The Stainless Steel Orifice Plate - 250mm x 250mm is a custom-fabricated flow restriction plate for onsite stormwater detention (OSD) systems. Made from Stainless steel at 250mm x 250mm x 3mm, each plate is precision-drilled to your specified orifice diameter, from 30mm to 125mm, to match your hydraulic engineer's OSD design. Corner mounting holes are pre-drilled for immediate bolted installation inside a pit or chamber.

Available with or without four stainless steel dynabolts for site convenience. The 3mm plate thickness provides the rigidity needed to maintain the exact orifice diameter under the hydrostatic pressure of a full OSD detention volume. Since 1957, Vincent Buda and Company has supplied the stormwater products that civil and drainage contractors rely on. Allow 3-5 business days from order confirmation for fabrication, then same-day or next-day delivery within the Sydney Metro. Courier delivery available Australia-wide.

Product Specifications

• Material: Stainless steel
• Plate size: 250mm x 250mm x 3mm
• Orifice diameters: 30mm to 125mm, available in 5mm increments
• Corner mounting: Pre-drilled holes for immediate bolted installation
• Optional fixings: Four x 8mm x 40mm stainless steel dynabolts, available as an add-on
• Lead time: 3-5 business days from order confirmation (custom fabricated, no returns)
• Product Drawings: See Product Drawings

Key Features at a Glance

• Custom Drilled to Spec: Each plate is fabricated to the orifice diameter specified by your hydraulic engineer, from 30mm to 125mm in 5mm increments.
• Off-the-Shelf Plate, Custom Hole: The 250mm x 250mm x 3mm plate is a standard size held in ready-to-fabricate stock, keeping lead times to 3-5 business days.
• Stainless Steel Construction: Provides long-term corrosion resistance in submerged OSD pit environments.
• Ready for Immediate Installation: Pre-drilled corner mounting holes mean the plate goes straight from delivery to the pit without additional preparation.

Primary Applications

• Onsite Stormwater Detention (OSD) Systems: Installed inside a pit or chamber to restrict peak outflow rates to the pre-development levels required by council.
• Hydraulic Engineer-Specified Flow Control: Used wherever a precision orifice diameter is required to meet a specific hydraulic performance target in an OSD design.
• Residential and Commercial Drainage Compliance: Suits stormwater management plans requiring a certified restriction device in new and remediated drainage systems.
• Retrofit OSD Installations: Custom-drilled plates allow compliance upgrades to existing pits without major civil works. See the full Stormwater collection for related products.