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The CPI 1-1/2" FPT Spinweld Fitting (Part #56) solves the most common RV tank connection challenge: achieving a secure, leak-free threaded connection that withstands road vibration and temperature changes. This precision-engineered fitting is designed specifically for RV fresh water and holding tank applications where reliability is non-negotiable.

Features & Specifications

1-1/2" Female Pipe Thread (FPT) - Standard NPT threading for universal compatibility with RV plumbing systems
2" Hole Size - Fits standard tank openings with secure spinweld installation
Durable Custom Plastics Construction - Engineered polymer resists corrosion, chemicals, and UV degradation
Spinweld Design - Heat-fused installation creates permanent, leak-proof bond to tank wall
OEM Grade Quality - Meets or exceeds original equipment manufacturer specifications
Multi-Application Use - Suitable for fresh water tanks, grey water tanks, and black water holding tanks
Temperature Resistant - Performs reliably in extreme RV operating conditions from -40°F to 150°F

Why Choose the CPI 1-1/2" FPT Spinweld Fitting?

When you're replacing or upgrading RV tank fittings, the CPI 1-1/2" FPT spinweld fitting delivers the professional-grade performance mobile technicians and DIY RVers trust. Unlike cheaper alternatives that crack under pressure or loosen over time, this fitting's spinweld installation method creates a molecular bond with your tank that's stronger than the tank material itself. The precision-molded female pipe threads ensure proper seal with standard plumbing components, eliminating the frustration of cross-threading or stripped connections. Whether you're installing a new tank, repairing a damaged fitting, or upgrading your RV's plumbing system, this 1-1/2" threaded tank fitting provides the leak-free reliability you need for worry-free travels.

Compare CPI FPT Spinweld Fittings

Choosing the right FPT fitting depends on your tank's hole size and the connection size you need. Compare our complete range of CPI spinweld fittings to find the perfect match for your RV tank application:

Model	Thread Size	Hole Size	Best For	View Details
Part #56 SKU: 56/500109	1-1/2" FPT	2"	Standard 1.5" connections with 2" tank openings	Current Product
Part #57HD SKU: 57HD/500501	1-1/2" FPT	2-1/2"	Heavy-duty flush design for larger 2.5" openings	View Part #57HD →
Part #65 SKU: 65	2" FPT	2-1/2"	Larger 2" connections for high-flow applications	View Part #65 →
Part #83-LL SKU: 83-LL	1/2" FPT	1-1/8"	Compact flush design for smaller connections	View Part #83-LL →

💡 Pro Tip: Measure your tank's existing hole diameter before ordering. If you're drilling a new hole, the 2" hole size for Part #56 is ideal for standard 1-1/2" plumbing connections. For larger flow requirements or different hole sizes, consider the alternative models above.

Technical Specifications

Part Number: 56
SKU: 56/500109
Thread Type: 1-1/2" Female Pipe Thread (FPT/NPT)
Tank Hole Size Required: 2" diameter
Material: High-grade custom plastics (engineered polymer)
Installation Method: Spinweld (heat fusion to tank wall)
Color: Natural/White
Weight: 0.15 lbs
Dimensions: 2" outer flange diameter, 1.5" thread connection
Temperature Range: -40°F to 150°F
Compatibility: Fresh water tanks, grey water tanks, black water holding tanks
Manufacturer: CPI (Custom Plastics Inc.)
Country of Origin: USA

What's Included

One (1) CPI 1-1/2" FPT Spinweld Fitting - Part #56
Manufacturer's quality guarantee
30-day return policy from Elkhart RV Parts
Installation requires professional spinweld equipment (not included)

Compatible Models & Alternatives

This fitting works with standard RV plumbing components including 1-1/2" MPT threaded pipes, valves, and adapters. For complete tank fitting solutions, explore our full range of CPI tank fittings and accessories. If you need a different thread size or hole size, see the comparison table above for alternative CPI spinweld fittings.

Frequently Asked Questions

How do I install a spinweld fitting on my RV tank?

Spinweld fittings require specialized heat-fusion equipment that melts the fitting base and tank material together, creating a permanent molecular bond. This installation method is typically performed by professional tank manufacturers or mobile RV technicians with spinweld tools. The process involves drilling a precise 2" hole in your tank, positioning the fitting, and using a spinweld tool to fuse it in place. DIY installation is not recommended without proper equipment.

Is this fitting compatible with my RV's fresh water tank?

Yes, the CPI 1-1/2" FPT spinweld fitting is designed for use with RV fresh water tanks, grey water tanks, and black water holding tanks. The food-grade custom plastics material is safe for potable water applications and resistant to the chemicals found in waste water systems. Verify that your tank has a 2" hole opening and requires a 1-1/2" female threaded connection.

What's the difference between FPT and MPT fittings?

FPT stands for Female Pipe Thread (internal threads), while MPT stands for Male Pipe Thread (external threads). This Part #56 fitting has female threads on the inside, so it accepts male threaded pipes, valves, or adapters. If you need to connect a female threaded component, you would need an MPT (male) fitting instead.

Can I use this fitting to replace a damaged tank fitting?

Replacing a spinweld fitting requires cutting out the old fitting and spinwelding a new one in place, which requires professional equipment and expertise. If your existing fitting is damaged, consult with a mobile RV technician or tank repair specialist who has spinweld capabilities. Attempting to remove and replace spinweld fittings without proper tools can damage your tank.

What size hole do I need to drill in my tank for this fitting?

This fitting requires a 2" diameter hole in your tank wall. Use a hole saw or step drill bit to create a clean, precise opening. Ensure the tank surface is clean, flat, and free of debris before spinweld installation. The fitting's flange will cover the hole perimeter and create a watertight seal when properly installed.

Is this fitting resistant to RV holding tank chemicals?

Yes, the custom plastics material used in CPI fittings is engineered to resist common RV holding tank chemicals, deodorizers, and waste treatment products. The fitting will not degrade, crack, or corrode when exposed to typical RV sanitation chemicals, making it ideal for long-term use in black water and grey water tank applications.

Why Buy from Elkhart RV Parts?

Elkhart RV Parts is your trusted source for authentic CPI tank fittings and RV plumbing components. We stock only genuine OEM grade parts directly from authorized manufacturers, ensuring you receive the same quality components used by RV manufacturers. Every product is backed by our 30-day return policy and ships quickly from our Indiana warehouse. Our team understands RV systems and can help you select the right fitting for your specific application.

Ready to upgrade your RV tank connections? Order the CPI 1-1/2" FPT Spinweld Fitting today for fast shipping and authentic OEM quality. Questions? Our AI Live Chat is here to help you find the perfect fitting for your application.

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