Alignment Assistant

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Machinery Alignment Tools

Calculators and reference data for rotating machinery alignment based on industry best practices consistent with API RP 686. Select a tool to get started.

Unit Conversions

mil/mm, mil/inch to mm/m, temperature conversions for alignment work

Indicator Sag

Calculate dial indicator bracket sag correction for reverse-indicator setups

Thermal Growth

Estimate vertical thermal expansion based on material, temperature rise, and centerline height

Shim Calculator

Calculate required shim changes at each foot from alignment readings and targets

Alignment Moves

Convert reverse-indicator readings to foot corrections at inboard and outboard bolt planes

Alignment Check

Compare measured alignment against Vendor or industry-standard tolerances — PASS/FAIL assessment

API 686 Tolerances

Look up typical alignment tolerances by coupling type consistent with API RP 686

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Unit Conversions

Common conversions for machinery alignment fieldwork.

Length / Displacement

Angularity (Slope)

Temperature

For thermal growth calculations, use the temperature rise (ΔT) from ambient to operating, not the absolute operating temperature.
Disclaimer: These conversion tools are provided as a support resource for qualified professionals. Results do not replace OEM/Vendor specifications, official data sheets, or approved engineering procedures. Always verify values against applicable Vendor documentation and/or Project Specification before use.

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Indicator Sag Correction

Calculate the sag of a dial indicator bracket assembly. Sag must be measured and subtracted from bottom readings in reverse-indicator alignment.

Sag Measurement

Bracket Sag
Sag per Inch of Span
Acceptance (Industry guideline: ≤ 0.8 mil/in)
Inconsistent sag readings? We can troubleshoot bracket setups and verify your alignment system on-site. Talk to a specialist
Mount the bracket on a pipe or shaft resting on V-blocks. Zero the indicator at 12 o'clock, rotate to 6 o'clock. The negative reading is the sag. A commonly accepted limit is ≤ 0.8 mil per inch of span (consistent with API RP 686 guidelines). Always verify against applicable project specifications.
Disclaimer: This indicator sag calculator is provided as a support resource for qualified professionals. Results do not replace OEM/Vendor specifications, alignment system manufacturer instructions, or approved procedures. Always refer to the Vendor documentation and/or Project Specification for your specific equipment and alignment tools.

Thermal Growth Estimation

Estimate vertical thermal expansion from ambient to operating temperature. Used to determine cold alignment offset targets.

Growth Parameters

CTE Used
Vertical Growth
Vertical Growth (mm)
Complex multi-casing trains with differential growth? We calculate and verify hot alignment targets on-site. Schedule a review
Growth = CTE × Height × ΔT. If the driver grows more than the driven, set the driver low by the differential in cold alignment. OEM data always takes precedence over calculated values.
Tip — Absolute vs. Relative Temperature: Absolute temperature is the total reading on the thermometer (e.g. 350°F operating). Relative (differential) temperature is the difference between two conditions (ΔT = Operating − Ambient). For thermal growth calculations, always use the relative temperature rise, not the absolute operating temperature. Example: a machine running at 350°F in an 80°F ambient has ΔT = 270°F — that 270°F differential is what drives expansion. Entering the absolute 350°F instead would overestimate vertical growth by approximately 30%, potentially leading to incorrect cold alignment offset targets.
Disclaimer: This thermal growth estimator is provided as a support resource for qualified professionals. Calculated values are based on generic material CTE data and simplified assumptions. They do not replace OEM/Vendor thermal growth data, hot alignment targets from the equipment manufacturer, or approved engineering procedures. Always refer to Vendor specifications and/or Project Specification for your specific equipment.

Shim Calculator

Calculate required shim changes at each bolt plane to correct vertical offset and angularity.

Machine Geometry

Vertical Correction at Coupling

Inboard Feet (IB)
Outboard Feet (OB)
Direction
Bolt-bound or base-bound? Running out of shim space? We've resolved hundreds of difficult alignment cases. Get field support
Positive offset = machine too high (remove shims). Positive angularity = gap opens at top (add at OB, remove at IB). Industry practice: max 5 shims per foot pack (consistent with API RP 686 guidance).
Disclaimer: This shim calculator is provided as a support resource for qualified professionals. Results do not replace OEM/Vendor alignment specifications, coupling manufacturer requirements, or approved field procedures. Always verify shim changes against Vendor documentation and/or Project Specification before use.

Alignment Move Calculator

Convert reverse-indicator dial readings to required corrections at each bolt plane.

Distances

Reverse-Indicator Readings (mils, TIR)

Enter Total Indicator Readings (TIR). Top set to zero. Positive = indicator pushed in (shaft high).

Vertical Moves (Shims)
Inboard Feet
Outboard Feet
Horizontal Moves (Jackscrews)
Inboard Feet
Outboard Feet
Want these verified by a 30+ year alignment specialist before you move the machine? Request a review
Disclaimer: This alignment move calculator is provided as a support resource for qualified professionals. Results do not replace OEM/Vendor alignment specifications, coupling manufacturer requirements, or approved engineering procedures. Always verify computed moves against Vendor documentation and/or Project Specification before adjusting machinery.

Alignment Tolerances Reference

Typical industry tolerances for rotating machinery shaft alignment. Values represent widely accepted field practices consistent with guidelines such as API RP 686. Always verify against the applicable standard edition and OEM/Vendor requirements.

Select Coupling Type

Flexible Element

Disc, diaphragm, metallic membrane

Gear Coupling

Lubricated gear-tooth mesh

Elastomeric

Rubber, urethane element

Rigid / Flanged

Solid or bolted flange

Typical Alignment Tolerances

ParameterToleranceNotes
Offset misalignment (reverse-indicator / laser)≤ 0.5 mil/in (0.05 mm/100mm)At each flex plane, after sag & thermal offsets
Rim & face angularity≤ 0.03°At each coupling hub
Rim & face offset≤ 1 mil (0.025 mm)At coupling center
Piping-induced shaft movement≤ 2 mils (0.05 mm)Any direction, all flanges bolted
Indicator bracket sag≤ 0.8 mil/in of spanMeasured and compensated
Shim packs per foot≤ 5 shims maxStainless steel, clean, flat
Not sure which tolerance applies to your coupling or equipment? We can review your alignment specification. Ask a specialist
Disclaimer: The tolerance values shown are commonly used industry guidelines provided as a support resource for qualified professionals. They are not reproduced from any copyrighted standard. These values do not replace the current edition of API RP 686, OEM/Vendor coupling specifications, or project-approved alignment procedures. Always refer to the applicable Vendor documentation and/or Project Specification and the current published edition of the relevant API standard for your specific equipment.

DBSE / Axial Spacing Check

Verify coupling axial gap against specified tolerances consistent with industry guidelines such as API RP 686.

Coupling Data

Deviation
Allowable Tolerance
Status
Typical industry limits: Flexible-element couplings ≤ ±20 mils (0.50 mm). Gear/elastomeric couplings ≤ ±40 mils (1.00 mm). These are commonly referenced values consistent with API RP 686 guidelines. Always defer to Vendor specifications if tighter.
Important: DBSE shall be checked as early as practically possible with the shaft towards the active thrust side. This ensures proper execution by accounting for axial float and confirming the coupling gap under the condition closest to the running position.
Disclaimer: This DBSE/axial spacing checker is provided as a support resource for qualified professionals. Results do not replace OEM/Vendor coupling specifications, coupling drawing dimensional data, or approved field procedures. Always refer to the Vendor documentation and/or Project Specification for your specific coupling and equipment.

Soft Foot Check & Correction

Step-by-step procedure for identifying and correcting soft foot conditions based on industry best practices consistent with API RP 686 guidelines.

What is Soft Foot?

Soft foot is a condition where one or more machine feet do not make full, flat contact with the baseplate. It causes frame distortion when bolts are tightened, leading to internal misalignment, bearing distress, and unreliable alignment readings.

TypeDescriptionFix
Parallel (Gap)Uniform gap under one footAdd shim equal to gap
Angular (Rock)Foot rocks on corner or edgeMachine/grind foot or step shims
Induced (Piping)External forces from pipingCorrect piping strain first
SquishyToo many or dirty shims compressReplace with clean SS shims (≤5)

Check Procedure

  1. Torque all hold-down bolts to specified values (refer to OEM specifications; API RP 686 provides general torque guidance).
    Use calibrated torque wrench. Oil-lubricate threads unless otherwise specified.
  2. Mount a dial indicator on the baseplate touching the machine foot near one bolt.
    Use magnetic base secured to the base — not to the machine.
  3. Zero the indicator, then loosen the bolt at that foot.
    Loosen only the single bolt being tested.
  4. Record the indicator movement (foot lift).
    Positive reading = foot lifted = soft foot at that location.
  5. Re-tighten the bolt and confirm indicator returns to zero.
    If it does not return, investigate for angular soft foot.
  6. Repeat for all feet, one at a time.
    Test all four (or six) feet. Test the fixed machine if alignment proves difficult.
  7. Correct any foot showing > 2 mils (0.05 mm) of lift.
    Add pre-cut stainless steel shims matching the gap. Re-check after correction.

Quick Soft Foot Check

Persistent soft foot or angular foot conditions? We resolve these on-site and get your train aligned. Get support
Disclaimer: This soft foot guide and checker is provided as a support resource for qualified professionals. Results do not replace OEM/Vendor installation specifications, equipment-specific soft foot acceptance criteria, or approved field procedures. Always refer to the Vendor documentation and/or Project Specification for your specific equipment.

Alignment Condition Check

Compare measured alignment values against Vendor or industry-standard tolerances (consistent with API RP 686) to determine if the machine is within acceptable limits.

Coupling & Tolerances

Industry-standard defaults (consistent with API RP 686) are pre-filled. Override with Vendor/OEM values if tighter tolerances apply.

Measured Alignment Values

Enter the measured offset and angularity from laser or reverse-indicator results. Use absolute values (unsigned).

Vertical Plane
Horizontal Plane
Vertical Plane
Offset
Angularity
Horizontal Plane
Offset
Angularity
Overall Status
Alignment out of tolerance or borderline? Our specialists can verify readings and perform precision corrections on-site. Request alignment support
Disclaimer: This alignment condition checker is provided as a support resource for qualified professionals. Results do not replace OEM/Vendor alignment specifications, coupling manufacturer requirements, or approved engineering procedures. Always verify alignment acceptance against applicable Vendor documentation and/or Project Specification before releasing equipment for operation.

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