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API high pressure and high temperature power plant gate valve

The power plant valve usually should be high pressure and high temperature with medium water, steam, air. So material WCB, WC6, WC9 are widedly usded as main body material. The valve are designed with pressure seal bonnet for class 600 900, 1500, 2500 depends on size and working condition. The valve are usually with butt weld ends connection to avoid any leakage.Hard face sealing surface are often adopted.

Following are some pic of Power plant gate valves SGV offer.

Body inner side machining:

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Metal seal Ball Valve sealing surface hardening technique

Metal seal Ball valve sealing surface hardening techniques

First, Overview
High-viscosity fluids in power plants , petrochemical systems , coal chemical industry , with dust mixed fluid and solid granular , highly corrosive fluid medium and so on required the ball valve should be metal seal , so the choice of a suitable metal hard sealing ball valve “ball and seat”  hardening process is very important.

Second, the usual hardening process are the following :

( 1 ) sphere surfacing deposit weld alloy , hardness usually up to 30HRC or more, spheres  surfacing process is complex, low productivity, and a large area of ​​surface welding easy to make parts deformation , as a reslut, currently use of the sphere surface hardening process become less .

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Valve sealing surface/inner leakage and deposited welding material

We all know that there are three major factors that affect valve life:

1 valve inner leakage: The main problem is the quality of the sealing surface
2 valve outside leakage: The main problem is the quality of the casting, but also packing problem
3 valve structure: The main problems in the design and processing of pieces

Here we discuss only the inner steel middle high pressure valve leakage problem, the requiement of valve sealing surfaces.

Valve sealing surface, at a predetermined pressure, temperature, medium, installation location,  ensure safe and reliable seal; while in the manufacturing process, the sealing surface materials and structures, welding, machining, assembly and grinding process shoudl be good; sealing surface should also to be ease of maintenance, specifically requires the following: Continue reading “Valve sealing surface/inner leakage and deposited welding material”

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How to avoid crack when deopsite weld for valve sealing surface?

How to avoid crack when deopsite weld for valve sealing surface?

—Songong Valve

Many factory Welding Worker face potential crack  risk when deposite weld valve seat and disc, especially for those experience less fresh welding worker.This phenomen is more widely exsist for complicated workpieces when using easy-crack electrode.

Surfacing in the most commonly encountered problem is cracking, to prevent cracking of the main methods are:
1, preheat, interpass temperature control, slow cooling after welding.
2, stress relief heat treatment after welding. Continue reading “How to avoid crack when deopsite weld for valve sealing surface?”

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China and main country Valve Welding material(electrode) for sealing surface

China Main Valve Sealing surfaceing Electrode Character,Use,Application 

D502 valve surfacing electrode line with GB EDCr-A1-03
Description: D502 is a titanium calcium type coating 1Cr13 valve welding electrode, AC and DC welding technology is good. Surfacing metal is 1Cr13 semi-ferritic chromium steel. Surfacing with air quenching properties, generally not subject to heat treatment, uniform hardness, but also softened by annealing at 750-800 ℃, when heated to 900-1000 ℃ air cooling or oil quenching, re-hardening.
Uses: This is a versatile surfacing welding rod for welding temperature below 450 ℃, carbon steel or alloy steel shafts and valves.
Chemical Composition of Deposited Metal (%) Chemical composition CSP Cr total of other elements
Guaranteed value ≤ 0.15 ≤ 0.030 ≤ 0.040 10.0 ~ 16.0 ≤ 2.50
Surfacing layer hardness: (after welding, air cooling) HRC ≥ 40
Reference current (AC, DC) electrode diameter (mm) φ2.5 φ3.2 φ4.0 φ5.0
Welding current (A) 50 ~ 80 80 ~ 120 120 ~ 160 160 ~ 200 Continue reading “China and main country Valve Welding material(electrode) for sealing surface”

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Thermoplastic materials as valve seat

A large number of thermoplastic materials are offered in valves, mainly as soft-seat  options for ball valve applications. Also lined valves like, lined butterlfy valve, lined globe valve, lined check valve. For this reason, the following section outlines some of the fundamental aspects of the properties, capabilities and application of these materials.

Material types
Mechanical properties
Chemical resistance

Material types

Table 1 shows the polymer types, used in valve applications, together with common abbreviations and Tradenames for the materials mentioned in these Guidelines. Continue reading “Thermoplastic materials as valve seat”

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Application of advanced technology in the domestic large pipeline valve:all welded ball valve

Application of advanced technology in the domestic large pipeline valve

Overview
All rely on imports in the year 2000 China’s large-scale all-welded pipeline ball valves. Localization process of digestion, absorption and innovation through the use of modern advanced design techniques, such as reverse engineering, screening engineering, numerical analysis of finite element method, anti-breaking design, the design of anti-corrosion, low torque design and advanced manufacturing technology and technology and equipment, was a success.
Reverse engineering technology and its applications

The key technology of all-welded body pipeline ball valves (Figure 1) is the body welding, welding ball valve assembly is the last step, not heat-treated. Therefore, the development of free weld heat treatment after welding technology research, anti-Sum learn the foreign pipeline valve welding process with technology product localization shortcut. Continue reading “Application of advanced technology in the domestic large pipeline valve:all welded ball valve”