Rock wool sandwich panels with a 120 kg/m³ core density, 50/75/100 mm thickness options, and 0.4–0.7 mm PPGI facings are the mainstream spec for industrial envelopes, with B2-classified cores rated to withstand over 1000°C without fibre melting [S1]. Procurement should anchor on three numeric gates: density ≥100 kg/m³ for structural spans, core thickness matching U-value targets, and a verified fire classification tied to the project hazard zone.
For readers comparing the rock wool family against other insulation cores (PIR, PU, EPS, glass wool), the binding-agent behaviour above 250°C and the fibre integrity above 1000°C are the differentiators that justify a roughly 20–30% price premium over PU/PIR in fire-rated assemblies [S1][S7].
Core Density, Thickness, and Facing Steel: The Three Numeric Gates
A 120 kg/m³ core with 50/75/100 mm thickness and 0.4–0.7 mm PPGI skins is the off-the-shelf spec carried by Chinese mill-direct suppliers, with shipping length capped under 11.8 m for road transport [S1]. Panel length is normally a customer's choice for cold-room variants reaching 150/200 mm thickness on the same 0.4–0.7 mm steel gauge [S1].
ROCKWOOL-branded stone-wool insulation is offered in separate floor, internal-wall, and external-wall product lines, each with its own declared thermal and acoustic performance band, sourced from [ROCKWOOL China](http://en.rockwool.com.cn/) [S5]. The point: a single brand may run 6+ product variants, so specifying only "rock wool" without naming the product line typically lands the wrong datasheet on the RFQ.
Fire Behaviour: What the Numbers Actually Mean On-Site
Rock wool fibres stay intact above 1000°C; the organic binder evaporates at temperatures exceeding 250°C, and the fibre layering alone retains panel rigidity to protect substrates below [S1]. This is why Chinese B2-classified rock-wool cores are accepted for many commercial envelopes while still being outranked by A1/A2 non-combustible grades on industrial or high-rise façades.
Standard fire-classification references for building insulation include EN 13501-1 (Euroclass A1–F) and GB 8624-2012 (China A1/B1/B2/B3); the B2 designation on the cited product line corresponds to the "combustible but not easily ignited" tier in the Chinese system [S1]. Where the building code mandates non-combustible (A1) insulation, B2 rock wool is non-compliant and the spec must be escalated.
Production Capacity and Lead Time Signals (2025–2026)
Hebei Guangxing Machinery Technology (GXTECH), founded 1987, runs two Hebei manufacturing bases totalling 88,000 m² with 300+ staff and CE / ISO 9001 certification, and lists 2025 deliveries including a 40,000 T/Y 2.4 m electric-furnace rock-wool line for Gansu, a 60,000 T/Y 1.2 m × 2 furnace line for Shandong, and a 1,300,000 m²/Y continuous PU/PIR sandwich-panel line for Shanxi [S3]. A 12 m 2+2 discontinuous PU/PIR line was commissioned in Paraguay, and a Russia-bound 2.4 m furnace 40,000 T/Y line is also on the project list [S3].
FinMach, a competing turnkey supplier, claims eight tailored continuous-sandwich-panel / rock-wool line deliveries in three years, signalling that mid-tier capacity additions are still being booked in 2026 [S6]. For a buyer's spec sheet, this is a useful 2026 supply-side fact: rock-wool-core panel capacity is expanding ahead of pure-PU/PIR, which improves rock-wool lead times for fire-rated projects.
Where Rock Wool Sandwich Panels Win — and Where They Lose
Rock wool sandwich panels are the right pick when fire rating, acoustic damping (STC 35–45 typical for 100 mm cores), and temperature stability dominate the spec — typically steel-structured warehouses, industrial plants, generator rooms, and external warehouse walls. PU/PIR wins on thermal conductivity per mm (λ ≈ 0.022 W/m·K vs rock wool ≈ 0.040 W/m·K), so for the same U-value a rock-wool panel is roughly 1.8× thicker and heavier; cold-storage designers must spec 150–200 mm cores to match PU's 100 mm U-value. [S1]
Rock wool is the wrong pick for: (a) cleanroom and pharmaceutical partitions where fibre shedding fouls HEPA filters — specify HMI panel-style coated or PU-faced cleanroom panels instead; (b) budget-driven commercial sheds where B1 PIR passes the fire spec at lower cost; (c) high-humidity exposure without a verified waterproof facing, where the cited "Waterproof Rock Wool Board" from Langfang Fuerda requires explicit verification that the facing is a closed-cell moisture barrier, not just a facer scrim [S2].
Decision Matrix: Rock Wool vs PU/PIR vs EPS for Envelope Panels
For a buyer: pick PU/PIR where wall thickness is constrained (cold rooms, high-rises), pick rock wool where fire rating and acoustic are the project drivers, and pick EPS only for budget commercial sheds with no fire-rating requirement. The cited Okorder.com sourcing channel lists rock-wool panel, blanket, and "real stone wool" as grouped products shipped from Tianjin, which is useful when consolidating LCL freight for fire-rated projects [S4].
Specification Checklist Before Issuing the RFQ
Lock down six items before sending the inquiry: core density (≥100 kg/m³ for structural spans, ≥120 kg/m³ for roofs), core thickness (50/75/100 mm standard, 150/200 mm for cold storage), facing steel (0.4–0.7 mm PPGI or Galvalume), fire classification certificate (B2 minimum, A1/A2 for high-rise), length under 11.8 m for road freight, and quality system certificates (CE + ISO 9001 + ISO 14001 as baseline) [S1][S3]. Langfang Fuerda's product line shows that factory location, R&D capability, and product range (rock wool board + pipe + felt) are useful proxies for vertical integration and consistent supply [S2].
Track two signals through 2026: GXTECH's next announced 40,000+ T/Y rock-wool line commissioning, and any new China GB 8624 revision that reclassifies B2 cores — both will shift project acceptance lists for fire-rated envelopes. For adjacent spec work on explosion-proof lighting in the same plant envelope, the explosion-proof lighting buying guide is a useful cross-reference when the rock-wool wall meets a hazardous-area boundary.
Spec-level background on the components involved: linear guide.