Faq

The shell test pressure for general-purpose valves is 1.5 times the rated working pressure of the material at 38°C. The high-pressure seal test is 1.1 times the rated working pressure of the material at 38°C. Low-pressure seal test requirements vary by standard.

Among these:

GB/T 13927-1992, ISO 5208:2008, EN 12266.2-2012 is 0.6MPa±0.01MPa;

GB/T 26481-2011, API 598-2009 is 0.4MPa~0.7Mpa;

MSS SP61-2013 is 0.56 MPa;

API 6D-2014 for Type I: 0.034MPa~0.1MPa, Type II: 0.55MPa±0.69MPa;

ISO 14313:2007 for Type I: 0.05MPa~0.1MPa, Type II: 0.55MPa±0.07MPa;

API 6A (idt ISO 10423:2003) for PSL3G: first: rated pressure, second: 2.0MPa ± 0.2MPa; PSL4: first: rated pressure, second: 2.0MPa ± 0.2MPa.

The specific test pressures for shell tests, high-pressure sealing tests, and high-pressure upper sealing tests are shown in Tables 1-1 and 1-2.

Classification of valves based on their purpose or primary structural characteristics.

General classification categorizes valves by both operating principle and structure, representing the most widely used classification method domestically and internationally. Common types include: gate valves, globe valves, plug valves, ball valves, butterfly valves, diaphragm valves, check valves, throttle valves, safety valves, pressure reducing valves, steam traps, and control valves.

Valve model designations are composed of codes representing valve type, actuation method, connection type, structural configuration, sealing surface material or lining material type, pressure rating or working pressure at operating temperature, and valve body material.

The valve model consists of seven parts, with their meanings shown in the diagram.

NPS：

Combined alphanumeric size designation for piping system components consisting of the letters NPS followed by a dimensionless integer number. This number is directly related to a characteristic dimension such as the bore or outside diameter of the end connection. The dimensionless number may be used as a dimensional designation for valves without the prefix “NPS”. Dimensionless size numbers do not represent measured values and cannot be used for calculations.

Class：

A combination of letters and numbers used to identify the pressure/temperature capability of a valve in relation to the mechanical and dimensional properties of the valve material. It consists of the letter Class followed by a dimensionless integer. The number following the letter Class does not represent a measured value and should not be used in calculations. The permissible pressure of piping elements depends on the Class value, the material and the permissible working temperature, unless otherwise specified in the respective standard. The permissible pressures are given in the pressure-temperature rating tables of the respective standards.

DN:

A combination of letters and numbers used to identify the size of piping system components. It consists of the letter DN followed by an integer number without a factor. This number is directly related to the characteristic dimensions of the end connection, such as the bore diameter or the outside diameter (expressed in mm).

Note:

1. Unless otherwise specified in the relevant standards, the numbers following the letters DN do not represent measured values and cannot be used for calculation purposes.
2. Those standards that utilize a DN marking system should give the DN in relation to the size of the pipe element, e.g. DN/OD or DN/ID.

PN:

A combination of letters and numbers used for reference purposes in connection with the mechanical and dimensional properties of piping system components. It consists of the letter PN followed by a non-factorized number.

Note:

1. The numbers following the letter PN do not represent measured values and should not be used for calculation purposes, unless otherwise specified in the relevant standard.
2. The term PN has no meaning except in connection with the relevant pipe component standard.
3. The permissible pressure of a piping element depends on the PN value, material and design of the element as well as the permissible working temperature, etc. The permissible pressure is given in the pressure-temperature rating table of the respective standard.
4. All piping components with the same PN and DN values and their mating flanges should have the same mating dimensions.

Valves commonly used in pipelines across various industrial enterprises.

A general term for mechanical products with movable mechanisms used to control the flow of media within pipelines.