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锅炉及压力容器都是典型的重要焊接结构。锅炉及压力容器的工作条件包括载荷、温度和介质等。从载荷性质来看,锅炉及压力容器除主要承受静载荷外,还承受低周疲劳载荷。因此,要求所使用的材料具有优良的常温机械性能,包括疲劳强度。锅炉及压力容器的环境工作温度对材料性能有着重要的影响。一般,按工作温度的高低将锅炉及压力容器分为高温容器(工作温度为100～650℃)、常温容器(工作温度为自然环境温度)和低温容器(工作温度为-20～-253℃)。对于高温容器和低温容器还要求所使用的材料分别具有优良的高温性能和低温性能。各种介质在工作条件下对锅炉及压力容器有着不同性质和不同程度的腐蚀作用,所以,对于接触腐蚀介质的容器,还要求所使用的材料具有优良的抗腐蚀性能。锅炉及压力容器是一种承受气压、液压或气—液压的重要受压元件,其工作条件十分恶劣,一旦发生破坏事故,将是灾难性的,会造成重大经济损失和伤亡事故。因此,对于锅炉及压力容器的制造,不仅要求技术先进、经济合理,更重要的是要求制造质量优良,以确保使用时安全可靠。由国内外锅炉及压力容器发生的大量故坏事故分析结果可知,缺陷的存在、性能的下降、应力水平的提高是焊接接头区成为结构中薄弱环节的三大要素。因此,从某种意义上讲,焊接接头的质量反映了锅炉及压力容器的制造质量,并直接影响结构的使用安全性。焊接接头的质量不仅与结构设计、材料选择、焊接工艺的制定有关,而且在很大程度上还与焊工对锅炉及压力容器焊接基础知识的学习和运用,以及实际操作技能的水平有关。为配合国家劳动总局最近下发的《锅炉及压力容器焊工考试规则》中对焊工提出的学习和运用理论知识的要求,一机部劳资司组织编写并出版了《锅炉及压力容器焊工基本知识》一书。本刊准备在今年第四、第五、第六期的“基础知识”栏内把这本书中的焊接材料、焊接工艺以及焊接接头性能和质量控制等有关章节,摘要介绍给在锅炉及压力容器制造厂从事受压元件焊接的焊工及有关人员,以供学习之用。你们读了之后,有什么收获和疑问,有什么要求和希望,请直接写信寄给我刊编辑部。
Boilers and pressure vessels are typically important welded structures. Boiler and pressure vessel working conditions include load, temperature and medium. From the nature of the load, boilers and pressure vessels in addition to the main static load, but also to withstand low cycle fatigue load. Therefore, the materials used are required to have excellent room-temperature mechanical properties, including fatigue strength. Ambient operating temperature of boilers and pressure vessels has an important effect on material properties. Generally, according to the working temperature, the boiler and pressure vessel are divided into high temperature vessel (working temperature is 100 ~ 650 ℃), normal temperature vessel (working temperature is natural environment temperature) and low temperature vessel (working temperature is -20 ~ -253 ℃) . For high temperature containers and cryogenic containers also require the use of materials have excellent high temperature performance and low temperature performance. Various media under the working conditions of the boiler and pressure vessel has a different nature and varying degrees of corrosion, therefore, for contact with corrosive media containers, but also requires the use of materials with excellent corrosion resistance. Boilers and pressure vessels are important pressure-bearing, hydraulic or gas-hydraulic pressure components and their working conditions are very poor. In the event of a damage accident, it will be catastrophic, causing significant economic losses and casualties. Therefore, for the manufacture of boilers and pressure vessels, it not only requires advanced technology and economic rationality, but more importantly requires that the manufacturing quality be good to ensure safe and reliable use. The analysis of a large number of bad accidents at boilers and pressure vessels at home and abroad shows that the existence of defects, the decrease of performance and the improvement of stress level are the three major factors that make the welded joints become the weak links in the structure. Therefore, in a sense, the quality of welded joints reflects the quality of the manufacture of boilers and pressure vessels and directly affects the safety of the structure. The quality of welded joints is not only related to the structural design, material selection, welding process development, but also largely to the learning and application of the basic knowledge of the welding of boilers and pressure vessels by the welder, as well as the level of practical skills. In order to meet the requirements of the welders’ theory of learning and applying proposed by the State Administration of Labor in the recently issued Rules for Examination of Boilers and Pressure Vessels, a labor department of the Ministry of Machinery organized and published the Basic Knowledge of Boilers and Pressure Vessel Welders, This book. This publication is prepared in the fourth, fifth and sixth of this year’s “basic knowledge” column will be the book of welding materials, welding process and welding joint performance and quality control and other relevant sections, briefed on the boiler and the pressure Manufacture of welders and related personnel engaged in pressure welding of pressure components at container factories for learning purposes. After you read, what are the gains and doubts, what are the requirements and hopes, please write to my editorial department directly.