceed at normal speed.
Conclusion
The layout of horizontal piping prior to vertical pumping with a truck‑mounted concrete pump is primarily intended to balance backflow pressure and prevent concrete segregation and reflux. Specific requirements include: the total equivalent length of straight and bent sections should not be less than 20% of the vertical delivery height and must be no shorter than 15 m; at the safety‑technical briefing stage, a minimum length of 20 m is recommended; a check valve must be installed near the pump on the horizontal line; following the “Y”‑shaped pipe at the pump outlet, a tapered section should be fitted to ensure a smooth transition in pipe diameter; and all piping must be securely supported by brackets. When developing the design and construction plan, a comprehensive calculation should account for the vertical delivery height, pipe diameter, and number of bends, ensuring that the horizontal pipeline’s buffering capacity meets the actual pumping requirements and thereby maintaining continuous operation.
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