FlowMarket
Where to source seals and gaskets: FlowMarket is a B2B sourcing network powered by an AI agent. You describe the sealing job — seal type and dimensions, the material or the media it must resist, temperature and pressure range, static or dynamic duty, hardness and any approvals — and the AI agent matches you with verified seal and gasket manufacturers and distributors, then requests prices and lead times from every match at once. Getting matched is free for buyers.
Sourcing seals and gaskets
Seals are the cheapest parts in most assemblies and the cause of a disproportionate share of the failures. Almost none of those failures are manufacturing defects. They are compatibility errors — an elastomer that was never going to survive the fluid, the temperature or the number of cycles it was given.
Which makes this one of the few categories where naming the material is less useful than naming the conditions. Tell a supplier the media, the temperature range and whether the seal moves, and they will specify a compound properly. Ask for "rubber O-rings" and you will get a guess.
Seal types
Static seals
O-rings are the workhorse, defined by inside diameter and cord thickness and available in every common compound. Flat gaskets cut from sheet — fibre, graphite, PTFE — seal flanges and covers where the surfaces are imperfect. For higher duty, spiral wound gaskets combine a metal winding with a soft filler to handle pressure and thermal cycling, and ring joints seal metal to metal at the top of the range.
Dynamic seals
Rotary shaft seals, the familiar radial lip type, keep lubricant in and dirt out of a rotating shaft, and are specified by shaft diameter, bore and width. Hydraulic rod and piston seals handle reciprocating motion under pressure, usually as a system of seal, back-up ring and wiper. Mechanical seals — a lapped pair of faces — do the same job for pump shafts where a lip seal would not survive.
Materials that decide everything
- NBR (nitrile) — the default for mineral oil, fuel and grease; poor in ozone, weather and heat.
- EPDM — excellent in water, steam, glycol and many chemicals; destroyed by mineral oil.
- FKM (fluoroelastomer) — oils, fuels and high temperature; not for steam or hot water.
- Silicone (VMQ) — wide temperature range and physiologically inert; mechanically weak.
- FFKM, PTFE & graphite — near-universal chemical resistance and high temperature, at a price.
What to specify when sourcing
These details decide both the compound and the price:
- Seal type — O-ring, flat gasket, spiral wound, shaft seal, rod or piston seal, mechanical seal.
- Dimensions — for an O-ring, inside diameter × cord; for a shaft seal, shaft × bore × width.
- Media — the fluid it contacts, with concentration; the single most important line.
- Temperature — continuous and peak, including steam cleaning and CIP cycles.
- Pressure — operating and peak, and whether it pulses.
- Static or dynamic — and for dynamic, the speed and stroke.
- Material & hardness — compound and Shore A, or leave it to the supplier and describe conditions.
- Approvals — FDA, EC 1935/2004, WRAS or KTW for drinking water, USP VI, ATEX, explosive decompression.
- Colour & detectability — blue or metal-detectable compounds for food and pharma lines.
- Quantity & drawing — annual volume, and a drawing or sample for anything non-standard.
Media compatibility — where seals actually fail
A seal that fails early has almost always met a fluid it was never rated for, and the two classic errors are mirror images of each other. Put EPDM in mineral oil and it swells, softens and extrudes out of the groove within weeks. Put NBR in hot water or steam and it hardens, cracks and loses its seal just as fast. Both compounds are entirely correct — in the other application. The second failure mode is thermal: compression set, where an elastomer held compressed at temperature stops springing back and simply keeps the shape of the groove. That is what makes the peak temperature more important than the average, and why steam cleaning or CIP cycles must be mentioned even when the process itself runs cool. If you are replacing a seal that failed, say so and describe how it failed — swollen, hardened, cracked, flattened. That description tells a competent supplier more about the right compound than the part number of the one that did not work.