Controlled chart data only

Hydraulic Torque-Wrench Pressure–Torque Chart Interpolator

Interpolate only between two adjacent points copied from the current controlled chart for one identified wrench. This page does not derive a wrench setting from generic piston area, arm length or assumed efficiency.

No universal wrench modelNo extrapolationSource required

Calculation / work-order identifier

Wrench make, model and serial / asset ID

Pressure–torque chart or calibration source, revision and date

Calibration / verification status and validity record

Pressure unit used by the chart

Torque unit used by the chart

Lower adjacent chart pressure P₁

Torque at P₁, T₁

Upper adjacent chart pressure P₂

Torque at P₂, T₂

Target pump pressure P inside [P₁,P₂]

Engineered target, joint procedure, equipment rating, reaction setup and safety review

Applicability gate: both points must be adjacent entries from the same current chart for the exact wrench/configuration and the target pressure must lie inside their interval. Use the manufacturer’s instructions, engineered joint target and equipment ratings. This interpolation is not a bolt-torque design, calibration certificate or safety approval.

Documented chart interpolation

Interpolated chart torque

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Normalized torque

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Target pressure

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Interval fraction

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Entered bracket

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Local chart slope

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Implemented arithmetic

f = (P − P₁)/(P₂ − P₁)
T = T₁ + f(T₂ − T₁), only for P₁ ≤ P ≤ P₂

Linear interpolation is general arithmetic, not an ISO hydraulic-wrench formula. It is valid here only when the controlled source permits interpolation between the two entered adjacent points. The original page’s ideal relation F=ΔpA and moment T=Fr is dimensionally correct for a specified piston and perpendicular arm, but it cannot by itself predict the calibrated output of an unidentified wrench mechanism.

Published manufacturer example

Enerpac L4111 Rev. E, W-Series manual lists W2000X as 1203 N·m at 300 bar and 1323 N·m at 330 bar, with table values rounded to the nearest whole unit. At 315 bar the interpolation is 1263 N·m. The same manual gives a W2000X metric torque factor of 4.0085 N·m/bar: 315×4.0085=1262.6775 N·m, which rounds to 1263 N·m.

Why the former universal model was removed

The former page accepted generic piston area, arm length and an assumed 95% efficiency, then labelled the result “output torque”. It also supplied arbitrary presets and universal “typical” accuracy, pressure and bolt-size claims. Actual settings are model/configuration and calibration dependent; Enerpac’s own instructions use model-specific pressure–torque tables and require the operator manual and rated compatible components.

ISO boundary

ISO 6789-1:2017, edition 1, is Published but marked “to be revised”; its official scope is hand torque tools of specified Type I and Type II classes. A powered hydraulic wrench is not established by that scope as an ISO 6789 hand torque tool—this is a scope inference, not a quoted exclusion clause. ISO/IEC 17025:2017, edition 3, confirmed in 2023 with corrected versions issued in 2018, concerns competence and consistent operation of testing/calibration laboratories; it does not supply a pressure–torque formula. Exact clauses and any project-specific calibration acceptance criteria remain NEEDS_LICENSED_SOURCE.

Operational boundary

Follow the exact tool/pump/hose manual, never exceed the lowest component rating, verify calibration status, use a qualified engineered torque target, position the reaction arm on a suitable reaction point, keep clear of pinch/reaction and pressurized components, and use the prescribed tightening sequence. The calculated number does not establish bolt preload, joint integrity or suitability.