Solvay RS 200 Sealant tape is an unsintered polytetrafluoroethylene (PTFE) thread sealing tape supplied on a spool for sealing tapered metallic and selected polymer pipe threads. The tape seals by cold flow of PTFE into the thread root and flank clearances under assembly torque, not by adhesion or chemical curing. It is manufactured from virgin PTFE resin and contains no solvent, silicone, filler, or curing agent. The product is non-adhesive, white, and is intended for use where chemical inertness and immediate pressure testing are required. Published nominal dimensional data for the grade include a thickness of 0.075 mm, a width of 12.5 mm, and a spool length of 15 m. The unsintered film density is 1.30–1.45 g/cm³, which is below the sintered PTFE density of 2.15 g/cm³. Tensile strength and elongation at break are controlled under DIN EN 751-3:1997 annex test methods; typical specified minimum tensile strength is 10 N/mm² with elongation at break not less than 50% at 23 °C.

Because the tape is unsintered, it undergoes fibrillation during wrapping. This orientation is deliberate and contributes to conformability over thread flanks. Production of unsintered PTFE tape involves paste extrusion of PTFE fine powder with a volatile lubricant, calendering to target thickness, and thermal removal of the lubricant below the sintering temperature. Incomplete lubricant removal is a documented process variable that can affect oxygen compatibility and lot-to-lot surface cleanliness; therefore oxygen service requires precision-cleaned lots verified under CGA G-4.1 or the end-user’s oxygen cleaning specification. The material is not hygroscopic and does not require pre-drying even at relative humidity above 60%, but condensation must be prevented during application in hot, humid environments. Storage is recommended at 5–30 °C with protection from mechanical damage and contamination.

In chemical service, PTFE resists aqueous acids, alkalis, solvents, fuels, refrigerants, and hydraulic fluids within the normal limits of PTFE. The tape is not suitable for service with elemental fluorine, chlorine trifluoride, oxygen difluoride, or molten alkali metals, which react with PTFE. The upper continuous service temperature in air is commonly cited as 260 °C, but mechanical seal load retention in a threaded joint may degrade at lower temperatures due to creep. In pressure-cycling liquid service, a conservative continuous limit of 120–150 °C is often applied unless the assembly is qualified at higher temperature. The lower service temperature is commonly cited as −200 °C, but cryogenic use requires torque validation because differential thermal contraction between fitting alloys can loosen the joint. Above 400 °C, PTFE decomposes and releases toxic gaseous products, so heating or welding adjacent to installed tape must be controlled. For gas service under DIN EN 751-3:1997, the product is evaluated for first, second, and third family gases and hot water within the standard’s defined pressure and temperature limits; published data for this specific grade beyond that gas standard is limited.

What distinguishes full-density unsintered PTFE tape from expanded microporous PTFE joint sealant?

Solvay RS 200 Sealant tape is sometimes confused with expanded microporous PTFE joint sealant tapes, but the two product classes occupy different sealing regimes. Expanded microporous PTFE is biaxially expanded to a density of 0.40–0.80 g/cm³ and contains a continuous fibril-node microstructure. It seals by bulk compressive recovery across a flange face or a wide gap. RS 200 is a full-density film with negligible open porosity and seals by cold flow into the thread root. The practical distinction is that RS 200 is not intended for flat-face flange gaskets; conversely, expanded microporous PTFE is not suitable for tapered thread sealing where thin-film penetration into thread flanks is required.

Thread engagement, wrap count, and torque decay on NPTF assemblies

Installation practice for RS 200 is governed by thread form, wrap count, and assembly torque. On tapered NPT or NPTF threads of 1/4 in through 1 in, fitting manufacturers’ application guides commonly specify 3–5 full wraps under moderate tension, applied in the direction of thread advancement so the leading edge is not peeled back during assembly. The first thread should be left uncovered to reduce tape shredding and to allow correct engagement. Because PTFE has a very low coefficient of friction, typically 0.04–0.10, the torque required to achieve a given preload is lower than with unlubricated metal-to-metal assembly. Torque tables for tape-sealed joints should be reduced by 25–40% from dry values or derived from joint qualification tests with strain-gauged studs. Over-tightening with unmodified dry torque values can exceed the fitting material yield strength, particularly on brass and stainless steel components.

PTFE is viscoelastic and exhibits cold flow under sustained compressive load. After thermal cycling or vibration, a taped joint may lose some initial preload due to tape creep and fitting relaxation. Critical joints should be retorqued according to a written procedure or validated by pressure-decay testing. The tape is not intended for use on straight threads, flared fittings, compression fittings, or flat-face flanges. In instrumentation systems, loose tape particles generated during assembly can obstruct small orifices, solenoid valves, and filter elements; filtration of 25 μm or finer downstream of taped threads is a typical control measure.

On automated wrapping lines, the unsintered film is tensioned against the thread. If wrapping tension exceeds the film yield point, the tape can neck or shred; published data for automated wrapping variability for this specific grade is limited, but thickness variation outside ±0.005 mm can alter wrap count by one full wrap. Therefore automatic dispensers should be validated for the actual spool lot with a standardized thread gauge and a calibrated torque wrench. Joints larger than 2 in may require full-width coverage of the thread root; published data for this specific grade in large-diameter threaded joints is limited.

When solvent-borne pipe dopes promote stress cracking in thermoplastic fittings

Solvent-borne pipe dopes and pastes can contain ketones, esters, aromatic hydrocarbons, or alcohol carriers that swell and stress-crack ABS, PVC, CPVC, and polycarbonate fittings. RS 200 contains no solvent and does not introduce solvent-chemical attack into polymer thread roots. It is therefore specified for mixed-metal and thermoplastic-to-metal assemblies where solvent contact with a polymer thread root is unacceptable. The tape is not a substitute for a proper thread sealant in all polymer fittings: high-tension wrapping on thin-walled PVC threads can generate hoop stress and split the female collar. A maximum of 2–3 wraps of 0.075 mm tape and hand-tight plus 1/4 to 1/2 turn assembly practice should be followed for polymer threads unless the fitting manufacturer specifies otherwise. Published data for this specific grade in PVC threaded assemblies is limited; qualification on the actual fitting batch is required.

Compared with anaerobic acrylic sealants, RS 200 requires no metal activator and can be used on passive or polymeric surfaces. Compared with solvent-borne pastes, it has no cure time, no volatile emissions, and no solvent-related shrinkage. Compared with high-density skived PTFE tape, the unsintered film remains sufficiently soft and thin to conform to thread flanks without excessive springback. However, the product’s gap-filling capacity is limited to the thread clearances of mating parts; large gaps, rough flange surfaces, or damaged threads require expanded PTFE gasketing, filled pastes, or repair of the fitting. The tape is electrically non-conductive and cannot be used where electrical continuity across a threaded joint is required for static dissipation or grounding.