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The Management Measures for Pipeline Weld Joint Marking were formulated to support the construction based on single-line diagrams, ensure the proper implementation of regulations and standards such as the Provisions on the Safety Management and Supervision of Pressure Pipelines, enhance the quality control of pressure pipeline installation, and guarantee the quality of the pipelines. 1 Before the single-line diagram is issued, the pipeline technician shall pre-mark the welding numbers on the single-line diagrams for use by themselves and their team, ensuring that the welding numbers on both diagrams are identical. Teams without a single-line diagram should refuse to carry out the work. 2 The team leader of the construction crew shall, in accordance with the pre-set welding codes, write the pipeline numbers and welding codes on the prefabricated pipe sections using paint or oil-based markers, and mark the welder’s number, welding code, and welding date on the single-line diagram to ensure consistency between the two. When the actual weld seam does not match the preset one, the number of weld seams can be increased or decreased as appropriate. When adding a weld joint between the preset weld joints N and N+1, they are labeled as N-1, N-2… ； When reducing the number of welds between the predetermined welds N, N+1, and N+2, the weld at N+1 can be removed and marked on the single-line diagram. A fixed port must be preceded by F before the welded port. The weld joints of socket-type connections and grooved tees, as well as those of butt joints, are numbered separately. A ‘I’ should be added before the numbers of socket-type connection and grooved tee weld joints to distinguish them from butt joint weld joints (for example, if a pipeline has 20 butt joint weld joints and 5 socket-type connection weld joints, then the numbers of the butt joint weld joints will be 1, 2, 3…19, 20) ； The serial numbers of the sockets are I1, I2, I3, I4, I5). 3 When technicians issue inspection orders, they mark the welds to be inspected on their own schematic diagrams (by circling the corresponding welds and annotating RT or PT, etc., next to them). 4 The flaw detection personnel carry out weld inspection in accordance with the assignment sheet; after inspecting each weld, they mark a “×” on that weld using a black or blue marker or blue paint. Welds that have not been inspected are not marked. 5. Acid wash the welds of stainless steel pipes; after cleaning, mark them with a black or blue marker pen along the edges of those welds. 6 Once the pipeline construction is completed, the team leader signs on the single-line diagram; the supervisor is responsible for collecting the fully labeled construction single-line diagrams and handing them over to the technician. The technician then compiles the single-line diagram and handover documents accordingly. Pipeline Number, Welding Order Number, Welder’s Number, Visual Inspection, Operation Time, Zone Number, Material Quality