Nitrile
General-purpose oil and fuel resistance for moderate-duty sealing applications.
FS-Seal
Moss Seal supplies FS-seals as the solution where a standard S-seal cannot cope with the clearance. Developed for casing and tubing hanger service, the FS-seal uses a larger elastomer cross-section with molded-in anti-extrusion springs to seal against casing that may be out-of-round, dimensionally inconsistent, or roughly finished. It is a one-piece, double-acting static seal, so it installs in a single step and holds pressure from either direction. We match compound, spring alloy, and size to your casing diameter, pressure rating, and well environment.
ENGINEERING
Cross-section design & operation
Open-coil springs are molded into the low-pressure corners of an elastomer body, so the seal carries its own extrusion protection and needs no separate back-up rings.
Cross-section design
The sealing element is thicker than an S-seal to increase contact force on the casing. A recess molded into the seal back lets the body flex inward when it meets a larger or out-of-round section, controlling radial compression instead of over-stressing the rubber.
How it works
On landing, the seal compresses against the casing and hanger bore to form the initial seal. The open-coil springs, molded with no initial tension so rubber bonds through the coils, sit at each heel and close the extrusion gap as pressure loads the elastomer.
Pressure response
Pressure from either side energizes the seal, and the springs flex to follow pressure fluctuations and small movements in the metalwork. Because the springs are larger in diameter than on a standard S-seal, they close clearances that would otherwise allow extrusion in a wellhead.
SELECTION
Materials & advantages
Performance advantages
Double-acting · Seals out-of-round casing · Tolerates rough casing finish · One-piece installation · Molded-in extrusion protection · Handles pressure cycling
