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Four inch stainless steel pipe coupling with threaded ends

Legend Valve

Legend Valve 404-091 4" 304 Stainless Steel Coupling FNPT x FNPT

SKU CH-Z802-E0Y1S

Four-inch 304 stainless steel coupling with FNPT threads connects two female pipes

  • 4-inch FNPT coupling joins pipes securely
  • 304 stainless steel resists corrosion in harsh environments
  • Legend Valve 404-091 built for industrial plumbing systems
  • Female NPT threads on both ends simplify installation
  • California Proposition 65 warning applies to this product

4-Inch 304 Stainless Coupling FNPT x FNPT

The Legend Valve 404-091 is a 4-inch coupling machined from 304 stainless steel with female National Pipe Thread ends on both sides. It joins two male-threaded pipes in industrial plumbing, water-treatment and process-piping systems where corrosion resistance is required. The fitting is supplied new and carries California Proposition 65 warnings for chemicals linked to cancer and reproductive harm.

Threaded Joint Limits and Chemical Exposure

The FNPT connection relies on thread engagement and sealant to hold pressure; its practical limit is the mechanical strength of the 304 stainless material and the quality of the thread seal. The Proposition 65 notice means installers must follow safe-handling practices and verify that the fluid chemistry is compatible with 304 stainless to avoid premature corrosion or leaching.

Installation Notes and Common Issues

Installation requires clean threads, appropriate pipe sealant or tape, and correct wrench torque to prevent leaks without galling the stainless threads. Over-tightening is the most frequent cause of damaged fittings, while under-tightening or the wrong sealant leads to weeping joints. Always confirm thread compatibility before assembly.

Highlights

  • 4-inch FNPT coupling joins pipes securely
  • 304 stainless steel resists corrosion in harsh environments
  • Legend Valve 404-091 built for industrial plumbing systems
  • Female NPT threads on both ends simplify installation
  • California Proposition 65 warning applies to this product

Specifications

BrandLEGEND VALVE

Questions about this item

Is the 4" size the only option for the 304 stainless steel FNPT coupling?

The listing describes a single 4" coupling made from 304 stainless steel with FNPT threads on both ends; no other diameters or thread types are shown for this model.

How does the 304 stainless steel perform in a live plumbing system?

304 stainless steel resists corrosion and handles typical water, air and chemical lines, while the FNPT threads create a tapered seal that tightens under pressure.

What does the FNPT x FNPT thread standard mean for installation?

FNPT indicates female National Pipe Taper threads on both sides, so the coupling accepts male NPT fittings and seals by thread interference without a separate gasket.

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