Regarding the issue of smooth transition in Class D welded joints?
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I would like to ask the experts: why are containers holding highly hazardous media at low temperatures required to have Class D weld joints (welds between the piping and the cylinder or head), and why is it required that there be a smooth transition on the other side of the piping weld? What is the reasoning behind this? What are the hazards if there is no such smooth transition?
Especially in low-temperature containers, excessive stress concentration can lead to accidents
A smooth transition is intended to reduce the stress concentration factor and improve fatigue resistance.
Personal opinion: It is mainly to reduce the edge stress and welding stress concentrations caused by sudden shape changes.
Avoid stress concentration, as it is the source of defects and failures
It is to reduce stress concentration, so as to prevent brittle fracture in low-temperature containers
Avoid stress concentration and edge stress caused by sudden shape changes
Avoid stress concentration, as defects tend to form and propagate at such locations. Stress concentration in cryogenic vessels increases the tendency for brittle failure at low temperatures.
Avoid brittle fracture of the weld seam caused by stress concentration.
Mainly to avoid stress concentration, notches are made on both sides of the D-shaped structure, which also facilitates root cleaning and the inspection of weld defects