溶接記号 — AWS A2.4 リファレンス
A 溶接記号表示 per AWS A2.4 Section 4.5 uses a 基線, arrow, 溶接の種類 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 規格 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 矢の側 of the joint, symbols above apply to the 反対側. This hub links the core 溶接記号, supplementary symbols, NDE callouts, process designations, and worked reading guides used by 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.
記号を詳しく見る
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 |
溶接士が記号を読み取れない場合、その後のすべての工程、すなわち溶接施工要領書との整合性、組立 (フィットアップ)、検査受入基準が破綻します。記号の理解度は、最後のチェックポイントではなく、最初のチェックポイントです。
— Field perspective, 鉄骨製作 QC
継手の種類と図面の線
The interactive above covers symbol anatomy. The full Blueprint Reading Guide adds joint 種類 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.基本溶接記号と補助記号 — AWS A2.4
Each symbol below maps to a 溶接施工要領書 (WPS) that defines how the weld is made, backed by a 溶接施工法確認試験記録 (PQR) proving the procedure produces sound results. Standard joints may follow 事前認定WPS rules that eliminate 資格試験, and a 認定溶接検査員 (CWI) verifies the finished work against 基準.
The chart below separates weld type symbols, supplementary symbols, and related drawing-reading pages. Start with the すみ肉溶接 symbol if you need the most common structural callout, then move to groove welds, plug/slot welds, NDE symbols, process designations, and the 印刷用 charts when you need a shop-floor reference.
溶接記号要素リファレンス
| 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 |
| 溶接サイズ | Left of weld symbol | Leg size (fillet) or groove depth (groove welds), in inches or mm |
| 溶接長さ | 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 |
| 仕上げ記号 | Above/below weld symbol | 平面 (straight line), 凸面 (outward arc), 凹面 (inward arc) — desired 溶接表面 (ビード表) profile |
| 仕上げ記号 | 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 | 仕様書, 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 製作 shop |
| CJP | In tail or note | Complete 溶込み (継手溶込み) — weld fuses full 板厚 of joint |
| PJP | In tail or note | 部分溶込み溶接 — groove depth less than full thickness |
「溶接記号表示は、机上のエンジニアと現場の溶接士との間の普遍的な言語です。それらがなければ、すべての継手は会話になってしまいます。」
— Widely cited in structural steel fabrication training, reflecting AWS A2.4 standard practice
溶接の種類を超えて
NDE callouts, process codes, and CWI Exam Prep — essential knowledge for reading and interpreting engineering drawings.