Regulations on the Grading of Importance of Product Quality Characteristics for Pressure Vessels

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Regulations on the Grading of the Importance of Product Quality Characteristics for Pressure Vessels) 1 Scope These regulations apply to the management of grading the importance of product quality characteristics for pressure vessels. 2 Concept of quality characteristic grading: Quality characteristic grading involves classifying products based on the importance of their quality characteristics, in order to determine which defects can lead to serious consequences and which ones are less significant. By grading the importance of quality characteristics, product quality requirement specifications are provided to the process, manufacturing, and inspection departments so that they can take preventive measures to ensure the product meets the required quality standards. 3 Quality characteristic grading methods 3.1 Basic principles Various factors such as compliance with current regulations and standards, user satisfaction, and economic losses should be taken into consideration comprehensively. 3.2 Grading Method The importance of product quality characteristics is graded into three levels, as shown in Table 1. Table 1 Classification Method: Characteristic Analysis
Classification Definition:
Critical – If the specified value limit is exceeded, it directly affects the product’s safety or results in the loss of the product’s overall functionality.
Important – If the specified value limit is exceeded, it causes the loss of some of the product’s functions.
Minor – If the specified value limit is exceeded, it leads to a gradual loss of the product’s functions.
3.3 Classification Markings: The markings indicating the importance of quality characteristics shall be indicated in the technical documents in accordance with the provisions in Table 2. Table 2: Grading labels – Importance, type, and level names. Critical: A; Important: B; Secondary: C. 4. Grading of product quality characteristics for pressure vessels is carried out in accordance with the provisions in Table 3. Table 3: Grading of product quality characteristics for pressure vessels. Serial number, Quality characteristic item, Quality characteristic level: 1. The material and grade must comply with the specifications in the drawings, and the markings must be correctly applied. The weld location at the joint of the two cylinders meets the technical standards; the minimum length of each section is: ≥300 mm for medium and low pressure vessels, and ≥600 mm for high pressure vessels. The joint diagram has been approved by the designer. The dimensions marked on B3 are in line with the assembly diagram, and the process tolerances and marking deviations comply with the process specifications. The types and quantities of various B4 specimens, as well as the cutting direction, comply with the process specifications. Non-destructive testing of the longitudinal and circumferential seams in A5 meets the requirements specified in the drawings and the tolerance specifications. The surface quality of the A6 longitudinal and circumferential seams meets the requirements of the tolerance specifications. The weld height for A7 shall not be lower than that of the base material. For containers (including specimens) that require post-weld heat treatment, the heat treatment parameters (rate of temperature increase, temperature in the furnace, holding temperature, holding time, rate of temperature decrease, and temperature upon removal from the furnace) must comply with the specifications laid down for the heat treatment process. All types of furnace test samples must be counted individually, with their types and quantities meeting the process specifications. Heat treatment operations shall be automatically recorded as well as manually documented, with the two records being consistent and fully signed. The A9 pressure test passed. The paint on A10 is even, with no peeling, flaking, or running, and its color is consistent. C