Why is a heat-number essential in a weld map?

• A. It identifies the welder's credential
• B. It records the welding speed
• C. It allows traceability of welds to material batch, filler, and process
• D. It ensures the correct color code for weld

Answer: (C)

The main idea is traceability. A heat-number uniquely identifies a melt or heat of the base metal, and it lets you link every weld made from that heat to the exact material batch, the filler metal lot, and the welding process used. With this linkage, if a defect or failure is found, you can trace it back to the specific material origin, the filler metal supplier, and the procedure that was applied, making investigations, quality control, and any recalls or documentation much more reliable. This is why a heat-number on a weld map is essential.

It isn’t about verifying a welder’s credential, recording welding speed, or ensuring a color code for the weld.