Hand Mining Tunnel Shield — 84 in Pipe

A rolled steel shield for the front of a hand-mined pipe jacking drive. The crew works the face by hand from inside the shield, under the hood, while the jacks in the shaft push the pipe string and the lead pipe, seated on a 3/4 in ledge ring, pushes the shield ahead. The shell is 1/2 in plate rolled to the pipe OD plus 1/2 in, loose rather than tight, with the hood running out past the invert at the crown and a 3/8 in bevelled knife edge welded inside it. Twenty 1/2 in stiffeners back the ledge ring. Nothing is welded to the crown to burn off before it goes in: two slots through the crown, backed by doubler pads inside, take T-head rigging lugs pushed up from inside. Hoist it into the shaft, drop the lugs back out and the shell is flush. Drawn on 84 in pipe at 100 in OD: about 101-1/2 in across, 100 in long and 4,280 lb of steel with the lugs. We roll the bore to the OD of the pipe on your job, so send us the pipe spec. Same shell, knife edge and ledge ring as the 87-1/2 in shield we rolled for 72 in pipe in January 2026. Built in our shop by CWB-qualified welders; bare steel unless you ask for paint, the T-lugs painted yellow so they come back out.