{
  "object_id": "c02-thermoplastic-pressure",
  "title": "Thermoplastic internal pressure, minimum wall and qualified factors",
  "model": {
    "SDR": "D_o/t_min",
    "P_T": "2*S_H/(SDR-1)*F_T*F_E*F_J",
    "equivalent_P_T": "2*S_H*t_min/(D_o-t_min)*F_T*F_E*F_J",
    "definitions": {
      "D_o": "Actual pipe outside diameter",
      "t_min": "Minimum product wall from the selected product/tolerance basis, not automatic nominal reference wall",
      "SDR": "Dimensionless outside-diameter/minimum-wall ratio",
      "S_H": "Qualified hydrostatic design stress, with its reference and method basis",
      "P_T": "Design-pressure quantity calculated by this historical method",
      "F_T": "Dimensionless temperature factor",
      "F_E": "Dimensionless environment factor",
      "F_J": "Dimensionless joint factor"
    },
    "units": "S_H and P_T use the same pressure unit; D_o and t_min use one consistent length unit. Examples use psi and separately mm geometry.",
    "pressure_reference": "Establish for actual application. Examples retain psi and do not calculate absolute or partial pressure.",
    "scope": "Selected historical thermoplastic method only; not a current product/code permission, metal method, external-collapse check or FRP laminate pressure formula."
  },
  "reference_basis": "Historical route uses HDS=HDB/2; actual qualified basis required. Do not substitute tensile strength, short-burst result or elastic modulus. Do not temperature-derate an already adjusted stress again unless method calls for it.",
  "factor_cases": [
    {
      "material_basis": "Historical PE3408 HDPE",
      "S_H_psi": 800,
      "SDR": 11,
      "temperature_degF": 100,
      "F_T": 0.79,
      "environment": "Hydrocarbon exposure, including small quantities under this basis",
      "F_E": 0.5,
      "joint": "Butt fusion",
      "F_J": 1.0,
      "teaching_application": true,
      "geometry_base_psi": 160,
      "after_temperature_psi": 126.4,
      "computed_P_T_psi": 63.2,
      "independent_assumed_geometry": {
        "D_o_mm": 110,
        "t_min_mm": 10,
        "SDR": 11,
        "base_psi": 160
      },
      "tabulated_nonhydrocarbon_value_psi": 125,
      "table_formula_difference_psi": 1.4,
      "limit": "Computed63.2 uses declared formula/factors,not a quoted pressure-table cell. Resolve table/calculation basis for application."
    },
    {
      "material_basis": "Selected historical CPVC table",
      "pipe": "NPS6 Schedule80",
      "joint": "Solvent cement",
      "reference_temperature_degF": 73,
      "reference_service": "Nonhydrocarbon",
      "table_reference_pressure_psi": 280,
      "teaching_temperature_degF": 120,
      "teaching_environment": "Crude oil",
      "F_T": 0.65,
      "F_E": 0.4,
      "F_J_already_in_reference": 1.0,
      "computed_psi": 72.8,
      "reported_rounded_psi": 73,
      "limit": "Rounding belongs to this reported example,not permission to round other limits upward; no additional threaded factor while retaining solvent-cement joint."
    }
  ],
  "eligibility_before_calculation": [
    "Establish actual material/product,pressure-service temperature and chemical compatibility",
    "Account for external heating as well as fluid temperature, including solar heating of aboveground pipe",
    "Use minimum wall and actual dimensions/tolerance; do not assign steel tolerance universally",
    "Identify the factor schedule and reference stress together",
    "Verify joint permission,not only numeric joint factor",
    "Unknown factor remains unknown; no default1 or accepted result",
    "Check actual fittings,flanges,valves,adapters and joints at same conditions",
    "Evaluate external pressure,surge,support,thermal movement and readiness separately",
    "Retain actual inputs and installed configuration through change"
  ],
  "conditional_distinctions": [
    {
      "method": "Historical HDPE",
      "hydrocarbon_environment_factor": 0.5,
      "joint_factor_butt_fusion": 1.0,
      "limit": "Factor does not authorize excluded high-aromatic exposure,unknown joint or another pipeline/code route."
    },
    {
      "method": "Historical PVC/CPVC",
      "hydrocarbon_environment_factor": 0.4,
      "joint_factor_solvent_cement": 1.0,
      "joint_factor_eligible_thread": 0.5,
      "limit": "Size/temperature/service restrictions and tableNR remain; factor does not authorize prohibited thread."
    },
    {
      "method": "Historical PP/PB/PVDF shared factor list",
      "threaded_joint_factor_listed": 0.5,
      "PVDF_threaded_scope": "Restricted selected Schedule80 application",
      "limit": "A joint-factor number does not override the selected negative PP/PB threading recommendation or establish permission for another joint/application.",
      "PP_threading_recommendation": "Should not be threaded in this selected historical basis.",
      "PB_threading_recommendation": "Should not be threaded in this selected historical basis."
    }
  ],
  "unknown_joint_example": {
    "F_J": null,
    "qualified_result": null,
    "action": "Establish actual joint permission/rating/factor before selection; do not replace missing information with1."
  },
  "limits": [
    "No current material designation/code/legal approval inferred",
    "Nonzero factor does not extend temperature envelope",
    "Pipe calculation does not establish component or whole-system rating",
    "Material modulus for external collapse differs hydrostatic design stress",
    "FRP numeric HDB stress/pressure ambiguity remains outside this method"
  ]
}