We take cryptocurrency — so the coins you hold can buy real hardware.Pay in crypto, spend it on real hardware. Free insured shipping worldwide over $399. Plain, unbranded boxes, sent from Germany.Free insured shipping over $399. Your rate is locked for 30 minutes once checkout opens.Rate locked 30 minutes. Every item sealed, serial-checked and covered by a 24-month warranty.Sealed, 24-month warranty.

Saved items Sign in
Black 4-inch union coupling with threaded ends

Legend Valve

Legend Valve 350-451 4" black union coupling

SKU CH-HKNW-JBZ5T

Connects two 4-inch FNPT pipes with a black iron union coupling for secure plumbing joints

  • 4" black union coupling connects large-diameter pipe runs
  • Female NPT threads on both ends allow direct threaded installation
  • Black steel construction resists mechanical stress in plumbing systems
  • Legend Valve 350-451 model identifies exact replacement part
  • California Proposition 65 notice flags chemical content for installer awareness

4-inch black union coupling

This 4-inch black union coupling joins two female NPT threaded pipes in plumbing systems. The union design allows quick disassembly for maintenance or replacement without cutting pipe. It is suited for installers who need a removable joint on black iron or steel pipework.

Verify thread size and pipe material

Confirm that both pipe ends are 4-inch female NPT before ordering. The coupling is intended for black iron or compatible steel pipe; using it with dissimilar metals or plastic threads may cause leaks or damage. Check system pressure and temperature limits against the fitting rating.

Black iron construction with FNPT threads

The black finish indicates standard iron construction for water, gas or oil lines where corrosion resistance is not the primary concern. Female NPT threads on both ends accept matching male-threaded nipples or pipe ends. The union nut permits repeated make-and-break cycles without degrading the pipe threads.

Highlights

  • 4" black union coupling connects large-diameter pipe runs
  • Female NPT threads on both ends allow direct threaded installation
  • Black steel construction resists mechanical stress in plumbing systems
  • Legend Valve 350-451 model identifies exact replacement part
  • California Proposition 65 notice flags chemical content for installer awareness

Specifications

BrandLEGEND VALVE

Questions about this item

Does the Legend Valve 350-451 union coupling include any gaskets or sealant, or must they be purchased separately?

The coupling is supplied as the fitting only; gaskets, thread sealant or tape are not included and must be sourced separately.

Is the 350-451 model the correct choice for a four-inch female NPT connection, or is another version required?

The 350-451 is a four-inch black union with female NPT threads on both ends, matching that exact specification.

What does the Proposition 65 warning on the 350-451 mean for a plumber installing it in a potable water system?

The warning indicates the product contains a chemical listed by California as causing cancer or reproductive harm; it does not prohibit use in potable water but installers should follow local codes and safety practices.

More in Fittings & Couplings

Similar items

Same shelf, same checkout — eight coins and a 30-minute rate lock.