How to understand Clause 6.1.3 of GB/T150.3-2011 regarding the maximum opening diameter for which no additional reinforcement is required?
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How to understand the maximum opening diameter without additional reinforcement specified in Clause 6.1.3 of GB/T150.3-2011? In the design, the following situation arises: tubes A and B are identical, made of 16Mn seamless steel pipes with specifications of φ89×9, and the outward elevation of each tube is 50 mm. The following results were obtained using the SW6 calculation software. The nozzles on the head require hole reinforcement, while those on the cylinder do not need such reinforcement. How should this be understood? Port A: Opening in an elliptical head. Calculation method: Equal-area method per GB150-2011. Calculated pressure: 1.62 MPa. Shell material: 16MnDR, nominal thickness: 18 mm. Connection pipe material: 16Mn, specification: φ89×9. A1=61, A2=223, A3=36, A4=0. A1+A2+A3+A4=321, which is less than A=1264.5; therefore, it fails the requirement (by -75%). Port B: Opening in a circular cylinder. Calculation method: Equal-area method per GB150-2011. Calculated pressure: 1.62 MPa. Shell material: 16MnDR, nominal thickness: 18 mm. Connection pipe material: 16Mn, specification: φ89×9. According to Section 6.1.3 of GB150, no additional reinforcement is required for this opening.
This situation should not occur. Please clarify the container diameter, calculation temperature, corrosion margin, the exact location of the openings, etc., so I can help you with the calculations...
Container diameter = 2800 mm, calculation temperature = 50 degrees； Corrosion margin = 4mm ； The hole in the head is located 1120 mm from the center of the head ； The takeover centerline is parallel to the head centerline. The opening in the cylinder nozzle is at the center. The nominal thickness of both the cylinder and the head is 18 mm.
Normally, it shouldn’t, right?? Theoretically, the wall thickness of the head calculated using the relevant formula is thinner than the wall thickness of the cylinder calculated using another formula. When the same sheet thickness is used for both the head and the cylinder, it means that more thickness is required for reinforcement on the head compared to the connections on the cylinder. As a result, there are cases where connections of the same size or even larger ones on the head do not require reinforcement, while connections of the same size or even smaller ones on the cylinder do require reinforcement!
This post was last edited by SDHZZXM on 2017-12-28 at 17:00. The problem lies in the fact that the distance from the center of the head to the opening in the head is 1120 mm; if the opening is slightly off-center, it exceeds the condition that allows a Φ89 opening to be exempt from reinforcement calculations...
Using the V3.1 network version, it was determined that reinforcement is needed. You can calculate it: what is the length of the major axis of the 89 mm diameter pipe at position 1120? This value is well above the diameter threshold at which no additional reinforcement is required, and it has nothing to do with 80% of the diameter of the head.
I think the problem lies in the thinning of the head thickness
The hole in the head is located 1120 mm from the center of the head, which exceeds the 80% limit; as a result, the calculated thickness of the head at that location is higher.
This post was last edited by zjq1962 on 2017-12-29 08:32. The diameter of the opening in the cover should be based on the maximum size. If the openings on the head are offset from the center, their maximum size may exceed the outer diameter of the nozzle. Therefore, even if all conditions fall within the scope of GB150.3, it is still possible that it does not fall under the category of reinforcement without openings. Similarly, making holes in the cylinder is also related to the position and direction of the holes in the pipe
Guys upstairs, even if the value of 1120 is reduced, say to 500, reinforcement is still needed! ! !