SH/T 3126-2013 in English

1 Scope

This specification specifies the design requirements for tracing and insulation of automatic control engineering instrument and measuring piping in petrochemical industry.

This specification is applicable to the design for tracing and insulation of automatic control instrument and measuring piping in petroleum refining, petrochemical industry and new construction, extension and renovation of factories using coal as raw materials to prepare fuel and chemical products.

2 Normative references

The following 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/T 8175 Guide for design of thermal insulation of equipment and pipes
GB/T 4272 General principles for thermal insulation technique of equipment and pipes

3 Terms and definitions

For the purposes of this specification, the following terms and definitions apply.

3.1
tracing
manner to raise the temperature of instrument and measuring piping medium by using heating medium

3.2
insulation
measure taken to add insulation layer on the outer surfaces of equipment, piping and their accessories in order to reduce the heat exchange between the surrounding environment and them, which may be classified into heat insulation and cold insulation according to the direction of heat flow

3.3
heat insulation
coating measure taken on the outer surface of equipment, piping and their accessories to reduce heat dissipation to the surrounding environment

3.4
cold insulation
coating measure taken on the outer surface of cryogenic equipment and piping to reduce heat transfer from the surrounding environment into them and prevent condensation or frost on the outer wall surface of them

3.5
scald insulation
insulation measure taken to prevent scald of personnel for instrument and measuring piping without heat insulation with surface temperature over 60℃

3.6
insulation layer
thermal insulation materials and their products which play a major role in maintaining the stability of medium temperature

3.7
thermal insulation construction
structural complex composed of insulation layer, moisture-proof layer and protective layer

3.8
electrical heat-tracing
method used to supplement the heat loss of the traced object by using electrical heat-tracing belt or other electrical heating facilities in the use process, so as to maintain the medium temperature within a certain range

3.9
maintain temperature
certain temperature at which the traced object is maintained by the design tracing system under the design conditions

3.10
maximum maintain temperature
maximum temperature at which the traced object can be maintained continuously by the electrical heat-tracing system

3.11
end termination connection
end termination connection of the electrical heat-tracing belt with respect to the power supply end

Foreword i
1 Scope
2 Normative references
3 Terms and definitions
4 Types and manners of instrument tracing
4.1 Principles of tracing
4.2 Types of tracing
4.3 Manners of tracing
5 Design of instrument tracing system
5.1 General requirements
5.2 Design of hot water tracing system
5.3 Design of steam tracing system
5.4 Design of electrical heat-tracing system
6 Manners of instrument insulation
7 Design of instrument insulation system
7.1 Structure of insulation
7.2 Calculation of thickness of insulation layer
7.3 Selection of insulation material
Annex A (Informative) Sketch of tracing structure
Annex B (Informative) Sketch of hot water tracing centralized distribution system
Annex C (Informative) Sketch of steam tracing decentralized arrangement system
Annex D (Informative) Sketch of steam tracing centralized distribution system
Annex E (Informative) Limit of rising height of steam tracing pipe
Annex F (Informative) Structure of heat insulation of instrument piping
Annex G (Informative) Sketch of electrical heat-tracing
Annex H (Informative) Sketch of installation of electrical heat-tracing belt
Annex J (Informative) Main performance of common insulation material and its products
Annex K (Informative) Main performance of common protective material
Bibliography
Explanation of wording in this specification