Bolt preload from torque API

Solves the nut-factor torque relation T=K·D·F for the induced clamp/preload, with preload stress and the share of proof load when proof strength and tensile-stress area are supplied. Answers 'What clamp force does my tightening torque produce?', 'Am I within 75-90% of proof load?'.

Price$0.04per request

MethodPOST

Route/v1/engineering/bolt-preload-torque

StatusLive

MIME typeapplication/json

Rate limit120/minute

Cache0s public

fastenerboltpreloadtorqueclamp-loadnut-factormachine-designtension

API URLhttps://x402.hexl.dev/v1/engineering/bolt-preload-torque

Integration docs

Example request

{
  "torqueNm": 100,
  "nominalDiameterM": 0.012,
  "nutFactorK": 0.2,
  "proofStrengthMpa": 600,
  "tensileStressAreaMm2": 84.27
}

Example response

{
  "preloadN": 41666.667,
  "preloadKn": 41.666667,
  "nutFactorK": 0.2,
  "nominalDiameterMm": 12,
  "formula": "F = T / (K * D)",
  "nutFactorReference": {
    "drySteel": 0.2,
    "zincPlated": 0.16,
    "lubricated": 0.12,
    "waxedPtfe": 0.1
  },
  "interpretation": "Preload scatter is dominated by K; a wrong friction class can change clamp force by 2x.",
  "proofLoadN": 50562,
  "preloadStressMpa": 494.4425,
  "percentOfProofLoad": 82.407,
  "recommendedPreloadRangeN": {
    "reusable_75pct": 37921.5,
    "permanent_90pct": 45505.8
  }
}

Input schema

{
  "type": "object",
  "required": [
    "torqueNm",
    "nominalDiameterM"
  ],
  "properties": {
    "torqueNm": {
      "type": "number",
      "description": "applied tightening torque (N·m)",
      "examples": [
        100
      ]
    },
    "nominalDiameterM": {
      "type": "number",
      "description": "nominal bolt diameter (m)",
      "examples": [
        0.012
      ]
    },
    "nutFactorK": {
      "type": "number",
      "description": "torque coefficient (default 0.2 dry steel)",
      "examples": [
        0.2
      ]
    },
    "proofStrengthMpa": {
      "type": "number",
      "examples": [
        600
      ]
    },
    "tensileStressAreaMm2": {
      "type": "number",
      "examples": [
        84.27
      ]
    }
  }
}

Output schema

{
  "type": "object",
  "additionalProperties": true
}