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Square head malleable iron plug with black finish

Anvil

Anvil 0318902681 square head plug 3 1/2 in Class 150 malleable iron

SKU CH-FFXQ-0WXV2 MPN 0318902681

Malleable iron square-head plug seals 3 1/2 in NPT threads for Class 150 service from -20 to 350 °F

  • Product typeDrain Components
  • Main materialHAWA
  • Malleable iron body withstands temperatures from minus 20 to 350 degrees Fahrenheit
  • Class 150 pressure rating suits standard plumbing installations
  • Square head design allows secure tightening with common wrenches
  • Male NPT threads ensure compatibility with standard pipe fittings
  • Solid plug construction provides reliable sealing for drain components

Anvil 3-1/2 in Square Head Plug

This Anvil plug is a Class 150 malleable iron fitting with a 3-1/2 inch nominal pipe size and male NPT threads. It is designed for plumbing drain and trap installations where a solid, threaded closure is required. The fitting suits professionals and DIYers assembling or servicing black iron piping systems.

Temperature range and pressure class

The plug operates from -20 degrees to 350 degrees Fahrenheit and carries a Class 150 rating for standard pressure service. Malleable iron construction provides mechanical strength for typical drain, waste and vent applications. No pre-applied thread sealant or separate seal is included with the component.

3-1/2 inch male NPT thread size

The single specification that determines fit is the 3-1/2 inch nominal pipe size with male NPT threading. Buyers must match this exact thread size and gender to the mating fitting. Systems requiring a different diameter, female threads or a different pressure class will not accept this plug.

How it compares

Measured against everything we stock in Drain Stoppers, Strainers & Traps, at today’s prices. Recalculated every night.

Price $40.99
Pricier than about 57% of the 4,240 comparable items (median $31.99).

Specifications

Product
Brand nameAnvil
Model name0318902681
Product typeDrain Components
Size & build
Main materialHAWA

Questions about this item

How do you install the 3 1/2 in malleable iron square head plug without damaging the threads?

Apply PTFE tape or pipe dope to the male NPT threads, then tighten with a wrench on the square head until snug; over-tightening cracks the iron casting.

What maintenance or replacement will this Class 150 plug need over time?

Inspect the threads and sealing surface annually for corrosion or scale; replace the plug if the square head rounds off or the iron shows cracking from thermal cycling.

At what temperature limit does this plug first become unsafe under sustained use?

The malleable iron rating ends at 350 Degrees F; sustained exposure above that temperature reduces strength and can cause leakage.

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