What does 2-6 mean on a fillet weld symbol?

In AWS A2.4 it means welds 2 in long at a 6 in pitch. The pitch is measured from the center of one weld to the center of the next, so the bare metal between welds is 6 - 2 = 4 in.

Is the pitch the gap between welds?

No. In AWS the pitch is center to center, so it includes one weld length. The gap is the pitch minus the weld length.

What does 3 × 50 (100) mean in ISO 2553?

It is written n × l (e): 3 welds, each 50 mm long. The 100 in brackets is the spacing between welds. Check the drawing notes for how that spacing is measured, because sources disagree on it.

What is the difference between chain and staggered intermittent welds?

Both put intermittent welds on both sides of a joint. Chain welds sit directly opposite each other. Staggered welds are offset, so the welds on one side face the gaps on the other side.

Welding symbols: lesson 4 of 7

Length and pitch: intermittent welds

Intermittent welds are short welds with bare metal between them. Read how long each weld is and how they are spaced.

How much bare metal is left between two welds?

AWS A2.4: length-pitch

Two numbers with a dash go to the right of the symbol. The first is the length of each weld. The second is thepitch: the distance from the center of one weld to the center of the next.

1/4 in leg, 2 in welds, 6 in pitch

Because the pitch is center to center, it includes one weld. The bare metal between welds is pitch minus length. For 2-6 that is 6 - 2 = 4 in.

ISO 2553: n × l (e)

ISO writes the number of welds, a multiplication sign, the length of each weld, and the spacing in brackets. 3 × 50 (100) means 3 welds, each 50 mm long.

a4, 3 welds of 50 mm

How the number in brackets is measured is not settled. Some guides read it as the gap from the end of one weld to the start of the next. Others, including the IFC data standard used in building models, read it as center to center. Our exercises only ask about the count and the length. On the job, check the drawing notes or ask before you weld.

Questions

What does 2-6 mean on a fillet weld symbol?: In AWS A2.4 it means welds 2 in long at a 6 in pitch. The pitch is measured from the center of one weld to the center of the next, so the bare metal between welds is 6 - 2 = 4 in.
Is the pitch the gap between welds?: No. In AWS the pitch is center to center, so it includes one weld length. The gap is the pitch minus the weld length.
What does 3 × 50 (100) mean in ISO 2553?: It is written n × l (e): 3 welds, each 50 mm long. The 100 in brackets is the spacing between welds. Check the drawing notes for how that spacing is measured, because sources disagree on it.
What is the difference between chain and staggered intermittent welds?: Both put intermittent welds on both sides of a joint. Chain welds sit directly opposite each other. Staggered welds are offset, so the welds on one side face the gaps on the other side.

Explained in our own words. For the full rules, see AWS A2.4:2020 and ISO 2553:2019.