Welding Symbols — AWS A2.4 Reference
A 용접 symbol per AWS A2.4 Section 4.5 uses a reference line, arrow, 용접 type graphic, dimensions, contour symbols, and a tail. AWS A2.4 Section 6.1 controls arrow-side placement, and AWS A2.4 Figure 4.3 shows 표준 element locations used by welders and inspectors.
How do you read a welding symbol once you know its parts? Position is the rule that matters most: symbols below the reference line apply to the arrow side of the joint, symbols above apply to the other side. This reference works through all 16 weld 유형 per AWS A2.4:2020 with worked examples for fabricators, welding engineers, and CWIs.
Per AWS A2.4:2020 Section 4.5, only the horizontal reference line and arrow are required elements of a welding symbol. Figure 4.3 shows where optional elements such as weld symbols, dimensions, supplementary symbols, and tail references are placed.
Explore the Symbol
Tap any chip to highlight that part of the welding symbol on the diagram. Each element is verified against AWS A2.4:2020.
Click any element above to highlight it on the diagram and read its definition from AWS A2.4:2020.
| You see… | It means… |
|---|---|
| Below ref line | Weld on the arrow side |
| Above ref line | Weld on the other side |
| Both sides of ref line | Weld on both sides |
| Open circle at junction | Weld all around the joint perimeter |
| Solid flag at junction | Field weld (made on site, not in shop) |
| Number left of weld symbol | Size (leg length for fillet; D(S) for groove) |
| Numbers right (e.g., 3–12) | Length–pitch for intermittent welds |
| Tail (V-shape opposite arrow) | Process / WPS reference / spec note |
용접공이 기호를 읽지 못하면, WPS 일치, Fit-Up, 검사 승인 기준 등 모든 후속 작업이 중단됩니다. 기호 이해는 마지막이 아닌 첫 번째 확인 지점입니다.
— Field perspective, structural fabrication QC
Joint Types and Drawing Lines
The interactive above covers symbol anatomy. The full Blueprint Reading 가이드 adds joint types per AWS A2.4:2020 Figure 5.1 and the 10 engineering drawing line conventions per ASME Y14.2-2014 — the “alphabet of lines” that carries the rest of a welding drawing’s meaning.
△ Blueprint Reading Guide — Joint Types + Drawing Lines Go deeper than anatomy. 5 joint types per AWS A2.4 Figure 5.1 (butt, corner, T, lap, parallel) and the 10 engineering drawing line conventions per ASME Y14.2-2014 — the alphabet that carries the rest of a welding drawing’s meaning.All 용접 기호 Types — AWS A2.4
Each symbol below maps to a welding procedure 사양 (WPS) that defines how the weld is made, backed by a procedure qualification record (PQR) proving the procedure produces sound results. Standard joints may follow prequalified WPS rules that eliminate qualification 시험, and a certified welding inspector (CWI) verifies the finished work against 코드.
Welding symbols are 설명 chart-by-chart below — each row maps to a specific weld type per AWS A2.4 with a worked example and link to its dedicated page. Of the symbols, the fillet weld symbol is the one most welders and inspectors encounter daily — fillet welds account for roughly four out of five welds on a typical structural steel drawing and are the dominant subject of CWI Part B drawing-interpretation questions, so start there if you are reading the chart from the top.
용접 기호 요소 참조
| Element | Location | Meaning |
|---|---|---|
| Weld symbol | Above or below reference line | Weld type — fillet triangle, groove V, plug circle, etc. Below = arrow side, above = other side. |
| Arrow side | Below reference line | Same side as arrow — weld on the surface the arrow points to |
| Other side | Above reference line | Opposite side from arrow — weld on far face of joint |
| Both sides | Both sides of line | Weld both sides — same symbol above and below reference line |
| Weld size | Left of weld symbol | Leg size (fillet) or groove depth (groove welds), in inches or mm |
| Weld length | Right of weld symbol | Length of weld in inches or mm. Omitted = full length. |
| Pitch | Right of symbol, as length-pitch (e.g. 3-12) | Center-to-center spacing of intermittent welds — pitch follows the dash after weld length |
| Contour symbol | Above/below weld symbol | Flush (straight line), Convex (outward arc), Concave (inward arc) — desired weld face profile |
| Finishing symbol | Adjacent to contour symbol | G (grind), M (machine), C (chip), H (hammer), P (planish), R (roll), U (unspecified) — per A2.4 §6.13 |
| Tail | Right end of reference line | Specification, process, or note — e.g. SMAW, AWS D1.1, or WPS number |
| Weld-all-around | Circle at arrow junction | Weld completely around the joint — all sides, no breaks |
| Field weld | Filled flag at reference line | Weld on-site during erection, not in the fabrication shop |
| CJP | In tail or note | Complete Joint Penetration — weld fuses full 두께 of joint |
| PJP | In tail or note | Partial Joint Penetration — groove depth less than full thickness |
"용접 기호는 책상에 앉은 엔지니어와 현장의 용접공 사이의 보편적인 언어입니다. — 그것이 없으면 모든 이음은 대화가 됩니다."
— Widely cited in structural steel fabrication training, reflecting AWS A2.4 standard practice
용접 유형 그 이상
NDE callouts, process codes, and CWI Exam Prep — essential knowledge for reading and interpreting engineering drawings.