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Classification of Pressure Ratings for Pipelines on Fully Automatic Wet-Spraying Trolleys
Release time:
2026-08-24
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Summary:
Fully automatic wet‑spraying rigs are used to convey wet‑mixed concrete in tunneling and underground construction projects, and their pipeline systems must maintain reliable sealing under conditions of sustained high‑pressure impact and abrasive particle erosion. In China, the pressure rating of concrete delivery pipelines is classified into three levels—low pressure, high pressure, and ultra‑high pressure—and this classification system is specified in GB/T 32543, “Construction Machinery and Equipment: Concrete Delivery Pipes—Connection Types and Safety Requirements.” The establishment of these technical parameters provides a unified basis for design and selection, facilitating compatibility and management across different equipment models and project conditions.
I. Classification Criteria and Technical Background of Pressure Ratings
The classification of pipeline pressure ratings is based on the relationship between the operating pressure range of the wet‑spraying rig’s hydraulic system and the structural strength of the pipeline. The main pumping pressure of the wet‑spraying rig’s hydraulic system typically ranges from 16 to 28 MPa, and the actual working pressure level determines the pressure‑resistance requirements for the delivery pipeline. Concrete delivery pipes are classified by nominal inner diameter into 80 mm, 100 mm, 125 mm, and 150 mm; among these, 125 mm is widely used in truck‑mounted pumps and wet‑spraying rigs, while 150 mm is predominantly employed in applications involving larger aggregate sizes or ultra‑long‑distance pumping.
II. Classification of Pressure Ratings and Parameter Characteristics for Rigid Pipelines
The Type 125 pump pipe (nominal inner diameter 125 mm) is the most widely used specification for wet‑spraying rigs. Based on its structural parameters, it is classified into two grades: low‑pressure and high‑pressure. The low‑pressure version has an outer diameter of Φ133 mm and a wall thickness of 4 to 5 mm, with standard flange connections; the high‑pressure version features an outer diameter of Φ140 mm and a wall thickness of 6 to 10 mm, with correspondingly reinforced flanges. The selection of wall thickness for high‑pressure delivery pipes is directly related to the operating pressure: for an outer diameter of Φ140 mm, a 6‑mm wall thickness is suitable for typical high‑pressure pumping conditions, while 8‑mm or 10‑mm wall thicknesses are recommended for ultra‑tall structures or long‑distance high‑pressure pumping.
Type 150 (nominal inner diameter 150 mm) pump hoses are likewise available in two grades: the low-pressure version has an outer diameter of Φ159 mm and a wall thickness of approximately 5 to 6 mm; the high-pressure version features an outer diameter of Φ168 mm and is equipped with a double-flange connection. In practical applications with truck-mounted pumps, the theoretical delivery pressure typically reaches 10 MPa under low-pressure conditions and can climb as high as 20 MPa under high-pressure conditions; some high-performance models even achieve a maximum outlet pressure of up to 28 MPa. In wet‑spraying rig systems, the pump’s outlet pressure generally ranges from 6 to 9 MPa, with high‑performance models capable of delivering pressures exceeding 8.5 MPa.
SANY Heavy Industry’s truck-mounted pumps offer adjustable delivery pressures to accommodate a wide range of pipe diameters. With a low-pressure flow rate of 108 m³/h and a high-pressure flow rate of 58 m³/h, and a delivery cylinder bore of 230 mm, these pumps can be configured to meet various pipeline pressure ratings, ensuring optimal pumping efficiency across different pressure levels.
III. Pressure Rating and Safety Factor of Conveying Hoses
The nozzle end of the wet‑spraying carriage must be equipped with a flexible hose to facilitate manual adjustment of the spray angle; the hose’s pressure rating is likewise a critical selection criterion. According to industrial hose standards, UPE ultra‑wear‑resistant concrete‑conveying hoses maintain a working pressure of approximately 8.5 MPa across various inner diameters. When selecting piping, it is essential to adhere to safety‑factor requirements: the hose’s rated working pressure must exceed the actual output pressure of the spraying equipment, and the safety factor should generally be no less than 2.5 to prevent sudden hose rupture under pulsating pressures.
For large concrete pumping equipment, operating pressures can exceed 4.0 MPa, necessitating the use of steel‑wire‑reinforced grouting hoses rated for higher pressure classes. Additionally, attention must be paid to the effects of pulsating pressure: intermittent material delivery during spraying generates pressure fluctuations, and high‑quality grouting hoses should withstand at least 500,000 pressure cycles without failure. The pressure‑rating specifications of end‑mounted rubber conveying hoses vary significantly with nominal diameter and connection type: the standard 125A model is limited to a maximum working pressure of 4 MPa, the high‑pressure 125AB steel‑belted model to 10 MPa, while specialized ultra‑high‑pressure hoses can operate at pressures exceeding 12 MPa, with a burst pressure of no less than 48 MPa.
IV. Correspondence Between Connection Methods and Pipe Pressure Ratings
The connection type of conveying pipelines is likewise tied to the pressure class. Type A connections are suitable for medium- and low-pressure pumping conditions, Type B connections are appropriate for medium‑high and high-pressure applications, while Type C connections are employed in ultra‑high‑pressure conveyance. In the context of ultra‑tall building applications, Type C connections utilize a flexible flange paired with a dedicated bolt‑tightening assembly, ensuring reliable sealing even under extreme pressures of 50 MPa and above. The revision of the GB/T 32543 standard, initiated in 2024, proposes the addition of new connection types such as AC and BA, to accommodate the diversified requirements for sealing structures at higher pressure classes.
High-pressure and low-pressure delivery lines shall not be mixed; high-pressure pumps must be equipped with high-pressure piping. The use of piping that is damaged, cracked, or whose wall thickness deviates from the specified tolerance is strictly prohibited. Prior to installation, verify the pipe markings to ensure that the pressure rating matches the prevailing operating conditions.
V. Comprehensive Matching for Pressure Rating Selection
In the practical application of wet‑spraying rigs and concrete pumping, the selection of the pipeline’s pressure rating must take into account multiple factors, including the equipment’s rated outlet pressure, the conveying distance and elevation, the concrete mix design, and the aggregate size. China Railway Equipment’s HP‑3017E intelligent wet‑spraying rig has a theoretical outlet pressure of 80 bar (approximately 8 MPa) and can be equipped with UPE ultra‑wear‑resistant hoses to meet a working pressure rating of 8.5 MPa.
In long-distance or ultra‑high‑rise pumping operations, it is advisable to prioritize the use of ultra‑high‑pressure delivery pipes with wall thicknesses of 8 mm or greater, and to shorten the pipe replacement cycle to mitigate the risk of fatigue‑induced fractures. Each pipe should be clearly marked on its surface with its nominal inner diameter, wall thickness, working pressure, and factory identification, facilitating routine inspections and operational management. Implementing a regular wall‑thickness inspection regime in conjunction with ledger‑based record‑keeping enables timely replacement when wall‑thickness wear exceeds prescribed limits, thereby effectively preventing pipe bursts and ensuring construction safety and operational continuity.
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