Can the shell forgings of high-pressure heat exchanger tube boxes be joined together by 150mm to meet the dimensional requirements?
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For the high-pressure heat exchanger, with a pressure of 16 MPa and an operating temperature of 350 degrees, the tube sheet forged for the tube box was 150 mm shorter than the designed dimensions. Due to the structure of the openings in the tube box and other factors, this 150-mm difference cannot be adjusted. Question: Is it possible to join 150 forged parts of the same material between the tube sheet and this cylinder to meet the requirements? Reordering is simply impossible to do due to issues with lead time and costs.
Checked the 150 standards and tolerance specifications; the requirement that the pressure-bearing cylinder stubs be at least 300 in length has been removed. Please give me some advice
Technically, there should be no problems; the main issue lies in technical management. The approval of relevant personnel in the production process is required, and if specified in the technical agreement, the consent of the user is also necessary.
What the poster means is to add a forged short section, that is, to weld two seams of 150mm together. A pressure as high as 16 MPa – isn’t that quite high considering the thickness as well? There are 2 welds within a range of 150 mm, and the heat-affected zones of these two welds must overlap! This plan needs to be handled with caution. If short sections are really to be added, they should be made longer if that’s allowed; 150 is too short.
The technical agreement isn’t defined in such detail; if the owner’s opinion is sought, it’s likely they won’t agree. Is it feasible to strictly control pre-welding heating, post-welding heat treatment, hardness control, etc.?
Yes, the wall thickness is 70. There are two welds; this 150-mm short section is entirely within the heat-affected zone
It should be no less than 300; cut off 150 of the waste material and add 300
It is said that the length of 300 doesn’t have any theoretical basis either; it was just decided arbitrarily. Once you complete the welding and carry out the corresponding heat treatment and flaw detection, there should be no theoretical issues, but in my opinion, it mainly comes down to the quality of the welding
This post was last edited by zjq1962 on 2018-4-27 at 08:13. This requirement still exists in GB/T150.4, in clause 6.5.5; in the original poster’s case, it is better to manufacture the cylinder anew. Although this will extend the production time and increase costs, it ensures the safety and reliability of the pressure vessel.
Not allowed. Due to structural reasons, the tube sheet segment can be less than 300; your case is not due to structural reasons.
This post was last edited by bravestorm on 2018-4-27 08:50. It’s possible; the main issue is that it might be too close to the weld seam at the exit point, but it’s just necessary to avoid that as much as possible rather than absolutely preventing it. Of course, if strict adherence to the specifications is required, then it’s not acceptable.