Pipe Fitting K-Factor Table (Crane TP-410)
Resistance coefficients (K) for valves and fittings, from Crane Technical Paper 410. K sets the minor pressure loss of a fitting via hL = K·V²/2g. Crane expresses K as n · fT — a fixed L/D equivalent (n) times the fully-turbulent friction factor (fT) for the pipe size. Use the tables below to look up n and fT, or let SimuPipe compute Crane K automatically.
- — resistance coefficient, — mean velocity
- — L/D equivalent for the fitting (from the table), — turbulent friction factor for the size
- — fluid density, — gravitational acceleration
Total loss in a line = straight-pipe friction (Darcy-Weisbach) + the sum of all fitting K-factors × velocity head.
For how to apply these values — K-factor versus equivalent length, the 2K and 3K corrections at low Reynolds number, and a worked example — see minor losses in pipes.
| Fitting / valve | n (L/D) | K @ 2″ (f_T 0.019) |
|---|---|---|
| Bends & elbows | ||
| 90° standard elbow | 30 | 0.57 |
| 90° long-radius elbow | 16 | 0.30 |
| 45° standard elbow | 16 | 0.30 |
| 180° return bend (close pattern) | 50 | 0.95 |
| Tees | ||
| Tee — flow through run (line) | 20 | 0.38 |
| Tee — flow through branch | 60 | 1.14 |
| Valves (full open) | ||
| Gate valve | 8 | 0.15 |
| Globe valve | 340 | 6.46 |
| Angle valve | 150 | 2.85 |
| Ball valve (full bore) | 3 | 0.06 |
| Butterfly valve (2–8") | 45 | 0.86 |
| Plug valve (straightway) | 18 | 0.34 |
| Swing check valve | 100 | 1.90 |
| Lift check valve | 600 | 11.4 |
Representative Crane TP-410 values — exact K varies by fitting construction (e.g. globe-valve seat type) and standard. Consult Crane TP-410 for the authoritative, complete set.
These K-factors are for fully open valves. For a throttling or control valve, size it by flow coefficient instead of a single K — use the control valve Cv / Kv sizing calculator.
A standard 90° elbow has a Crane TP-410 K-factor of about 0.4 to 0.8 (≈ 0.57 at 2″ pipe). A long-radius 90° elbow is roughly half that — 0.2 to 0.43, about 0.30 at 2″ and dropping to ≈ 0.2 in large 12–16″ pipe. A 45° elbow matches the long-radius 90° at ≈ 0.2 to 0.43. K rises in smaller pipe because K = n·fT and the turbulent friction factor fT is higher at small sizes.
| Elbow type | ½" | 1" | 2" | 4" | 6" | 8–10" | 12–16" |
|---|---|---|---|---|---|---|---|
| 90° standard elbow | 0.81 | 0.69 | 0.57 | 0.51 | 0.45 | 0.42 | 0.39 |
| 90° long-radius elbow | 0.43 | 0.37 | 0.30 | 0.27 | 0.24 | 0.22 | 0.21 |
| 45° elbow | 0.43 | 0.37 | 0.30 | 0.27 | 0.24 | 0.22 | 0.21 |
K = n·fT with n = 30 (90° standard) or 16 (90° long-radius and 45°). Nominal pipe size, clean commercial steel.
| Nominal size | f_T (clean steel) |
|---|---|
| 1/2" | 0.027 |
| 1" | 0.023 |
| 2" | 0.019 |
| 4" | 0.017 |
| 6" | 0.015 |
| 8–10" | 0.014 |
| 12–16" | 0.013 |
Multiply the fitting's n by f_T for your size to get K. Example: a 90° elbow (n = 30) in 6″ pipe → K = 30 × 0.015 = 0.45.
| Feature | K |
|---|---|
| Pipe entrance — inward projecting (Borda) | 0.78 |
| Pipe entrance — sharp-edged (flush) | 0.50 |
| Pipe entrance — slightly rounded | 0.23 |
| Pipe entrance — well-rounded | 0.04 |
| Pipe exit (into a tank or atmosphere) | 1.0 |
These are direct K values (not scaled by f_T). Sudden contractions and enlargements instead depend on the diameter ratio β = d/D — a sudden enlargement is K = (1 − β²)² referenced to the upstream velocity.
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- Resistance coefficients follow the Crane Technical Paper 410 method: K = n · f_T, where n is the fitting's equivalent-length ratio L/D and f_T the fully turbulent friction factor for clean commercial steel of that nominal size. The n values are Crane's; the K shown is the product at the 2″ f_T unless a size column says otherwise.
- The f_T ladder is the classic TP-410 table (the values in the 1976–2009 printings, still the most widely reproduced). Later editions revised several steps (for example 3/4″ 0.024 and 4″ 0.016 and a split 2-1/2″ / 3″ row); the classic ladder is kept deliberately and in full because mixing editions row by row gives an inconsistent set — if you work to a specific edition, apply its ladder throughout.
- Crane publishes f_T in steps, and this page reproduces the steps rather than interpolating between sizes, which would fabricate precision the source does not have.
- Entrance and exit coefficients are direct K values (independent of size) from the same source. All values are for fully turbulent flow; at low Reynolds numbers the loss of a fitting is higher than K·v²/2g predicts, which the calculators flag.
- This is the same data the friction-loss calculator's fittings picker, the per-pipe fittings list in the editor and the embeddable K-factor widget use, so a K entered anywhere on the site is this table's K.
Frequently Asked Questions
What is a pipe fitting K-factor?
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What is the Crane TP-410 K = n·f_T method?
Why does the K-factor depend on pipe size?
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