7,000-ton forging press weld repair

Tom's welding-course teaching specimen — a 20-inch-thick weld repair on the head of a 7,000-ton press that stamps eighteen-wheeler aluminum truck wheels. Head dome ~10 feet high, ~350 tons, would fill a third of the classroom volume.

Friction has a big effect on how many tons you need. With a lubricant with a lower friction factor, you might be able to forge something with a 10,000-ton press as opposed to a 15,000-ton press. I don't know that I've seen any really big presses made recently. I was working on a weld repair — if you take the welding course I bring in a 20-inch-thick weld repair, on a big head of a 7,000-ton forging press. That press was stamping out truck wheels, aluminum truck wheels. If you want to look at an eighteen-wheeler on the highway, look at the size of the forging — 7,000-ton press to make that aluminum forging. The dome of that head was about ten feet high, and 80% of it was square and 80% of the way across the room in the short direction. It would have filled up a third of the volume of this room and weighed about 350 tons.

---

Tom passes around a ~13-inch-thick SMAW repair weld (500–800 passes) from a 1950s-era 7,000-ton forging press in Erie, Pennsylvania. The press had cracked; a replacement would cost ~$100M, so "good old boys" repaired it. Tom uses the sample to discuss WWII-era armor-plate practice of peening every half inch as a mechanical stress relief — knowledge lost by the 1980s when the Navy tried to repair the USS Iowa turret.

[Tom produces a section of weld from a forging press.] This actually brings me to a reason I brought this in. This is not part of a battleship — it is an arc weld on a fairly thick plate, came off a huge forging press. We can pass this around. This is about a thirteen-inch-thick weld made with — I think I estimated five or six or eight hundred SMAW, manual metal arc welding passes. The weld is here, this lighter area, and it goes all the way down. This was a forging press made in the 1950s. It developed a crack. If you had to rebuild this 7,000-ton press, it'd probably cost you a hundred million dollars. So they wanted to repair the casting. They brought in some good old boys — this is happening in Erie, Pennsylvania — and you can actually see the weld beads on the top here.

17-inch-thick weld on a top casting of a 1948-vintage 7,000-ton forging press, repaired by skilled Georgia-based welders without adequate preheat-through-section or post-weld heat treatment. Cracked twice (first from residual stress alone, second on the first forging stroke). Used to illustrate that excellent welder craft is not a substitute for engineering oversight on heavy sections. Cost: ~$5M.

Another hydrogen case — I showed you the 17-inch-thick weld from the forging press. This press had gone into service around 1948 or so. It's a 7,000-ton press that had been making forgings for over 50 years, close to 60 years. One day it just cracked in the top head of this forging press. The piece is about eight feet tall — it had some hydraulic ports, and a great big hydraulic chamber, with posts coming down from there, and the whole thing stands six or seven stories tall. But it was this top casting. When I was standing next to it to get up to the top, you had to get on a ladder, because the casting was about eight feet tall.