Class C flammable liquids in pressure pipelines

According to the information you provided, pipelines for Class C flammable liquids were not covered by the supervision regulations for pressure pipelines under the old standard GB/T20801-2006; however, the new standard GB/T20801-2020 includes them within the scope of pressure pipelines. Since TSG-D0001-2009 has not been updated, there is a problem of inconsistency with the new standards. Under such circumstances, it is recommended to follow the latest standard GB/T20801-2020, and under this standard, pipelines carrying Class C flammable liquids should be brought under regulatory oversight. If an exact safety declaration document is required, it is recommended to consult the local safety regulatory authorities for the most authoritative response. .

Where does it state that Category C refers to pressure pipelines?

The “Catalogue of Special Equipment” is defined as follows: “A pressure pipeline refers to a tubular device that uses a certain pressure to transport gases or liquids. It includes pipelines whose maximum operating pressure is 0.1 MPa (gauge pressure) or higher, whose medium is gas, liquefied gas, steam, or a liquid that is flammable, explosive, toxic, corrosive, and whose maximum operating temperature is equal to or higher than its standard boiling point, and whose nominal diameter is 50 mm or larger.” 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. ”(Here, flammability refers to the fire hazard level, which is determined in accordance with the provisions of GB50160 \"Code for Fire Protection Design of Petrochemical Enterprises\" (which classifies it into six levels: Class A/A/B, Class B/A/B, and Class C/A/B) and GB50016 \"Code for Fire Protection Design of Buildings\" (which classifies it into three levels: Class A, Class B, and Class C).

According to TSG-D0001-2009, Class C flammable liquids are not classified as flammable media, and thus are not subject to regulation as pressure pipelines. It is said that in the most recent response from the State Administration for Market Regulation, category C flammable liquids have been included among flammable media. However, TSG-D0001-2009 has not been repealed yet, and its authority remains valid. At the end of the supplementary provisions in Chapter 4 of TSG07-2019, it is stated: \"For any other notices, documents, etc. related to the licensing of special equipment production and filling units that were issued prior to the implementation of these rules, if their requirements differ from those specified in these rules, the requirements of these rules shall prevail.\" It was announced that a total of 12 regulatory documents, including the \"TSG R1001-2008 Rules for Licensing the Design of Pressure Vessels and Pressure Pipelines\" and the \"TSG D3001-2009 Rules for Licensing the Installation of Pressure Pipelines\", have been repealed. It is inferred that \"especially after the abolition of TSGR1001-2008, there was no official basis left for the classification and grading of pressure pipelines. Moreover, the classifications for GC-class industrial pipelines provided by TSGD0001 and GB/T 20801.1-2006 also lost their authority (for reasons see the red bold text above). As a result, TSG 07-2019 became the only standard for determining the licensing level of pressure pipelines.\" ”

The draft of TSG-DXXXX-20XX, \"Technical Code for Safety of Industrial Pipelines,\" has been released. The section on combustible gases and liquids is entirely based on GB50160; in addition, combustible media such as aerosols are also covered. In other words, it acknowledges that pipelines for Class C combustible media should be included in the category of pressure pipelines. In line with new versions such as GB20801 and SH3501, it is an emerging trend to classify Class C flammable medium pipelines as pressure pipelines.

Around the time when the draft of the TSG-DXXXX-20XX \"Technical Regulations for the Safety of Industrial Pipelines\" was released, Professor Dao Yanyan put forward a suggestion that I found quite reasonable: \"A note 1 can be added to Table A-3 in Appendix A of the regulations, stating that the flammable liquids covered by these regulations include Class A and B liquids, as well as Class C and D liquids whose maximum operating temperature is equal to or higher than their standard boiling point or flash point.\" Corrections are made in the form of annotations, keeping the ranges for flammable liquids of categories A, B, and C unchanged; this approach is less noticeable compared to making outright changes to the ranges for flammable liquids in pressure pipelines. Moreover, the operating temperature of the vast majority of pressure pipelines for Class C flammable liquids, including long-distance oil pipelines, is below their flash point or standard boiling point. ”

Therefore, for chilled water pipelines with a diameter of DN80–150, operating temperature of 2–7 degrees, pressure of 0.5 MPa, and containing 30% Class C flammable liquids, should these be considered pressure pipelines that require a tightness test?

Indeed, pipelines for Class C lubricants, which are commonly used in the fine chemical industry, must be submitted for inspection