Nibco 4851-3 Closet Flange FIP...
IN STOCK (leaves warehouse same day if ordered before 3pm ET)
$18.19
Nibco 4851-3 Closet Flange FIPT - PVC DWV

Nibco 4851-3 Closet Flange FIPT - PVC DWV

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Model: K355320

In Stock (leaves warehouse same day if ordered before 3pm ET)

$18.19
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The PVC DWV closet flange features a female NPT thread connection. The closet flange is secured to the floor of the dwelling so that a toilet can be affixed to it and allow for a pipe connection (under the floor) to continue the piping for evacuation of the used water. Please refer to NIBCO technical data sheets and catalogs for engineering and installation information. Polyvinyl chloride (PVC) is the most frequently specified of all thermoplastic materials because of its light weight, durability, and cost-effectiveness. PVC DWV is easy to install and is joined by solvent cementing or threading. PVC fittings exhibit high corrosion and chemical resistance and will not rust, scale, pit or corrode. NIBCO® plastic fittings are backed by a 5-year limited warranty. Because of its longstanding reputation for innovation and precision in design and manufacturing, NIBCO is the preferred brand in the industry.

  • Maximum service temperature 140-DegreeF
  • Do not test or use with compressed air or other gases
  • ASTM D2665 and D3311
  • NSF/ANSI Standard 14
  • NSF U.P. Certified

Plastic Fittings Installation Instructions

Manufacturer Resources

Product Specs

All Application(s):
DWV Drain / Waste / Vent
All Basic Material:
PVC - Polyvinyl Chloride
Classification:
PVC DWV Closet Flanges
End Connection:
Solvent Weld
Pipe Schedule:
40
Plastic End Connection Type:
F (NPT)
Product Group:
Fitting
Product Type:
PVC DWV Closet Flanges
System Use:
Commercial Plumbing, Residential Plumbing
Product Subgroup:
Closet Flange
Department:
Plumbing
Product Color:
White
Country Of Origin:
United States
Product Width:
7 in
Product Length:
7 in
Product Height:
2.45 in
Product Weight:
0.666 lb

Nibco K355320 – Frequently Asked Questions

1) Will the Nibco 4851-3 closet flange work with 4 inch PVC DWV pipe?
The 4851-3 is a 4 inch by 3 inch PVC DWV closet flange, so it sits over 4 inch drain and steps down to a 3 inch threaded outlet. The flange body is Schedule 40 PVC for drain, waste and vent service. If your closet bend is 3 inch only, or 4 inch only with no reducer, this is the wrong combination and you want a straight 4 inch or straight 3 inch flange instead.
2) Does the Nibco 4851-3 closet flange glue on or thread on?
It threads. The outlet on the 4851-3 is a female NPT connection, so it screws onto a male threaded closet bend or nipple rather than being solvent cemented at that joint. That matters on a repair where the existing stub is threaded steel or a threaded PVC male adapter. If your closet bend is a plain PVC hub with no threads, you need a solvent weld flange or a male threaded adapter cemented into the bend first.
3) Is a PVC closet flange OK for a commercial restroom or only residential?
Both. The 4851-3 is rated for commercial and residential plumbing, and it is certified to NSF/ANSI Standard 14 and NSF U.P. for potable-adjacent drainage use. It also meets ASTM D2665 and D3311 for PVC DWV fittings, which is what most jurisdictions and spec sheets call out on a drainage submittal.
4) Can a PVC closet flange handle hot water or a steam line drain?
Maximum service temperature on this PVC DWV flange is 140 degrees F. That covers normal toilet and fixture drainage without trouble, but it rules out any line carrying sustained hot discharge above that, such as a commercial dish machine or boiler blowdown drain. For those you want a higher-temperature material, not PVC DWV.
5) Can I air test a PVC DWV closet flange installation?
No. Nibco states plainly not to test or use PVC DWV fittings with compressed air or other gases. Use a water test on the drainage system. This is the one instruction on a plastic DWV job that gets ignored and causes an injury, so it is worth passing to whoever is doing the rough-in test.
6) What do I need besides the closet flange to set a toilet?
The flange itself bolts to the floor and gives the toilet something to fasten to while the outlet carries waste into the piping below. You will still need closet bolts, a wax ring or gasket, and floor fasteners suited to your subfloor, plus a male threaded adapter if the closet bend below is a plain PVC hub rather than threaded, since the 4851-3 connects with female NPT threads.
7) Will a Nibco PVC closet flange corrode or rust like a cast iron one?
No. PVC will not rust, scale, pit or corrode, which is the usual reason a flange gets replaced in the first place on older cast iron or steel closet bends. On a slab bathroom or a wet coastal property that is the practical argument for going plastic on the replacement.
8) What color is the Nibco 4851-3 closet flange, and does it match my other DWV fittings?
White, which is the standard color for PVC DWV fittings and matches the rest of a white PVC drainage run. It is a visual cue on the job too: white PVC DWV against the black of ABS tells the inspector at a glance which system you have run, and the two are not interchangeable at a solvent joint.
How fast can I get the Nibco K355320 delivered?
Most orders ship the same day from our distribution partners, with quick delivery throughout the continental U.S. Need it urgently? Contact Us for expedited shipping options.
Can I return it if it doesn’t work for me?
Yes—ZenSupply offers a hassle-free return policy. If the product isn’t the right fit, reach out to our support team for a return authorization or setup a return by following our return instructions.
Does the Nibco K355320 come with a warranty?
Absolutely. The Nibco K355320 is backed by a manufacturer’s warranty. For full warranty terms, check the product documentation or Contact Us.
How do I get technical support or installation help for the Nibco K355320?
You can call, text, or email our expert support team for fast answers. We’re here to help with product selection, installation tips, and troubleshooting. Contact Us
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