Safety valve introduction and selection

Abstract: Starting from the definition, the difference and selection of safety valve and relief valve are introduced in detail. And analyzed the main domestic safety valve series, lists the selection of safety valve selection of general rules. Keywords: Safety valve Relief valve Optional safety valve Optional overview Safety valve is an important safety accessories on boilers, pressure vessels and other pressure equipment. The reliability and performance of its movement is directly related to the safety of equipment and people, and with energy conservation and environmental protection are closely related. And some users and design department in the selection, always choose the wrong model. To this end the selection of safety valve to be analyzed. Second, the definition of the so-called safety valve in the broad sense, including the relief valve, from the management point of view, directly installed in a steam boiler or a class of pressure vessels, the necessary conditions must be approved by the technical supervision of the valve, narrowly referred to as Safety valve, other commonly known as the relief valve. Safety valve and relief valve in the structure and performance are very similar, both in the opening pressure automatically discharge the internal media, in order to ensure the safety of the production plant. The existence of such an inherent similarity in the dry, people often use the two mix, in addition, some production facilities in the rules also provide for the choice of what can be. Therefore, the differences between the two are often overlooked. Thus there are many problems. If you want to make a clear definition of both, you can follow the "ASME Boiler and Pressure Vessel Code," the first part of the definition set out to understand: (l) safety valve (Valve) Driven automatic pressure relief device. It is characterized by having an open full opening action. For gas or steam occasions. (2) relief valve (Relief Valve), also known as a relief valve by the media before the static pressure drive automatic pressure relief device. It opens proportionally as pressure increases beyond the opening force. Mainly used for fluid applications. (3) Safet relief valve (Safet Relief Valve), also known as safety relief valve A pressure-driven by the media automatic pressure relief device. Depending on the use of the occasion not only for the safety valve is also suitable as a relief valve. In Japan, for example, safety valves and relief valves are clearly defined, and safety devices commonly used for large storage pressure vessels such as boilers are referred to as safety valves and are installed on pipelines or other facilities The relief valve. However, if the Ministry of MITI's "Technical Standard for Thermal Power Generation" is concerned, safety valves, such as boilers, superheaters, reheaters, etc., are to be designated as an important part of the safety and security of equipment. In the lower side of the pressure reducing valve needs to be connected with the boiler and turbine occasions, need to install the relief valve or safety valve. So, safety valve requirements than the relief valve more reliable. In addition, judging from the rules and regulations of high-pressure gas regulations of Japan's Ministry of Labor and Ministry of Transport and shipping associations at all levels, we regard the guarantee of emissions as a safety valve without any guarantee The valve of discharge is called the relief valve. Whether in the country Kai-type or micro-Kai collectively referred to as safety valve. Third, the selection 1. Classification Currently mass-produced safety valve spring and rod two categories. There are also impulse-type safety valve, pilot-operated safety valve, safety switch valve, safety relief valve, static heavy-duty safety valve. Spring-loaded safety valve depends mainly on the force of the spring to work, spring-loaded safety valve has closed and not closed, the general flammable, explosive or toxic media should be used closed, steam or inert gas can choose not closed Type, in the spring-loaded safety valve with wrench and without wrench. The role of the wrench is to check the valve flap flexibility, and sometimes can also be used as a manual emergency pressure relief. Lever safety valve rely mainly on the leverage of the hammer work, but because of the large size of the lever safety valve often limits the scope of selection. When the temperature is high, select the safety valve with a radiator. The main parameters of the safety valve displacement, the displacement of the valve seat depends on the caliber and the valve opening height, the opening height is different, is divided into two kinds of micro-Kai and full Kai. Micro-Kai refers to the valve opening height of the valve seat throat diameter 1/40 ~ l / 20. Throttle refers to the valve opening height of the valve seat throat diameter 1/4. 2. The selection of safety valve is determined by the operating pressure of the nominal pressure of the safety valve, the operating temperature of the safety valve to determine the temperature range, the calculated value of the safety valve determines the fixed pressure spring or lever range, and then use the media to determine the safety Valve material and structure type, and then calculated according to safety valve relief valve throat diameter. The following general rules for the selection of safety valve. (L) General use of hot water boilers are not closed with micro-valve wrench safety valve. (2) steam boiler or steam pipe is generally not closed with a wrench full safety valve. (3) water and other liquid incompressible media commonly used closed micro-valve, or safety relief valve. (4) high-pressure water supply Generally closed full Kai-type safety valve, such as high-pressure water heaters, heat exchangers. (5) compressible gas and other gases generally use closed-type safety valve, such as gas tanks, gas pipelines. (6) E-class steam boilers generally use heavy-duty safety valve. (7) large-caliber, large displacement and high pressure systems generally use pulse safety valve, such as temperature and pressure reduction devices, power station boilers. (8) General purpose built-in safety valves for tank trucks, tank trucks and storage tanks for transporting liquefied gas. (9) The top of the tank with hydraulic safety valve, need to be used in conjunction with the breathing valve. (10) Downhole drainage or natural gas pipeline generally with pilot-operated safety valve. (11) liquefied petroleum gas station tank pump outlet liquid return pipe commonly used safety valve. (12) Negative pressure or negative pressure may occur during operation of the system is generally used vacuum negative pressure safety valve. (13) Bellows relief valves are generally used for container or piping systems with large back pressure fluctuations and toxic flammability. (14) medium freezing point lower system generally use insulation jacket safety valve. 3. Comparison of the major domestic manufacturers and the choice of connection size Domestic manufacturers of safety valves are more connected size are mostly not uniform. Mainly divided into the following categories: (1) to JB / T2203-1999 "spring-loaded safety valve structure length" based generic class. At present, most of the safety valve manufacturers are designed and manufactured according to this standard. Such as Zhejiang Luofu boiler annex plant, Hangzhou valve factory, valve plant in Jiangsu Wujiang, Shanghai Valve Factory, Kaifeng High Pressure Valve Factory, MSC valve factory. However, this standard is also not perfect, incomplete specifications, micro-Kai safety valve maximum nominal diameter of D NI 00, all-relief valve DN200 DN, the middle of the lack of DN65, DN125 two specifications. According to our factory production of safety valve specifications and grasp of the information, the current nominal diameter of the micro-Kai-type valve up to DN250, all-valve safety valve nominal diameter of DN400. After my research, the connection size of the manufacturers are not uniform, such as DN150 Kai-type safety valve, boiler accessories plant in Shanghai, Shanghai, Shanghai and Wujiang valve factory in Jiangsu valve factory are different. In order to have a uniform standard, the users can interchange the same specifications when choosing and installing, it is recommended that Hefei General Machinery Research Institute to amend the JB / T2203-1999 "spring-loaded safety valve structure length". Recommended design institutes and users according to the standard selection, safety valve manufacturer by standard design and manufacturing. (2) American Standard System based on API526 "Flanged Steel Safety Relief Valve". Domestic imports of chemical equipment and other safety valve with the connection size generally in accordance with this standard, as shown in Figure 5. This standard is the nominal diameter of DN25 ~ DN200 (l "~ 8"), the nominal pressure of 2 ~ 42MPa, throat diameter from D-T (9.5 ~ 146mm). This standard is more scientific and standardized on pressure, materials, temperature, throat diameter and other considerations. According to the throat diameter to determine the specifications, the same throat diameter can have several specifications, on the contrary the same specifications may have several throat diameter can choose. Such as DN100 ~ DN150 (4 "~ 6") throat diameter L, M, N, P four kinds of options. With the continuous promotion of international trade and the localization of imported equipment, the standard will be greatly promoted domestically. At present, the standard has not yet turned into a national standard. (3) Pilot Operated Pressure Relief Valves series based on Anderson Greenwood & Co., a globally influential company. Pilot generally known as the safety valve, as shown in Figure 6, the pilot-operated safety valve consists of the main valve and pilot valve, pilot valve operation of the main valve on and off. This valve displacement; from the impact of back pressure; can be very close to the opening pressure without leakage operation; opening and closing pressure differential advantages. Generally applicable to natural gas pipelines. At present, there is no pilot safety valve standard and connection dimensions. And this type of valve has just been developed, has not been widely promoted. According to my factory experience and information available, most domestic manufacturers in accordance with the company's data design and manufacturing, such as the attachment factory in Luoyang, Zhejiang, Aerospace Institute 11 and so on. It is suggested that Hefei General Machinery Research Institute drafts and issues the pilot safety valve standard as soon as possible. (4) The safety valve designed and developed by the Eleventh Institute of China Aerospace Industry Corporation has formed itself into a system. There are many kinds of HT series safety valves developed by Aerospace 11, including HTO common safety valve (as shown in Figure 1), HTB balanced bellows safety valve, HTR discharge valve, HTN special safety valve and HTGS high performance steam safety valve . HTXY liquid pressure relief valve, HTXD pilot safety valve, etc., and good performance. However, except HTXD series pilot safety valve and Anderson Greenwood company connecting the same size, the rest with the American Standard, GB are not the same. Please pay attention when choosing this point. (5) Designed and developed by Lanzhou Refinery A type, TA type fully open spring-loaded safety valve into a system. The series of diameter DN25 ~ DN150 (1 "~ 6 '), the nominal pressure l.6 ~ 4.0MPa, throat diameter D ~ R (9.5-115mm). The system connection size and the American Standard and GB are different, (6) For the boiler, power plant equipment, temperature and pressure relief device supporting the impulse safety valve series (shown in Figure 8), such as Harbin Boiler Factory, Dongfang Boiler Factory, Wuhan Boiler Factory, Qingdao Power Station Auxiliary Plant and other supporting special safety valve.Such series of valve structure and connection size of the manufacturers are generally not the same, there may be some the same .Option must pay attention to the difference between the valve throat diameter and connection size .4 throat diameter calculation throat diameter The calculations are generally in accordance with "Boiler and Pressure Vessel Safety Technical Specification" listed in Annex V. Or in accordance with APIRP520 refinery pressure relief system design and installation of the recommended implementation of the first part of the design "in the formula. The above two formulas calculate the basic results The same or little difference. Fourth, concluding remark Safety valve selection is a more important job, the selection of appropriate or not will directly affect the safety of the equipment. Some lessons learned, space is limited, it may be entirely different, for your reference. References 1, the safety valve of foreign standards compilation (M) Hefei General Machinery Research Institute, 1985

Fume &dust extracted by air exhauster while plasma cutting. This system has one ventilation outtake and one gliding extraction intake, the extraction intake moves along with the gantry, the sealed rubber strip at the head of ventliation outtake, can makes a sealing function with the help of minus pressure generated by the fan.

pipe intersecting lines Cutting Machinery

Scope of application

The machine is a formed cutting equipment used for fully automatic incising intersecting lines with slope 

on pipes and cutting pipe end, for example, one-time molding cutting intersecting lines 

or opening holes on bearing steel pipes and gas and liquid transporting steel pipes by flame or plasma

with high precision and high efficiency. It can be widely used in oil drilling platform, shipbuilding industry, 

chemical industry, industrial boiler and power station boiler, pressure vessel, electrical power transmission

tower, water conservancy, water supply, bridges, crane, construction and other industries.

Features of pipe intersecting lines cutting machinery

1.Self-developed 5-7 axis CNC system; Ac-servo control

2.3D graphical display, simulation function, simulate processing

3.Parametric programming of graphic database or special intersecting line software

4.online test or demonstration for steel pipe, real-time dynamic tracking compensation

5.Compensation function of cutting gap, thickness, ellipse, groove angle. 

6.Nesting of pipe fittings, continuous cutting, long pipe separate into short slabs.

Model	CPC series(Blocking plate), FWPC series(Friction wheel)
Cutting diameter	50~1500 mm (customizable)	Cutting length	3000~12000m  mmcustomizable)
Cutting manner	flame/plasma is optional	Rotation driving	Blocking plate (Friction wheel is optional)
Cutting thickness	flame 6~50mm plasma 3~30mm	Length localization precision	0.3mm/2000mm
Groove angle	flame±60°/plasma±45°	Angle localization precision  Angular positioning precision	0.1~0.2°/360°
Cutting speed	50~6000mm/min	Auxiliary function	height detection, pipe ellipticity modification
Rapid travel rate	≤12000mm/min	Controlling  Axis	X,Y,Z,A,B,W+ detection
Programming method	Parametric programming of graphic database /Special programming software supporting

CNC Plasma Cutting Machine

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