1 Scope
This specification specifies the minimum requirements for the design of sealing and purging of instrument measurement and tubing for automatic control engineering in petrochemical industry.
This specification is applicable to the engineering design of the sealing and purging of instrument measurement and tubing for petroleum refining, petrochemical industry or the construction, expansion and renovation of plants for making fuels and chemical products by taking coal as the raw materials.
This specification is not applicable to positive pressure ventilation system adopted for corrosion protection or in areas subject to explosion hazards.
2 Normative references
The following referenced documents are indispensable for the application of this specification. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB 150.3-2011 Pressure vessels - Part 3: Design
3 Terms and definitions
For the purpose of this specification, the following terms and definitions apply.
3.1
diaphragm sealing
sealing method in which diaphragm is used to prevent the direct contact between the measured medium and the sensor element of the instrument
3.2
liquid sealing
sealing method that prevents the direct contact between the measured medium and the sensor element of the instrument by filling the sealing vessel with sealing liquid
Foreword i
1 Scope
2 Normative references
3 Terms and definitions
4 Instrument sealing
4.1 Scope of service
4.2 Diaphragm sealing
4.3 Liquid sealing
5 Instrument purging
5.1 Scope of service
5.2 Characteristics of purging fluid
5.3 Design of purging gas system
5.4 Design of the flushing liquid system
6 Design of the purging set
6.1 Purge set composition
6.2 Design of purging set
Annex A (Informative) Corrosion resistance for diaphragm material in corrosive media at different temperature and concentration
Annex B (Informative) Property and application of sealing liquid
Annex C (Informative) Typical drawing of purging set connection
Annex D (Informative) Hook-up drawing for purging set tubing
Bibliography
Explanation of wording in this specification
