Regarding the issue of submitting pressure pipelines for inspection to the Special Inspection Institute
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Pressure pipelines must be reported to the local special equipment inspection agency for inspection, in accordance with the provisions of the **2015 New Catalogue of Special Equipment. Pressure pipelines refer to tubular devices that use a certain pressure to transport gases or liquids; they are defined as those with a maximum operating pressure of 0.1 MPa (gauge pressure) or more, where the medium is a gas, liquefied gas, steam, or a liquid that is flammable, explosive, toxic, corrosive, and has a maximum operating temperature equal to or higher than its standard boiling point, and whose nominal diameter is 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. Among them, the safety supervision and management of oil and gas pipelines shall also be carried out in accordance with laws and regulations such as the Work Safety Law and the Oil and Gas Pipeline Protection Law. ), what does the maximum operating pressure in a pressure pipeline mean? What is the relationship between the maximum operating pressure and the design pressure and operating pressure? For example, a pipeline has a design pressure of 0.98 MPa, an operating pressure of 0.8 MPa, a nominal diameter of DN40, and carries a lean liquid as the medium. According to the requirements for pressure pipelines, since its diameter does not meet the DN50 standard, it should not be considered a pressure pipeline. But if the designer classifies it as a GC2 pipeline grade, is it then a pressure pipeline? Could everyone let me know, so we can discuss it?
The maximum operating pressure is obvious from the name! The pressure pipelines listed in the catalog are divided into two categories: one category includes those that are toxic, explosive, or corrosive, with DN50 being the relevant specification; the other category consists of those that are non-toxic, non-flammable, and non-corrosive, with DN150 being the relevant specification. According to the catalog requirements, your pipeline is not considered a pressure pipeline
The maximum operating pressure refers to the highest pressure that this pipeline experiences under the most severe operating conditions; the design pressure should not be lower than the maximum operating pressure. Pressure pipelines refer to pipes in which the medium is gas, liquefied gas, steam, or a liquid that is flammable, explosive, toxic, corrosive, and has a maximum operating temperature equal to or higher than its standard boiling point, with a nominal diameter of 50 mm or more. This definition does not apply to pipes with a nominal diameter of less than 150 mm and a maximum operating pressure of less than 1.6 MPa (gauge pressure), nor to pipes that transport non-toxic, non-flammable, and non-corrosive gases, or to the pipes that form part of such equipment. Based on years of experience dealing with the Special Inspection Institute, pipelines such as vent pipes, pipelines after safety valves, and pipelines after pumps, whose pressures are instantaneous, are not considered pressure pipelines. For steam pipelines, if the pressure exceeds 1 kilogram and the pipe diameter is greater than 50, they are classified as pressure pipelines. For non-toxic and harmless gases such as nitrogen and compressed air, as long as the pressure is less than 16 kilograms, this limit can be reduced to 150. The DN40 pipe mentioned above does not fall under the category of pressure pipes, so it does not require inspection; however, if it involves toxic, flammable, or corrosive substances, leakage tests and non-destructive testing are necessary.
0.8MPa? That’s far higher than 0.1MPa, but the pipe diameter does not meet the requirements.
The design may be based on the old regulations; 15 years ago, according to those old rules, pipes with a diameter of 25 or more were considered pressure pipes. Under the new regulations, DN40 is not considered a pressure pipeline. If the user is concerned about potential safety hazards, they can request that the wall thickness of non-pressure pipes be measured during the regular inspections of pressure pipes, and a separate inspection report can be issued.