Considering replacing 4 in. SCH 40 carbon steel with SCH 10S 304L stainless press-fit (ASTM A312/A403, EPDM seals) on a 30% glycol chilled water loop at about 45°F with chlorides <30 ppm to cut corrosion and embodied carbon. Anyone seeing seal creep or fitting rotation under pump vibration, and is there any real-world gain stepping to 316L here versus the extra cost/CO2?
At 45°F and <30 ppm chlorides, 304L + EPDM is fine; install fixed points on both sides of the pump and mark witness lines so you can catch any “seal creep” before a big pump turns it into a lazy-susan… I wouldn’t jump to 316L unless your chlorides or temps wander higher; see Victaulic’s stainless press guidance: https://www.victaulic.com/products/vic-press-for-stainless-steel/. Are you dosing anything that bumps chloride or pH, @OP?
With 30% glycol at 45°F, add flex connectors; if hot CIP, consider 316L. @OP.
If you’re worried about corrosion, 316L might not be worth the extra cost. Have you considered installing supports to minimize vibration near the pump?