— — — Intermittent weld
Intermittent weld · Soldadura en plano · ISO 1101 + ASME Y14.5
Example in plan
How to interpret it
On the drawing, “△ a 4 L 40 P 120” states a intermittent weld requirement.
What controls
Weld that does not run the full length of the joint but is distributed in welded segments separated by unwelded gaps. Next to the symbol are two numbers that must be read correctly: the length of each welded segment and the pitch, which is the distance from the start of one segment to the start of the next, not the gap between them. It is used when the required strength does not call for a continuous weld and the aim is to limit heat input and consumables. It is not suitable when the joint must be leak-tight or will be exposed to corrosion in the gaps.
How to verify
Tape measure along the joint: length of each segment, distance between consecutive starts and total number of segments, checked against the drawing. The size of each segment is checked with a weld gauge as for any fillet weld. The ends of the joint deserve separate attention: many drawings require the first and last segments to start at the edge, and this is checked by measuring from the end.
Common mistakes when interpreting it
- Reading the second number as the spacing between segments rather than the pitch between starts.
- Using an intermittent weld on joints that must be leak-tight or that are exposed to the weather: the unwelded gap is a moisture trap.
- Starting the layout from one end without checking where the last segment falls at the other.
How to get it in the workshop / if it comes out of tolerance
Distinguish pitch from spacing: with 40 mm segments and a pitch of 120, there are 80 mm left unwelded between segments. If this is misread, the shop ends up welding twice as much as needed or leaving the joint under-welded. Distribute the segments symmetrically about the center of the joint and work from the center outward to spread the distortion.
If there are fewer segments than expected when you measure, the layout was almost always done using the gap instead of the pitch. End craters are the weak point of this weld: fill them before breaking the arc. If the part still distorts, alternate the order of the segments instead of running them in sequence from one end to the other.
Related symbols
Other symbols in Flat welding
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