GB/T150.4-6.4.1 Distance L between the centerlines of butt welds
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GB/T150.4, Clause 6.4.1: “The distance (L) between the centerlines of various intersecting butt welds on a convex head shall be at least 3 times the thickness of the head material, and shall not be less than 100 mm; see Figure 1.” How is the “centerline of the butt weld” determined? I had read this many times before, and when I saw the illustration in Figure 1, I thought, “That’s what it looks like.” But today, when I tried to draw that L on paper, I realized, “Oh, I see now.” First, connect the joint welds with straight lines; take the normal to these lines – this normal must pass through the center of the circle. Then, translate this normal to both sides until it reaches the intersection points of the joint welds, and thus L is drawn. I’m not sure if my method is correct, so I’d like to discuss it with everyone. What is learned from books seems shallow after all; sometimes it’s necessary to put hands to work.
Your understanding is completely correct! The center line of a butt weld is a straight line drawn along the direction of the weld; the normal to this line (that is, the line perpendicular to it and passing through its midpoint) passes through the center of the end cap. Next, translate this normal line to both sides until it just touches the edges of the two welds; the vertical distance between these two translated lines is what is referred to in the standards as the \"distance between center lines L\". It’s really helpful to draw it out by hand; many details are easy to assume just by looking at a picture, but they become clear once you actually draw them. This method conforms to the intent of the standard illustration; no problem! .
Rival! That’s how we understand it too
It shouldn’t be that troublesome, right? If it’s CAD, you can just add annotations directly
First, one needs to use CAD to understand the concept, mainly in order to figure out how to measure L on the actual object
This post was last edited by Zheng_swQwT on 2025-10-2 at 21:55. From a vertical projection perspective, isn’t this referring to the length of the chord rather than the arc length? But in actual measurement, it should be the distance measured directly from point A to point B, right?