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Galvanised malleable iron 3-inch FNPT pipe cap

Value Brand

Value Brand 3 in FNPT Galvanized Cap

SKU CH-KRJ9-YV86Q

A galvanised malleable-iron pipe cap with a 3-inch FNPT thread, rated to 300 psi at 150 °F and meeting ASME B 16.3, B 16.4, ASTM A197, A47, FM, NSF-61, AB1953 and UL standards

  • Galvanised malleable iron resists corrosion for long service life
  • FNPT threaded connection enables quick assembly with standard pipe threads
  • Class 150 rating handles 300 psi water, oil or gas at 150 °F
  • Meets ASME B16.3, B16.4, ASTM A197, A47, FM, UL, NSF-61 and AB1953 standards
  • California Proposition 65 warning: contains a chemical known to cause cancer and reproductive harm

3-Inch FNPT Galvanized Cap

This 3-inch FNPT galvanized cap seals the end of a threaded pipe in water, oil or gas systems. It is made from galvanized malleable iron to Class 150 specifications and meets ASME B16.3, B16.4, ASTM A47 and ASTM A197 standards. The fitting carries FM, UL, NSF-61 and AB1953 approvals for potable-water use.

Sustained-pressure performance

The cap is rated for 300 psi at 150 degrees Fahrenheit water, oil or gas and 150 psi for saturated steam service. Galvanized malleable iron construction maintains thread integrity under continuous operating pressure without the deformation seen in lighter-duty castings. It is suited for systems that run at design pressure for extended periods rather than intermittent cycles.

Threaded-interface limits

FNPT taper threads require proper sealant and torque to achieve the rated 300 psi seal; over-tightening can crack the malleable iron body. The Class 150 pressure class caps the maximum working pressure below heavy-duty Class 300 fittings, so it cannot be used in higher-pressure steam or hydraulic circuits. California Proposition 65 warnings apply to chemicals present in the galvanized coating.

How it compares

Measured against everything we stock in Hose Fittings, Adapters & Clamps, at today’s prices. Recalculated every night.

Price $15.99
Cheaper than about 55% of the 2,955 comparable items (median $17.99).

Specifications

Product
Brand nameZORO SELECT

Questions about this item

Does the galvanized malleable iron cap generate heat or noise when left under pressure all day?

No — it is a passive iron fitting with no moving parts, so it produces no noise or heat during continuous operation.

What pipe thread must I already have for this 3-inch FNPT cap to seal correctly?

You need a matching 3-inch male NPT thread on the pipe or nipple you are capping.

Will this Class 150 cap mate with older ASME B16.3 or B16.4 fittings already in my system?

Yes — it meets both ASME B16.3 and B16.4 standards, so it threads onto legacy Class 150 malleable-iron fittings without mismatch.

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