Solvay SM5142 sealant tape is deployed as an edge seal in vacuum-bag consolidation, not as a compounding ingredient. The application ratios specified below are linear consumption ratios based on mold periphery and local pleat or overlap factors; they are not addition percentages in a resin formula.

For autoclave cure cycles above 120 °C, bag-side vacuum integrity becomes the controlling process variable

In autoclave-cured carbon fibre/epoxy prepreg programmes, SM5142 sealant tape is applied directly to the machined flange of an Invar, nickel-electroformed steel, or monolithic graphite tool before the uncured prepreg stack is placed. The tape is unrolled with the release liner retained until the outer 100 mm of the bag film is ready to be pressed, then the liner is removed in 300 mm increments to prevent pre-tack contamination from airborne release agents. End laps are set at 25–35 mm, and each vacuum port base is sealed with a 50 mm strip centred under the port flange. On production wing-skin tools with 8.4 m periphery, the tape is laid as one continuous loop, but the vacuum bag is pleated at 100–150 mm intervals around concave radii; failure to pleat produces film bridging that can tear the seal lip when autoclave pressure exceeds 0.60 MPa. The tape is hand-rolled with a 25 mm-wide PTFE roller at a pressure sufficient to eliminate visible air channels, because entrapped air expands during the ramp and forms a leak path at the tape-to-bag interface. Solvent wiping of the tape edge after application is avoided because ketone and acetate solvents swell the elastomer and reduce re-tack; if flange cleaning is required, solvent is applied before tape placement and fully flashed off. Material acceptance is controlled under AS9100D clause 8.4.3, with the procurement specification typically requiring a certificate of conformance and, for parts that will see cabin interior exposure, outgassing data per ASTM E595 with total mass loss ≤1.0% and collected volatile condensable material ≤0.1%. The linear application ratio is 1.08–1.15 × tool periphery to cover end laps, corner pleats, and waste from port cut-outs; the example 8.4 m tool flange therefore consumes 9.1–9.7 m per cure cycle. Autoclave debulk is first performed at 0.085–0.095 MPa vacuum and 45–60 °C for 30–45 min, then the closed bag is evacuated to ≤10 kPa absolute and isolated; a production leak criterion of ≤1.0 kPa rise over 5 min is common before the load is transferred. Cure is executed at 1.5–2.0 °C/min to 177 °C, held for 120–180 min, and cooled at ≤2.0 °C/min to 60 °C before venting. The tape is not intended for direct resin contact; resin bleeding to the flange must be removed before bag closure. Terminal laminates produced in this segment include carbon/epoxy wing skins, spar caps, control surface skins, and nacelle inlet panels.

What Limits Bag Film Contact Upon Liquid Resin Infusion?

In liquid resin infusion of wind blade shells, SM5142 sealant tape is not exposed to autoclave pressure but to sustained vacuum of less than 20 mbar absolute for 6–12 h while low-viscosity epoxy or unsaturated polyester flows between the mold flange and the bag surface. The tape is laid continuously on a release-treated steel or composite mold flange that may exceed 75 m for a 60 m half-shell. Double parallel strips are used on the root transition, where the bag film changes direction over a concave radius and creates peel forces at the outer tape edge. The bag film is laid over the tape, pleated at 200–300 mm intervals, and sealed to the tape edge with a hand roller. Vacuum is drawn to 0.085–0.095 MPa and held for 15 min before leak check; the target leak-up rate is ≤5 mbar/min from a starting pressure ≤20 mbar absolute. The fabrication line operates under DNV GL ST-0376 and IEC 61400-5, with the tape controlled as a process consumable in the laminate work instruction rather than as a final part constituent. Linear consumption is 1.20–1.35 × mold flange length; the additional 20–35% is consumed in pleats, double strips at insert locators, and bag repositioning after initial vacuum. Infusion is performed with a low-viscosity epoxy system at 20–25 °C mold temperature, using 0.2–0.5 L/min per resin inlet; after infusion, the mold is ramped to 60–70 °C for 8–12 h. The tape remains under vacuum for 10–18 h. Operator records show local leaks most frequently appear where the bag film is tensioned over a concave root transition and the tape is less than 2 mm thick; the corrective action is to add a second strip and reverse the overlap direction to match the vacuum draw. The sealant is not formulated for direct contact with styrene-rich polyester resin; if resin bleeds onto the flange, it must be wiped before tape application because solvent-laden resin film reduces tack. Terminal products are glass/epoxy or carbon/epoxy hybrid blade shells, spar caps, shear webs, and root rings for blades of 45–90 m.

On marine hull lamination programmes, SM5142 sealant tape is applied over polished steel or FRP mold flanges at ambient shop temperatures of 10–32 °C and relative humidity up to 85%. The tape is used as the vacuum edge seal for bagged glass-reinforced polyester or vinyl ester hull laminates, where the bag is often repositioned once after the first debulk and before the final leak check. Linear application is 1.10–1.20 × mold perimeter, with 25 mm end laps and a single pleat on convex radii. Vacuum consolidation is performed at 0.085–0.095 MPa, and the bag is accepted only if pressure rise is ≤1.0 kPa over 3 min after pump isolation. The lay-up includes a sacrificial flow mesh, perforated release film, and peel ply over the laminate; the tape is never placed in contact with the resin flow front. Structural certification follows ISO 12215-5:2019 for scantlings, with classification society verification under ABS Rules for Building and Classing Reinforced Plastic Vessels. Post-cure at 40–60 °C for 12–24 h is applied to the bagged laminate after resin gelation, and the tape is removed before sanding or gelcoat application because residual adhesive transfer can reduce gelcoat adhesion on the flange. Terminal parts include transoms, deck sandwich panels, structural bulkheads, and stringer caps.

When a 150 °C oven cure cycle replaces autoclave pressure

When a 150 °C oven cure cycle replaces autoclave pressure, the vacuum bag edge must withstand prolonged negative pressure in a circulating-air oven while the tool flange heats unevenly. In out-of-autoclave CFRP production for vehicle body panels, SM5142 sealant tape is applied to the flange of a matched aluminium or mild steel tool; the tool is heated at 1.0–1.5 °C/min to a 120–150 °C plateau and held for 60–120 min, with oven air temperature uniformity maintained within ±5 °C. Because no external pressure holds the bag film against the tape, the seal relies on the room-temperature tack and the vacuum differential. Application consumption is 1.05–1.10 × tool periphery, with 150–200 mm pleat spacing at concave corners and 20–30 mm end laps. The production acceptance standard is drawn from IATF 16949 clause 8.5.1 and the OEM control plan; for interior-adjacent structural parts, VOC and fogging testing is carried out according to VDA 278, and the tape must not release condensable volatile material that could contaminate a Class A surface. After bag closure, the part is debulked at 0.085–0.095 MPa for 20–30 min, then ramped to cure; vacuum is held until the tool cools below 60 °C. The tape is not specified for direct hot debulking above its rated continuous service temperature; if the oven plateau is increased beyond the supplier datasheet rating, a higher-temperature sealant grade must be substituted. Terminal products in this segment include CFRP roof bows, B-pillar outer reinforcements, floor tunnel braces, and rear diffuser inner panels.

Where filament-wound FRP tanks and ducts are consolidated by temporary vacuum bagging after wet lay-up, SM5142 serves as the edge seal between the cylindrical mold end dams and the bag sheet. The tape is cut to perimeter × 1.05–1.15 per closure, with double strips at nozzle cut-outs and flanged end closures; contact time is 2–6 h, and the bag is removed immediately after the laminate reaches trim hardness. Fabrication follows ASME RTP-1 for reinforced thermoset plastic vessels, ASTM D3299 for filament-wound tank construction, and ISO 14692 for oil and gas piping. Vacuum is drawn to 0.085–0.095 MPa, and the bag is accepted when leakage does not exceed 1.0 kPa rise over 3 min; the wet lay-up is then post-cured at 40–60 °C for 8–12 h without the bag. Because the tape is used on flanges that may later receive a conductive liner or internal surface veil, any adhesive residue is solvent-removed and wiped dry before the next laminate ply is applied. Terminal parts include chemical storage tanks, scrubber shells, FRP piping spools, and duct sections.