GC3 pressure pipelines transport non-toxic, non-flammable fluids in pipes with a pressure of ≤1.0 MPa

The definition of pressure pipelines specifies that the pipe diameter is greater than or equal to DN50

The Work Safety Supervision Bureau has a document providing an answer to the question you asked. According to Item 114 of the 2014 Catalogue of Special Equipment, pressure pipelines refer to tubular devices that use a certain pressure to transport gases or liquids. They are defined as pipelines with a maximum operating pressure of 0.1 MPa (gauge pressure) or more, carrying gases, liquefied gases, steam, or liquids that are flammable, explosive, toxic, corrosive, and have a maximum operating temperature equal to or higher than their standard boiling point, and with a nominal diameter of 50 mm or more. Except for pipes with a nominal diameter of less than 150 mm and a maximum operating pressure of less than 1.6 MPa (gauge pressure), as well as the pipes that form part of the equipment used for transporting non-toxic, non-flammable, and non-corrosive gases. Notice from the General Office of the Quality Inspection Administration for Pressure Pipelines on Issues Related to the Safety Supervision of Pressure Pipelines and Cylinders, Quality Inspection Office Special [2015] No. 675: To the Quality and Technical Supervision Bureaus (Market Regulation and Supervision Departments) of all provinces, autonomous regions, and municipalities directly under the Central Government: In order to implement the requirements regarding functional transformation and the delegation of powers, and to further improve the safety supervision of pressure pipelines and cylinders, and in light of the newly revised “Catalogue of Special Equipment” (hereinafter referred to as the “Catalogue”) and the “Technical Regulations for Safety Supervision of Cylinders” (TSG R0006-2014, hereinafter referred to as the “Cylinder Regulations”), the following opinions on issues related to the safety supervision of pressure pipelines and cylinders are hereby communicated: I. Issues related to the safety supervision of pressure pipelines (1) Regarding the range of media covered by pressure pipelines in the new Catalogue. The toxic, non-flammable, and non-corrosive gases referred to in the definition of pressure pipes in the new Catalogue – namely, pipes with a nominal diameter of less than 150 mm and a maximum operating pressure of less than 1.6 MPa (gauge pressure) that transport such gases – do not include liquefied gases, steam, and oxygen. (II) Regarding the categories and types of pressure pipeline components in the new Catalogue. The nominal diameter of pressure pipeline components included in the new Catalogue shall be 50 mm or greater. 1. The “ductile iron pipes” listed in the new Catalogue do not include other types of cast iron pipes besides this variety ； 2. The new “Catalog” includes the category of “composite pipes”, which specifically covers three types: metal-metal composites, metal-non-metal composites, and non-metal-non-metal composites ； 3. Typical products in the category of “metal valves” under the new Catalog include: pressure regulating valves, control valves, gate valves, ball valves, butterfly valves, globe valves, check valves, steam traps, diaphragm valves, throttle valves, plug valves, piston valves, low-temperature valves, pressure reducing valves (self-acting), eye valves (used in the metallurgical industry), orifice plates (used in the metallurgical industry), drain valves, temperature reducing valves, and pressure reducing valves, among others ； 4. The “rotating compensator” category in the new Catalog does not include the “special-type metal expansion joints” that were listed in the previous Catalog” ； 5. The new Catalog does not include the items from the original Catalog such as “cast pipe fittings,” “manifolds,” “filters,” “special types of metal expansion joints,” “metal bellows,” “fasteners,” and “flame arrestors,” as well as “pressure pipeline supports” and “pressure pipeline materials.” The document has many pages; only the relevant parts have been attached, and it should explain your question perfectly.

For installation per item (1), for diameters below DN150 and pressures less than 1.6, this includes compressed air and nitrogen. So do compressed air pipelines and gas pipelines such as those for nitrogen below DN150 not fall under the category of pressure pipelines? This is different from the GC3 classification standard, right? According to the GC3 classification, nitrogen and compressed air should belong to GC3 category of pipes

First, it has to be a pressure pipeline; only then is there classification. Aren’t all pressure pipelines classified in some way?

According to clause (1), for diameters below DN150 and pressures less than 1.6, this includes compressed air and nitrogen; so do pipelines for compressed air and gases such as nitrogen that are below DN150 not fall under the category of pressure pipelines? This is different from the GC3 classification standards, right? According to the GC3 classification, nitrogen and compressed air should fall under GC3 category of pipelines. Aren’t compressed air and nitrogen considered pressure pipelines? ?

For steam and compressed air, it depends on the specific design parameters; it cannot be uniformly classified as GC3

Below 150, with a pressure of less than 1.6; based on the above, it may not be considered a pressure pipeline, but according to GC3’s definitions it does fall under the category of pressure pipelines

The last edit to this post was made by FMSD on 2019-2-22 at 08:50. I believe that steam pipes with a gauge pressure of more than 0.1 MPa and a nominal diameter of 50 mm or greater are considered pressure pipes

Steam pipes are classified by 1 kilogram and DN50

You need to address water, steam, and compressed air separately; steam pipes with a diameter of less than 50 do not fall under the category of pressure pipes； The medium is water; it is considered a pressure pipeline only when the temperature is above the boiling point ； The diameter of the pipe for conveying compressed air must be 150 or more to be considered a pressure pipeline