root pass

root pass

[′rüt ‚pas]
(metallurgy)
The first weld bead deposited in a multiple pass weld. Also known as root sealer bead.
References in periodicals archive ?
Firstly, XRD residual stress measurements were performed on the weld metal cap pass after electrochemical polishing of the distorted superficial layer and on the face of the root pass weld metal in the as-welded condition, as shown in Figure 2(b) (location 1) and in Figure 2(c).
The welding process comprised five passes: one root pass, that is, the first layer of the girth weld seam, followed by one hot pass, that is, the second layer of the girth weld seam, and three subsequent passes, that is, 2 filler passes and 1 cap pass.
Nicholson: Lincoln Electric is renowned worldwide so I guess when I picked up my first Fleetweld 5P back in the late '80s to put in a root pass would be the start of my pipelining career.
For the root pass, since this is the first weld pass to be made, argon gas is used as backing gas on the pipe interior diameter to displace all oxygen from atmospheric air.
Vertical Up Welding face a welding speed reduction of 60-70 per cent when welding the same root pass with basic vertical-up electrodes.
A DC arc is normally used for the root pass to achieve full penetration.
0402-20 GTAW Root Pass Welding of 6% Molydenum Austenitic Stainless Steel Pipe--Open Root Joint with Hand-fed Filler.
Welders can complete a root pass using STT[R] and then switch to a different welding process for the fill and cap when using an advanced multi-process welding power source like the company's Power Wave[R] 455M/STT[R].
* TIP 0402-20 "GTAW root pass welding of 6% molybdenum austenitic stainless steel pipe--open root joint with hand-fed filler"