Renovation of the tower
Thread Content
Currently, due to changes in wind pressure values, the thickness of the cylinder for a certain project’s tower is found to be insufficient; therefore, reinforcement rings need to be added. But the current situation is as follows: 1. The material is Q245R, with a weld coefficient of 1.0 ； 2. The tower has been installed, and the internal tower trays have also been installed ； 3. The design pressure is negative, at -0.1 MPa ； 3. After calculation, the wall thickness of the upper tower section is not up to standard; it is possible to increase the wall thickness or add reinforcing rings to meet the requirements ； 4. The original tower underwent overall welding followed by heat treatment ； Adding a reinforcement ring is now the optimal solution, and the questions are as follows: 1. Is it necessary to register this with the local pressure vessel inspection agency? ； 2. Is it necessary to remove the tray when welding the reinforcement ring? ； 3. Is a hydrostatic test (air pressure test) conducted after welding is completed?
1. According to the regulations, this needs to be reported to the boiler inspection agency, and relevant tests and inspections must be repeated. However, from the perspective of the using unit, it is not necessary to submit such reports, provided that no safety issues arise and there are no obstacles during the re-inspections； 2. I’m not familiar with equipment design, but the pre-welded components of the tray have already been welded; it’s not very meaningful to remove the tray. However, efforts should be made to prevent the welds of the reinforcement rings from overlapping those of the tray. 3. Our company believes that hydrostatic testing is generally used to check for leaks at the sealing points, and conducting it provides extra safety.
If the tower is a regulated pressure vessel (negative pressure is excluded), installing reinforcement rings constitutes a modification to the pressure vessel, and written notification must be provided to the local authorities responsible for safety supervision of special equipment. The reinforcement ring is welded on the outside of the tower, requiring less welding heat; moreover, it does not alter the tower’s inherent pressure resistance. Therefore, there is no need to remove the tower plates or conduct pressure tests.
The original tower undergoes heat treatment, and heat treatment is required again after further work is carried out on it; heat treatment entails removing the tower trays.
Registration is definitely required, and supervision and inspection are also necessary; the plan must be approved. Based on what the poster has described, it’s a tower made of Q245R material, with a weld coefficient of 1.0 and heat treatment as well – it seems that this container belongs to a high-class category. After welding the reinforcement ring, local heat treatment should be carried out; hydraulic testing is not necessary, but it must be approved.
Well, it’s like manufacturing on-site; subsequent heat treatment processes, inspection and testing, etc. are all essential
This post was last edited by letitbe on 2017-11-27 at 09:28. Based on the description, the problem lies in the design itself; it’s not caused by changes in wind pressure. If wind pressure were the issue, then thickening the cylinder would be necessary to reduce the axial compressive stress on the cross-section and thereby improve stability. Since the description mentions reinforcement rings, it indicates that the initial calculation of external pressures for the design was not accurate
The original design by the original unit was fine; the wind pressure value was changed from 800 to 1057
This post was last edited by letitbe on 2018-1-5 at 15:43. Can the wind pressure value be changed arbitrarily? This isn’t even considered a design flaw – so what would count as a flaw? Look up 47041 – when did wind pressure become related to the external pressure reinforcement ring?