Zeron 100 countersunk screws (CSK) are super duplex stainless steel flat-head fasteners (UNS S32760 / Werkstoff 1.4501) with a countersunk taper-profile head, either 82° (American series, ASME B18.6.3) or 90° (metric series, DIN 7991 / ISO 10642). The taper head seats into a matching machined countersink so the finished installation is flush with the joint surface, the standard call for any installation where a protruding bolt head would be a snag hazard, hydrodynamic drag source, or aesthetic problem.
82° or 90° flat-head countersunk · Internal hex drive · PREN ≥ 40 · Hardness ≤ 28 HRC
Used on machined equipment housings (subsea instrument-pod faces, ROV manipulator covers), recessed-mount panels (FPSO deck access plates, FGD inspection-port covers), structural skin panels, marine vessel hull-mount equipment, and any flush-finish installation in chloride-bearing service. Internal hex socket drive (Allen key) is the standard pattern; Phillips and slotted available on request for non-critical applications.
ASME B18.6.3 (inch flat countersunk machine screws, 82° head) + DIN 7991 / ISO 10642 (metric hexagon socket countersunk head, 90°) + ASTM A1082 (super duplex material) + ASTM A479 (source bar) + ASME B1.1 / ISO 965 (thread tolerance class 2A / 6g) + NACE MR0175 (sour service ≤ 28 HRC).
M2 to M20 metric / #4 to 3/4" UNC. Stock at common machine-screw sizes (M5, M6, M8, M10, M12). Custom lengths machined from solution-annealed bar within 5-7 working days. Internal hex drive sized per ISO 4762 for matching Allen-key tooling.
| Service | Recommended supply state |
|---|---|
| Subsea instrument-pod cover screws (flush mount) | FLT (cold-water Charpy) |
| FPSO deck access plate fasteners | SA |
| FGD scrubber inspection-port cover screws | SA + AFP coating (repeated disassembly) |
| Marine vessel hull-mount equipment | SA |
| Snag-hazard avoidance (flush-finish required) | SA |
| Hydraulic-block end-cap screws (counterbored) | FG |
Send the spec (head angle 82° or 90° + size + length + drive type + supply state + standards + quantity) to info@torqbolt.com or +91-22-66157017 / WhatsApp.
