GB/T 12246-2025 Pilot operated pressure reducing valves English, Anglais, Englisch, Inglés, えいご
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ICS 13.220.10
CCS H 57
National Standard of the People's Republic of China
GB/T 12246-2025
Replaces GB/T 12246-2006
Pilot operated pressure reducing valves
先导式减压阀
Issue date: 2025-10-31 Implementation date: 2026-05-01
Issued by the General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China
the Standardization Administration of the People's Republic of China
Contents
Foreword
1 Scope
2 Normative References
3 Terms and Definitions
4 Structural Types
5 Technical Requirements
6 Test Methods
7 Inspection Rules
8 Marking and Painting
9 Packaging, Transportation, and Storage
Figure 1 Integrated Pilot-Operated Pressure Reducing Valve / Pilot Piston-Type Pressure Reducing Valve
Figure 2 Integrated Pilot-Operated Pressure Reducing Valve / Pilot Diaphragm-Type Pressure Reducing Valve
Figure 3 Independent Pilot-Operated Pressure Reducing Valve / Pilot Diaphragm-Type Pressure Reducing Valve
Table 1 Recommended Material for Parts
Table 2 Inspection Items
1 Scope
This document specifies the structural types, technical requirements, test methods, inspection rules, marking, painting, and packaging, transportation, and storage for pilot-operated pressure reducing valves.
This document applies to the design, production, and inspection of pilot-operated pressure reducing valves with nominal sizes DN15~DN800 and nominal pressures PN10~PN100, or nominal sizes NPS½~NPS32 and nominal pressures Class150~Class600, for gases, liquids, and steam with temperatures not exceeding 300°C.
2 Normative references
The contents of the following documents, through normative citations in the text, constitute essential provisions of this document. For dated references, only the edition cited applies. For undated references, the latest edition (including any amendments) applies.
GB/T 699 Carbon structural steel for quality
GB/T 1220 Stainless steel bars
GB/T 1222 Spring steel
GB/T 1239.2-2009 Technical requirements for cold-coiled cylindrical helical springs-Part 2: Compression springs
GB/T 2059 Copper and copper alloy strips
GB/T 3077 Alloy structural steels
GB/T 4622 (All parts) Spiral-wound gaskets for pipe flanges
GB/T 9124 (All parts) Steel pipe flanges
GB/T 12220 Industrial valves-Marking
GB/T 12225 General-purpose valves-Technical requirements for copper alloy castings
GB/T 12226 General-purpose valves-Specifications for gray iron castings
GB/T 12227 General-purpose valves-Specifications for ductile iron castings
GB/T 12228 General-purpose valves-Specifications for carbon steel forgings
GB/T 12229 General-purpose valves-Specifications for carbon steel castings
GB/T 12230 General-purpose valves-Technical requirements for stainless steel castings
GB/T 12244 Pressure reducing valves-General requirements
GB/T 12245 Pressure reducing valves-Performance test methods
GB/T 17241 (All parts) Cast iron pipe flanges
GB/T 21465 Valves-Terminology
JB/T 106 Marking and painting for valves
JB/T 2205 Pressure reducing valves-Face-to-face dimensions
JB/T 7928 Industrial valves-Supply requirements
3 Terms and definitions
The terms and definitions defined in GB/T 12244, GB/T 12245, and GB/T 21465, as well as the following terms and definitions, apply to this document.
3.1 Integrated pilot-operated pressure reducing valve
A pilot-operated pressure reducing valve with the pilot valve integrated into the main valve structure.
3.2 Independent pilot-operated pressure reducing valve
A pilot-operated pressure reducing valve with the pilot valve independent of the main valve structure and connected to the main valve only via pipelines.
4 Structural types
The pilot-operated pressure reducing valve (hereinafter referred to as "pressure reducing valve") can be classified into integrated pilot-operated pressure reducing valves and independent pilot-operated pressure reducing valves based on the combination of the pilot valve and main valve, and into pilot-piston-type pressure reducing valves and pilot-diaphragm-type pressure reducing valves based on the main valve driving component, as shown in Figures 1 to 3.
5 Technical requirements
5.1 General requirements
5.1.1 The face-to-face dimensions of flange-connected pressure reducing valves shall comply with the provisions of JB/T 2205 or the requirements of the purchase order.
5.1.2 The flange dimensions and sealing surface forms of steel pressure reducing valves shall comply with the provisions of GB/T 9124 (All parts) or the requirements of the purchase order.
5.1.3 The flange dimensions and sealing surface forms of iron pressure reducing valves shall comply with the provisions of GB/T 17241 (All parts) or the requirements of the purchase order.
5.1.4 Unless otherwise specified in the purchase order, the nominal pressure and nominal size of the connection flanges at both ends of the valve body shall be consistent.
5.1.5 The pressure reducing valve shall be equipped with a pressure adjustment mechanism and anti-loosening device. The pressure shall be adjustable by rotating the handwheel or other components (adjustment screw) clockwise to increase the downstream pressure, with the valve disc in the open state.
5.2 Springs
The design and manufacture of springs shall comply with the Class 2 accuracy requirements in GB/T 1239.2-2009. The spring pressure class shall be selected according to the appropriate range specified in the purchase order. The spring index (ratio of mean diameter to wire diameter) shall be selected within the range of 4 to 9. Both ends of the spring shall have support surfaces covering no less than three-quarters of a turn, with no less than one full turn as the support. The working deformation of the spring shall be controlled within the range of 30% to 70% of the deformation under test load.
5.3 Performance requirements
5.3.1 Shell strength
During the shell test, the pressure reducing valve shall not exhibit structural damage, and no visible leakage shall be permitted.
5.3.2 Sealing performance
For soft-sealed (elastic-sealed) structures, the seat sealing shall show no visible leakage. For metal hard-sealed structures, the seat sealing leakage shall not exceed 0.5% of the maximum flow rate, or the rate of pressure rise at the outlet shall not exceed 0.2 MPa/min.
All connections of the pressure reducing valve shall show no visible leakage.
5.3.3 Pressure regulation performance
Within the specified pressure regulation range, the outlet pressure shall be continuously adjustable between the maximum and minimum values without any sticking or abnormal vibration.
5.3.4 Flow coefficient
The deviation of the flow coefficient (Kv or Cv) under the maximum opening condition of the pressure reducing valve shall not exceed 10% of the manufacturer's specified value.
5.3.5 Flow characteristics
During the flow characteristic test, the pressure reducing valve shall not exhibit abnormal vibration, and the deviation of the outlet pressure from the flow characteristics shall not exceed 10% of the outlet pressure.
5.3.6 Pressure characteristics
