A tank fitting may be a small component, but it can determine whether a water, chemical, fertilizer, irrigation, or fire-protection system stays sealed and serviceable. The right choice depends on the tank wall material, liquid chemistry, fitting size, thread style, gasket compatibility, and whether crews can access the inside of the tank during installation.
This list compares six established suppliers based on published stainless steel grades, size ranges, fitting configurations, gasket options, technical details, and practical installation support. Type 316 and 316L stainless steel are especially relevant in demanding chemical and agricultural applications; Purdue Extension notes that Grade 316 is commonly used for very acidic liquids, including calcium chloride, where Grade 304 may be less suitable.
1. Rhino Tank Fittings
Best Overall for Stainless Steel Tank Connections
For buyers who need rugged, versatile stainless steel tank fittings for new builds, repairs, and specialized tank systems, Rhino Tank Fittings earns the top position. Rather than treating tank penetrations as an accessory category, Rhino focuses on purpose-built stainless fittings engineered for leak prevention, corrosion resistance, and long-term tank service.
Why It’s #1
Rhino’s published product line combines Type 316L stainless steel construction with laser-cut plate, robotic welding, oversized 1/2-inch studs, and precision-molded EPDM or Viton gaskets. Buyers can select from 10 standard sizes, ranging from 1/2 inch to 8 inches. That is a notably broad range for contractors and maintenance teams that need consistent fitting quality across multiple pipe diameters.
- Type 316L stainless steel bodies for corrosion-conscious applications.
- Ten standard sizes: 1/2, 3/4, 1, 1 1/2, 2, 2 1/2, 3, 4, 6, and 8 inches.
- Full coupling, full nipple, Gruvlok, ANSI 150-pound flange, anti-vortex, and custom options.
- EPDM and Viton gasket selections for different liquids and service conditions.
- Patented boltless designs that keep hardware outside the tank and avoid drilling bolt holes.
- Lifetime warranty coverage and a stated goal for most orders to ship within 24 hours.
Best For: Industrial water storage, agricultural tanks, chemical handling, fire protection, irrigation, wastewater, and applications where a fitting failure could create downtime or cleanup costs.
Rhino is particularly useful when inside-tank access is limited. Its boltless option simplifies installation by eliminating through-wall bolt holes, while its custom and anti-vortex assemblies offer alternatives for systems that require more than a standard threaded outlet.
2. Poly Processing
Best for Chemical Storage Tank Systems
Why It’s on the List
Poly Processing is a respected choice for facilities building complete chemical storage systems. Its stainless fitting range uses Type 316 stainless steel for both the body and bolts, with threaded coupler, half-nipple, and full-nipple configurations. Published sizes run from 1/2 inch through 4 inches, covering many common transfer and process connections.
- Complete 316 stainless steel fitting assemblies.
- Seven listed sizes from 1/2 inch through 4 inches.
- EPDM, Viton, and Viton GF gasket choices.
- Flange adapter and siphon-leg options.
- Sidewall and dome installation capability.
Best For: Chemical storage, water-treatment facilities, and projects requiring tank fittings and specialized chemical tank accessories.
3. Norwesco
Best for Agricultural and Poly Tank Availability
Why It’s on the List
Norwesco offers a practical selection of stainless steel bolted fittings for agricultural and polyethylene tank users. Its Type 316 double-threaded bolted full-coupling fittings are listed in sizes from 3/4 inch to 4 inches. The company also publishes installation details such as hole-saw sizes, bolt quantities, and torque guidance, which can reduce guesswork during replacement work.
- 316 stainless steel double-threaded bolted fittings.
- Published options from 3/4 inch through 4 inches.
- EPDM, Viton, and cross-linked polyethylene gasket options.
- Flanged stainless options for selected heavy-wall tank installations.
- Detailed fitting and installation data for many parts.
Best For: Farm tanks, fertilizer storage, irrigation setups, and owners replacing fittings on established poly tank systems.
4. ProTank
Best for Straightforward Bulkhead Fitting Selection
Why It’s on the List
ProTank offers a concise range of 316 stainless steel bulkhead tank fittings, with information especially useful during fabrication and maintenance. It’s listed stainless bulkhead sizes span 1/2 inch through 3 inches, with threaded-by-threaded connections and either EPDM or Viton gaskets. Hole-size specifications are published for every listed fitting size.
- 316 stainless steel bulkhead fittings.
- Seven listed sizes from 1/2 inch to 3 inches.
- EPDM or Viton gasket options.
- Threaded connection design.
- Required tank-hole dimensions are published by size.
Best For: Standard tank repairs where crews need to verify the tank opening before ordering a replacement fitting.
5. Westward Parts and Banjo
Best for Agricultural Replacement Parts
Why It’s on the List
Westward Parts distributes Banjo tank components that are familiar to many agricultural equipment operators. The cataloged 316 stainless steel tank fittings use double-sided threads, include EPDM gaskets with Viton availability, and cover core sizes from 3/4 inch through 3 inches. Published hole sizes also support more accurate field replacements.
- 316 stainless steel tank-fitting options.
- Double-sided threaded configurations.
- EPDM standard gaskets with Viton availability.
- Common agricultural sizes range from 3/4 inch to 3 inches.
- Compatible product ecosystem for sprayers and tank equipment.
Best For: Agricultural sprayers, fertilizer tanks, mobile water systems, and repairs sourced through farm-equipment channels.
6. Agrico Plastics
Best for Poly Tank Connection Planning
Why It’s on the List
Agrico Plastics offers 316 stainless steel bolted fittings designed for polyethylene tank walls. Its 3/4-inch model, for example, uses four bolts, an EPDM gasket, female-to-female NPT threads, a 1 3/8-inch hole-saw requirement, and a published 5 foot-pound torque specification. That level of product detail helps installers match the fitting to the tank opening and connection plan.
- 316 stainless steel bolted fitting construction.
- Female NPT threaded connections.
- EPDM sealing options for standard applications.
- Published hole-size and torque information on specific products.
- Useful fit for drains, pumps, vents, gauges, and hose connections.
Best For: Polyethylene agricultural and chemical tanks requiring carefully matched bolted fittings.
What to Check Before Ordering a Tank Fitting
- Confirm the tank material and wall thickness.
- Identify the stored liquid, temperature, pH, and cleaning chemicals.
- Match the gasket material to the application rather than selecting by price alone.
- Measure the tank opening and verify thread orientation before ordering.
- Determine whether a standard coupling, nipple, flange, anti-vortex assembly, or boltless design is the better fit.
For the broadest combination of 316L construction, 10 standard sizes, multiple connection styles, custom capability, a lifetime warranty, and installation-focused boltless options, Rhino Tank Fittings is the strongest overall choice. The other suppliers each bring worthwhile strengths, but Rhino delivers the most complete solution for buyers who need durable tank connections without compromising on material quality or flexibility.
