Process-equipment platform in Hamilton.
A Hamilton chemical-process operation needed elevated access to a new 12-ft-diameter mixing tank installed in their batch reactor area. The platform had to support the tank's service load, integrate with an existing catwalk, and isolate vibration from the mixer drive. Limited floor space and active production around the install made the design more constrained than the structural calc.
The brief
Tank already procured: ~12 ft diameter, ~16 ft tall, mounted on a 4-leg base. Top fittings (sample ports, vent, agitator drive) needed regular operator access during batch runs. An existing catwalk on the east side of the room was close enough that the new platform could tie in, far enough that the platform needed its own structural columns. The mixer drive operating speed (per equipment vendor) transmitted a measurable harmonic that had to be isolated.
The constraint
Floor space around the tank base was limited to ~3 ft on the east and west, ~5 ft on the north and south. Adjacent process equipment (existing reactor, control panel) couldn't move. We needed columns that fit in the 3-ft space, foundation that didn't conflict with existing slab penetrations, and an access route from the platform to the existing catwalk that didn't cross the tank's safety swing-radius for the mixer.
What we built
- Platform size10 ft × 12 ft (around the tank top fittings)
- Live load125 psf + 1.3 kN concentrated
- Equipment loadper tank vendor (static + dynamic factor)
- Deck height~15 ft above slab
- DeckBar-grate (process drainage; spill tolerance)
- Columns4 × wide-flange with grouted baseplates
- Vibration isolationNeoprene pads under each column base; tuned to mixer operating frequency
- AccessShip's ladder (steep-pitch alternative, equipment-access scope per OBC §3.4.6)
- Catwalk tie-inBolted moment connection to existing catwalk landing
- Guard42" pipe rail with mid-rail, full perimeter except catwalk side (handed off to existing guard)
- FinishTwo-coat epoxy industrial paint; wash-down rated
Vibration isolation
Steel platforms with deck-to-column natural frequencies overlapping the equipment's operating range can amplify harmonic load. We sized the platform stiffness so the natural frequency landed well above the mixer's operating-frequency danger zone. Neoprene isolation pads at the column bases provided additional decoupling — the platform doesn't transmit harmonic to the slab below the way a hard-mounted platform would.
Verification at install: we ran the mixer at full load with an accelerometer on the platform and on the slab adjacent. Readings were well within acceptable ranges for a process platform and non-detectable to operators a few feet away.
The catwalk tie-in
The existing catwalk was older-vintage with no available as-built drawings. We pulled samples (HSS section size, deck thickness, anchor type) at site measure to confirm capacity for the new bolted connection. The existing structure could support the additional load from the new platform's egress route within an acceptable safety factor on the moment connection.
If the existing catwalk had failed the capacity check, we'd have built a separate stair down from the new platform — a more expensive solution but feasible. Catching this at site measure (rather than at install) was the kind of thing pre-fabrication verification exists for.
Install — 2 days
- Day 1: column erection (during a scheduled morning shutdown), vibration pads set, primary frame bolted up. Production resumed afternoon shift.
- Day 2: deck, ship's ladder, guards, catwalk tie-in. Shutdown 10 PM to 6 AM for the catwalk-side connection (which required a hot-work permit due to one existing weld modification).
Outcomes
- Operator access to top fittings reduced from rope-and-harness work to routine ladder-and-platform.
- No measurable vibration transfer to adjacent equipment.
- Project came in under the original quote; no change orders.
Client testimonial pending publication approval.