Classification of Pipeline Levels
1. Overview
In current Chinese regulations, industrial pipeline classifications can be divided into two systems. One is the classification system for pressure pipelines, involving regulations such as the Safety Technical Supervision Regulations for Pressure Pipelines – Industrial Pipelines TSG D0001-2009 and the Rules for Licensing Design of Pressure Vessels and Pressure Pipelines TSG R1001-2008. The other is the design, construction, and acceptance standards for industrial metal pipelines, primarily involving norms such as Design Code for Industrial Metal Pipelines GB 50316-2000, Construction Quality Acceptance Code for Petrochemical Metal Pipeline Engineering GB 50517-2010, Construction and Acceptance Code for Petrochemical Highly Toxic and Flammable Media Pipeline Engineering SH 3501-2011, and Construction Quality Acceptance Code for Industrial Metal Pipeline Engineering GB 50184-2011.
The classifications of fluid categories and pipeline levels differ between the two systems. The former is used for design, manufacture, installation, use, repair, modification, inspection, etc., of pressure pipelines; the latter is primarily used for construction, inspection, and acceptance of industrial metal pipelines.
During PID design and pipeline list preparation, the classification of pressure pipelines is involved. The technical requirements section of the pipeline list is completed by the material specialty, including radiographic testing. Given the significant proportion of EPC projects, the process specialty should broaden its knowledge to better support project teams and on-site work. Below, I will introduce the classifications of fluid categories, pipeline categories, and radiographic testing in various standards, along with relevant precautions.
2. Introduction to Relevant Standards
2.1 Safety Technical Supervision Regulations for Pressure Pipelines – Industrial Pipelines TSG D0001-2009
This regulation specifies applicable conditions for industrial pipelines:
- Highest working pressure greater than or equal to 0.1MPa (gauge).
- Nominal diameter greater than 25mm.
- Transporting gases, steam, liquefied gases, liquids with a highest working temperature equal to or higher than their standard boiling point, or flammable, explosive, toxic, corrosive liquids.
Fluid categories involve fire hazards, toxicity, and corrosion. Their classifications are as follows:
- Toxicity should comply with Grading Standard of Hazardous Degree of Occupational Contact Toxic Substances GB5044-85. Toxicity hazard levels include extremely hazardous, highly hazardous, and moderately hazardous.
- Fire hazards should comply with Code for Design of Fire Protection in Petroleum and Chemical Industries GB50160-2008 and Code for Design of Building Fire Protection GB50016-2006. Gas fire hazards are divided into Class A and Class B; liquids are divided into liquefied hydrocarbons, Class A, Class B, and Class C.
- Corrosivity refers to fluids causing visible necrosis on skin contact within 4 hours, or corrosion rates exceeding 6.25mm/year on 20 steel at 55°C.
Based on the state, fire hazard, toxicity, corrosion, design temperature, and design pressure of the medium, pressure pipelines can be classified into GC1, GC2, and GC3 levels.
2.2 Rules for Licensing Design of Pressure Vessels and Pressure Pipelines TSG R1001-2008
The classification of fluid categories and pipeline levels in this regulation is consistent with the Safety Technical Supervision Regulations for Pressure Pipelines – Industrial Pipelines, except for the definition of GC3 level. It specifies pipelines transporting non-toxic, non-flammable fluids with design pressures less than or equal to 1.0MPa and design temperatures above -20°C but below 185°C, differing slightly from the upper limit specified in TSG D0001.
2.3 Design Code for Industrial Metal Pipelines GB 50316-2000
This standard classifies fluids into A1, A2, B, D, and C categories. The selection of pipeline materials, components, and design all follow the rules based on these fluid categories.
2.4 Construction Quality Acceptance Code for Petrochemical Metal Pipeline Engineering GB 50517-2010
Pipeline levels are divided into SHA1, SHA2, SHA3, SHA4, SHB1, SHB2, SHB3, SHB4, SHC1, SHC2, SHC3, SHC4, and SHC5. Inspection, installation, and testing requirements vary according to the pipeline grade. The meanings of letter codes in pipeline levels are detailed in Table 2-1.
2.5 Construction and Acceptance Code for Petrochemical Highly Toxic and Flammable Media Pipeline Engineering SH 3501-2011
This standard specifies requirements for construction, inspection, and testing of steel pipelines transporting toxic and flammable media in petrochemical projects. Pipeline grades are divided into SHA1, SHA2, SHA3, SHA4, SHB1, SHB2, SHB3, SHB4. Requirements related to pipeline systems are largely consistent with GB 50517.
2.6 Construction Quality Acceptance Code for Industrial Metal Pipeline Engineering GB 50184-2011
Based on the fire hazard, toxicity, and corrosion of the fluid media, design temperature, and design pressure, this standard divides pipeline weld inspection levels into five grades: I, II, III, IV, and V. The radiographic testing percentages for these levels are 100%, ≥20%, ≥10%, ≥5%, and no non-destructive testing required, respectively.
3. Summary
By summarizing the above standards and their applications, I have compiled a reference table for pipeline classification and radiographic testing for designers
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