GB/T 14478-2025 Basic technical specification of inlet valves for large and medium-sized hydraulic turbines
1 Scope
This document specifies the basic technical requirements and model compilation methods of inlet valves for large and medium-sized hydraulic turbines, and describes the test methods.
This document is applicable to the design, manufacture and acceptance of the butterfly valves with nominal diameter of 1000mm to 10000mm and the ball valves with nominal diameter of 500mm to 5000mm.
Other butterfly and ball valves (including storage pumps, water pumps and pump turbines) shall be executed by made reference to this document.
2 Normative references
The following documents contain requirements which, through reference in this text, constitute provisions of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 150 (all parts) Pressure vessels
GB/T 191 Packaging - Pictorial marking for handling of goods
GB/T 8564 Specification installation of hydraulic turbine generator units
GB/T 9652.1 Specification of hydraulic turbine governing systems
GB/T 9652.2 Testing specification of hydraulic turbine governing systems
GB/T 15468-2020 Fundamental technical requirements for hydraulic turbines
GB/T 22581-2008 Fundamental technical requirements for francis pump-turbine
GB/T 28546 Specification for package, transportation and storage of large and medium hydraulic units
GB/T 40582 Basic terminology of hydropower station
DL/T 1066 Guide of maintenance management for hydropower station equipments
3 Terms and definitions
For the purposes of this document, the terms and definitions given in GB/T 2900.45 and GB/T 40582 and the following apply.
3.1
nominal diameter of inlet valve
D
minimum inner diameter of valve body throughflow at the connection of inlet valves and upstream/downstream pressure diversion pipe flanges
Note: In millimeters (mm). In case of different inner diameters on both sides, the smaller one shall prevail.
3.2
maximum static head
Hst
height of water column formed from horizontal center line of inlet valve to the upstream normal storage level after the inlet valve is closed
Note: In meters (m).
3.3
maximum static pressure
pc
water pressure formed from horizontal center line of inlet valve to the upstream normal storage level after the inlet valve is closed
Note: In megapascals (MPa).
3.4
maximum momentary pressure
pmmax
maximum gauge pressure generated at the horizontal center line of inlet valve in transient process
Note: In megapascals (MPa).
3.5
design pressure
pd
pressure used in the strength design of overflow parts of turbine inlet valves
Note: In megapascals (MPa).
3.6
test pressure
pt
pressure of pressure-containing components used for turbine inlet valves and piping systems in factory or field tests
Note: In megapascals (MPa).
3.7
extention section
section of the upstream side of inlet valve connected with the upstream pressure inlet pipe
3.8
expansion joint
section with expansion function connecting the downstream side of inlet valve to the downstream pressure inlet pipe (such as a volute or distribution ring pipe)
3.9
assembly of inlet valve
assembly consisting of valve body, valve, shaft, boom and seal components
3.10
hydraulic power self-excited oscillation
oscillation, that intensifies over time, caused by any small perturbation of pressure or flow that introduces an unstable hydraulic system,
4 Basic technical requirements
4.1 The design pressure of inlet valves shall not less than the highest transient pressure. The design, manufacture and inspection of the pressure-containing components of inlet valve and piping system shall meet the requirements of GB/T 150 (all parts), GB/T 15468-2020, 4.2.1.21 and GB/T 22581-2008, 4.2.1.21.
4.2 During normal shutdown or overhaul of units, inlet valves shall be able to be closed reliably.
4.3 Under any operating condition of units, the inlet valve shall be able to be closed under hydrodynamic conditions, without harmful oscillation that leads to permanent deformation.
4.4 Operating state of the inlet valve gate shall be at full-on or fully closed position, not for flow regulation.
4.5 The profile design of butterfly valve shall avoid the oscillation caused by Karman vortex.
4.6 Where the pressure difference on both sides is not greater than the maximum static pressure, the inlet valve shall be able to be normally opened or closed.
4.7 The inlet valve body shall be assembled in the factory. After the final assembly and the installation at power station, the operation shall be flexible, and the position of full opening and full closing shall be accurate. When the inlet valve has no final assembly conditions in the factory, the relay is not involved in the assembly, but the relay shall be separately tested for seal leakage, action and stroke inspection. The opening and closing time of inlet valves shall be adjustable.
Contents Foreword 1 Scope 2 Normative references 3 Terms and definitions 4 Basic technical requirements 5 Model compilation method of inlet valves 6 Test methods 7 Installation and operation 8 Supply scope of complete set 9 Acceptance and guarantee 10 Nameplate, packaging, transportation and storage Annex A (Informative) Names of some structural parts of bimetal sealed inlet ball valve Annex B (Normative) Model compilation method of inlet valves Annex C (Informative) Spare parts of inlet valve
