Decades-old mistake may have caused bridge beam to fail

The Philadelphia Inquirer ^ | January 23, 2017 | Jason Laughlin

[norwaypinesavage]

You’re in the right zone. HAZWOPER training is unnecessary.

[sig226]

You wished a Philadelphia reprieve
But the bridge is broke
Now youse can’t leave

Burlington Shave

[MurrietaMadman]

Burlington Shave
I had a few
On that two lane bridge
I rue

[null and void]

I was alluding to HAZ - the Heat Affected Zone, the area near a weld where the heat draws the temper and weakens the steel.

[Ruy Dias de Bivar]

We used plug welds for mistakenly punched holes on electrical transmission towers clear through the 1970s. they were considered safe.

[norwaypinesavage]

Note that I said "you're in the right zone"

[null and void]

Ah! Totally missed that!

[Tolerance Sucks Rocks]

Do you guys use bolts for these holes now?

[Ruy Dias de Bivar]

The way we did it was to take the angle iron, clamp a thick piece of copper on the underside, then fill the hole with 7024 DC welding rod. When done right the copper won’t stick but will hold the weld in till it solidifies. Then turn the angle iron over and do the other side, then grind down flat.

But then, that was forty years ago.