What is the root face on a weld joint?

The root face, also called the land, is the flat unbevelled edge at the bottom of the groove. It controls how much metal the root pass must fuse through. A larger root face supports the puddle and resists burn-through but needs a more penetrating process or a back-gouge.

What is the root opening for?

The root opening is the gap between the two parts at the bottom of the joint. It gives the arc access to the root so the weld fully penetrates. Too small a gap risks lack of fusion at the root; too large a gap risks burn-through and wastes filler.

Why is a 60 degree groove angle common?

A 60 degree included angle gives the electrode enough access to fuse both bevel faces and the root while keeping the volume of deposited metal reasonable. Narrower angles save filler but risk lack of sidewall fusion; wider angles fuse easily but cost more weld metal and distortion.

When should I use a double-V instead of a single-V?

Above roughly 25 mm of thickness a double-V or double-bevel prep is preferred. Welding from both sides roughly halves the volume of a single-V, balances the shrinkage so the plate stays flatter, and reduces total filler and distortion.

Does submerged arc need a different prep?

Yes. Because submerged arc penetrates deeply, it tolerates a larger root face and often a closed root, so less of the joint must be bevelled. This calculator increases the root face and closes the gap when you select the SAW process.

Weld Joint Preparation Calculator

Correct joint preparation is what makes a full-penetration weld possible. The bevel angle, the flat root face, and the root opening together decide whether the arc can reach and fuse the root without burning through. This tool returns typical AWS D1.1 prequalified geometry for the common joint types and draws the cross-section so you can check fit-up at a glance.

How it works

The recommendation is driven by joint type, thickness, and process. The defaults follow prequalified detailing practice:

Single-V butt: 60 degree included angle, a 2 to 3 mm root opening, and a small 0 to 2 mm root face for stick, MIG, and flux-cored.
Submerged arc: the same 60 degree angle but a larger root face up to 6 mm and a closed root, because its deep penetration fuses through more land.
T and corner joints: a single-bevel groove around 45 degrees on the prepared member.

Above about 25 mm the tool flags a double-sided prep, which welds from both faces to halve the fill volume and balance shrinkage:

double-V volume  ~  half of single-V volume
=> less filler, less angular distortion

Tips and notes

The SVG diagram is schematic. It shows the relationship between angle, face, and gap, not a to-scale drawing for cutting.
Below about 6 mm a square-groove (no bevel) with a small root opening is usually prequalified and avoids beveling altogether.
A backing bar or ceramic backing lets you open the root gap and guarantee full penetration without back-gouging.
Always cross-check the exact figures against the prequalified joint tables in your code or a qualified WPS before production.