Welding preparation in vertical position — need for edge preparation Statement: “Vertical welding does not require plate edge preparation up to 16 mm thickness.” Evaluate the correctness of this statement for butt joints.

Introduction / Context:
Joint preparation (edge beveling) ensures full penetration and sound fusion in butt welds. The requirement depends on base metal thickness, welding process, position, and access. A common misconception is that position alone (e.g., vertical) eliminates the need for bevels up to relatively large thicknesses.

Given Data / Assumptions:

• Material: typical structural steel plates.
• Joint type: butt joint welded in vertical position (up or down).
• Objective: full penetration weld with acceptable profile and defect-free root.

Concept / Approach:
Square-edge butt joints without bevels are generally limited to small thicknesses where complete penetration can be achieved (often around 3–8 mm depending on process and root gap). As thickness increases, bevels (single-V, double-V, U-grooves) are introduced to provide access for the arc and allow proper fusion and penetration. The welding position (vertical) does not change the fundamental need for joint geometry at larger thicknesses; it can make welding more challenging, not easier.

Step-by-Step Solution:
Identify typical practice: up to about 5–8 mm, a square butt with gap may suffice.For thicknesses 10–12 mm and above, single-V or double-V preparations are common to ensure penetration and manageable heat input.The statement that bevels are unnecessary up to 16 mm is overly permissive and contradicts standard procedure specifications.Therefore, the statement is incorrect.

Verification / Alternative check:
Procedure qualification records (PQRs) and codes (e.g., AWS D1.1) routinely specify groove preparations for thicker plates irrespective of position; vertical welding often requires controlled passes and bevels.

Why Other Options Are Wrong:
“Correct” ignores thickness-driven access requirements.

Conditional or material-specific claims are not generally true; aluminium also needs bevels as thickness increases.

Backing bars may help root support but do not eliminate the need for bevels at 16 mm.

Common Pitfalls:
Attempting full penetration on thick plates with square edges causing lack of fusion; underestimating heat input and interpass control in vertical welding; not planning for multi-pass sequences required by beveled joints.

Final Answer:
Incorrect