456A Blueprint Reading, Weld Symbols & Joint Preparation 1 — Questions and Answers
Question 1: On a weld symbol, on which side of the reference line is a weld symbol placed to indicate the 'arrow side' of the joint?
- Below the reference line (Correct answer)
- Above the reference line
- To the left of the reference line
- Inside a flag on the reference line
Correct answer: Below the reference line
According to AWS A2.4 (and the equivalent CSA standard used in Canada), weld symbols placed below the reference line indicate welding on the arrow side of the joint (the side the arrow points to). Symbols placed above the line indicate the other side. This convention is consistent throughout all standard weld symbols.
Question 2: What does a weld symbol with a circle at the junction of the arrow and reference line indicate?
- Weld all around the joint (Correct answer)
- The weld is to be made in the field (site weld)
- The weld is a complete joint penetration weld
- The weld must be visually inspected after completion
Correct answer: Weld all around the joint
A small circle at the junction of the arrow and reference line is the 'weld all around' symbol. It indicates that the weld is to be made completely around the joint perimeter. It is commonly used for tube-to-plate connections, pipe attachments, and structural sections where a continuous seal weld is required.
Question 3: What does a filled (solid) flag at the junction of the reference line and arrow indicate on a weld symbol?
- Field weld — the weld is to be made at the installation site, not in the fabrication shop (Correct answer)
- The weld requires NDT inspection
- Complete joint penetration is required
- The weld is to be made on both sides simultaneously
Correct answer: Field weld — the weld is to be made at the installation site, not in the fabrication shop
A solid (filled) flag at the arrow-reference line junction is the field weld symbol. It indicates that the weld is not to be made in the fabrication shop but at the job site during erection or installation. This is important for shipping logistics, inspection scheduling, and welding procedure applicability.
Question 4: On a fillet weld symbol, where is the weld size (leg length) shown?
- To the left of the weld symbol (Correct answer)
- To the right of the weld symbol (after the symbol)
- Above the reference line always
- Inside the triangle of the fillet symbol
Correct answer: To the left of the weld symbol
The weld size (leg length in mm) for a fillet weld is written to the left of the fillet weld symbol. The length of the weld (if specified) is written to the right of the symbol. Both values appear on the same side of the reference line as the symbol (arrow side below, other side above).
Question 5: What is the meaning of the number in parentheses on a groove weld symbol, such as a V-groove with (5) written in it?
- The root opening (gap between the parts) in millimetres (Correct answer)
- The groove angle in degrees
- The required penetration depth in millimetres
- The number of weld passes required
Correct answer: The root opening (gap between the parts) in millimetres
A number in parentheses within a groove weld symbol represents the root opening (the gap at the root of the joint) in millimetres. This is a critical dimension for welding procedure setup, affecting root pass penetration. It is distinct from the groove angle (shown outside the symbol) and the weld depth.
Question 6: What does 'CJP' written on a weld symbol in a drawing note indicate?
- Complete Joint Penetration — the weld must fuse through the full thickness of the joint (Correct answer)
- Centre Joint Position — the weld is made from the centre outward
- Cold Joint Prevention — preheat is required
- Certified Joint Procedure — a qualified WPS must be used
Correct answer: Complete Joint Penetration — the weld must fuse through the full thickness of the joint
CJP stands for Complete Joint Penetration. It specifies that the weld must achieve full fusion through the entire joint thickness, from root to face. CJP welds are required for high-stress joints (moment connections, pressure boundaries) and must be supported by a qualified WPS. They require back gouging and a back weld, or a backing bar, to achieve the required root penetration.
456A Blueprint Reading, Weld Symbols & Joint Preparation 1
On a weld symbol, on which side of the reference line is a weld symbol placed to indicate the 'arrow side' of the joint?