Zeron 100 washers are super duplex stainless steel washers (UNS S32760 / Werkstoff 1.4501) supplied in three pattern families, plain (flat) per DIN 125 / ASME B18.21.1, spring lock per DIN 127 / ASME B18.21.1, and Belleville disc springs per DIN 6796 / DIN 2093. Plain washers spread bearing load and protect the joint face from rotational scoring during nut tightening. Spring lock washers (helical split washers) provide vibration resistance through the spring-back force that bites into the bolt head and joint face. Belleville washers are conical disc springs that maintain bolt preload under thermal cycling, gasket creep, or joint relaxation, critical for pressure-temperature-cycling flange joints in process plants.
Plain washers + spring lock washers + Belleville disc springs · PREN ≥ 40 · Same heat tree as matching bolts/studs
All three patterns ship from the same heat tree as the matching Zeron 100 bolts and studs, one alloy, one MTC family, no galvanic mismatch when stainless steel + duplex + super duplex would otherwise share a flange. Sizing covers M6-M100 metric and 1/4-inch through 4-inch UNC/UNF.
| Pattern | Standard | Function | Use case |
|---|---|---|---|
| Plain (flat) washer | DIN 125 / ASME B18.21.1 | Bearing-load distributor + bolt-head rotation barrier | Default washer under any nut or bolt head; protects joint surface from scoring |
| Plain heavy washer | DIN 7349 / ASME F436 | Higher bearing-load capacity (thicker) | Slotted-hole or oversized-hole structural connections; heavy hex pattern joints |
| Spring lock (helical split) | DIN 127 / ASME B18.21.1 | Spring-back force resists nut rotation under vibration | Vibration-prone joints; mostly redundant on properly preloaded super duplex bolts |
| Belleville disc spring | DIN 6796 / DIN 2093 | Maintains preload during thermal cycling, gasket creep, joint relaxation | Pressure-temperature cycling flange joints, gasket-loaded connections |
| Belleville stack (paired) | DIN 2093 | Stack 2-6 disc springs in series for higher deflection at constant load | Long-term gasket-loaded joints in process plants |
| Tooth lock (external/internal) | DIN 6797 / DIN 6798 | Teeth bite into bearing surface for vibration resistance + electrical bonding | Specialty applications, not generally specified for super duplex due to galling risk |
DIN 125 (plain) + DIN 127 (spring lock) + DIN 6796 (Belleville disc spring, high-load) + DIN 2093 (Belleville general) + ASME F436 (heavy plain washer) + ASME B18.21.1 (lock washer general) + ASTM A1082 (super duplex material spec) + NACE MR0175 (sour-service hardness) + NORSOK M-650 + M-630 MDS 055.
All three patterns: M3 to M64 metric, #4 to 1-1/2 inch UNC/UNF, with stock inventory at the high-volume sizes (M16, M20, M24, M30, M36 metric; 1/2", 5/8", 3/4", 7/8", 1", 1-1/4" UNC). Custom Belleville disc-spring sizes per buyer load deflection curve available cut-from-bar within 14 days.
| Joint type | Recommended washer |
|---|---|
| Standard ANSI Class 150-300 flange bolting | Plain (DIN 125) on the nut side; no washer under bolt head |
| ANSI Class 600+ high-pressure flange bolting | Plain heavy (DIN 7349 / F436) both sides |
| Pressure-temperature cycling joints (steam, hot oil) | Belleville disc spring (DIN 6796) under nut for preload retention |
| Gasket-loaded process flange (PTFE / spiral-wound) | Belleville disc spring stack for creep compensation |
| Vibration-prone equipment fasteners (rotating machinery) | Plain + locking nut, or spring lock if locking nut not used |
| Subsea / FLT-temperature joints | Match washer to fastener supply state, FLT washers from cold-Charpy heat lots |
| Repeated-makeup bolted joints | Plain (replace on each disassembly cycle if scored) |
Send the spec (pattern + bolt size + supply state + standards / MDS + quantity + destination port) to info@torqbolt.com or +91-22-66157017 / WhatsApp.
