Power Station Gate Valve

Power station gate valve is dedicated to thermal power generation system of high pressure and high temperature pipeline, through the vertical lifting gate to achieve the medium cut-off key equipment. Its core structure includes:

Valve body and bonnet
Welded connection structure (valve body stubs are welded at both ends) to avoid the risk of flange leakage;
Top-mounted design, supporting online maintenance.
Gate system
Wedge type single gate: using wedge structure to force sealing, higher adaptability to high pressure working conditions;
Double gate (elastic gate): compensation of sealing surface wear by spring preload.
Sealing surface
Cobalt-based cemented carbide plasma spray welding layer: covering the gate and seat, hardness ≥ HRC, resistant to 540 ℃ high temperature washout.
Valve stem
Nitride treated stainless steel (e.g. SUS316), corrosion and abrasion resistant, precise control of lift stroke.

 Material standards for key moving parts

Gate plate
Base material: ASTM A105 forged steel (≤425℃) or ASTM A182 F304/F316 stainless steel;
Sealing surface overlay: mandatory cobalt-based cemented carbide (Stellite 6), in accordance with AWS A5.13 ERCoCr-A welding wire standard, thickness of overlay layer ≥ 0.8mm.
Valve stem
Material: ASTM A182 F6a (martensitic stainless steel) or ASTM A276 316;
Surface treatment: nitriding hardening treatment (surface hardness ≥ HV 800).

 High temperature working conditions special requirements

Above 540 ℃ sealing surface: cladding hardness should be ≥ HRC 50 (conventional conditions ≥ HRC 45);
Valve body filler weld: according to ASME Section IX for welding process evaluation, the welding material used with the parent material of the same grade AWS E90XX series.

 Manufacturing Standards

Design and manufacturing specifications

API 600: A special standard for steel gate valves covering valve body structure, material selection and high temperature and high pressure adaptability requirements, applicable to the main steam pipeline of power stations.
ASME B16.34: Provides for valve pressure-temperature ratings, wall thickness calculations and connection end forms (welded/flanged), supercritical units need to meet Class 2500 requirements.
API 6D: additional requirements for the design of pipeline valves, emphasising the welded body structure and thermal stress resistant design.
Material Specification

Valve body / bonnet to meet ASTM A216 Gr.WCB (carbon steel) or ASTM A217 Gr.WC6/WC9 (chromium-molybdenum steel), ultra-high-temperature conditions with the material to comply with ASTM A182 F91/F92 for ultra-high temperature service.
The sealing surface is forced to overlay cobalt-based cemented carbide (Stellite 6), thickness ≥ 0.8mm.

 

Power station Gate Valve

 

Power station gate valve through the hard seal welding + wedge compression structure, in the high temperature, high pressure, corrosive media to achieve zero leakage and reliable cut-off, is to protect the safe operation of the power plant, 'pipeline switch guard! '

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