Can I mix galvanized and black (iron) pipe when plumbing ...

I'm in the process of installing new natural gas service (Nat. Gas, M425, 1-1/4"). Unfortunately, my local Big Box Store only stocks 1" black pipe but carries 1-1/4" galvanized pipe. Is it possible to use galvanized pipe for the mainline (from the exterior nipple for the meter connection, running up and through the attic) and then use smaller 1" black iron pipe, manifolds, and fittings or CSST connectors for branching off? I've come across some common myths regarding galvanized pipes, but I need information on any specific code violations.

Feel free to reach out to us to discuss your specific needs for galvanized tee fittings. Our knowledgeable sales team is ready to assist you in finding the best solutions.

After going through UPC and IRC codes meticulously, it appears there are no issues with using black iron, galvanized, or CSST pipes individually [1]. However, I found no explicit mentions about mixing these types of pipes.

Here are some key findings from my research:

1. Using galvanized pipes with natural gas is no longer a problem because modern zinc coating processes prevent flaking, and the current natural gas composition is non-corrosive. Therefore, galvanized pipes are permissible both outdoors and in moist environments.
2. Black iron pipes should not be used outside or in wet conditions.
3. CSST pipes require proper bonding and must be installed by a certified technician.
4. Galvanized and black pipes do not undergo galvanic corrosion since both are made from "soft steel"; the only difference is the zinc coating on galvanized pipes.

The relevant codes for my area are located in Snohomish County, Washington State, USA.

If you are in need of more information, please visit this page on equal tees.

[1] IRC G2414.42(403.4.2), ASTM A 43/A 53M: https://up.codes/viewer/washington/irc-2015/chapter/24/fuel-gas#G2414.4.2

This specification encompasses seamless and welded black and hot-dipped galvanized steel pipe ranging from NPS 1/8 to NPS 26.

Black steel pipe
Black steel pipes are crafted from steel that hasn't been galvanized. They get their name due to the dark iron oxide coating created during the manufacturing process. This characteristic dark surface gives them the term black steel pipe.

Black iron pipe
Black iron pipes are made from untreated iron. Once iron pipes undergo galvanization, they are often referred to as white iron pipes, or water and gas pipes. Structures built before the 1960s predominantly used black iron pipes for water and gas lines. Although these pipes are classified as steel, their composition is slightly different, which makes them more flexible. It's worth noting that water can easily corrode these pipes compared to actual steel pipes.

Black iron pipe versus black steel pipe: Major Distinctions
The primary difference lies in their construction. Black iron pipes have seams and can easily be connected using valves, whereas steel pipes, mainly used in industrial applications, require welding. While black iron pipes are common in residential natural gas and propane lines, black steel pipes are preferred in gas transmission and fire sprinkler systems due to their seamless production and superior fire resistance.

Texture
Steel pipes have a smooth surface, almost cold to the touch, making them resistant to scratches. However, this does not mean they cannot be damaged by tools like wrenches. By contrast, black iron pipes have a rough texture and can flake if handled excessively but are equally susceptible to heat.

Repair
A common issue with black iron pipes, especially in residential settings, is leakage at the connections, which can be challenging to repair. On the other hand, steel pipes, usually welded, do not face this problem but are more expensive than black iron or PVC pipes.

Cost
Generally, steel pipes cost about 20% more than black iron pipes. Although pricier, steel pipes are more energy-efficient and durable, which justifies their extensive use in large-scale industrial operations in the U.S. Nevertheless, black iron pipes are more readily available, adding to their convenience.

Further reading:
1.Detection method of black steel pipe
2.Maintenance of seamless black steel pipe

For additional information, you can visit this page on 45 degree tee.