【Question】Issue with large openings in equipment
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As title: A device is now being designed with an inner diameter of φ600mm, a height of 954mm, and a thickness of 6mm (SW6 recommends 3mm). The design pressure is 0.45 Mpa, and the design temperature is 155°C. Due to structural requirements, two large-diameter holes must be made in the equipment: Hole 1: φ454mm, Hole 2: φ350mm. Calculated using SW6, all cases passed the analytical method tests, with pass rates of 65% and 100% respectively. After discussing with others, it was said that as long as they are not on the same cross-section, making these two large openings in the container makes the analysis feasible. What I would like to ask is: 1. Are there any relevant standards specifying requirements regarding the spacing of such large openings on the same cross-section? 2. Since I have limited experience with this analysis method, does the fact that it passes the analysis mean that reinforcement rings are not necessary either, even for large openings, with a pass rate of over 50%? 3. Even through calculations using the analysis method, if two large openings are created consecutively, will it still have an impact on the strength of the container? (What I mean is that SW6 calculations are based on a single opening; if two large openings appear consecutively with a minimum distance of 240 mm between their edges, satisfying the requirements of clause 6.6.1(a) of the analysis method, will there still be an impact?) Above, I hope the experts from HaiChuan can answer my questions. Thank you!
1. According to the relevant standards I am aware of, there are no specific spacing requirements for large openings on the same cross-section. However, this also needs to be determined based on specific design standards and engineering requirements. 2. The fact that an analysis method is used does not mean that reinforcement rings are completely unnecessary. Although analytical methods can provide reasonable estimates and analyses of the structure, for special cases such as large openings, it is recommended to incorporate appropriate reinforcement measures during design to ensure the safety of the equipment. 3. Having two large openings in succession may affect the strength of the container. Even if the minimum edge distance requirements specified in the analysis method are met, the presence of two large openings alters the internal structure of the container, resulting in uneven stress distribution. Therefore, precise calculations and analyses are still necessary during the design phase to ensure the strength and stability of the equipment. In short, for such special design requirements, it is recommended that you consult with and work together with professional engineers to ensure the safety and reliability of the equipment. .
Check GB150 for the requirements regarding the areas where no holes are allowed in the openings used for analysis, as well as the requirements for welds
Thank you, I have seen this. I still feel uneasy inside. I’ve never experienced such a large opening.
As long as the requirements are met, it doesn’t matter; this calculation is safer than the pressure-area method. Special attention should be paid to ensuring that there are no openings in the area around the hole, as well as to meeting the weld requirements.
If the calculation shows it’s qualified, then it’s qualified. What is your qualification rate? If you’re really worried, calculate it based on three connections
Poster, in your equipment model, the distance between the two openings and the upper cover (lower head) is relatively small; this distance also needs to take into account the requirement that the openings be within the reinforcement range.
It’s the % in parentheses after the result shows qualified during SW6 calculation
Thank you for the reminder. According to the standards, there should be no defects in the A/B welds within the reinforcement area. My understanding is that it would be best to carry out 100% RT inspection in this area to ensure there are no defects – is that correct?
How is this three-way calculation you mentioned carried out? I’ve never dealt with it before; could you provide the standards so I can study them? Thank you