2" NPT Poly Bulkhead Fitting w/ EPDM Gasket - Each

The 2" NPT Poly Bulkhead Fitting w/ EPDM Gasket is a heavy-duty, commercial-grade tank adapter designed to establish a leak-proof, mechanical process connection through the dome, sidewall, or flat mounting landing of polyethylene storage vessels (such as the 35- to 250-gallon double-wall containment tanks).

Frequently specified for top-draw suction assemblies, chemical fill ports, overflow lines, and interstitial leak probe mounts, this fitting provides female NPT threads on both internal and external faces while isolating the tank wall penetration from hydraulic pressure and corrosive chemical degradation.

Mechanical Architecture & Design Features

• Material Construction: Precision-molded from virgin high-density polypropylene (PP). Polypropylene provides superior mechanical rigidity, dimensional stability, and high chemical resistance against concentrated acids, bases, and salts.

• Left-Hand External Threading: Engineered with left-hand (reverse) external threads on the body shaft. When standard right-hand male NPT pipe fittings or nipples are tightened into the female NPT internal bore, the tightening torque naturally forces the heavy-duty hex locking nut tighter against the tank wall rather than loosening the bulkhead seal.

• Die-Cut EPDM Elastomeric Gasket: Fitted with an oversized, chemical-grade EPDM (Ethylene Propylene Diene Monomer) sealing gasket. EPDM offers excellent elasticity, high tensile resilience, and outstanding resistance to ozone off-gassing, caustic solutions, dilute acids, and UV degradation. (Note: For concentrated sodium hypochlorite service exceeding 12.5%, Viton/FKM gaskets are recommended for extended service life, whereas EPDM is the standard for general aquatic chemicals, mild acids, sodium bisulfate, and coagulants).

• Full-Flow NPT Internal Female Bore: Tapered 2" FNPT threads on both the wet (flange) side and dry (nut) side allow direct threading of rigid PVC, CPVC, or polypropylene drop tubes/suction lances into the tank interior and ball valves or cam-lock adapters onto the exterior.

• Heavy-Duty Friction-Relief Washer: Many industrial variants include a low-friction Polyethylene/Nylon slip washer positioned between the hex nut and the gasket or tank wall, preventing the gasket from puckering or tearing as torque is applied during installation.

Technical Specifications

• Nominal Internal Pipe Size: 2" Female NPT (FNPT) on both sides.

• Required Tank Hole Saw Diameter: 3-1/4" (approx. 82.5 mm to 83 mm / 3.25" rough cutout).

• Maximum Tank Wall Thickness: Clamps tank walls up to 1.00" to 1.25" thick (accommodating heavy-duty 1.9 SG rotomolded double-wall domes and thick flat landings).

• Flange / Hex Nut Outer Diameter: Approximately 4.25" to 4.50" (approx. 10.8 cm to 11.4 cm).

• Maximum Hydraulic Working Pressure: 150 PSI (approx. 10.3 bar) at 70°F (21°C).

• Operating Temperature Limits: 32°F to 150°F (0°C to 65.5°C).

• Wetted Materials: Virgin Polypropylene (body and nut), EPDM elastomer (compression gasket).

Installation Guidelines & Torque Protocol

    Flange Head (Inside or Top Dome)
             │
             ▼
        ┌─────────┐
        │ 2" FNPT │
  ──────┴─────────┴────── Tank Wall (Thru-Hole: 3-1/4")
  ░░░░░[ EPDM GASKET ]░░░ (Always on Flange Head Side)
  ───────────────────────
             ▲
             │
      Left-Hand Nut (Tighten Counter-Clockwise from Nut Face)

1. 1. Hole Preparation: Drill a clean 3-1/4" hole through the reinforced tank flat using a standard hole saw. De-burr both inner and outer edges thoroughly using a deburring blade or utility knife; any trapped shavings under the gasket will cause weeping.

   2. Gasket Placement Rule: The EPDM gasket must always be installed against the flange head directly contacting the tank wall. Never place the gasket on the nut side; the nut turns against a bare wall or friction washer, and rotating against a gasket will buckle and destroy the elastomeric seal.

   3. Threading & Tightening: Hand-tighten the left-hand nut until snug against the tank surface. Using a commercial spanner or smooth-jaw adjustable bulkhead wrench, turn the nut an additional 1/4 to 1/2 turn past hand-tight. Do not over-torque; excessive torque will crush the EPDM gasket and cause cold-flow deformation of the polypropylene threads.

   4. Thread Sealant: When installing male 2" pipe into the female ports, use PTFE (Teflon) tape or an approved non-hardening, poly-compatible thread paste. Avoid excessive wraps that could over-stress the tapered female NPT hub.