To ensure the welding quality of the pressure pipeline valve's surfacing welding, qualification of welding procedure should be carried out before welding. The purpose of the evaluation is to evaluate whether the company can weld welded joints that meet the requirements of the corresponding specifications and technical conditions. However, for surfacing welding, including corrosion-resistant surfacing welding and wear-resistant surfacing welding, there are different features for requirements...
Purposes and General Requirements of Surfacing Read
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1. General requirements for valves (1) The valve should be located in a place where it is easy to operate, install and maintain. The valves on the rows of pipelines should be arranged in a centralized manner, which is conducive to the installation of operating platforms and ladders. (2) There are process operation requirements and locking requirements for some valves' positions, and they should be arranged and marked according to PID instructions. (3) The valves on the bottom...
The Layout of the Valve Read
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A butterfly valve is a regulating valve with a simple structure, which can also be used for cutting off and connecting media in low-pressure pipelines. A butterfly valve is a valve whose closing part is a disc, which rotates around the valve shaft to achieve the purpose of opening and closing. It mainly plays the role of cutting off and throttling the medium in the pipeline. A butterfly valve is applied to pipelines that deliver various corrosive and non-corrosive fluid...
Selection Principles and Applications of Butterfly Valves Read
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The accident caused by operation of valves People often care about the operation of the main equipment, but they think that the operation for the valve is simple and not enough attention has been paid. However, explosions and personal accidents occur from time to time due to misoperation of valves, causing great losses. For example, once there was a major accident due to a closed valve that was supposed to be opened because of misoperation on the Irish Nuclear Power Plant on Three Mile Island...
The Operation of Valves Read
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4. Selection of materials of ball valves 4.1 Materials of valve bodies and ball shafts Titanium and titanium alloys have excellent properties such as low density, high specific strength, good corrosion resistance, high and low temperature resistance, cold and hot forming, and good welding performance. They especially have excellent corrosion and scouring resistance in seawater, and their corrosion rates in seawater is close to zero, which are preferred structural...
Design and Development of a New Type of Marine Titanium Alloy Ball Valve (Part Two) Read
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1. Introduction A ball valve is widely used in marine pipelines to realize the function of connecting and stopping the seawater due to its advantages of small fluid resistance, rapid opening and closing as well as convenience. At present, the ball valves used in the seawater pipelines of ships are generally made from copper alloy or stainless steel, and its structure is a soft sealing structure with an elastic valve seat or a floating valve seat. In the process of use,...
Design and Development of a New Type of Marine Titanium Alloy Ball Valve (Part One) Read
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A pneumatic butterfly valve consists of a butterfly valve and a pneumatic actuator. It is usually used for cutting off the media, and it can also be designed to a valve with adjusting functions. A pneumatic butterfly valve features in small sizes, light weights, simple structure and low costs. Maintenance of pneumatic butterfly valves Like other mechanical products, butterfly valves also need to be maintained. Good maintenance can keep performance and significantly extend the service life...
Maintenance of Pneumatic Butterfly Valves Read
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According to the working pressure of the gas pipeline, reasonably select the valve body material, which can not only meet the safe operation of the pipeline, but also achieve the purpose of reducing the cost and making the best use of it. 1. For medium-pressure B-grade (0.2MPa) transmission and distribution pipelines, it is recommended to use gray cast iron valves. The biggest advantage is that it has good corrosion resistance and is cheap, which is very suitable for underground pipelines; 2. For...
Material selection for the valve body of the gas valve Read
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01. Pressure test method for check valve Test state of the check valve: the axis of the lift check valve is at a position perpendicular to the horizontal; the axis of the swing check valve and the axis of the flap are approximately parallel to the horizontal. In the strength test, the test medium is introduced from the inlet end to the specified value, and the other end is closed, check the valve body and the valve cover. If there is no leakage, it is qualified. The sealing test is to introduce...
Pressure test methods for check valve safety valve pressure reducing valve Read
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Characteristics of the shipping industry The shipyard is very simple. Therefore, there is very little space on board. The operator must reduce the volume to keep the gas tank as small as possible. They make it this through LNG (liquefied natural gas). The natural gas is turned into a liquid by cooling. The main isolation valve must still operate at -165 °C. What will influence valve design? Temperature has an important influence on the design of the valve. For example, users may need it for...
Low temperature valves for liquefied natural gas applications Read
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