The second number is centre to centre
A call-out written 2-6 means a two inch weld every six inches, measured centre to centre. The bare joint between two segments is four inches, not six. Read it as a gap and you mark eight inch centres, which on a 48 inch joint gives six segments where the drawing asked for eight — a quarter of the weld missing from a joint somebody sized deliberately.
The layout falls out of that. Starting an inch in from each end, the first segment runs from 1 to 3 inches, the next from 7 to 9, and so on to the eighth at 43 to 45, leaving two inches of bare joint at the far end. The page prints the start marks so the tape only has to come out once.
Two thirds of the metal, a fifth of the time
This is the part worth taking away. On the default joint — 48 inches, one side, a quarter inch leg with ten percent convexity — a continuous weld deposits 0.468 pounds and an eight segment 2-6 deposits 0.156. That is 66.7 percent less weld metal, which sounds like it should be most of the cost.
It is not. At 5 pounds an hour the continuous weld is 5.6 minutes of arc and the intermittent one is 1.9, but the intermittent version also pays for eight stops and restarts. At twenty seconds each that is another 2.7 minutes, so the bench time goes from 5.9 minutes to 4.5 — a saving of 23.7 percent, not 66.7. Two thirds of the metal came out and three quarters of the time stayed in.
The page prints the break-even: at these numbers, if a stop and restart costs more than 32 seconds, the continuous weld finishes first despite laying three times the metal. On awkward work — overhead, in a fixture, anywhere the welder has to move themselves rather than the gun — thirty seconds a restart is not a stretch. That is why an experienced fabricator will sometimes run a continuous weld on a joint the drawing allows to be stitched, and it is not laziness.
A leg is not a throat
The cross-section of an equal-leg fillet is the leg squared over two — 0.03125 square inches for a quarter inch leg, 0.0344 with ten percent convexity on top. The throat is a different dimension entirely: the leg divided by the square root of two, so 0.177 inches for a quarter inch leg. Mixing them up is a factor of 1.41 in a linear dimension and a factor of two in the area, and it is the most common error in weld arithmetic. The form takes the leg, which is what a drawing gives you.
What the page will not tell you
Whether the joint may be intermittent. That belongs to the drawing and to whoever is responsible for the design. An intermittent weld leaves unwelded joint line, which behaves differently under fatigue and which can hold water in a way a continuous weld does not, and swapping one for the other in either direction is an engineering change rather than a shop-floor optimisation. The page lays out the pattern you were handed and tells you what it costs to make.
Questions people ask
What does a 2-6 weld symbol mean?
Two inch weld segments on six inch centres. The 2 is the length of each segment and the 6 is the pitch, measured centre to centre, so the bare joint between the end of one segment and the start of the next is four inches. Reading the second number as a gap is the standard mistake and it gives you eight inch centres and a quarter fewer welds than the drawing asked for.
How many segments fit on a joint?
Take the joint length, subtract the set-back at each end, subtract one segment length, divide by the pitch, round down, and add one. A 48 inch joint set back an inch at each end with 2 inch segments on 6 inch centres gives 8 segments, ending at 45 inches and leaving 3 inches of bare joint at the far end. Where that leftover lands is worth checking before you strike an arc, because an uneven end is what people notice.
Does intermittent welding actually save time?
Much less than it saves metal. On the default joint it removes 66.7 percent of the weld metal but only 23.7 percent of the bench time, because eight segments buy eight stops and restarts. The break-even is printed on the page: at these numbers, if each stop and restart costs more than 32 seconds, the continuous weld is faster despite depositing three times as much.
What is the difference between chain and staggered intermittent welds?
Chain puts the segments on the two sides of the joint directly opposite one another; staggered offsets the second side by half a pitch so the welds alternate down the joint. Both double the segment count. Which one a joint gets is on the drawing, and the difference matters for how the joint behaves rather than for how long it takes to make.
Is the fillet leg the same as the throat?
No, and confusing them is a factor of 1.41. For an equal-leg fillet the throat is the leg divided by the square root of two, so a quarter inch leg has a 0.177 inch throat. The cross-sectional area for volume calculations is leg squared over two, not throat squared over two. Drawings give the leg, so that is what this form asks for.