Safety issues during pressure sealing

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In recent years, pressure sealing technology has been widely used in thermoelectric systems and petrochemical industries, and has been welcomed by users. However, two views on safety issues in pressure sealing deserve attention.: One is that pressure sealing is unsafe ； The other side thinks that there is nothing and anyone can carry out construction operations. These two views are actually based on a lack of understanding of the basic content and characteristics of pressure sealing technology. This article proposes safety measures to ensure the smooth elimination of leaks on the basis of construction safety based on the characteristics of pressure sealing safety issues, the basis and risks of pressure sealing safety operations, and other issues. In the early days of the promotion of pressure plugging technology in my country, its construction and operation methods were considered to be inconsistent with certain provisions of the "Pressure Vessel Safety Supervision Regulations" and were suspected of violating regulations. Its safety was questioned, mainly referring to the safety of bolts. Testing of the stress on the bolts during the on-site pressure sealing process showed that the stress on the bolts increased, but within the allowable range, the working condition of the bolts was safe. This provides an important scientific basis for the safety of pressure sealing operations. Of course, this conclusion is conditional. First, the original bolts are not damaged and are all intact. ； Second, the injection pressure that the bolt can withstand can meet the sealing specific pressure requirements for sealing under pressure to eliminate leakage. Another issue of concern is the impact of pressure sealing when equipment and pipe walls leak on the safety performance of the leak site. We know that under the action of external pressure on equipment and pipelines, circumferential compressive stress will occur in the pipe walls. When the external pressure increases to a certain value, the pipe walls will gradually deform and collapse. This phenomenon is called instability of equipment and pipelines. The external pressure that causes instability is called critical pressure. The equipment and pipelines allow operating external pressure (that is, the difference between external pressure and internal pressure), which cannot exceed or be close to the critical pressure. Pressure sealing eliminates leakage on equipment pipelines by generating sufficient sealing specific pressure through the injection pressure (external pressure). At this time, does the sealing specific pressure exceed or approach the critical pressure? Experiments show that the critical pressure is related to the elastic modulus (E) and wall thickness/outer diameter ratio of the equipment pipeline material. The larger the elastic modulus, the higher the critical pressure. Steel has a larger elastic modulus than aluminum and plastic, so the critical pressure of steel equipment pipelines is higher than that of aluminum and plastic. The larger the wall thickness of the same outer diameter, the higher the critical pressure. ； The larger the outer diameter of the same wall thickness, the lower the critical pressure. It has been proved by theoretical calculation and practice that if the equipment pipeline is not damaged and the wall thickness is not significantly thinned, it is safe to seal the leakage part under pressure. The above two important conclusions are undoubtedly an important basis for the safety of pressure sealing construction operations. However, the leakage location and its damage are relatively complex. We adopt different methods and measures according to different leakage situations. (1) Most of the leakage parts can meet the safe construction operation requirements of pressure sealing technology, and leakage can be eliminated using conventional construction operation methods. (2) If the lens gasket flange seal leaks with a tapered sealing surface, the corresponding method must be used for pressure sealing according to the specific conditions of the lens gasket flange on site, otherwise the safety of the pressure seal cannot be guaranteed. (3) If there is thinning and leakage in the equipment pipeline wall, the thinning situation must be clearly detected so that measures can be taken to ensure the safety of the pressure sealing construction operation. However, if it cannot be detected clearly for some reason, the leakage cannot be eliminated by pressure sealing method. (4) Cracks in equipment pipelines are the most dangerous defects, and many blasting accidents originate from cracks. According to foreign reports, accidents caused by cracks account for 89.4% of all accidents. Therefore, leakage from cracks should attract special attention. There are many reasons for cracks and they are relatively complex, but they will generally continue to expand. Different measures can be taken to eliminate or prevent continued expansion according to different situations. Then use pressure sealing to eliminate leaks. It should be particularly pointed out that if there are no crack arrest measures, leakage cannot be eliminated by pressure sealing. Pressure-sealed construction operations are key to ensuring safety. Because, even in leakage areas that have a safe basis for construction operations, if safety regulations are not strictly implemented and safety measures are not implemented, the safety of the pressure seal cannot be guaranteed. Not to mention other special leakage locations. The construction operation of pressure sealing not only ensures the safety of the leakage site and system, but also ensures the safety of the operator himself. Due to the closest contact between the operator and the leaking medium, the operator is extremely vulnerable to various injuries from the leaking medium and various accidents caused by the leaking medium (including fire and explosion accidents, fatal poisoning accidents, etc.). Therefore, personal protection and operation site protection and management are very important. These protections are based on * * and relevant regulations on pressurized sealing operations. The safety of pressure sealing construction operations is ultimately determined by the technical safety quality and management level of the construction team and construction personnel, and is related to the technical ability, operation level and safety awareness of the operators. It is hard to imagine that a construction unit that has not received professional training in pressure sealing technology, knows little about pressure sealing technology, or does not have the conditions to research and train construction teams and personnel may complete individual projects during pressure sealing construction, but it does not mean that they can operate safely. Because they do not understand the pressure sealing technology, they must fall into blind operation, which is very dangerous. Jiangda Yangsheng Enterprise has been developing and researching pressure sealing technology for more than 20 years, and has always regarded safety issues as an important content and component of this technology. It can be said that without safety, there is no pressure sealing technology, and it is recognized that without safety, there is no possibility of project success. We conduct research with a scientific attitude, not denying the risks in construction operations, but also carefully studying the possibility and feasibility of eliminating risks. We sum up experience from practice, learn lessons, and formulate a set of scientific and effective safe operation techniques and measures to ensure construction quality and safety, and use this to train required construction personnel to ensure quality and safety in pressure sealing construction, making great contributions to the safe production of many enterprises.