Boeing BMS 8-346 Waterseal Tape Guide
Boeing BMS 8-346 Waterseal Tape — Class 1 & Class 3
Two Patco polyurethane tapes cover this specification. Match the Class on your drawing below, check the specs, and request a quote.
Boeing Material Specification BMS 8-346 covers flame-retardant, pressure-sensitive waterseal and moisture barrier tapes for aircraft interiors. Class 1 and Class 3 are different constructions, not two grades of the same tape — and they do not substitute for one another.
New to Boeing specs? BMS 8-346 is a material specification: it defines what the waterseal tape is, not how it is installed. See our BMS vs BAC guide → for how Boeing material and process specs differ when you order.
Patco D9100 / D9100SW
Best for: sealing floor-panel joints in galleys, lavatories and entryways — trafficked areas, and it goes straight over wet sealant.
Tough aromatic PU film, urethane adhesive. Widths ¼" to 48". Also in self-wound D9100SW.
Verify: Patco D9100 data sheet (PDF) · Boeing BMS 8-346 Type I & II, Class 1
Patco 9425FR SealDry
Best for: moisture barrier and corrosion protection over large areas — seat tracks, cargo linings — where installed weight matters.
Lightweight PU film, hydrophobic acrylic adhesive.
Verify: Patco 9425FR data sheet (PDF) · Boeing BMS 8-346 Rev. E, Type I, Class 3
Class 1 and Class 3 are not interchangeable in either direction. The Class 1 product is tougher and rated to a far wider temperature range; the Class 3 product is lighter and thinner. Match the Class on your controlling drawing exactly — if it is unclear, send us the callout and we will confirm.
Find your class
Match the callout on your drawing to the product. The Airbus and Bombardier equivalents are listed too, since the same two tapes cover them.
| If your drawing calls out… | You need |
|---|---|
| BMS 8-346 Ty I, Cl.1 | Patco D9100 (or D9100SW, linerless) |
| BMS 8-346 Ty II, Cl.1 | Patco D9100 (or D9100SW, linerless) |
| BMS 8-346 Ty I, Cl.3 (Rev. E) | Patco 9425FR SealDry |
| Airbus A2MS 535-007 Rev. A, Ty VI | Patco 9425FR SealDry |
| Bombardier BAMS 535-007 Rev. B, Ty VI | Patco 9425FR SealDry |
| Airbus ABD0031 §7.3.2 / §7.4 · AIMS 10-05-004A · Fokker FK05-193 | Patco D9100 |
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At a glance
Full specifications
| Specification | D9100 / D9100SW | 9425FR SealDry |
|---|---|---|
| BMS 8-346 | Type I & II, Class 1 | Type I, Class 3 (Rev. E) |
| Backing | Interior-grade aromatic polyurethane | Polyurethane film, self-extinguishing |
| Adhesive | Urethane-based | Hydrophobic acrylic |
| Liner | 94# coated kraft paper (D9100SW is linerless) | Blue HDPE film, die-cuttable |
| Color | Transparent | Clear |
| Total thickness | 9.0 mil (0.229 mm) — PSTC-133 | 6.0 mil (0.152 mm) |
| Substrate thickness | 7.0 mil (0.178 mm) — PSTC-133 | — |
| Weight | 8.6 oz/yd² (291.59 g/m²) | 5.0 oz/yd² (169.53 g/m²) |
| Tensile strength | 70 lb/in (122.59 N/cm) — ASTM D-3759 | 34 lb/in (59.54 N/cm) |
| Adhesion to steel | 40 oz/in (4.38 N/cm) — ASTM D-3330 | 28 oz/in (3.06 N/cm) |
| Elongation | 600% | 550% |
| Puncture resistance | 25 lbs (11.34 kg) — ASTM D-1000 | — |
| Abrasion / wear index | 0.98 — ASTM D-4060 | — |
| Application temperature | 50 to 120°F (10 to 49°C) | — |
| Operating temperature | −65 to 300°F (−54 to 148°C) | −10 to 250°F (−23 to 121°C) |
| Flammability | FAR 25.853(a) | FAR 25.853(a) — 4.56" avg burn length |
| Other approvals | Airbus ABD0031 §7.3.2 & §7.4; AIMS 10-05-004A (ABS 5093); Fokker FK05-193; NSN 8030-01-542-1415 | Airbus A2MS 535-007 Rev. A Ty VI; Bombardier BAMS 535-007 Rev. B Ty VI |
| Size options | Incremental widths ¼" to 48" × 108 ft (36 yd) | 2", 3", 24" and 48" × 36 yd |
| Storage conditions | 60–80°F, 40–60% RH | 40–80°F, original dry carton, off the floor |
| Shelf life | 24 months from D.O.M. (at 25°C) | 24 months from D.O.M. |
Typical values are stated at time of manufacture and are not for use in writing specifications. Always verify against the controlling drawing and the current manufacturer data sheet.
Get pricing, lead time and a Certificate of Conformance
Send us these five things and we will come back with the correct product, stocked widths, lead time and pricing — plus a Certificate of Conformance on request.
- Spec callout (Type & Class)
- Width
- Quantity
- Aircraft or application
- Required delivery date
Applications
| Floor-joint sealing | D9100 — sealing floor-panel joints on aircraft decking in wet areas: galleys, lavatories and entryways |
| Over wet sealant | D9100 — applies directly over wet sealant; repositionable during application |
| High-wear protection | D9100 — surface protection for high-traffic areas; tough, abrasion-resistant film |
| Sound damping | D9100 — secondary sound-damping in floor and panel applications |
| Corrosion protection | 9425FR — corrosion protection on interior structure, including seat track protection |
| Cargo area protection | 9425FR — cargo area and cargo lining moisture protection; abrasion guard on panels |
| Weight-critical areas | 9425FR — at 5.0 oz/yd² it saves meaningful weight across a large installed area |
| Moisture barrier | Both — preventing moisture ingress to the floor structure, helping inhibit corrosion |
| Visual inspection | Both — transparent film lets the sealed joint be inspected without removing the tape |
Sealing a galley or lavatory but don't see BMS 8-346 on the drawing? Some wet-area callouts specify a galley wet-seal tape rather than a Boeing waterseal spec. Our Patco 1800 galley tape is a flame-retardant PVC wet-seal tape for those applications (Fokker FK05-159/160, FAR 25.853(a)). It is not a BMS 8-346 product — confirm your drawing's callout before choosing.
What the Type and Class codes mean
A BMS 8-346 callout is written by Type and Class. Here is what each part refers to:
The pressure-sensitive polyurethane film tape form — a tough PU film carrier for moisture sealing in aircraft interiors. Both Patco products are qualified to Type I.
A related construction within the same specification. The D9100 is qualified to both Type I and Type II, so one product satisfies either at Class 1.
The standard waterseal class, met by the D9100 — the heavier-duty of the two constructions, and what most floor-joint callouts reference.
A separate class met by the 9425FR SealDry — a lighter, thinner PU film with an acrylic adhesive. A different construction, not a higher grade of the same one.
When the drawing allows either. Specify D9100 where the joint takes foot traffic, sees wide temperature swings, or the tape goes over wet sealant. Specify 9425FR where installed weight matters across a large area, or the requirement is moisture barrier and corrosion protection rather than a trafficked floor-joint seal. When the drawing names a Class, the drawing wins.
Data sheets and certification
Patco D9100 / D9100SW
- Technical data sheet (PDF)Patco / Berry Global
- Boeing BMS 8-346 Type I & II, Class 1
- Airbus ABD0031 §7.3.2 & §7.4 · AIMS 10-05-004A (ABS 5093)
- Fokker FK05-193 · FAR 25.853(a)
- NSN 8030-01-542-1415
- Incremental widths ¼" to 48" × 108 ft
- Certificate of Conformance available on request
Patco 9425FR SealDry
- Technical data sheet (PDF)Patco / Berry Global
- Boeing BMS 8-346 Rev. E, Type I, Class 3
- Airbus A2MS 535-007 Rev. A, Type VI
- Bombardier / de Havilland BAMS 535-007 Rev. B, Type VI
- FAR 25.853(a) App. F Pt. I(a)(1)(ii) — 4.56" avg burn, 0 s flame, 0 s drip
- Lot-specific Certification of Compliance available on request
See how BMS 8-346 sits among the other authorities on our Specifications by Authority page, browse every sheet in the Technical Data Sheets library, or read our FAR 25.853 guide — both tapes meet it.
Frequently asked questions
What is Boeing BMS 8-346?
BMS 8-346 is a Boeing Material Specification for flame-retardant, pressure-sensitive aircraft waterseal and moisture barrier tapes used to seal floor joints in wet cabin areas such as galleys, lavatories, and entryways. The tapes act as a moisture barrier that helps protect the floor structure from corrosion, and must also meet FAR 25.853(a) flammability requirements.
Which tape meets BMS 8-346 Type I & II, Class 1?
The Patco D9100 (and the self-wound D9100SW variant) is the qualified product for BMS 8-346 Type I & II, Class 1. It is a clear polyurethane film tape with a urethane adhesive, also approved to Airbus ABD0031, AIMS 10-05-004A, Fokker FK05-193, and FAR 25.853(a).
Which tape meets BMS 8-346 Class 3?
The Patco 9425FR SealDry is qualified to BMS 8-346 Revision E, Type I, Class 3. It is a 6.0 mil lightweight polyurethane film with a hydrophobic acrylic adhesive, also approved to Airbus A2MS 535-007 Rev. A Type VI, Bombardier/de Havilland BAMS 535-007 Rev. B Type VI, and FAR 25.853(a).
What is the difference between BMS 8-346 Class 1 and Class 3?
They are different constructions, not two grades of the same tape. Class 1 is met by the D9100 — a 9.0 mil polyurethane film with a urethane adhesive, 70 lb/in tensile, rated −65 to 300°F, and the heavier-duty choice for trafficked floor joints. Class 3 is met by the 9425FR — a 6.0 mil lightweight polyurethane film with an acrylic adhesive, 34 lb/in tensile, rated −10 to 250°F, built for weight savings and corrosion protection. Neither substitutes for the other; match the Class on your drawing.
What is the difference between Patco D9100 and D9100SW?
They are the same polyurethane waterseal tape. The standard D9100 is supplied with a kraft paper release liner; the D9100SW is self-wound (linerless) for faster, waste-free application. Both are qualified to BMS 8-346 Type I & II, Class 1.
Can BMS 8-346 tape be applied over wet sealant?
Yes, in the case of the Patco D9100, which is designed to be applied directly over wet sealant and is repositionable during application. That is part of why it is used for floor-joint sealing in galleys and lavatories. Always follow the applicable maintenance procedure for your aircraft.
Does BMS 8-346 waterseal tape meet FAA flammability requirements?
Yes. Both the Patco D9100 and the 9425FR meet FAR 25.853(a), the FAA interior flammability vertical-burn criteria, in addition to their Boeing BMS 8-346 qualifications. The 9425FR is certified at a 4.56" average burn length against an 8.0" limit, with zero flame time and zero drip. Always confirm current values against the manufacturer data sheet for your specific application.
Not sure which Class your drawing needs?
Send us the callout, width, quantity, aircraft or application, and required delivery date. We'll confirm the right Patco product, stocked sizes, lead time and pricing. Certificate of Conformance available on request.
Ask Our Team →Specification details are provided for reference and are drawn from the current Patco D9100 / D9100SW and 9425FR technical data sheets and certificates of compliance. BMS 8-346 is a Boeing Material Specification; Boeing and BMS are trademarks of The Boeing Company. Airbus, ABD, ABS, AIMS, and A2MS are trademarks of Airbus; BAMS is a trademark of Bombardier; Fokker is a trademark of its respective owner; Patco and SealDry are trademarks of Berry Global. Typical test values are stated at time of manufacture and are not for use in writing specifications. Always verify requirements against the controlling drawing and the current manufacturer data sheet before purchase.