Valve is an important component in the pipeline system of petrochemical plant, it is one of the main leakage sources in the equipment, so it is very important to leak the valve. Valve sealing performance refers to the sealing parts of the valve to prevent the leakage of the media capacity. The main sealing parts of the valve are: the matching surface between the headstock and the seat, the filler and the stem and the filling letter, and the connection between the valve body and the valve cover. Valve sealing is a measure of the quality of the valve performance of one of the important standards, the world's valve sealing has different standards.

Small series collection of valve seal grade and classification standards hope to help!

01

Classification standard of valve seal grade in China

At present, the most commonly used valve SEAL classification standards in China are as follows: two kinds. 1.

1 China National standard on the classification of valve seal grade GB/T 13927--2008 "industrial valve pressure test." 1.

2 China Machinery Industry standard Classification of valve SEAL grade machinery industry standard jb/t 9092--1999 "valve Inspection and test".

02

International classification standard for Valve seal grade

At present, more commonly used in the International Valve SEAL classification standards are mainly the following five kinds. 2.

1 Classification of Valve seal grade by International Organization for Standardization

ISO standard ISO5208--2008 Industrial valve pressure test of metal valves. 2.

2 American Petroleum Association (APL) Classification of valve seals the American Petroleum Association standard API 598--2004 "valve inspection and testing". 2.

3 American Standardization Association of Valves and pipe fittings industry Manufacturers (MSS) Classification of valve SEAL grade American Standard for valves and fittings industrial manufacturers standards "pressure test for steel valves" MSS SP61---2003 allowable valve leakage requirements are as follows:

(1) In the case of a valve seal with a sealing surface using plastic or rubber, there should be no visible leakage during the duration of the seal test. (2) The maximum allowable leakage on each side of the shutdown should be: the liquid is the nominal size (DN) per millimeter, 0 per hour.

4 ml, the gas is nominal size (DN) per millimeter, 120 ml per hour.

(3) The leakage allowed by the check valve can be increased by 4 times times. 2.

4 American National standards/American Instrumentation Association Standard (ANSI/FCI) classification of control valve SEAL Grade American National Standard ansi/fci70-2 (ASME B16.

104)-2006 "Control valve seat leakage". 2.

5 Classification of valve seal grade by EU standard European standard EN 12266-1--2003 the first part of the test of industrial valve valves.

Pressure tests, test methods and acceptance criteria-mandatory requirements.

03

Selection of valve seal grade 3.

1 Domestic valve seal grade selection (1) July 1, 2009 the implementation of the national standard gb/t13927--2008 (Industrial valve pressure test is modelled on the European standard ISO 5208--2008). Applicable to industrial metal valves, including gate valve, globe valve, check valve, plug valve, ball valve, butterfly valve inspection and pressure test. The grading and maximum allowable leakage of seal tests are the same as those of ISO 5208--2008. The standard is a revision of the gb/t13927--1992 (General valve pressure test), with a new AA, CC, E, EE, F and G six grades compared to gb/t13927--1992. The new standard stipulates that "the choice of the level of leakage should be related to the valve product standards or orders of strict requirements of the contract." If there is no special stipulation in the product standard or the order contract, the Non-metallic flexible sealing valve is required by a class, and the metal seal valve is in the D level.

"D-level is usually applicable to the general valve, the more critical valves should be selected D-level above the leakage level." (2) Machinery industry standard jb/t 9092--1999 "valve inspection and test" is the revision of the ZB J16006---90. The maximum allowable leakage of seal tests is based on the American Petroleum Association standard api598--1996. It is suitable for the inspection and pressure test of valves, globe valves, plug valves, ball valves, check valves and butterfly valves for petroleum industry, including metal seals, elastomeric seals and nonmetallic seals (e.g. ceramics).

At present, GB/T 9092--1999 is being revised. (3) The engineering design should pay attention to: National standard gb/t19672--2005 (Pipeline valve technical conditions) is the reference to the European standard ISO 14313--1999 and the American Petroleum Association standard API 6d--2002. National standard GB/T 20173--2006 "oil and gas industry pipeline conveying system pipeline valve" is modelled on the European standard ISO 14313--1999. GB/T 19672_2005 and GB/T 20173--2006 these two standards for valve leakage of the acceptance criteria are the same as the ISO 5208 level A and D requirements.

Therefore, when the engineering design is higher than its standard leakage requirements, it should be given in the order contract. 3.

2 Foreign valve seal grade selection (1) The former Soviet Union to the valve seal classification is mainly the 1950s application, with the disintegration of the former Soviet Union, now most countries do not choose this seal grade classification, but the use of European and American Standard SEAL grade classification. European standard EN 12266-1_2003 seals are classified in accordance with ISO 5208--2008 standards, but are missing AA, CC and EE grades three. ISO 5208-2008 and 1999 have added AA, CC, E, EE, F and g six levels.

The ISO 5208--2008 Standard provides a comparison of several sealing levels with API 598 and EN 12266 standards.

Other nominal size seal grades can be calculated according to the diameter of leakage.