DSS-Th.03.02 — Spontaneous Tempered Break (NiS-related; documentation)

A spontaneous tempered break is a sudden fracture of fully tempered glass with no evident external impact, commonly associated with nickel sulfide (NiS) inclusions or residual/internal stresses. Result is the characteristic fine “dice” fragmentation. Any fractured lite is an integrity condition and is out of in-place restoration scope (CAT-5 by condition/location). This DSS defines identification and documentation only; it does not prescribe repair. Inspect from a safe position under VIS lighting/geometry; record surface numbering and worked-surface status on Forms:

• Pane presents a uniform mosaic of small interlocking fragments (“dice”), often retained by gaskets/pressure plates or an interlayer (if laminated tempered).
• May show a rosette/dense crack nucleus near the suspected inclusion site; sometimes accompanied by a “ticking” sound as stresses equilibrate.
• No clear external impact nucleus (no bullseye/chip), and often no directional hot-particle peppering nearby.
• In IGUs, fragmentation occurs on one ply; the mate ply remains intact.

Safety / MSRT.

• Treat as unstable; do not perform MSRT. Secure area per site protocol before close documentation.

Visual signature

• Fine, uniform dice pattern across the pane (distinct from heat-strengthened fracture, which shows larger islands/longer ligaments).
• Absence of impact nucleus or mechanical contact evidence.
• If laminated tempered, offset dice patterns ply-to-ply with interlayer retention.

Viewing / lighting

• Document at 36 in and 72 in (12 in macros only if safe), normal incidence for overall state and oblique sweep (~60°-120°) to emphasize mosaic density and any suspected origin.
• For IGUs, use parallax/reflection to identify which ply (#1/#2 or #3/#4) has fragmented.

Location / access

• Record pane ID and surface numbering (#1-#4; laminate-internal). Note product family (tempered / laminated tempered / IGU).

• CAT-5 (default): Any fractured tempered lite → Non-Repairable / Out of In-Place Scope. Document and refer per project protocol (replacement; manufacturer/engineer review).
• Reassign only if unbroken: If re-inspection shows no fragmentation (e.g., only a crack system), classify under M.07.02 (through-thickness crack) or M.04.02 (impact star) as appropriate-still integrity (CAT-5).

CAT is governed by integrity/location; acceptance is evaluated separately under VIS-A §6.

• vs. Impact star/bullseye (M.04.02): Impact presents a central nucleus with radial/annular arms; spontaneous break lacks a clear impact origin.
• vs. Heat-strengthened fracture: Heat-strengthened glass forms larger, irregular fragments and longer crack ligaments-dice size is a key discriminator.
• vs. Patterned/etched glass: Decorative patterns lack polygonal, fractured boundaries and loose granules; raking light and gentle observation (no touch) confirm.
• IGU confusion: Ensure you’ve identified which ply has fragmented via parallax; cavity debris/fogging (A.01 family) should be recorded separately.

• Safety & stabilization. Confirm barricades/support before close approach; avoid loading the fractured lite.
• Photo set (VIS):
• Overall: 72 in and 36 in, normal incidence, full pane + framing.
• Oblique: at least one oblique sweep showing mosaic density and any suspected origin (rosette, edge zone).
• Detail (if safe): macro of representative fragmentation field; macro of suspected origin area.
• IGU/laminate: parallax/reflection shot establishing which ply is fragmented.
• Record distance/angle in-frame.
• Forms: Pane ID; product family; surface numbering; worked surface Y/N (generally N); reveal status (N/A); lighting/time; geometry checklist; photos attached.
• Optional fragment survey (off-lite only). If a removed specimen is available and safe to handle, a representative fragment size survey may be recorded for reference; do not attempt on an installed lite.
• Disposition. Record CAT-5 and notify responsible party per protocol (replacement, temporary shoring, manufacturer/engineer review). Mechanism note “suspected NiS-related spontaneous break” may be included (informative).

• Th.03.02 Spontaneous Tempered Break (NiS-related; documentation) - Pane exhibits full “dice” fragmentation on surface #___ / ply [outboard/inboard] under VIS geometry (normal + oblique). No impact nucleus observed. Integrity condition; MSRT not applicable. Classification: CAT-5 (out of in-place scope). Photo set and forms attached; area secured per site protocol; acceptance per VIS-A §6 (separate).