Bulkhead pipe fittings play a crucial role in tanks, containers, plumbing systems, and industrial fluid transfer setups. They allow a secure, leak-free connection through a tank wall or panel, letting liquids safely pass from one side to the other.
When made from 316 stainless steel, these fittings offer exceptional corrosion resistance and durability, making them ideal for water treatment, chemical processing, agriculture, metal finishing, marine environments, and any application where reliability truly matters.
A bulkhead pipe fitting is a specialized connector designed to pass through the wall of a tank, drum, container, or reservoir. It creates a watertight and pressure-resistant seal around a drilled hole, allowing plumbing components to be attached on both sides.
Unlike standard pipe fittings, a fitting bulkhead includes:
A threaded body (usually stainless steel)
A sealing gasket (EPDM, Viton, or PTFE)
A locking nut
Internal or external NPT threads for pipe connection
Its purpose is simple: Create a leak-proof connection through a flat or curved surface while maintaining the structural integrity of the container.
Bulkhead pipe fittings are widely used in water tanks, rainwater harvesting, irrigation systems, chemical storage, and industrial pipelines.
While bulkhead fittings come in PVC, brass, and polypropylene, more engineers and buyers are shifting toward stainless steel—especially 304 and 316 grades. This shift is due to stainless steel’s unmatched performance characteristics:
Superior Corrosion Resistance: Effective against water, chemical solutions, acidic fluids, and seawater.
High Mechanical Strength: Resists mechanical stress and pressure.
High Heat Resistance: Maintains integrity in high-temperature systems.
Exceptional Longevity: Significantly outlasts plastic and brass in demanding environments.
It is the preferred material in industrial systems where safety and reliability are non-negotiable.
Most stainless steel bulkhead fittings maintain their natural metallic finish. They are not plated or coated because:
Inherent Protection: Stainless steel already possesses a high level of corrosion resistance due to its composition.
Stability: A raw, polished stainless surface ensures lifetime stability. Surface coatings are unnecessary and could potentially weaken the natural protection.
Hygiene: This clean, uncoated finish is ideal for food-grade, chemical-grade, and sensitive industrial environments.
Manufacturing high-precision stainless steel fittings typically involves:
CNC Turning and CNC Milling: The stainless steel bar stock is machined into precise shapes. Threads are cut using high-accuracy turning equipment to ensure a reliable, leak-free assembly.
Ultrasonic Cleaning: After machining, parts are placed in an ultrasonic cleaning tank to remove metal shavings, cutting oil, dust, and debris. This step ensures a clean metal surface for proper sealing.
Gasket and Component Assembly: EPDM or Viton gaskets are matched with the body. Locknuts are fitted and manually inspected to ensure a high-precision fitting, ready for demanding environments.
Bulkhead fittings come in several variations based on connection type and size:
| Category | Common Examples |
| Thread Types | Female NPT bulkhead, Male NPT bulkhead, Double-female variations |
| Connection Styles | Straight, 90-degree elbow, Bulkhead Union, Bulkhead to Hose Barb adapter |
| Common Sizes | 3/8″, 1/2″, 3/4″, 1″, 1-1/2″, 2″ |
The most commonly used sizes worldwide for tanks are 3/4” and 1” stainless steel bulkhead fittings.
Bulkhead pipe fittings are used anywhere a fluid needs to pass through a tank wall or system panel.
Water Management: Water storage tanks, rainwater collection, sump tanks, and irrigation systems.
Chemical Processing: Acid tanks, electroplating baths, chemical dosing systems, and waste liquid management, where 316 stainless steel is mandatory for its resistance to harsh chemicals.
Marine & Offshore: Ideal for saltwater exposure, which rapidly degrades brass and plastic.
Food & Beverage: Mixing vessels and storage tanks, where stainless steel’s non-reactive, hygienic properties are critical.
A simple, well-installed fitting bulkhead can last for decades. Follow these steps for reliable installation:
Drill the Correct Hole Size: Use a hole saw or step bit. (Example: A 3/4″ NPT fitting often requires a 1-1/4” to 1-5/16” hole.)
Insert from the Inside: Insert the bulkhead body through the hole from the inside of the tank.
Position the Gasket: Ensure the gasket is on the inside wall of the tank, sitting flush against the tank surface, for the best seal.
Tighten the Locknut: Install the locknut from the outside. Hand-tighten first, then use a wrench carefully to avoid overstressing the tank wall (no need to overtighten).
Attach Pipe/Hose Fittings: NPT threads require sealing tape or pipe sealant for best results when attaching the pipes.
Test for Leaks: Fill the tank or pressurize the system slightly to ensure a leak-free connection.
Common Installation Mistakes to Avoid
Over-tightening the locknut.
Installing the gasket on the outside of the tank wall.
Using the wrong gasket material for the fluid/chemical.
Cross-threading the pipe connections.
| Feature | Stainless Steel (304/316) | Brass | Plastic (PVC/Polypropylene) |
| Corrosion Resistance | Superior (Saltwater, Acid, Chemicals) | Moderate (Poor in seawater/chemicals) | Good (General chemicals) |
| Strength/Pressure | Highest (Withstands high pressure/stress) | Moderate (Good for general water) | Low (Not suitable for high pressure/heat) |
| Lifespan | Longest (Decades) | Moderate | Shortest |
| Cost | Highest | Moderate | Lowest |
If reliability matters, stainless steel is always the top choice.
