# Blind flange

Blind flange closing a line end or a spare branch: raised-face blind with bleed plug and eyebolt, spiral-wound gasket, stud bolts with two nuts and the mating weld-neck flange on a bevelled stub. Port A is the blind face, so a line ending here bolts straight onto it.

**Standards:** ASME B16.5, ASME B16.47, ASME B16.20, ASME PCC-1

## Installation

```bash
npx -y https://decktwin.com/cli/deck-twin-0.2.2.tgz add blind-flange
```

Copies `piping/blind-flange.tsx`, any helper files it imports and the shared `lib/` into `src/components/deck-twin/`. Needs `three`, `@react-three/fiber` and `@react-three/drei`.

## Usage

```tsx
import { Canvas } from '@react-three/fiber'
import { OrbitControls } from '@react-three/drei'
import { Stage } from './components/deck-twin/lib/stage'
import { BlindFlange } from './components/deck-twin/piping/blind-flange'

export default function Scene() {
  return (
    <Canvas shadows camera={{ position: [8, 5, 9], fov: 35 }}>
      <Stage>
        <BlindFlange />
      </Stage>
      <OrbitControls makeDefault />
    </Canvas>
  )
}
```

## Props

| Prop | Type | Default | Range |
| --- | --- | --- | --- |
| `nps` | `number (NPS, in)` | `6` |  |
| `rating` | `150 \| 300 \| 600 \| 900 \| 1500 \| 2500` | `300` |  |
| `schedule` | `"10" \| "20" \| "40" \| "STD" \| "80" \| "XS" \| "160" \| "XXS" \| "10S" \| "40S" \| "80S"` | `"40"` |  |
| `mating` | `boolean` | `true` |  |
| `stub` | `number (m)` | `0.2` | 0 – 1 |
| `tag` | `string` | `""` |  |
| `...group` | position, rotation, scale… |  |  |

## Ports

Flange faces in the component's local frame, metres. Origin: pipe centreline, flow along X.

| Id | Label | Position | Direction | Size | Class |
| --- | --- | --- | --- | --- | --- |
| `A` | Blind face | 0.002, 0.000, 0.000 | -1, 0, 0 | 6" | 300 |

## P&ID

A line ending in a flange bar followed by a thicker solid bar (or a filled half-circle cap): a blinded end or spare connection.

ISO 10628-2 / PIP PIC001 (piping)

A single solid bar across the line between two flange bars is a spade / blind in the line; a figure-8 is a spectacle blind. A line ending with a plain dome is a pipe cap (welded), not a blind.

Piping class (ASME B16.5 / B16.47) fields and the props they set:

| Field | Prop |
| --- | --- |
| Nominal size | `nps` |
| Flange rating | `rating` |
| Wall schedule | `schedule` |
| Tag number | `tag` |

## Typical suppliers

Weldbend · Texas Flange. The geometry is generic and sized from public standards. It is not vendor CAD.

## Source

`piping/blind-flange.tsx`. This is the component file only: it imports shared code, so install it with the command above rather than pasting it alone. https://decktwin.com/r/blind-flange.json has every file.

```tsx
// Blind flange closing a line end: ASME B16.5 / B16.47 blind with raised face, spiral-wound gasket, stud bolts and the mating weld-neck flange.
import type { Kit } from '../lib/kit'
import { KitMesh, useKit, type GroupProps } from '../lib/mesh'
import { port, type Port } from '../lib/ports'
import { blindThickness, flange as flangeDims, type Rating, type Schedule } from '../lib/standards'
import { GAP, boreOf, buttWeld, flangeLength, jointStuds, jointTag, portFlange, spiralWound, straight } from './_piping'

export interface BlindFlangeProps {
  nps?: number
  rating?: Rating
  schedule?: Schedule
  /** draw the mating weld-neck flange, gasket and studs (the plant assembler draws the same parts when a line ends here) */
  mating?: boolean
  /** pipe stub behind the weld neck, m */
  stub?: number
  /** joint tag, empty for none */
  tag?: string
}

export const defaults = { nps: 6, rating: 300 as Rating, schedule: '40' as Schedule, mating: true, stub: 0.2, tag: '' }

// Origin at the gasket centre. Port A is the blind's raised face, pointing back down the line (-X).
export function ports(p: BlindFlangeProps = {}): Port[] {
  const { nps, rating } = { ...defaults, ...p }
  return [port('A', 'Blind face', [GAP / 2, 0, 0], [-1, 0, 0], nps, rating)]
}

export function BlindFlange({ nps = defaults.nps, rating = defaults.rating, schedule = defaults.schedule, mating = defaults.mating, stub = defaults.stub, tag = defaults.tag, ...group }: BlindFlangeProps & GroupProps) {
  const data = useKit((k) => build(k, nps, rating, schedule, mating, Math.max(0, stub), tag), [nps, rating, schedule, mating, stub, tag])
  return (
    <group {...group}>
      <KitMesh data={data} />
    </group>
  )
}

export default BlindFlange

function build(k: Kit, nps: number, rating: Rating, schedule: Schedule, mating: boolean, stub: number, tag: string) {
  const f = flangeDims(nps, rating)
  const tb = blindThickness(nps, rating)
  const x0 = GAP / 2
  const rf = f.raisedFaceHeight
  const seg = nps >= 6 ? 48 : 32
  k.lathe('machined', [[0, x0], [f.raisedFace / 2, x0], [f.raisedFace / 2, x0 + rf]], [0, 0, 0], 'x', seg)
  k.lathe('flangeSteel', [[f.raisedFace / 2, x0 + rf], [f.od / 2, x0 + rf], [f.od / 2, x0 + rf + tb], [0, x0 + rf + tb]], [0, 0, 0], 'x', seg)
  const xo = x0 + rf + tb
  // 3/4" bleed tapping with hex plug in the centre of the outer face
  k.cyl('flangeSteel', 0.022, 0.006, [xo + 0.003, 0, 0], 'x', 20)
  k.hex('nut', 0.03, 0.012, [xo + 0.012, 0, 0], 'x')
  // DIN 580 eyebolt in the rim for handling heavier blinds
  if (nps >= 6) {
    const s = Math.min(2, Math.max(0.7, f.od / 0.4))
    const xm = x0 + rf + tb / 2
    k.cyl('flangeSteel', 0.02 * s, 0.006 * s, [xm, f.od / 2 + 0.003 * s, 0], 'y', 16)
    k.cyl('galvanised', 0.008 * s, 0.03 * s, [xm, f.od / 2 + 0.012 * s, 0], 'y', 10)
    k.torus('galvanised', 0.022 * s, 0.006 * s, [xm, f.od / 2 + 0.048 * s, 0], 'x', 8, 20)
  }
  if (!mating) return
  const fl = flangeLength(nps, rating)
  portFlange(k, nps, rating, [-GAP / 2, 0, 0], [1, 0, 0], { studs: false, bore: boreOf(nps, schedule) })
  if (stub > 0) {
    straight(k, 'pipePaint', [-GAP / 2 - fl, 0, 0], [-1, 0, 0], stub, nps, schedule, 'open', 'bevel')
    buttWeld(k, nps, [-GAP / 2 - fl, 0, 0], [1, 0, 0])
  }
  spiralWound(k, nps, rating, [0, 0, 0], [1, 0, 0])
  jointStuds(k, nps, rating, [0, 0, 0], [1, 0, 0])
  if (tag) jointTag(k, nps, rating, tag)
}
```