Flap gates are the simplest way to prevent water from returning back into pipes and openings. Gates are designed so that whatever the size, a small flow will open the gate with unseating pressure and will remain watertight with seating pressure. Also known as tide gates and floodgates because of their ability to prevent back flow into a discharging system. Normally flap gates are round or rectangular cast iron. If required, both round and rectangular can be ductile, 2% nickel or NiResist. Rectangular flap gates can be fabricated in A36 steel, 304(L) or 316(L) stainless steel.

Stainless Steel Flap Gates Specifications

Fabricated flap gates where shown in the plans and specifications and listed in the gate schedule shall be as manufactured by Coldwell-Wilcox Technologies of Cincinnati, Ohio. Gates shall be 304(L) stainless steel or 316(L)

All materials will comply with applicable provisions and recommendations of the following, except as otherwise shown or specified:

Frame, Leaf ASTM A276 Type 304(L) or 316(L) Stainless Steel
Stem ASTM A276 Type 304(L) or 316(L) Stainless Steel
Fasteners ASTM A276 Type 304 or 316 Stainless Steel
Seals Neoprene ASTM D2000 50-60 Durometer
Seats UHMW
Stem Cover Butyrate, Clear
Handwheel ASTM A-126, Class B Cast Iron, A36 Steel
HandCrank A36 Steel

Gates shall be designed and shop tested to the applicable CWT standard. Design and operating heads shall be per the site schedule and/or specifications.

The frame shall be Type 304(L) or 316(L) stainless steel.

Hinge arms shall be fabricated or cast in one of several materials listed in the materials schedule. The hinge arms shall be UHMW or bronze bushed. The hinge pins shall be bronze or stainless steel as detailed in the materials section. The hinge arm and pin configuration is designed to be in double shear with arm to flap adjusting screws to align the flap seat face to the frame seat face. Pivot lug bosses shall be flap and frame mounted with non-corrosive grease fittings without bushings. Bushing and grease fitting configuration shall be as specified in the job specification.

Installation shall be in complete accordance with manufacturer’s instructions and recommendations. Anchor bolts will be set in accordance with approved manufacturer’s drawings.

The flap gates shall be the latest standard product in regular production by a manufacturer whose products have proven reliable in similar service. A single manufacturer shall supply the flap gates.

Manufacturer’s data and drawings shall be submitted for approval in accordance with site specifications and engineering drawings. Manufacturer’s submittal shall include but not limited to gate material specification sheet, gate data summary sheet, site plan drawings and paint/coating data sheets.

The flap shall be Type 304(L) or 316(L) stainless steel.

Bronze: Seat facings shall be malleable extruded bronze of a composition, which will resist dezincification and will increase in working ability with cold working. The extruded seat facings shall be a special shape to fill and permanently lock in the machined dovetail grooves when impacted into place. Attaching pins and screws shall not be allowed. The installed seat facings shall be machined to a 63 micro-inch finish or better.

Neoprene: Seat facings shall be the best grade of neoprene having a tensile strength of 1,500 p.s.i., a minimum elongation of 400 percent and a durometer hardness of 50-60. An exact slot shall be machined in the seat face to accept the neoprene which shall be mechanically retained without the use of fasteners.

Cast Iron: The castings shall be machined to a 125 micro-inch finish or better forming the cast Iron seat facings.

Each gate shall be fully assembled and shop-inspected in the vertical position for proper seating. The flap shall be fully opened and closed to ensure that it operates freely and seals.

Contractor shall make adjustments required to place system in proper operating condition. Contractor shall conduct functional field test of each flap gate in the presence of the Owner’s Project Representative to demonstrate that each part and all components together function correctly.