Fasteners Catalog
Encyclopedic catalog of mechanical fasteners: threaded fasteners (bolts, screws, studs), nuts, washers, dowels, pins, rivets, captive hardware (PEM, helicoil, threaded inserts), thread standards (UN / M / ACME / Tr / NPT / BSP / Whitworth), strength grades (SAE J429, ASTM A325/A490, ISO 898-1, A2/A4 stainless), coatings + finishes, and OEM / distributor sources. SI metric primary; UN imperial cross-referenced where the standard remains in industrial use.
1. Threaded Fasteners — Master Classification
| Family | Definition |
|---|---|
| Bolt | Threaded fastener intended to be tightened by torque on the head, mated with a nut (per ASME B18.2.1). The threaded shank is gripped between head and nut. |
| Cap screw | A bolt-type fastener (often called a “machine bolt” in trade) intended to mate with an internal thread tapped into the joined part — no nut. Hex-head cap screw is the most common form. |
| Machine screw | Smaller-diameter threaded fastener (typically < 1/4” / M6); cylindrical head styles (pan, flat, round, fillister); for threaded parts, sheet metal, or with a nut |
| Set screw | Headless threaded fastener; tightened in tapped hole to bear against shaft (collar / pulley retention) |
| Stud | Threaded both ends, no head; one end installed permanently, other receives nut |
| Self-tapping / thread-forming | Cuts or forms its own mating thread in unthreaded hole |
| Self-drilling (TEK) | Drilling point on tip; drills + taps + fastens in one operation |
Terminology note: “bolt” vs “screw” — ASME B18 distinguishes by function (gripped by nut vs torqued into tapped part); trade usage often blurs this for hex-head cap screws.
2. Hex-Head Bolts and Cap Screws
| Style | Standard | Notes |
|---|---|---|
| Hex bolt (machine bolt) | ASME B18.2.1, ISO 4014 (partial thread) / ISO 4017 (full thread) | Plain hex head, used with nut |
| Hex cap screw (finished hex) | ASME B18.2.1, ISO 4014 / 4017 | Closer tolerance, washer face under head; threads into tapped hole or nut |
| Heavy hex bolt | ASME B18.2.1, ASTM A325, A490 | Larger across-flats; structural |
| Heavy hex structural | ASTM F3125 (replaces A325/A490) | Wider head, shorter thread, “ST” head marking |
| Flange hex bolt | ASME B18.2.1, ISO 4162 / DIN 6921 | Integral washer flange, often serrated for anti-loosening |
| 12-point flange bolt | NAS, JIS, MIL-S-8879 | Aerospace + automotive race engines; high-torque |
Length convention: ASME measures under the head (under-head to tip); flat / countersunk styles measure overall.
Thread engagement minimum: 1× nominal diameter in steel, 1.5× in aluminum, 2× in plastic for safe pull-out at proof load.
3. Socket-Head Cap Screws (SHCS) and Variants
| Style | Standard | Notes |
|---|---|---|
| Socket head cap screw (SHCS) | ASME B18.3, ISO 4762 / DIN 912 | Cylindrical head, internal hex (Allen); high tensile (Grade 12.9 / Alloy steel typical) |
| Low-head socket cap | ASME B18.3, DIN 7984 | Reduced head height; smaller hex |
| Button-head socket | ASME B18.3, ISO 7380 / DIN EN ISO 7380-1 | Domed head, decorative + lower clearance |
| Flat-head socket (countersunk) | ASME B18.3, ISO 10642 / DIN 7991 | 82° (US) or 90° (ISO) countersink |
| Shoulder bolt / stripper bolt | ASME B18.3, DIN 9841 | Precision-ground shoulder for pivot + alignment |
| Set screws (socket) | ASME B18.3, ISO 4026/4027/4028/4029 | Cup, flat, cone, dog, knurled-cup points |
Socket cap screws are predominantly black-oxide alloy steel Grade 12.9 (metric) / Grade 8 alloy (inch); 18-8 / 316 stainless variants common.
Socket sizes: metric MX → hex AF; e.g., M6 cap = 5 mm hex, M8 = 6 mm, M10 = 8 mm, M12 = 10 mm, M16 = 14 mm, M20 = 17 mm, M24 = 19 mm, M30 = 22 mm.
Drive variants (alternatives to hex):
- Torx (T-star, 6-lobe) — Camcar Textron / ITW; T10–T100; higher torque transfer, lower cam-out
- Torx Plus — improved 6-lobe; Mercedes + BMW
- Pentalobe (5-lobe) — Apple proprietary
- Robertson (square) — Canadian; furniture, decking
- Phillips (PH 0–4), Pozidriv (PZ 0–4) — sheet metal + wood
- Tri-Wing, Spanner (2-pin), Polydrive, External Torx (E-star) — security / OEM-restricted
- Slotted — heritage, low torque
- Combination (e.g., slotted + Phillips combo head) — service-friendly
4. Specialty Bolts
| Style | Standard | Service |
|---|---|---|
| Carriage bolt | ASME B18.5, DIN 603 | Round head + square neck under head (anti-rotation in wood + soft metal) |
| Plow bolt | ASME B18.5, ANSI / Class 5 (agriculture) | Countersunk flat head + square neck; ag-equipment wear parts |
| Step bolt | ASME B18.5 | Truncated dome head + square neck; tower / utility |
| Stove bolt | ASME B18.6.3 | Slotted truncated head + machine thread; stove + sheet metal |
| Lag screw / coach screw | ASME B18.2.1, DIN 571 | Hex head + wood thread; structural wood |
| Eye bolt | ASME B18.15, DIN 580 | Forged eye; lifting (rated WLL stamped) |
| Eye nut | DIN 582 | Lifting nut |
| Swing eye / hoist ring | RUD VRS / Crosby / Cisco | Articulated lifting; 4:1 design factor |
| T-head bolt | ASME B18.5 | T-slot table fixturing |
| U-bolt | ASME B18.31.5, DIN 3570 | Pipe + cable clamping |
| J-bolt | various | Anchor + suspension |
| Anchor bolts | ASTM F1554 (Grade 36 / 55 / 105) | Foundation anchorage; bent or headed |
| Stud bolt (heavy hex) | ASTM A193 (high temp) / A320 (low temp) / A453 | Flanged-pipe joints + pressure vessels |
| Constant-tension load-indicating bolt | ASTM F959 | Direct-tension-indicator washer or strain-gauge bolt |
| Tension-control bolt (TC bolt) | ASTM F2280 / F3125 Grade F1852 | Splined-end snaps off at specified tension; structural |
5. Machine Screws — Head Styles
| Head | Standard | Notes |
|---|---|---|
| Pan head | ASME B18.6.3, ISO 1580 / DIN 85 | Domed top, flat bearing; most-common general |
| Round head | ASME B18.6.3 | Higher dome (legacy) |
| Fillister head | ASME B18.6.3 | Cylindrical with rounded top; higher torque |
| Flat (countersunk) | ASME B18.6.3, ISO 2009 / DIN 963 | 82° (US) or 90° (ISO) flush |
| Oval head | ASME B18.6.3 | Countersunk with domed top |
| Truss head | ASME B18.6.3 | Wide low-profile dome; sheet metal |
| Binding head | ASME B18.6.3 | Undercut head for wiring binding posts |
| Cheese head | DIN 84 / ISO 1207 | Tall cylindrical; instrument |
6. Self-Tapping and Self-Drilling Screws
| Style | Standard | Notes |
|---|---|---|
| Type A (formerly AB) | ASME B18.6.4 | Gimlet point, coarse spaced thread; soft sheet metal, plastic |
| Type B | ASME B18.6.4 | Blunt point, slightly finer; metal sheet 0.4–4 mm |
| Type AB | ASME B18.6.4 | A point + B thread |
| Type C | ASME B18.6.4 | Machine-screw thread; for tapping into thicker metal (replaces machine screw + tapped hole) |
| Type 25 / 23 / D / F / G | ASME B18.6.4 | Thread-cutting (flutes at point cut chips into thread) |
| Type 1 (BSR) | ASME B18.6.4 | Slotted; bottom-of-flute starts cut |
| Thread-forming (Plastite, Powerlok, Taptite, Trilobular) | OEM | Three-lobed cross-section forms (not cuts) mating thread; preferred in metal + plastic (no chips) |
| Self-drilling / TEK | ASME B18.6.4-XL, ISO 15480 | Drill-point tip; drills + taps + fastens in one motion; structural steel deck, metal roofing |
Drill capacity (TEK / self-drilling): #1 (1.0 mm), #2 (2.0 mm), #3 (3.5 mm), #4 (4.5 mm), #5 (12.5 mm). Length must equal substrate + 3 thread-pitches minimum for full drill engagement.
OEMs / brands: Camcar Textron Acument (Taptite, Torx-Plus), ITW Buildex (Teks), Hilti (S-MD), SFS Group, Würth, EJOT, Powers Fasteners, Tapcon (Buildex masonry).
7. Studs and Threaded Rods
| Form | Standard | Use |
|---|---|---|
| Tap-end stud | ASME B18.31.2 | Tap end (interference fit) + nut end |
| Double-end stud | ASME B18.31.2 | Equal threads both ends |
| Continuous threaded rod / All-thread | ASTM F1554, DIN 975, ISO 898 | Cut-to-length anchor / hanger |
| Pressure-vessel stud | ASTM A193 B7 / B16 / B8 / B8M | High-temp flange + nuclear |
| Low-temp stud | ASTM A320 L7 / L43 | Cryo + low-temp |
| Wheel stud | SAE J429 Grade 5/8 / 9 | Pressed into hub |
Hot torque-tensioning tools (subsea, wind turbines, refinery flanges): hydraulic torque wrench (HYTORC, Enerpac, Norbar, Atlas Copco), bolt tensioner (Enerpac, HYTORC, Boltight / Nord-Lock).
8. Nuts
| Form | Standard | Notes |
|---|---|---|
| Hex nut | ASME B18.2.2, ISO 4032 / DIN 934 | Standard |
| Heavy hex nut | ASME B18.2.2, ASTM A194 | Wider across flats; structural + pressure vessel |
| Hex jam (thin) nut | ASME B18.2.2, ISO 4035 / DIN 439 | Half-height; locking jam against full nut |
| Flange nut | ASME B18.2.2, DIN 6923, ISO 4161 | Integral washer flange |
| Serrated flange nut | DIN 6923-S | Anti-loosening serrations |
| Wing nut | ASME B18.6.9, DIN 315 | Hand-tightened |
| Cap (acorn) nut | ASME B18.6.9, DIN 1587 | Domed closed top (cosmetic, thread protection) |
| Castle / castellated nut | ASME B18.2.2, DIN 935 | Slots for cotter pin; axle nuts |
| Slotted nut | ASME B18.2.2 | Slots for cotter pin |
| Square nut | DIN 557 / DIN 562 | Furniture / sheet metal |
| Tee / T-slot nut | DIN 508 | Machine-table fixturing |
| Weld nut | DIN 928 / DIN 929 | Square or hex projection-welded |
| Cage / clip / J-nut | OEM (automotive) | Spring-clip captive nut in panel |
| Coupling nut (long nut) | DIN 6334 | Joins threaded rods |
| Knurled / thumb nut | DIN 466 / 467 | Hand-tight |
Locking nuts:
| Style | Mechanism | Std / Trade |
|---|---|---|
| Nylon-insert lock nut (Nyloc / Stover / Esna) | Nylon ring deforms onto thread; reusable (~5×) | IFI 100/107, DIN 985 (low) / DIN 982 (high) |
| All-metal prevailing-torque (Stover, Cleveland, Top-Lock) | Pinched or deformed thread crest creates friction; reusable | DIN 980 / IFI 100/107 |
| Distorted-thread (Flex-Loc, Top-Lock) | Out-of-round at crown | OEM |
| Two-piece spinning ratchet (NORD-LOCK Wedge-Locking) | Wedge action on cam faces | EN 14399 |
| Free-spinning prevailing-thread (Spiralock — Stanley) | Specially-shaped 30° wedge thread | OEM |
| Mechanical pin-lock (Lockwiring) | Wire through drilled head | NASM33540 |
| Adhesive thread-locker | Loctite blue 242, red 271, green 290 / 620 / 638 | Henkel Loctite, 3M Scotch-Grip, Permatex |
| Self-locking by pellet (Nylok, Long-Lok) | Nylon patch on bolt threads | IFI-124, MIL-N-25027 |
Strength grades for nuts must match bolt-grade to avoid stripping in nut:
- Grade 2 bolt → Grade 2 nut (≤ 3/4”)
- Grade 5 bolt → Grade 5 nut
- Grade 8 bolt → Grade 8 nut (heavy hex)
- ISO 8.8 bolt → ISO class 8 nut
- ISO 10.9 bolt → ISO class 10 nut
- ISO 12.9 bolt → ISO class 12 nut
9. Washers
| Style | Standard | Function |
|---|---|---|
| Flat (plain) | ASME B18.21.1 (Type A: narrow / wide; Type B), DIN 125 (narrow) / DIN 9021 (wide / fender) | Spread load; protect surface |
| Fender washer | ASME B18.22.1, DIN 9021, ISO 7093 | Extra-wide OD (sheet-metal protection) |
| Finishing washer | various | Countersunk recess for round-head fastener |
| Structural F436 washer | ASTM F436 | Heavy-duty for A325 / F3125 structural bolts |
| Through-hardened | ASTM F436 | C50–C55 HRC |
| Split lock (Helical spring) | ASME B18.21.1, DIN 127 | Spring + bite on cone face; widely considered weak vs Nord-Lock under vibration |
| Internal-tooth lock | ASME B18.21.1, DIN 6797I | Tooth bite into surface (smaller cosmetic damage) |
| External-tooth lock | ASME B18.21.1, DIN 6797A | More holding, more cosmetic damage |
| Belleville (conical spring) disc | DIN 6796, DIN 2093 | Maintains preload through thermal / settling movement; stacked alternating for travel + load |
| NORD-LOCK wedge-locking | NORD-LOCK proprietary | Two cams with radial teeth + cam ramps > thread pitch ⇒ self-locking |
| Schnorr washer | DIN 6908 | Conical-serrated bevel; pre-loaded |
| Wave washer | ASME B18.21.1 | Light spring (axial play take-up); fan / pulley |
| DTI (direct tension indicator) | ASTM F959 | Bumps compress as bolt tensions; visual gap gauge |
| Sealing washers (bonded EPDM, nylon, copper, aluminum, fiber) | DIN 7603 / OEM | Hydraulic + leak-proof |
NORD-LOCK is the gold standard for vibration-resistant bolted joints — junker-test certified per DIN 65151.
10. Pins
| Pin | Standard | Use |
|---|---|---|
| Dowel pin (solid, hardened) | ASME B18.8.2, ISO 2338 (m6) / ISO 8734 (m6 hardened) / DIN 6325 (hardened, m6) | Precision location; press-fit into one part, slip into other |
| Straight (parallel) pin, unhardened | DIN 7 / ISO 2338 | General location |
| Taper pin | ASME B18.8.2, DIN 1 / ISO 2339 | 1:48 taper; collar + shaft |
| Spring (slotted/Coiled) pin | ASME B18.8.2, DIN 1481 (slotted) / DIN 7343 (coiled) / ISO 8748 (heavy) / ISO 8750 (coiled) | Roll-pin; compressed at install — friction holds |
| Solid groove pin | DIN 1471 / 1472 / 1473 / 1474 | Grooved exterior bites into hole |
| Clevis pin | ASME B18.8.1, ISO 2341 | Headed, drilled for cotter, removable |
| Cotter pin (split pin) | ASME B18.8.1, ISO 1234 / DIN 94 | Bent over castle nut or clevis |
| Hitch pin / R-clip | various | Spring-steel quick-release |
| Quick-release ball-detent | various OEM | Push-button ball locks |
| Drive (drive-fit) pin | DIN 1474 | Bites in by interference |
| Knurled half-length pin | DIN 1472 / 1473 | Easier install than full-knurled |
Hardened dowel pins: AISI 12L14 surface-hardened (HRC 58–62) or A2 / O1 tool steel. Tolerance m6 (slip + press) standard, h7 / n6 / r6 also available.
11. Rivets
| Style | Standard | Service |
|---|---|---|
| Solid rivet | ASME B18.1.2, DIN 660 (round-head) / DIN 661 (countersunk) | Heritage; aircraft (driven AN/MS), boiler (legacy); driven hot or cold |
| Semi-tubular rivet | ASME B18.7 | Reduced clinching force; light assemblies |
| Blind (pop) rivet | ISO 14589, DIN 7337 | Mandrel pulls through; one-side access; aluminum, steel, stainless, monel; aircraft + sheet metal |
| Structural blind rivet | DIN 7337 | Higher shear (Avdel, Huck, Bulb-Tite) |
| Hi-Lok / Hi-Lite (Hi-Shear) | NAS1738, MS90353 | Aerospace; threaded collar instead of bucked tail |
| Lockbolt (Huck, Magna-Lok) | various | Pulled-stem collar swaged onto grooved pin; railcar, body-on-frame truck, structural; alternative to bolts |
| Drive rivet | DIN 1476 | Hammer-driven through soft pin; nameplates |
| Friction-stir-welded rivet | OEM | Newer; aerospace + auto |
| Squeeze rivet | OEM | Pneumatic squeezer in panel assembly |
| Self-piercing rivet (SPR) | OEM | Aluminum auto-body assembly (Audi, Land Rover); rivet pierces top sheet without pre-hole, flares into bottom sheet |
| Solid-clinch (no rivet, mechanical fold) | TOX, BTM | Sheet-metal joining without consumables |
| Friction-stir rivetless (FSR) | OEM | Adhesion via friction heat |
| Tubular rivets (split-cup) | DIN 7338 | Brake-shoe linings, fabric |
Material codes (aircraft / AN):
- AD — 2117-T4 (aluminum)
- A — 1100-F (soft, low-strength)
- B — 5056 (magnesium-bearing)
- D — 2024-T31 (driven cold; high-strength)
- DD — 2024-T31 ice-box (driven within freezer cycle)
- E — 7050
- M — Monel (Cu-Ni)
- F — Steel
- C — Stainless
Driven heads: AN426 (countersunk 100°), AN430 (round), AN442 (brazier), AN455 (truss), AN470 (universal mushroom).
Blind-rivet OEMs: Avdel (Stanley Engineered Fastening), POP (Stanley → Newfrey), Huck (Arconic / Howmet Aerospace), Bollhoff Rivnut, Gesipa (SFS), Bulten, Marson (Stanley), Cherry Aerospace (PCC).
12. Captive Hardware (PEM-Style)
Hardware installed permanently into thin sheet metal — common in electronic enclosures, server chassis, automotive, defense:
| Component | Trade | Function |
|---|---|---|
| Clinch nut | PEM SP/SS, Whitesell, Camcar | Pressed into pre-drilled hole; cold-flow displaces parent metal into knurled barrel for retention |
| Self-clinching stud | PEM FH / FHS / TPS | Threaded stud captivated in sheet |
| Self-clinching standoff | PEM SO / SOS / SOA / KFS / KFB | Threaded + unthreaded standoffs (motherboard mounting) |
| Self-clinching panel fastener | PEM PF / PFS | Loaded screws retained in panel |
| Self-clinching cable tie mount | PEM CMSF | — |
| Threaded insert (rivet nut / Riv-Nut) | Bollhoff Rivkle, Avdel Avtainer, POP Nut, Plusnut, AVK | Blind-installed (one-sided); flared / collapsed body grips through-hole |
| Inserts for plastics (heat-staked / ultrasonic) | Tappex Microbarb, Spirol, Tri-Star, Avibank | Brass or stainless inserts molded / pressed / ultrasonically embedded |
| Wire thread insert (Helicoil) | Heli-Coil (Stanley Engineered Fastening) | Coiled stainless / Inconel spring forms internal thread; repair stripped threads + reinforce soft material |
| Solid-bushing thread insert | KEENSERT (Heli-Coil), Recoil, E-Z Lok, Time-Sert | Solid threaded insert with keys / external thread; higher pull-out than Helicoil |
| Mil-grade key-locking | KEENSERT, Slimsert | Aerospace, defense |
| Captive screw + retainer | PEM PF1x / PF2x / PEM5x, Southco K2 | Captive panel screw with retainer + spring |
| Quarter-turn fastener | Southco D6 / 91 / E5 (DZUS) | Quick-release panel fastener |
| Spring-loaded plunger / ball detent | various | Indexing |
PEM = PennEngineering — origin of self-clinching hardware in 1942 (Eastern Steel acquired by PennEngineering 1953). Reference catalogue: PEM Specification (“Pencom” merged 2022).
13. Thread Standards
13.1 Inch — Unified (UN, UNC, UNF, UNEF, UN-8)
ASME B1.1:
- UNC — Unified Coarse (e.g., 1/4-20, 3/8-16, 1/2-13, 5/8-11, 3/4-10, 1-8)
- UNF — Unified Fine (1/4-28, 3/8-24, 1/2-20, 5/8-18, 3/4-16, 1-12)
- UNEF — Extra Fine (1/2-28, 5/8-24, 3/4-20)
- UN — Constant 8, 12, 16 series (1-8 UN, 1-1/2-12 UN)
Classes of fit (B1.1):
- 1A / 1B — loose (drywall screws, hot-dip galvanized)
- 2A / 2B — general industrial (default)
- 3A / 3B — close fit (precision, aerospace)
- 5 / 4 — interference (heritage)
13.2 Metric — ISO (M, MJ)
ISO 261 + ISO 262:
- M — standard metric (e.g., M3 × 0.5, M5 × 0.8, M6 × 1.0, M8 × 1.25, M10 × 1.5, M12 × 1.75, M16 × 2.0, M20 × 2.5, M24 × 3.0)
- M-fine — finer pitch (M8 × 1.0, M10 × 1.25, M12 × 1.5, M16 × 1.5, M20 × 1.5)
- MJ — controlled-radius root, aerospace (ISO 5855); higher fatigue life
Tolerance classes (ISO 965):
- External: 4g, 6g (default), 8g
- Internal: 4H, 5H, 6H (default), 7H
13.3 Pipe Threads
| Standard | Form | Sealing | Use |
|---|---|---|---|
| NPT (ANSI/ASME B1.20.1) | Tapered 60° | Interference of crests; needs PTFE tape / pipe dope | US plumbing + low/mid-pressure |
| NPTF (Dryseal, ANSI/ASME B1.20.3) | Tapered 60°, controlled root + crest | Self-sealing (interference fit) | Hydraulic, fuel |
| NPS / NPSM / NPSL | Parallel 60° | O-ring or gasket | Mechanical mating only (not sealing) |
| BSPT (ISO 7-1) | Tapered 55° (Whitworth profile) | Interference + sealant | Industrial, Asia + EU |
| BSPP / G (ISO 228) | Parallel 55° | Bonded washer or O-ring on face | Hydraulic + pneumatic |
| Rp / Rc (ISO 7) | Rp parallel internal / Rc tapered internal | Sealant | EU pipe |
| JIS metric pipe (PT / PS) | Equivalent to BSPT / BSPP | — | Japan |
| Metric flat-seat O-ring (DIN 3852) | Parallel metric | O-ring face | EU hydraulic |
| SAE J514 J-series straight thread O-ring boss (ORB) | Parallel UN | O-ring in boss | US hydraulic |
13.4 Power-Transmission and Motion Threads
| Standard | Form | Use |
|---|---|---|
| ACME (ASME B1.5) | 29° trapezoidal flank | Lead screws, jacks, clamps, valve stems |
| Stub ACME | Shallower thread | Coarse-positioning |
| Centralizing ACME | Tight centering tolerance | Precision actuators |
| Trapezoidal (Tr / metric ISO 2901–2904) | 30° trapezoidal flank | EU lead screws (e.g., Tr 16×4, Tr 30×6) |
| Buttress (ASME B1.9 / DIN 513) | 7°/45° asymmetric | One-direction thrust (gun-barrel breech) |
| Square (heritage) | 0° flank | Heavy translation (legacy); less common now |
| Ball-screw (ISO 3408) | Modified-circular gothic-arch | Recirculating ball; CNC, precision actuation; not a “thread” in the load-transmitting sense |
13.5 Heritage
| Standard | Form | Notes |
|---|---|---|
| Whitworth BSW (BS 84) | 55° rounded crest/root | British heritage (pre-1960s); restoration only |
| BSF (British Standard Fine) | 55° | Heritage |
| BA (British Association) | 47.5° | Instrument (heritage) |
| Sellers (American Standard) | 60° flat root | Pre-Unified; restoration |
14. Strength Grades and Materials
14.1 SAE J429 (Inch Carbon + Alloy Steel)
| Grade | Material | Tensile (ksi / MPa) | Proof (ksi / MPa) | Marking |
|---|---|---|---|---|
| 2 | Low carbon | 74 / 510 (1/4–3/4”) | 55 / 380 | (none) |
| 5 | Med-C tempered | 120 / 825 | 85 / 585 | 3 radial lines |
| 5.1 | Same as 5, thread-rolled | 120 / 825 | 85 / 585 | 3 lines, smaller |
| 5.2 | Low-C martensite | 120 / 825 | 85 / 585 | 3 lines, single mfr ID |
| 7 | Med-C alloy, rolled after HT | 133 / 915 | 105 / 720 | 5 radial lines |
| 8 | Med-C alloy, quenched + tempered | 150 / 1035 | 120 / 825 | 6 radial lines |
| 8.2 | Low-C martensite | 150 / 1035 | 120 / 825 | 6 lines, mfr ID |
14.2 ISO 898-1 (Metric Carbon + Alloy Steel)
Property class shown as two numbers (e.g., 8.8): first × 100 = nominal tensile MPa; first × second × 10 = nominal yield MPa.
| Class | Tensile MPa | Yield MPa | Common material |
|---|---|---|---|
| 4.6 | 400 | 240 | Low carbon |
| 4.8 | 420 | 320 | Low carbon, cold-worked |
| 5.8 | 520 | 400 | Med carbon, cold-worked |
| 6.8 | 600 | 480 | Med carbon, cold-worked |
| 8.8 | 800 | 640 | Med-C Q+T (workhorse industrial; equivalent ~Gr 5) |
| 9.8 | 900 | 720 | Med-C Q+T (<M16) |
| 10.9 | 1040 | 940 | Alloy Q+T (heavy-duty; structural) |
| 12.9 | 1220 | 1100 | Alloy Q+T (socket cap screws default) |
| 14.9 | 1400 | 1260 | Aerospace + race engines (special order) |
14.3 Structural (ASTM F3125, replaces A325 + A490 + A354 + F1852 + F2280 + A449)
| Grade | Replaces | Tensile | Yield | Service |
|---|---|---|---|---|
| F3125 Grade A325 | A325 | 120 ksi (≤1”) / 105 ksi (>1”) | 92 ksi / 81 ksi | Standard structural |
| F3125 Grade A490 | A490 | 150 ksi | 130 ksi | High-strength structural |
| F3125 Grade F1852 | F1852 | 120 ksi | 92 ksi | Twist-off (TC) bolt at A325 |
| F3125 Grade F2280 | F2280 | 150 ksi | 130 ksi | Twist-off TC at A490 |
| F3125 Grade A354 BD | A354 BD | 150 ksi | 130 ksi | Threaded rod / stud equivalent A490 |
14.4 Pressure-Vessel + Refinery (ASTM A193 / A194 / A320)
| Bolt grade | Material | Service |
|---|---|---|
| A193 B5 | 4–6Cr-½Mo | Up to 540 °C HC |
| A193 B6 | 12Cr | Up to 540 °C HC |
| A193 B7 | AISI 4140 Q+T | Up to 400 °C; workhorse refinery flange (most common) |
| A193 B7M | 4140 Q+T (HRC 22 max) | Sour service per NACE MR0175 |
| A193 B8 / B8M / B8T / B8C | 304 / 316 / 321 / 347 SS | High temp + corrosion |
| A193 B16 | Cr-Mo-V | High-temp creep service (steam) |
| A320 L7 / L7M / L43 | Low-temp alloy | Cryo |
| A453 660 | Iron-Cr-Ni-Mo precipitate | Bolts for matching coefficient with austenitic flange |
Matching nuts: A194 2H (B7 standard), A194 7 / 7M (B16, low-temp), A194 8 / 8M (B8 SS).
14.5 Stainless Steels (ISO 3506)
| Grade | Composition | Marking | Service |
|---|---|---|---|
| A1 | 303 (Cu, S free-machining) | A1-70 | Not for structural — corrosion-susceptible; machined parts |
| A2 | 304 / 18-8 | A2-70 (medium), A2-80 (cold-headed strain-hardened) | General; most common stainless fastener |
| A3 | 321 / 347 (stabilized) | A3-70 | High-temp |
| A4 | 316 (Mo-bearing) | A4-70 (med), A4-80 (strain-hardened) | Marine, chloride |
| A5 | 316L low-C | A5-70 | Welded marine |
| C1–C4 | Martensitic 410/420 | C1-70 to C4-80 | Wear, harden + temper |
| F1 | Ferritic 430 | F1-45 to F1-60 | Mild corrosive |
| Duplex (D Series, ISO 3506-3) | 2205, 2507 | D2 / D4 / D6 / D8 | Sea water, chloride pitting |
Property numbers (70, 80, 100) = nominal tensile / 10 in kgf/mm² × 9.81 ≈ MPa × 10⁻¹.
14.6 Specialty Materials
| Material | Service |
|---|---|
| Inconel 718 / X-750 / 625 | High-temp + corrosion (gas turbine, exhaust) |
| Hastelloy C-276 | HCl, oxidizing chemical |
| Titanium Gr 5 (Ti-6Al-4V) | Aerospace + medical + marine; high specific strength |
| Monel 400 / K500 | Sea water + HF |
| Alloy 20 | Sulfuric acid |
| Beryllium copper C17200 | Non-sparking, non-magnetic, conductive |
| Silicon bronze C65500 | Marine fasteners, wood |
| Nylon (PA66 / PEEK / PTFE) | Light non-conductive, chemical |
| MP35N | Aerospace high-strength corrosion-resistant |
| 17-4 PH | Precipitation-hardened SS; aerospace |
| H-13 / A2 / D2 tool steel | Wear (dowel pins) |
15. Coatings and Finishes
15.1 Plating
| Coating | Process | Service | Thickness |
|---|---|---|---|
| Zinc plate (electroplated) | Alkaline / acid cyanide-free / chloride bath | Mild indoor; sacrificial galvanic; commodity | 5–15 µm |
| Zinc clear (passivated) | + Cr-free or Cr3+ passivate | Default low-cost finish | 5–15 µm + passivate |
| Zinc yellow | + Cr3+ passivate (heritage Cr6+ banned in EU under RoHS) | Visual marker for grade | 5–15 µm |
| Zinc black | + black passivate | Cosmetic | 5–15 µm |
| Zinc-nickel (8–15% Ni) | Alloy plate | 6–10× corrosion resistance vs Zn; automotive | 5–15 µm |
| Zinc-iron / Zn-Mn | Alloy plate | High-corrosion auto | 5–15 µm |
| Cadmium plate | Electroplate | Marine + aerospace (heritage; toxic; phased out under REACH) | 5–15 µm |
| Tin plate | Electroplate | Electronic / solderable | 3–25 µm |
| Nickel | Electroplate | Wear + corrosion (decorative + mild) | 5–25 µm |
| Electroless nickel (EN) | Autocatalytic Ni-P | High-precision uniform thickness, hard | 10–50 µm |
| Hard chrome | Electroplate | Hard wear (hydraulic rods); not normally on threaded fasteners | 5–250 µm |
| Silver | Electroplate | Aerospace bolt + nut anti-galling at high temp | 5–13 µm |
| Copper | Strike layer | Underplate for other coatings | 1–5 µm |
15.2 Hot-Dip and Mechanical Galvanizing
| Process | Coating | Notes |
|---|---|---|
| Hot-dip galvanizing (HDG) — ASTM F2329 / A153 | Zn 45–100 µm | Heavy industrial + structural exposed; thread tolerance must allow for thickness (oversized nuts) |
| Mechanical galvanizing — ASTM B695 | Zn 5–80 µm tumbled with glass beads + chemicals | Avoids hydrogen embrittlement for hardened bolts |
| Sherardizing | Zn-diffusion in heated drum | Hardness + corrosion; heritage |
15.3 Diffused / Zinc-Flake (Dacromet / Geomet / Magni / Delta-Tone)
| Coating | Chemistry | Service |
|---|---|---|
| Dacromet (NOF Metal Coatings; legacy) | Zn flake + Al flake + Cr6+ binder | Old auto + industrial; Cr6+ banned EU |
| Geomet (NOF MetCoat) | Zn flake + Al flake + Cr3+ silicate; Cr6+-free | Cr6+-free Dacromet successor; widely used auto |
| Magni 565 / 575 (Magni) | Cr-free zinc-aluminum flake + organic topcoat | Auto OEM (Ford WSS, GM GMW3359, Stellantis PS9106) |
| Delta-Tone / Delta-Protekt (Dörken MKS) | Zn-Al flake | EU auto |
| Zintek / Zintek Plus | Zn-Al flake | EU |
Performance: zinc-flake topcoated systems provide 500–1000 hours salt-spray ASTM B117 — far above electrolytic zinc (≥120 h white rust, ≥48 h red rust).
15.4 Organic / Polymer / PTFE Topcoats
| Coating | Trade | Service |
|---|---|---|
| PTFE / Xylan | Whitford Xylan, AkzoNobel Resicoat, Endura | Low-friction (preload control); hydraulic, oil-and-gas downhole |
| Magni Black / Silver topcoats | Magni | Cosmetic + lubrication control |
| Doerken Delta-Seal | Dörken | Black topcoat |
| Cataphoretic e-coat (CED, KTL) | OEM auto | After plating; corrosion + adhesion for paint |
| Powder coat | various | Cosmetic + corrosion |
15.5 Passivation (Stainless)
ASTM A967 / ASTM F86 / AMS 2700:
- Citric acid (modern, eco) — A967 Type 1
- Nitric acid — A967 Type 2 / Type 6
- Removes free iron and forms Cr-rich passive oxide; standard QA for medical, food, marine stainless
15.6 Black Oxide
ASTM D769 / MIL-DTL-13924. Magnetite (Fe3O4) conversion. Cosmetic + light corrosion; oil-impregnated. Standard finish for tool-grade SHCS and dowel pins.
15.7 Phosphate Coatings
ASTM TT-C-490 / DIN EN 12476. Zinc phosphate or manganese phosphate; conversion coat under oil or paint. Common on bolts intended for break-in lubrication.
16. Bolted Joint Mechanics — Reference
16.1 Preload
Target preload = 0.75 × proof load (recommended for static; reduce to 0.60–0.70 for fatigue / re-use).
Torque-preload relation (Motosh / Shigley):
- T = K × d × F
- K = nut factor (0.10–0.35 depending on lubrication; 0.20 dry steel-on-steel default; 0.15–0.18 for waxed; 0.10 for moly-graphite lubricant)
- d = nominal diameter
- F = preload
Scatter on torque-only tightening: ±25–30%. Reduces to ±10% with angle-control, ±5% with bolt-tension measurement (ultrasonic, strain-gauge).
16.2 Embedding / Relaxation
- Embedding losses 5–10% in first 24 hours; re-torque after settling for critical joints
- Belleville stack or Schnorr washer compensates for embedding + thermal cycling
16.3 Fatigue
S-N curve for bolts: stress range Δσ at thread root governs life. Rolled-after-heat-treat threads have 50–100% higher fatigue limit than cut threads. ISO 3800 governs fatigue testing.
16.4 Galling and Lubrication
Stainless-on-stainless prone to galling under high pressure. Mitigation: anti-seize (Loctite, Permatex, Never-Seez nickel / copper / aluminum-based), thread lubricant, dissimilar materials in mating couple.
16.5 Hydrogen Embrittlement
Risk for high-strength fasteners (≥ 32 HRC / ISO 10.9) electroplated in acid bath. Mitigations:
- Bake at 190–230 °C for 4–24 hours within 4 hours of plating (ASTM F1941, ISO 9587/9588)
- Mechanical galvanizing instead of electroplate
- Zinc-flake coating (no electrolysis)
17. Joining Adjacent — Non-Fastener Permanent Methods (Cross-Reference)
Treated in joining-taxonomy:
- Welding (SMAW, GMAW, FCAW, GTAW, SAW, LBW, EBW, FSW) — see welding-processes
- Brazing + soldering — flux + filler metal
- Adhesives — epoxy, methacrylate, anaerobic (Loctite thread-locker is adjacent), urethane, cyanoacrylate
- Mechanical clinch (TOX, BTM) — no consumable
- Press-fit + interference + shrink-fit
18. Major OEMs and Distributors
18.1 OEM Manufacturers
| OEM | HQ | Strengths | Notable lines |
|---|---|---|---|
| Würth Group | Germany | Distribution + OEM, full-line fasteners + chemicals + tools | WIT, WURTH brand line |
| Bossard | Switzerland | Engineering + distribution + OEM | ecosyn-fix (vibration-resistant), ecosyn-MRX |
| Acument Global / Camcar Textron | USA | Torx, Torx-Plus, Taptite | Plate-Lok, Trilobular, Torx, MAThread |
| Nedschroef | NL | Automotive + industrial cold-formed | NS series |
| KAMAX | Germany | Automotive cold-formed | engine + chassis + wheel |
| LISI Automotive / Aerospace | France | Aerospace + auto critical fasteners | Hi-Lok, Hi-Lite (aerospace); engine cold-formed |
| Howmet Aerospace (Alcoa Fastening Systems) | USA | Aerospace fasteners | Huck, Cherry, RECOIL, Marson, Voi-Shan |
| Stanley Engineered Fastening | USA / EU | Avdel, POP, Heli-Coil, Spiralock, Tucker, NPR | Pop blind rivets, Avdel, Heli-Coil, Tucker stud-welding |
| Arconic (now part of Howmet) | USA | Aerospace fasteners legacy | — |
| PennEngineering (PEM) | USA | Self-clinching nuts, studs, standoffs (PEM brand) | PEM SP, FH, SO, KFE |
| Southco | USA | Access hardware (latches, quarter-turn, hinges) | DZUS, K2 |
| Bollhoff | Germany | Captive + automotive + plastic-mold inserts | Rivkle, Helicoil, Spirol |
| Tappex (UK) | UK | Threaded inserts for plastic | Microbarb, Multisert |
| Spirol International | USA | Coiled-pin + tube + inserts | spiral pins, slotted spring |
| Atlas Aerospace (PCC) | USA | Aerospace solid + blind | Cherry, Cherrymax, Hi-Shear |
| Hilti | Liechtenstein | Construction anchors + powder-actuated + self-drill | DX (powder-actuated), Kwik-Bolt anchor, S-MD self-drilling |
| Powers Fasteners (DeWALT) | USA | Anchors + powder-actuated | Power-Stud, Trubolt, Power-Bolt |
| Simpson Strong-Tie | USA | Structural connectors + anchors | Strong-Bolt, Titen, Wedge-All |
| ITW (Buildex / Tapcon / Red Head / Hi-Shear) | USA | Anchors + Teks + powder-actuated | Tapcon (masonry), Teks (self-drill) |
| Nord-Lock Group | Sweden | Vibration-resistant washers + Superbolt + Boltight | Nord-Lock washer, X-Series, Superbolt tensioner |
| EJOT | Germany | Self-tap + self-drill + construction | Delta PT (plastic), JT (steel) |
| SFS Group | Switzerland | Construction self-drill + auto inserts + Gesipa blind | — |
| Gesipa (SFS) | Germany | Blind rivets | PolyGrip, MagnaGrip |
| Avdel (Stanley Engineered Fastening) | UK / USA | Aerospace + auto blind rivets | Avtainer, Avdelok |
| McMaster-Carr | USA | Distributor (huge catalog) | — |
| Fastenal | USA | Distributor (industrial supply) | — |
| Würth Industry North America | USA | Distributor + VMI service | — |
| Grainger | USA | Distributor | — |
| RAF Electronic Hardware | USA | Standoffs + spacers (electronic) | RAF, Keystone, Bivar |
| Trifast | UK | Distribution + cold-formed | — |
| Sundram Fasteners | India | Cold-formed + cold-headed | TVS Sundram |
| Nifco | Japan | Plastic fasteners + clips | Auto trim + electronic |
| Illinois Tool Works (ITW) | USA | Many sub-brands (Buildex, Shakeproof, Hi-Shear) | Shakeproof toothed washers |
| Cleveland Steel Tool | USA | Heavy structural | — |
| Bay City Bolt / Lake Erie / Birmingham Fastener | USA | Specialty + industrial | — |
| OBO Bettermann | Germany | Cable + anchor systems | — |
| Hexagon Manufacturing | various | — | — |
18.2 Aerospace-Specific
NAS / MS / AN catalog references + qualified-product manufacturers:
- LISI Aerospace (formerly Hi-Shear Technology + Eurofast)
- Howmet Fastening Systems (Cherry, Huck, Voi-Shan, Recoil)
- B&B Specialties (NAS distributor)
- Click Bond (composite-bondable hardware)
- Triumph Group / Precision Castparts (PCC) — Cherry Aerospace, SPS Technologies
18.3 Stud-Welding
Drawn-arc + capacitor-discharge stud-welding (CD stud welding):
- Nelson Stud Welding (Doncasters)
- Stanley Engineered Fastening — Tucker
- Köster + Image Industries
- Stronghold (Köster)
19. Selection Heuristics
| Criterion | Recommendation |
|---|---|
| Joint integrity over many tightening cycles | Use threaded insert (Helicoil / KEENSERT) in soft / aluminum / magnesium parent |
| Vibration-prone joint | Nord-Lock washer (preferred), or Spiralock thread + medium thread-locker (Loctite 243), or castle nut + cotter |
| High temperature (> 200 °C) | Avoid nylon-insert nuts (Nyloc degrades); use all-metal lock nuts or safety wire |
| Cryogenic / sub-zero | A320 L7 stud + A194 7 nut; avoid carbon steel A325 < −20 °C |
| Marine / chloride | A4 / 316 SS (mild), duplex 2205 (D2), super-duplex 2507 (D8), Monel 400 (HF) |
| Sour service (H₂S) | NACE MR0175 / ISO 15156 — B7M (HRC ≤ 22), L7M, Inconel 625/718 |
| Galvanic isolation | Stainless to aluminum → use sealant + insulating bush; or stainless equivalent throughout |
| Anti-tamper / security | Pentalobe, Tri-Wing, Spanner, One-way, Shear-bolt heads |
| Easy field disassembly | Captive screws (PEM / Southco K2); quick-release (Southco D6, DZUS) |
| Field repair of stripped thread | Helicoil (most common) or KEENSERT (higher pull-out) |
| Stripping prevention in soft material | Specify large washer + threaded insert; size for shear |
| Dissimilar-metal galvanic risk | Match coating Series (anodic index within 0.25 V; ASTM B843) |
20. Common Pitfalls
- Mixing grade bolt with mismatched nut: nut stripping before bolt yield; specify same / one-step-up nut class
- Using lock washers (split / star) on critical vibration joint: Junker-test shows these are unreliable; Nord-Lock or Schnorr preferred
- Re-using nylon-insert nuts > 5 times: nylon worn and locking torque vanishes
- Galvanic corrosion: zinc-plated bolt in stainless flange — zinc sacrifices preferentially and joint loses preload
- Hydrogen embrittlement: high-strength (Gr 8 / 12.9) bolt electroplated without bake → delayed brittle failure
- Hot-dip galvanized bolt + unmatched nut: zinc coating + nut tolerance — specify oversize / 2B-OS nut
- PTFE tape on NPT > 4 turns: excessive sealant blocks bore; 2–3 turns standard
- Using anti-seize as a thread-lubricant for torque-controlled assembly: nut-factor K drops dramatically — preload jumps 30–50% above spec
- Torquing a bolt that’s already preloaded (“checking torque”): doesn’t verify preload — only re-friction
- Specifying stainless A2 in heavily chloride or pitting service: use A4 or duplex; A2 fails in pitting
- Cup-point set screw with shaft rotated to keyway: better with key + dog-point set screw or shaft flat
- Mixed thread series at one joint (UNC + UNF): catastrophic stripping; verify both sides
- Long heat treatment after rolling thread: relieves cold work; rolled threads should be rolled after heat treatment for best fatigue
- Carriage bolt in oversize hole: square neck doesn’t seat — install with washer pulling square into wood