Form-in-place gasketing dispenses a liquid sealant bead onto a flange and cures it into an elastomer gasket bonded to the part. With a UV-curable material the cure takes seconds, which is what makes the method viable for a production line. This guide walks through the process from surface prep to inspection.

When to Use Form-in-Place

Form-in-place gasketing pays off when you have medium-to-high volume, complex or non-planar flange paths, tight control requirements on gasket position, or a history of seam leaks with cut gaskets. It removes cut-gasket inventory and scrap, gives an exact fit to any 2D path, and delivers consistent bead volume from an automated dispenser. For very large flanges or very low volume, a cut gasket may still be simpler.

Step 1: Surface Preparation

The gasket has to adhere to the flange to stay positioned and to seal at the bead-to-flange interface.

• Clean the flange with isopropyl alcohol to remove machining oil, mold release, and handling residue.
• On low-energy plastic flanges, add plasma or corona treatment, or a compatible primer, and verify surface energy with a dyne pen.
• On metal flanges, a light abrasion improves durability for demanding service.
• Bond within the material’s stated open time after preparation.

Step 2: Bead Design

• Compression target: Size the dispensed bead so that at assembly it compresses 20 to 40 percent. Under-compression risks leaks; over-compression fatigues the gasket.
• Groove or hard stop: A retaining groove positions the bead and caps how far it compresses. On a flat flange, design a metal-to-metal hard stop so fastener torque cannot crush the gasket.
• Flange stiffness: Space fasteners closely enough that compression stays even. A flexible flange bows between bolts and opens the seal mid-span.
• Cross-section: A rounded bead compresses predictably. Avoid a tall, narrow bead that can roll or shadow its own base during cure.

Step 3: Dispensing

Use a programmable dispenser with volumetric or progressive-cavity metering for a repeatable bead. Program the path to follow the flange centerline with a controlled tie-in where the path closes on itself, so there is no thin spot or overlap lump. Keep the needle standoff and travel speed constant; changes in either alter bead width. Dispense at a stable material temperature, since viscosity drifts with temperature and changes the deposited volume.

Incure’s Uni-Seal form-in-place gasket line is 100 percent solids with no solvent, cures rapidly under low-energy LED lamps, and cures to a soft, resilient elastomer with good elastic memory, moisture and temperature resistance, and chemical resistance to oils and process fluids. For help matching a grade to your flange material and service conditions, Email Us with the enclosure drawing.

Step 4: Curing

Cure the dispensed bead under a UV source sized to the flange. A UV LED flood lamp covers a bench-scale part in one exposure; higher volume runs on a conveyor curing system. Verify the delivered dose at the bead with a radiometer against the data sheet. Expose a deep bead from more than one angle so the base cures. If the exposed bead surface stays tacky, that is oxygen inhibition; raise the surface dose or add an inert purge.

Step 5: Inspection

• Visual: Check for continuity, consistent width, a clean tie-in, and no gaps or thin sections. A fluorescing grade makes this a fast blacklight check.
• Cure confirmation: Press-test the bead for full elastomer feel, no soft or tacky spots.
• Dimensional: Spot-check bead height against the design value on a sample.
• Leak test: Assemble a sample joint and test at design pressure.

Common Defects and Fixes

• Thin or missing sections: dispenser clog, air in the material, or travel speed too high. Purge, degas, slow down.
• Bead too wide or too narrow: wrong needle standoff, wrong material temperature, or metering drift. Recalibrate.
• Gasket peels off the flange: inadequate surface prep or bonding outside the open time.
• Seal leaks despite a good bead: flange too flexible, or compression outside the 20 to 40 percent window. Revisit the joint design and account for thermal expansion mismatch between the gasket and flange materials.

Setting Up the First Run

Before committing a production lot, run a short qualification on scrap flanges. Dispense a dozen beads at the programmed settings, cure them, and section three of them to confirm bead height, adhesion to the flange, and full through-cure. Adjust needle standoff and travel speed until the sectioned bead matches the design cross-section consistently. Then bolt up three sample joints and leak test. Only once bead geometry and seal performance both repeat should the program be released. Keep the qualification samples and their measurements as the reference for future troubleshooting.

Validation

Run compression set after aging at maximum service temperature, thermal cycling with a seal check, and fluid immersion in the specific chemicals the joint contacts. The number that matters is retained seal performance after aging.

Summary

Form-in-place gasketing is a five-step process: prepare the flange, design the bead for correct compression, dispense a repeatable bead, cure to a verified dose, and inspect. Get those right and the method gives a consistent, seam-free seal at line speed. Incure supports form-in-place gasketing from material selection to line integration.

Contact Our Team to set up a form-in-place gasket process.

Visit www.incurelab.com for more information.