Pump & Valve Gaskets.

Why pump and valve flanges punish gaskets

Pump and valve gaskets live in a more demanding environment than almost any other static seal on a process line. A pump flange cycles pressure with every rotation of the impeller, a valve bonnet takes the full torque of the stem packing every time the valve cycles, and both are exposed to whatever fluid the plant moves: caustics, aromatic fuels, superheated steam, or slurry with abrasive solids. The gasket has to survive the fluid chemistry, hold against the line pressure, keep sealing through thermal cycling, and do all of that while fighting the bolt-load relaxation that pulls every flange looser over time.

Cannon Gasket manufactures custom die-cut and waterjet-cut gaskets for pump bodies, valve bonnets, diaphragm-actuator housings, and the dozens of flange connections that stitch a process line together. We supply chemical-process OEMs, oil & gas operators, water and wastewater contractors, and food & beverage equipment builders with material grades matched to the service, and we document the material traceability the same way on every job.

Pump and valve material short list

Pump and valve material selection almost always starts with the process fluid. Once the chemistry narrows the candidates, you filter by temperature, then by pressure class and bolt load. The short list below covers ~90% of the pump and valve flanges we see.

• Buna-N / Nitrile is the default for oil-pump housings, hydraulic pump bodies, and any flange that touches petroleum oils, fuels, or greases up to about +250°F. Low cost, wide availability, and predictable compression behavior.
• EPDM is the right spec for water-service pumps, municipal water valves, HVAC circulator pumps, and anywhere the process fluid is potable water, steam, or a water-glycol blend. Chlorine-resistant grades available for pool and water-treatment pumps.
• Viton is the standard for valves and pumps wetted by aggressive chemicals, aromatic fuels, hot oils, and any service above +300°F where an elastomer is still the right call. Standard grades run to +400°F; ETP grades extend chemical coverage to the most aggressive callouts.
• Klingersil is an aramid-reinforced compressed sheet for chemical-process valves, high-pressure pump housings, and flanges that have out- grown an elastomer. Grade-dependent temperature ceiling up to +750°F.
• Flexible graphite is the default for high-temperature steam valves, boiler- feed pumps, and fire-safe valve applications. Chemically inert, thermally stable from cryogenic to +1000°F, and compliant with most fire-safe valve standards.
• PTFE covers chemical-service valve seats and low-bolt-load plastic valve bodies where even Viton is out of its depth. Watch for cold-flow under sustained bolt load; we'll recommend a glass- or carbon-filled grade if creep is a concern.

How pump and valve gaskets fail

• Chemical attack. The elastomer swells, hardens, or softens until it can no longer hold compression. Fix: verify the compound against the actual process fluid (not a generic datasheet lookup) and send us a list of every fluid that touches the flange, including off-cycle cleaners.
• Compression set. The gasket takes a permanent deformation and stops springing back into the flange face. Fix: move to a lower-compression-set compound (FKM, peroxide-cured EPDM) or a compressed-fiber sheet that does not rely on elastic recovery.
• Bolt relaxation. Thermal cycling walks the bolt load down over weeks or months until the flange leaks. Fix: specify a gasket with lower creep-relaxation (graphite, Klingersil) or run a hot re-torque procedure at the first shutdown.
• Blowout. The gasket extrudes radially outward under pressure spike, often at a pump-start transient. Fix: reinforce with aramid or steel core for pressures above 600 psi, or move to a spiral-wound design for high-pressure pump flanges.
• Valve-bonnet leak path around the stem. The bonnet gasket is compressed unevenly because the stud pattern is not symmetric. Fix: verify torque sequence and flange flatness; for heavily asymmetric bonnets, consider a machined metallic jacket over a soft core.

Flange profiles we cut for pumps and valves

Pump and valve work spans the full range of flange geometries: raised-face ring gaskets, full-face gaskets with bolt- hole patterns cut to match cast iron or ANSI steel flanges, valve-bonnet gaskets with irregular stem-hole cutouts, and pump-housing gaskets with suction and discharge ports and bolt- pattern holes that have to line up with a machined casting. Cannon Gasket die-cuts in-house for runs that justify a steel rule die, and waterjets any geometry where the volume or the material thickness favors a tool-free process. We hold tolerances down to ±0.010" on die-cut elastomer and tighter on waterjet composite sheet.

Flange standards and certifications for pump and valve work

Pump and valve gaskets routinely have to match a named flange standard and carry certifications for the end market. The most common callouts we see on pump and valve RFQs include ASME B16.21 and B16.5 flange patterns for raised-face and flat-face gaskets, API 6A for wellhead valves, API 6D for pipeline valves, API 607 / API 6FA for fire-safe valve seating, NSF-61 for potable-water service, FDA 21 CFR 177.2600 for food-processing pumps, and USP Class VI for pharmaceutical-process valves. Cannon Gasket carries qualified material grades for each of these and ships with mill certification and traceability on request.

Not sure which standard applies? Start with our gasket material selection guide for a decision framework, or send us the flange spec and process conditions and we'll recommend a material.

Materials Cannon Gasket supplies for pump and valve service

Industries that rely on pump and valve gaskets

Pump and valve gasket specification overlaps heavily with our oil & gas and industrial process equipment work. If you're building to one of those sector specs, start with the industry page for a capability summary and a list of preferred materials.

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