Medical & Pharmaceutical Gaskets & Seals

Challenge

On single-use bioreactor lines, tri-clamp gaskets run through SIP at 121 °C and 1 bar gauge cycle after cycle. Peroxide-cured silicone tends to swell after 40–50 sterilisation cycles, lose compression, and start passing micro-leaks. Each one is a batch hold while QA investigates, and that can cost two to three days of production.

Solution

Platinum-cured silicone is the grade that holds up here. It produces fewer extractable by-products than peroxide-cured silicone and keeps its compression set through repeated thermal cycling, and it is available certified to USP Class VI and FDA 21 CFR 177.2600 with documented extractables data. The replacement interval reads off the compound's compression-set curve at 121 °C, which for a typical grade lands near 80 cycles.

Result

Specifying the right cure system stops the joint weeping between changes. Scheduling the swap before the curve rolls off turns an unplanned batch hold into planned maintenance, and gives QA documented evidence of proactive control for a TGA (Therapeutic Goods Administration) audit.

Challenge

A Water for Injection (WFI) loop running at 80 °C continuous, sanitised periodically at 121 °C, asks two things of its gaskets: contribute no extractables above the system's limits, and survive thousands of cycles between 80 °C and 121 °C. USP <1231>, the pharmacopoeial standard for WFI systems, sets the extractables guidance.

Solution

For the flanged connections, virgin PTFE envelope gaskets with a silicone core take extractables off the table. The PTFE wetted surface is inert to WFI at every operating temperature, and the silicone core carries the thermal cycling. Tri-clamp joints take platinum-cured silicone with extractables documentation to ASME BPE.

Result

Gasket extractables are among the first things a WFI audit looks at. Getting the wetted material and its documentation right up front is what keeps commissioning and annual requalification clean rather than a source of rework.

Challenge

When a Class 7 cleanroom (ISO 14644-1:2015) starts failing particle counts at the supply diffusers, degraded duct-flange gaskets are a common cause. Closed-cell neoprene hardens with age, often within about five years, and stops sealing against the sheet-metal faces, letting unfiltered air bypass the filtration.

Solution

Closed-cell EPDM foam, die-cut to the flange profile, is the more durable choice. Peroxide-cured EPDM foam holds compression and resilience across a wider range than neoprene (-50 °C to +110 °C continuous) and resists the ozone attack that ages neoprene in recirculated air. A low-outgassing formulation keeps volatile organic compound (VOC) levels under cleanroom limits.

Result

EPDM's saturated polymer backbone is why it resists ozone where neoprene's chlorinated structure does not, so the foam keeps sealing instead of flattening over a few years. Matching the foam to the flange profile is what brings particle counts back inside ISO Class 7.