A tank or vessel access platform wraps around the cylindrical shell of a storage tank, process vessel, reactor, or blender — providing a permanent walkway at a defined elevation for valve operation, sight glass reading, sampling, level gauge inspection, and tank top manway access. Types include: circumferential wrap-around platforms (360° ring walkway following tank shell curvature); semi-circular end-cap platforms (half-ring at vessel head); straight approach platforms (rectangular platform with curved nosing at tank shell); and tank roof walkways (flat or curved platform on top of cylindrical or conical tank roof). All are fabricated from SS 316L RHS curved to tank shell radius with curved flooring panels and a handrail following the vessel curvature.
The platform primary structure consists of radial cantilever arms welded or clamped to the tank shell using SS stitch clamps or full weld-around brackets — radial arms project 600–1,200 mm from the shell face and carry the curved perimeter beam. Curved chequer plate or curved bar grating sections are bolted between the radial arms and the perimeter beam. The perimeter handrail is bent to the platform curve radius and mounted on posts on the outer perimeter beam. For wrap-around platforms, the full circumferential ring beam is curved to the tank shell OD + platform width radius, and the radial arms are typically 600–900 mm centres around the circumference. Self-draining design: all platforms slope 2° toward the tank shell drain connection.
Challenges
Wrap-Around Platform Clamp Marks on Polished Tank Shell (GMP/Food Vessel)
SS strap clamp contact marks polish-sensitive vessel shell — visible indentations unacceptable on GMP vessels.
Differential Thermal Expansion Between Tank Shell and Platform Frame
Tank expands during heating; platform frame is fixed — differential movement stresses weld connections and shell brackets.
Curved Bar Grating Fabrication Tolerance on Tight Radii (<1,000 mm Tank Shell)
Very small tank radii require severe curve in bar grating — grating sections crack or buckle if cold-bent on tight radius.
Water Pooling on Top Chord of Wrap-Around Platform (Hygiene Issue)
Horizontal top surface of curved primary beam retains water and product residue — not self-draining; harbours bacteria.
Wind Load on Elevated Tank Platforms (H >5 m Outdoor Tanks)
Large elevated platforms on outdoor storage tanks act as wind sails — significant lateral wind load on shell brackets and tank shell.
Solutions
- PTFE-Lined Stitch Clamps on GMP Vessels (Clamp Touches PTFE Pad, Not Shell): PTFE or neoprene pad between SS strap clamp and vessel shell — no metal-to-metal contact; no indentation on polished finish.
- Slip-Joint (Slotted Hole) Radial Arm Connection Allowing ±15 mm Thermal Movement: Slotted holes in shell bracket allow radial arms to slide ±15 mm — accommodates thermal expansion without stress.
- Welded Segmental Curved Beam Construction for Small-Radius Tanks (<1,200 mm OD): Build curve from short straight segments welded at calculated chord angles — avoids cold-bending; accurate radius; no cracking.
- Hollow Perimeter Beam Profile (RHS on Edge) — No Top Horizontal Surface: Perimeter beam oriented with narrow face up (RHS 60×40 on its 40 mm face) — no flat ledge to retain water; fully self-draining profile.
- Finite Element Analysis (FEA) on Shell Bracket Loads for Wind-Exposed Tanks >6 m Elevation: FEA of bracket-to-shell joint confirms adequate shell reinforcement — additional annular stiffener ring on shell if required.
Applications
- Pharmaceutical: Reactor, bioreactor, and mixing vessel access platforms — GMP handrail, electropolished chequer plate, PTFE clamp pads.
- Food & Dairy: Dairy tank and silo circumferential walkways — self-draining swaged grating, hygienically designed handrail profiles.
- Brewery: Fermentation vessel and bright beer tank wrap-around platforms — bar grating, integral drain channels.
- Chemical: Storage tank and reactor head access platforms — SS 316L bar grating, full anti-fall handrail to EN ISO 14122.
- Water Treatment: Clarifier, filter, and reactor tank access walkways — bar grating; anti-slip; designed for outdoor exposure.
Models & Capacities
Tank & Vessel Access Platform — Standard Configuration Reference | |||||||||||
Model | Type | Tank Diameter Range [mm] | Platform Width [mm] | Platform Elevation [mm] | Angular Extent [°] | Live Load [kN/m²] | Radial Arm Spacing [mm] | Flooring Type | Handrail Standard | Shell Attachment |  |
VPF-WA-600 | Wrap-around (full ring) | Ø600–Ø1,500 | 600 | 500–2,000 | 360° | 2.0 | 600 | Perf plate 3 mm (curved) | EN ISO 14122-3 | SS strap clamps (PTFE-lined) |  |
VPF-WA-900 | Wrap-around (full ring) | Ø1,000–Ø3,000 | 900 | 500–4,000 | 360° | 3.0 | 750 | Swaged grating (curved) | EN ISO 14122-3 | SS stitch weld brackets |  |
VPF-WA-1200 | Wrap-around (full ring) | Ø2,000–Ø6,000 | 1,200 | 500–6,000 | 360° | 3.0 | 900 | Bar grating 25×3 (curved) | EN ISO 14122-3 | Full weld bracket |  |
VPF-SC-600 | Semi-circular (180°) | Ø600–Ø2,000 | 600 | 500–2,500 | 180° | 2.0 | 600 | Perf plate (curved) | EN ISO 14122-3 | SS strap clamps |  |
VPF-SC-900 | Semi-circular (180°) | Ø1,000–Ø3,000 | 900 | 500–3,500 | 180° | 3.0 | 750 | Bar grating (curved) | EN ISO 14122-3 | Stitch weld bracket |  |
VPF-SAP-600 | Straight approach + curved nosing | Any (tangent approach) | 600 | 300–2,500 | — | 2.0 | — | Chequer plate / perf plate | EN ISO 14122-3 | SS bracket weld |  |
VPF-ROOF-STD | Tank roof walkway (flat) | Ø1,000–Ø5,000 | 750 | On tank roof | — | 2.0 | 1,000 | Bar grating / chequer plate | Top rail + mid rail | Roof saddle clamps |  |
VPF-ROOF-CON | Tank roof walkway (conical) | Ø2,000–Ø10,000 | 750 | On conical roof | Radial spoke | 2.0 | 1,200 | Bar grating (straight radial spokes) | Top rail | Roof weld bracket |  |