Standards
Surface Treatments
Certifications
- ISO 9001 - 2015 Certified
- PED 2014/68/EC
- NACE MR0175 / ISO 15156-2
- NORSOK M-650 Qualified
- API 6A Certified
- DFAR
- MERKBLATT AD 2000 W2/W7/W10
Incoloy 925 Keys (UNS N09925)
Parallel / square / Woodruff / gib-head keys ASME B17.1 / DIN 6885 / ISO 2491
Incoloy 925 keys (UNS N09925) are precision-machined rectangular or curved-cross-section bars used to transmit torque from a shaft to a mating hub (or vice versa) in rotating machinery. The key sits in a matching keyway machined into both shaft and hub, mechanically locking the two against rotation. Key types are differentiated by cross-section (square / rectangular / Woodruff curved-bottom / gib-head with retaining tab) and by fit (parallel / taper). For sour-service rotating equipment, centrifugal pumps, compressors, turbo-machinery, downhole tool drive shafts, the key shares the corrosive H₂S environment with the shaft, requiring a sour-service-qualified material with NACE MR0175 hardness control. Incoloy 925 in the aged condition (110 ksi YS / 35 HRC max) is the standard CRA key material for sour-service rotating-machinery service. TorqBolt manufactures Incoloy 925 keys in 3 mm to 50 mm key width, lengths to 500 mm, in the solution-annealed and aged condition with hardness controlled within the 35 HRC NACE MR0175 sour-service cap.
Need Incoloy 925 keys? Email info@torqbolt.com with key type, cross-section (W × H), length, fit class, quantity. WhatsApp +91-22-66157017.
Key Variants Manufactured
| Variant | Description | Standard | Use |
|---|---|---|---|
| Parallel key (square / rectangular) | Constant cross-section; sits in matching shaft + hub keyway; parallel sides | ASME B17.1 / DIN 6885 / ISO 2491 Form A (rounded) / B (flat) | Most common; pumps, fans, gearbox couplings |
| Square key | Square cross-section parallel key (W = H) | ASME B17.1 | Light to moderate torque; smaller shaft sizes |
| Rectangular key | Rectangular cross-section (H < W) | ASME B17.1 / DIN 6885 | Higher torque; larger shaft sizes; standard pump-shaft choice |
| Gib-head key | Tapered key with raised head at one end for removal access | ASME B17.1 / DIN 6887 | Removable taper-fit applications; field-serviceable couplings |
| Woodruff key | Half-moon (semicircular) cross-section; sits in semicircular shaft slot | ASME B17.2 / DIN 6888 / ISO 3912 | Tapered shaft ends; small machinery; allows angular self-alignment |
| Taper key (machine key) | Tapered top surface (1:100 typical); locks via wedge action | ASME B17.1 / DIN 6886 | Permanent torque-transmission; high-shear-load applications |
Standard Size Range (Parallel Key per DIN 6885)
| Shaft Diameter | Key Width × Height | Keyway Depth (shaft / hub) | Length Range |
|---|---|---|---|
| 10 to 12 mm | 4 × 4 mm | 2.5 / 1.8 mm | 8 to 45 mm |
| 17 to 22 mm | 6 × 6 mm | 3.5 / 2.8 mm | 14 to 70 mm |
| 22 to 30 mm | 8 × 7 mm | 4.0 / 3.3 mm | 18 to 90 mm |
| 30 to 38 mm | 10 × 8 mm | 5.0 / 3.3 mm | 22 to 110 mm |
| 38 to 44 mm | 12 × 8 mm | 5.0 / 3.3 mm | 28 to 140 mm |
| 44 to 50 mm | 14 × 9 mm | 5.5 / 3.8 mm | 36 to 160 mm |
| 50 to 58 mm | 16 × 10 mm | 6.0 / 4.3 mm | 45 to 180 mm |
| 58 to 65 mm | 18 × 11 mm | 7.0 / 4.4 mm | 50 to 200 mm |
| 65 to 75 mm | 20 × 12 mm | 7.5 / 4.9 mm | 56 to 220 mm |
| 75 to 85 mm | 22 × 14 mm | 9.0 / 5.4 mm | 63 to 250 mm |
| 85 to 95 mm | 25 × 14 mm | 9.0 / 5.4 mm | 70 to 280 mm |
| 95 to 110 mm | 28 × 16 mm | 10.0 / 6.4 mm | 80 to 320 mm |
| 110 to 130 mm | 32 × 18 mm | 11.0 / 7.4 mm | 90 to 360 mm |
Mechanical Properties (Aged)
Tensile 165 ksi min / Yield 110 ksi min / Shear strength ~95 ksi (assumed 0.58 × UTS for ductile shear) / Hardness 32–35 HRC (NACE cap). For high-shear-load keys in NON-sour applications, hardness can be raised to 40–45 HRC by selective omission of the second age step, specify "non-NACE high-hardness" at RFQ stage if needed.
Standards
- ASTM B805, UNS N09925 input bar (square / rectangular bar stock)
- ASME B17.1, Keys and Keyseats (inch series)
- ASME B17.2, Woodruff Keys (inch series)
- DIN 6885, Drive Type Fastenings, Parallel Keys (metric)
- DIN 6886, Taper Keys
- DIN 6887, Gib-Head Keys
- DIN 6888 / ISO 3912, Woodruff Keys (metric)
- ISO 2491, Parallel Keys (metric)
- NACE MR0175 / ISO 15156-3 Table A.10, sour service
- EN 10204 3.1 / 3.2; NORSOK M-630 MDS A30
Applications
- Sour-service centrifugal pump shaft-to-impeller keyed couplings
- Reciprocating compressor crankshaft keyed connections
- Sour-gas turbine + expander shaft-to-impeller keys
- Downhole-tool drive-shaft torque-transmission keys
- Subsea pump + ROV-tool drive-shaft keyed assemblies
- Sour-service mixer + agitator drive keyed couplings
- Wellhead-actuator drive-shaft keys (sour H₂S exposure)
Manufacturing Sequence
- Bar input per ASTM B805 in annealed condition (square / rectangular bar matched to key cross-section, or round bar for Woodruff blanks)
- Cut to length + face both ends square
- Mill / grind cross-section to ASME B17.1 / DIN 6885 dimensional tolerance (typically h9 width, h11 height for parallel keys)
- For Woodruff: form half-moon profile by milling from round bar
- For gib-head: milling head feature at one end
- For taper key: machine taper top surface (1:100 typical)
- Solution anneal + age cycle per heat-treatment specification
- Final inspection: cross-section dimensional, length, end-square, 100% hardness, sample tensile
- Marking: heat number bagged with packaging (keys typically too small for individual stamping)
Frequently Asked Questions
What's the difference between a key and a pin? A key transmits TORQUE between a shaft and a hub through their mating keyways, the load path is shear across the key cross-section. A pin transmits load (shear or tension) across two components through a drilled hole in both. Keys are sized by shaft diameter (ASME B17.1 / DIN 6885 tables); pins by load and component thickness.
Which key type for which shaft? Parallel rectangular for most pump + general shaft applications (DIN 6885); Woodruff for tapered shaft ends (allows angular self-alignment); gib-head for removable taper-fit; taper key for permanent high-load lock. If unsure, specify shaft diameter + application and we'll recommend.
Lead time? Standard parallel keys (size 6×6 to 25×14 mm): 4–6 weeks. Woodruff / gib-head / taper variants: 6–8 weeks. Custom non-standard cross-sections: 8–10 weeks.
Documentation Package & Related Products
EN 10204 3.1 MTC (3.2 with TPI on request); chemistry, tensile, 100% hardness, dimensional inspection, NACE MR0175 reference. Related: bars (input stock), pins (alternative torque-transmission), washers, full datasheet.
Request a Quote
Email info@torqbolt.com · Phone +91-22-66157017 · WhatsApp +91-22-66157017. Specify key type (parallel / Woodruff / gib-head / taper), cross-section W × H, length, fit class, quantity, applicable standards (ASME B17.1 / DIN 6885 / ISO 2491), MTC level.
References: ASTM B805; ASME B17.1 / B17.2; DIN 6885 / 6886 / 6887 / 6888; ISO 2491 / 3912; NACE MR0175 / ISO 15156-3 Table A.10; EN 10204. INCOLOY® is a registered trademark of Special Metals Corporation.
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