Problems needing attention in selecting safety val

Problems needing attention in selecting safety valves

there are many domestic manufacturers of safety valves, and most of the connection sizes are not unified. It is mainly divided into the following categories:

(1) general category based on JB/t2203-1999 structural length of spring loaded safety valves. At present, most domestic safety valve manufacturers are designed and produced according to this standard. Such as Zhejiang Luofu boiler accessories factory, Hangzhou valve factory, Jiangsu Wujiang valve tool factory, Shanghai Valve Factory, Kaifeng high pressure valve factory, Hai'an valve factory, etc. However, this standard is not perfect, and the specifications are incomplete. The maximum nominal diameter of the micro lift safety valve is dni00, and the maximum nominal diameter of the full lift safety valve is DN200. There are two specifications, DN65 and DN125, missing in the middle. According to the specifications of the safety valve produced by our factory and the information we have, the nominal diameter of the micro open safety valve is up to DN250 at present, and the nominal diameter of the full open safety valve is up to dn400. According to my research, the connection dimensions of various manufacturers are also different, such as DN150 full lift safety valve, Zhejiang Luofu boiler accessories factory, Shanghai Valve Factory and Jiangsu Wujiang valve tool factory. In order to have a unified standard, users can exchange the same specification when selecting and installing, Hefei General Machinery Research Institute is suggested to revise JB/t2203-1999 "structural length of spring safety valve". It is suggested that the design institute and users should select according to the standard, and the manufacturer of safety valve should design and manufacture according to the standard

(2) American Standard System Based on api526 steel flange safety relief valve. The connection dimensions of safety valves equipped with domestic imported chemical equipment are generally in accordance with this standard, as shown in Figure 5. The nominal diameter of this standard is dn25~dn200 (L "~8"), the nominal pressure is 2~42mpa, and the throat diameter is D-T (9.5~146mm). This standard is relatively scientific and standardized, and takes into account the pressure, material, temperature, throat diameter, etc. The specification is determined according to the throat diameter. There can be several specifications for the same throat diameter. On the contrary, there may be several throat diameters for the same specification. For example, the year-on-year increase of dn100~dn is 2, and the modified plastic is 9.32 But at the same time, the surplus of surplus enterprises is 4.351 billion yuan, and the throat diameter of 150 (4 "~6") has four options: l, m, N and P. With the continuous promotion of international trade and the localization of imported equipment, the standard will be greatly promoted in China. At present, the standard has not been transformed into a national standard

(3) the pilotoperatedpressurereliefvalves based on Anderson Greenwood & Co., which has great international influence, is listed. It is generally called pilot safety valve in China, as shown in Figure 6 and with spring washer. The pilot safety valve is composed of main valve and pilot valve, which operates the opening and closing of the main valve. This valve has a large displacement; Not affected by back pressure; It can operate without leakage under very close opening pressure; Small opening and closing pressure difference, etc. It is generally applicable to natural gas pipelines, etc. At present, there is no standard for pilot operated safety valve and connection size in China. And this type of valve has just been developed and has not been widely promoted. According to our experience and information, most domestic manufacturers design and manufacture according to the company's data, such as Zhejiang Luofu boiler accessories factory, aerospace 11th Research Institute, etc. It is suggested that Hefei General Machinery Research Institute draft and issue the standard of pilot operated safety valve as soon as possible

(4) the A-type and Ta type closed full open spring safety valves designed and developed by Lanzhou Refinery form a system. The diameter of this series is dn25~dn150 (1 "~6"), the nominal pressure is 1.6~4.0mpa, and the throat diameter is d~r (9.5-115mm). The connection size of this system is different from American Standard and national standard, and it is specially used by LANLIAN

(5) impulse safety valve series for boilers, power station equipment and temperature and pressure reduction devices (as shown in Figure 8). Such as Harbin boiler plant, Dongfang Boiler Plant, Wuhan boiler plant, Qingdao power station auxiliary equipment plant and other supporting special safety valves. The structure and connection size of this series of valves are generally different from manufacturers, and some may be the same. Pay attention to the difference of valve throat diameter and connection size when selecting

(6) the safety valve designed and developed by the 11th Research Institute of China Aerospace Industry Corporation forms a system by itself. The HT series safety valves developed by the 11th Institute of aerospace industry have many varieties, including HTO ordinary safety valves (as shown in Figure 1), HTB Balanced Bellows Safety valves, HTR relief valves, HTN special safety valves, and HTGS high-performance steam safety valves. Htxy liquid relief valve, htxd pilot safety valve, etc., with good performance. However, except that the connection size of htxd series pilot safety valves is the same as that of Anderson Greenwood, the investment standards and national standards for R & D and technical support increased by other customers in Asia are different. Please pay attention to this when selecting