diff --git a/app/src/components/FallbackDiagram.tsx b/app/src/components/FallbackDiagram.tsx
index 29bb745..22dbe55 100644
--- a/app/src/components/FallbackDiagram.tsx
+++ b/app/src/components/FallbackDiagram.tsx
@@ -510,6 +510,47 @@ function DynamicsDiagram({ height, freq, scruton, sectionShape, sectionSize, sho
   );
 }
 
+export interface PiperackProps {
+  width: number;
+  height: number;
+  elevation: number;
+  spacing: number;
+  numFrames: number;
+  phiTotal: number;
+  eta: number;
+}
+
+function PiperackDiagram({ width, height, elevation, spacing, numFrames, phiTotal, eta }: PiperackProps) {
+  const vw = 400, vh = 300;
+  const s = Math.min((vw - 80) / width, (vh - 80) / (elevation + height));
+  const cx = vw / 2, ground = vh - 40;
+  const w = width * s;
+  const h = height * s;
+  const elev = elevation * s;
+  
+  void spacing;
+  void eta;
+
+  return (
+    <svg viewBox={`0 0 ${vw} ${vh}`} className="w-full h-full">
+      <rect width={vw} height={vh} fill="none" />
+      <line x1={cx - w - 20} y1={ground} x2={cx + w + 20} y2={ground} stroke="#94a3b8" strokeWidth={1} />
+      {/* Colunas */}
+      <line x1={cx - w / 2} y1={ground} x2={cx - w / 2} y2={ground - elev - h} stroke="#475569" strokeWidth={3} />
+      <line x1={cx + w / 2} y1={ground} x2={cx + w / 2} y2={ground - elev - h} stroke="#475569" strokeWidth={3} />
+      {/* Viga */}
+      <rect x={cx - w / 2} y={ground - elev - h} width={w} height={h} fill="#3b82f6" opacity={Math.max(0.2, phiTotal)} stroke="#334155" strokeWidth={1.5} />
+      
+      {/* Seta de vento */}
+      <defs><marker id="parrow" markerWidth={8} markerHeight={6} refX={8} refY={3} orient="auto"><polygon points="0,0 8,3 0,6" fill="#22c55e" /></marker></defs>
+      <line x1={30} y1={ground - elev - h / 2} x2={Math.max(35, cx - w / 2 - 20)} y2={ground - elev - h / 2} stroke="#22c55e" strokeWidth={2} markerEnd="url(#parrow)" />
+      <text x={(30 + Math.max(35, cx - w / 2 - 20)) / 2} y={ground - elev - h / 2 - 8} textAnchor="middle" fontSize={8} fill="#22c55e">Vento</text>
+      
+      <text x={cx} y={ground + 18} textAnchor="middle" fontSize={9} fill="#475569">b = {width}m | h = {height}m | z = {elevation}m | φ = {phiTotal.toFixed(2)} | n = {numFrames}</text>
+    </svg>
+  );
+}
+
 export type FallbackDiagramProps =
   | { type: 'warehouse'; props: WarehouseProps }
   | { type: 'cylinder'; props: CylinderProps }
@@ -520,7 +561,8 @@ export type FallbackDiagramProps =
   | { type: 'bridge'; props: BridgeProps }
   | { type: 'tower'; props: TowerProps }
   | { type: 'isolatedRoof'; props: IsolatedRoofProps }
-  | { type: 'dynamics'; props: DynamicsProps };
+  | { type: 'dynamics'; props: DynamicsProps }
+  | { type: 'piperack'; props: PiperackProps };
 
 export default function FallbackDiagram(input: FallbackDiagramProps) {
   return (
@@ -536,6 +578,7 @@ export default function FallbackDiagram(input: FallbackDiagramProps) {
       {input.type === 'tower' && <TowerDiagram {...input.props} />}
       {input.type === 'isolatedRoof' && <IsolatedRoofDiagram {...input.props} />}
       {input.type === 'dynamics' && <DynamicsDiagram {...input.props} />}
+      {input.type === 'piperack' && <PiperackDiagram {...input.props} />}
     </div>
   );
 }
diff --git a/app/src/components/three/Piperack3D.tsx b/app/src/components/three/Piperack3D.tsx
index be63d4a..7358072 100644
--- a/app/src/components/three/Piperack3D.tsx
+++ b/app/src/components/three/Piperack3D.tsx
@@ -4,6 +4,7 @@ import SceneCanvas from '../SceneCanvas';
 import { WindArrow } from './WindArrow';
 import { useCanvasTheme } from '@/lib/theme';
 import type { PipeDef } from '../../lib/modules/piperack';
+import FallbackDiagram from '../FallbackDiagram';
 
 export interface Piperack3DInput {
   width: number;
@@ -94,8 +95,15 @@ function PiperackModel({
 export function Piperack3D(props: Piperack3DInput) {
   const isDark = useCanvasTheme() === 'dark';
 
+  const fallback = (
+    <FallbackDiagram
+      type="piperack"
+      props={props}
+    />
+  );
+
   return (
-    <SceneCanvas moduleId="piperack" fallback={<div />}>
+    <SceneCanvas moduleId="piperack" fallback={fallback}>
       <ambientLight intensity={isDark ? 0.3 : 0.6} />
       <directionalLight position={[10, 15, 10]} intensity={isDark ? 1 : 1.5} castShadow shadow-bias={-0.001} />
       <Environment preset="city" />