Weld Fittings

A weld fitting arrives with one end deliberately unfinished — a plain machined weld prep, no thread, no flare, no seal — to be butt-welded onto tube or socket-welded into a block. The finished connection sits at the other end — an O-ring boss port, a 37° nose, an ORFS face, a flange head. The weld becomes the structural joint; the seal stays where it can be broken and remade.

Fabricators reach for these when the metal in front of them has no boss to thread into: a plate, a block, a port cut away for repair. On the connection side the usual rules apply — SAE J514, J1453, J1926 and J518 — while the weld end is a machined preparation, not a sealing feature. What you give up is reversibility, plus the heat-affected zone left behind.

Where it's specified

• Manifold and block building — a weld boss puts a standard port on a face never drilled or tapped for one
• Custom tube assemblies — a weld end builds a run to a length or angle no catalogue part covers
• Repairing a damaged port — the ruined thread is cut out and a new connection welded in, saving the housing
• Joints that must not be disturbed — a weld cannot loosen under vibration or be undone by mistake

Range and materials. Weld bosses and bungs, nipples, elbows and tees, socket-weld and butt-weld ends, weld-on flange halves and weld pads come in carbon steel and stainless, with connection ends in O-ring boss, JIC 37°, ORFS, NPT, BSP and SAE flange. Sizes follow the connection end each part carries.

Ordering notes. Order unplated or plan to refinish: plating burns off around the bead, so a plated part welded as supplied corrodes first at the joint. Match the base metal to the tube or block it goes onto, and take out every O-ring before striking an arc. Once cool, clean the bore: spatter and scale left inside travel straight to the pump.