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The union features solder cups. These fittings are used to allow repair to the line without damage. Please refer to NIBCO technical data sheets and catalogs for engineering and installation information. In addition to its inherent qualities of beauty, durability and low maintenance, copper's reusability makes it an ideal application in sustainable projects. NIBCO® copper fittings are manufactured in an ISO 9001 certified facility, and backed by a 50-year limited warranty. Because of its longstanding reputation for innovation and precision in design and manufacturing, NIBCO is the preferred brand in the industry.
Copper Fittings Installation Instructions
- Lead-free*
- Dezincification resistant
- ASTM B75 Alloy C12200
- NSF/ANSI/CAN-61 and 372
- Material and workmanship per ASME B16.22
- Material, workmanship and dimensions per MSS SP-104
- NFPA 99 Health Care Facilities Gas and Vacuum Systems and the Compressed Gas Association, Pamphlet G4.1 (medical gas)
Copper Fittings Installation Instructions
Manufacturer Resources
Product Specs
- All Basic Material:
- Copper
- Classification:
- Solder Pressure Unions
- End Connection:
- Solder
- Metal End Connection Type:
- C x C
- Product Group:
- Fitting
- Product Type:
- Solder Pressure Unions
- System Use:
- Commercial Plumbing, Compressed Air, Fire Protection, Heating, HVAC, Industrial, Irrigation, Lead Free*, Residential Plumbing
- Product Subgroup:
- Union
- Department:
- Plumbing
Nibco NBC-633-W – Frequently Asked Questions
1) What size copper pipe does the Nibco 633-W solder union fit?
The 633-W wrot copper union is made in 1/4, 3/8, 1/2, 3/4 and 1 inch sizes. Both ends are solder cups (C x C), so the stated size is the copper tube it socket-solders onto, not a thread size. The 1 inch size is also offered cleaned and bagged for oxygen and medical gas work.
2) Is the Nibco 633-W union threaded or solder, and can I use it on a threaded line?
Solder on both ends. The 633-W has copper solder cups, so it sweats directly onto copper tube and will not thread onto iron pipe or a threaded nipple. If you need to break into a threaded line, you need a union with a female or male thread on one end, not this one.
3) Can the Nibco 633-W copper union be used on potable drinking water?
Yes. The 633-W is lead-free and certified to NSF/ANSI/CAN 61 and 372, which are the drinking water standards inspectors look for on potable systems. It is listed for both residential and commercial plumbing service.
4) What is the difference between the wrot and the cleaned and bagged version of the Nibco 633-W union?
Same fitting, different preparation. The standard wrot copper union ships as normal stock. The cleaned and bagged version, offered in 1 inch, is degreased and sealed at the factory, which is what medical gas and oxygen service require so no oil or particulate gets into the line. If your job is brazed medical gas piping, order the cleaned and bagged one; for ordinary water or hydronic work, the standard wrot is what you want.
5) Why put a union in a copper line instead of just soldering a coupling?
A union gives you a mechanical break point. The 633-W is a three-piece fitting with a nut, so the joint can be taken apart with wrenches later and the pipe put back together without cutting or reheating. That is the point of installing one ahead of a pump, water heater, valve or any component you expect to pull out for service. A soldered coupling has to be cut out.
6) Does the Nibco 633-W union meet spec for medical gas piping?
It is covered by NFPA 99 Health Care Facilities gas and vacuum systems and Compressed Gas Association Pamphlet G4.1 for medical gas. For that service order the cleaned and bagged version so the fitting arrives sealed and oil-free.
7) What standards does the Nibco 633-W solder union conform to?
Material and workmanship are per ASME B16.22, with material, workmanship and dimensions per MSS SP-104. The copper is ASTM B75 alloy C12200, and the fittings are made in an ISO 9001 certified facility. Those are the citations a submittal or an inspector will ask for on a commercial job.
8) Can I use a Nibco 633-W copper union on a hydronic heating or compressed air line?
Yes. Beyond plumbing, the 633-W is rated for heating, HVAC, compressed air, fire protection, irrigation and general industrial service. It is a pressure-rated solder fitting, so the limit in practice is the solder alloy and the system temperature, not the fitting type.
9) Will a copper union corrode or fail on aggressive water like a brass one can?
The 633-W is dezincification resistant, which is the failure mode that takes out yellow brass fittings on aggressive or high-chloride water. The body is wrot copper, ASTM B75 alloy C12200, not cast brass, so there is no zinc to leach out.
10) What part number do I order for a 3/4 inch Nibco copper solder union?
The 3/4 inch 633-W wrot union is Nibco part 9256500. The rest of the range: 1/4 inch is 9256200, 3/8 inch is 9256300, 1/2 inch is 9256400, 1 inch is 9256600, and the cleaned and bagged 1 inch is 9256600CB.
How fast can I get the Nibco NBC-633-W delivered?
Most orders ship the same day from our distribution partners, with quick delivery throughout the
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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 NBC-633-W come with a warranty?
Absolutely. The Nibco NBC-633-W 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 NBC-633-W?
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