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CPI 1 1/4" Flush FPT Spinweld Fitting w/Membrane - Part # 55M (500153)
The CPI Part # 55M is a professional-grade 1 1/4 inch flush female pipe thread spinweld fitting designed specifically for RV fresh water and holding tank installations. This fitting includes an integrated membrane seal for superior leak protection and is engineered for 2 inch hole size applications. Trusted by RV manufacturers and service professionals, this authentic CPI fitting delivers reliable performance in demanding mobile environments.
Why Choose This CPI Spinweld Fitting
This flush-mount FPT spinweld fitting combines precision engineering with durable construction to provide long-lasting tank connections. The included membrane creates a watertight seal that prevents leaks and contamination, while the flush design sits cleanly against your tank surface for a professional installation. With a proven 4.9-star rating from verified customers, this fitting is the trusted choice for RV tank repairs and new installations.
Key Features & Benefits
Premium membrane seal technology ensures leak-free operation in fresh water and holding tank applications. The 1 1/4 inch female pipe thread accepts standard plumbing connections, while the spinweld installation method creates a permanent, vibration-resistant bond to your tank. The flush-mount design minimizes protrusion and reduces the risk of damage during travel. Manufactured by CPI (Custom Plastics), this fitting meets OEM specifications for quality and durability.
Technical Specifications
Part Numbers: 55M, 500153
Thread Size: 1 1/4 inch FPT (Female Pipe Thread)
Fitting Style: Flush mount
Installation Method: Spinweld
Hole Size Required: 2 inches
Material: High-grade plastic with integrated membrane
Applications: RV fresh water tanks, RV holding tanks
Manufacturer: CPI (Custom Plastics)
Weight: 10 oz
Compatible Applications & Use Cases
This versatile spinweld fitting is ideal for RV fresh water tank drain connections, holding tank outlet fittings, tank vent installations, and general plumbing connections requiring a 1 1/4 inch female thread. The 2 inch hole size makes it compatible with standard RV tank installations. Perfect for motorhome repairs, travel trailer upgrades, fifth wheel maintenance, and camper restoration projects. Professional RV technicians and DIY enthusiasts rely on this fitting for permanent tank repairs and new construction.
Compare Similar Spinweld Fittings
| Model | Thread Size | Style | Hole Size | Part Number | Best For | View Details |
|---|---|---|---|---|---|---|
| Part # 55M | 1 1/4" FPT | Flush w/Membrane | 2" | 55M / 500153 | Leak-proof tank connections | Current Product |
| Part # 55 | 1 1/4" FPT | Threaded (No Membrane) | 2" | 55 | Standard installations | View Details → |
| Part # 57M | 1 1/2" FPT | Flush w/Membrane | 2 1/4" | 57M | Larger diameter needs | View Details → |
| Part # 56 | 1 1/2" FPT | Threaded (No Membrane) | 2" | 56 | Larger standard fittings | View Details → |
💡 Helpful Tip: Choose membrane-style fittings (like Part # 55M) for critical connections where leak prevention is essential, such as fresh water tank drains and holding tank outlets. Standard threaded fittings work well for vent lines and less critical applications.
Related Products & Complete Your Installation
Pair this fitting with our complete selection of RV tank fittings and parts for a professional installation. Browse our full range of spinweld parts and tank fittings to find compatible components for your RV plumbing system.
Installation & Professional Support
Spinweld fittings require specialized installation equipment for proper bonding to tank surfaces. For installation guidance, technical specifications, or product compatibility questions, our AI Live Chat provides instant access to deep product knowledge and expert assistance. Get answers to your questions in real-time without waiting.
Authentic CPI Quality You Can Trust
Every CPI fitting sold through Elkhart RV Parts is 100% authentic OEM-grade product sourced directly from authorized suppliers. We stand behind the quality of every part with our commitment to verified authenticity and customer satisfaction. With an average rating of 4.9 stars from verified customers, this fitting has proven its reliability in real-world RV applications.
Order with Confidence
Fast shipping, responsive customer service, and authentic parts make Elkhart RV Parts your trusted source for RV tank fittings and plumbing components. Order your CPI Part # 55M flush FPT spinweld fitting today and experience the difference that quality parts make in your RV maintenance and repair projects.
| Material | Membrane |
|---|---|
| Thread type | Flush FPT |
| Diameter (inches) | 1.25 |
| Hole size (inches) | 2 |
- What is the size of the spinweld fitting? The Spinweld fitting is 1 1/4 inches with a 2 inch hole size.
- What type of tanks is this fitting compatible with? This fitting is designed for RV fresh water and holding tanks.
- What does fpt stand for in this fitting? FPT stands for Female Pipe Thread, indicating the type of threading on the fitting.
- Is this fitting a new product or used? This fitting is a new product.
- Who is the vendor or manufacturer of this spinweld fitting? The vendor of this fitting is CPI.
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