What are the local heat treatment techniques?
Thread Content
This post was last edited by A calm mindset HAPPY on 2018-2-2 at 10:46. Under what circumstances is local heat treatment used, and how does its effectiveness compare to that of overall heat treatment? Are there any examples or data comparisons? Thank you!
For pressure vessels, overall heat treatment is preferred. Local heat treatment is generally applied to large containers, such as certain types of towers. Due to transportation constraints, these containers need to be transported in sections, which requires that each section undergo heat treatment successfully; local heat treatment is then carried out on the joints formed during on-site assembly. Or large containers welded on-site, which are manufactured in multiple sections; heat treatment is carried out on each section before they are welded together as a whole, with local heat treatment applied at the joints between sections, and so on ；
As for the effect of local heat treatment, it is certainly not as good as that of overall heat treatment, but it is often done out of necessity due to specific circumstances. Local heat treatment must take full account of the combined effects of thermal stress, welding residual stress, and even the compressive stress caused by the container’s own weight.
Due to the aforementioned issues, the current relevant standards and specifications impose certain restrictive requirements on local heat treatment, such as requirements regarding the width and range of heating in the case of heating an entire ring section.