With the development of long-distance pipeline construction, carbon steel flange blind plates have become an important part of pipeline pressure testing. Before and after pressure testing, each section of the pipeline is scanned with a ball pass, usually 4-5 times. Especially after the pressure test, it is difficult to clean the stored water in the pipeline, and the cleaning frequency will be higher. The construction method of using repeated welding heads at the ball receiving point has the following problems: firstly, it increases the labor intensity of workers; The second is that the repeated welding head method has high consumables, requires large equipment multiple times, and high costs. A new simple and fast opening large flange blind plate construction method is proposed to address the problems of high labor intensity, high consumables, frequent need for large equipment, and high cost caused by the use of repeated welding head method at the starting point during ball sweeping after pressure testing of long-distance pipelines. This construction method introduces the structure, working steps, and strength verification of the quick opening blind plate. Through application in the Se'ninglan gas pipeline project, it has been proven that the fast opening blind plate construction method improves work efficiency by three times compared to the repeated welding head construction method. This not only reduces the labor intensity of workers, but also lowers costs. The preparation work that carbon steel flanges need to do before measurement is to determine different measurement methods and accuracy based on specific situations according to the methods and methods used

Preparation before measurement:

1. Before measurement, according to the position of the large flange, sketch the connection of each large flange of the equipment and number it consecutively, so that the fixture can be installed according to the method and principle, and can be used normally.

2. During installation, carbon steel flanges may have different outer diameters, misaligned joints (not concentric), and uneven gasket thickness. Therefore, the processed fixture should correspond to the carbon steel flange on the side and cannot be interchanged. Therefore, measuring the dimensions and numbers of each part is the key to fixture processing and installation

3. When measuring, arrange three people, two of whom will measure, one will proofread and fill out the form, and the measuring tool will be a vernier caliper. If conditions permit, external calipers and steel plate rulers can be used. Measurement is a meticulous task and a prerequisite for fixture installation. Measurement and recording should be prepared accurately, and the form should be filled out carefully and clearly. In actual measurement work, they should cooperate with each other and be able to cooperate and use according to the correct principles