Symbol Misread on a Skewed T-Joint
A shop drawing shows a T-joint between a 10 mm plate and a 20 mm plate. The welding symbol has an arrow with a break, pointing to the near side of the joint, and a fillet symbol on the arrow side with a size of 8 mm and a length of 75-25. The tail carries a reference to a note that says 'both sides where accessible.' The fabricator welds only the arrow side, full length, with an 8 mm fillet. The inspector finds the far side unwelded over 60% of its length. The fabricator says the broken arrow means the far side is not part of the symbol, and the 75-25 is a length-pitch that was ignored because the weld was made continuous.
1. Interpret the symbol as written and decide whether the fabricator's reading is defensible.
Read the worked answer
The arrow side is the side the arrow touches; the other side is the other side. A fillet symbol above the reference line applies to the arrow side; a symbol below applies to the other side. Here the fillet is on the arrow side, so the 8 mm fillet is required there. The '75-25' is a length and pitch notation, meaning 75 mm weld length on 25 mm centers, i.e., intermittent welding, not a continuous weld. The tail note 'both sides where accessible' is a supplementary instruction that expands the requirement to the other side where access allows. The fabricator's reading is not defensible: the broken arrow does not cancel the far side, and ignoring the pitch turned an intermittent weld into a continuous one, which is a different (and over-welded) configuration. The far side is unwelded where accessible, so the joint is nonconforming. The correct action is to interpret the symbol per the drawing standard in force, confirm intent with the designer, and repair by adding the required far-side welds or obtaining an approved deviation.
2. What document control failure does this reveal, and how would you prevent recurrence?
Read the worked answer
The drawing carries a symbol with a pitch notation plus a tail note that conflicts in plain reading with a continuous interpretation, and the shop had no clarification step. That is a document control and communication failure, not just a welder error. Prevention: a pre-job drawing review where the inspector and supervisor walk each symbol and confirm arrow side, other side, size, length-pitch, and tail notes; a weld map or traveler that lists each weld with its symbol interpretation; and a formal RFI to the designer where a note and symbol appear to conflict. The traveler should be signed off before welding. The inspector should also verify that the welders hold current qualification for the joint and position, and that the WPS covers the 8 mm fillet on 10 mm plate.