Stainless T-Drill collars
A T-Drill collar is a branch outlet pulled out of the wall of the run tube to form an integral collar. It replaces a welded tee's three welds with one. We make them by hand in 304/304L and 316/316L stainless, 5/8" to 2" collars on 2" to 4" tube, faced square for orbital butt welding.
Updated
How a T-Drill collar is made
- Lay out. The collar location and clock orientation are marked on the run tube from your drawing.
- Drill. A pilot hole is drilled through the tube wall at the mark.
- Pull. A forming tool is drawn back out through the hole, extruding the surrounding wall into a raised collar.
- Face. The collar end is faced square to the branch axis so the branch tube butts up clean.
- Check. Location, height and face are checked against your drawing before the part ships.
All five steps are done manually in our shop. It's not a high-volume process; see prototypes and specialized port locations for the work it suits.
Other names for a T-Drill collar
You'll see the same feature called collaring, a pulled tee or pulled outlet, an extruded outlet or extruded tee, and a branch collar. They all describe an integral collar formed from the tube wall.
T-Drill vs welded tee vs weldolet
| Branch method | Welds per branch | Separate fitting | Flow path |
|---|---|---|---|
| T-Drill (pulled collar) | 1 orbital butt weld at the collar | None, formed from the run tube | Smooth, no internal weld bead at the branch |
| Welded tee | 3 circumferential welds | Yes, tee fitting | Weld beads at each joint |
| Weldolet / saddle | Branch weld plus outlet-to-run weld | Yes, outlet fitting | Depends on fit-up and weld |
About T-Drill collars
What is a T-Drill collar?
A T-Drill collar is a branch outlet formed by pulling (extruding) metal out of the wall of a tube to create an integral collar. A pilot hole is drilled, then a forming tool draws the collar outward. The collar becomes part of the run tube, so the branch needs only one weld where it meets the branch tube instead of the three welds a fabricated tee needs.
Is a T-Drill collar the same as collaring or an extruded outlet?
Yes. T-Drill collars, T-Drilling, collaring, pulled outlets and extruded outlets all describe the same thing: an integral branch collar formed out of the run tube wall.
How does a T-Drill collar compare to a welded tee?
A welded tee puts three circumferential welds at every branch. A T-Drill collar puts one, at the branch. For stainless liquid cooling lines that means fewer welds to make and inspect, fewer potential leak paths, a smoother flow path with no internal weld bead at the tee, and less material and fitting inventory.
How does a T-Drill collar compare to a weldolet or a saddle fitting?
A weldolet or saddle is a separate fitting welded onto a hole in the run tube. A T-Drill collar has no separate fitting: the collar is formed from the tube itself and faced square, so your branch tube or fitting butts straight up to it for an orbital butt weld.
Are the collars ready for orbital welding?
Yes. After each collar is pulled, its end is faced square so the branch tube or fitting butts up clean for an orbital butt weld. Parts ship ready to weld on your line.
Need T-Drill collars on stainless tube?
Send a drawing and get a price and lead time within one business day.