What is Black Iron Piping?

Earlier this year, we started selling a selection of black iron pipe and fittings on our web store. Since then, we've learned that a lot of shoppers don't know much about this great material. Simply put, black iron piping is one of the best options for gas lines that exists. It is strong, easy to install, resists corrosion, and maintains an airtight seal. The black coating helps prevent corrosion.

Black iron pipe used to be found in water lines, but has been much more popular for gas since the advent of copper, CPVC, and PEX. It is a great option to gas for two reasons. 1) It is strong, and 2) it is relatively easy to put together. Just like PVC, black malleable iron uses a system of pipe and fittings that fit together with compounds instead of welding. Despite its name, black iron pipe is actually made of a low-grade "mild steel" compound. This gives it much better corrosion resistance than traditional cast iron piping.

Black Iron Pipe Properties

Since this post is all about black iron pipe and fittings, we will go in depth about a few of its traits and properties. It's important to be knowledgeable when it comes to your home's plumbing.

Black Iron Piping Pressure Limits

"Black iron" is a term that usually refers to a type of black-coated steel, but many different types of black iron pipe exist. The main problem with this is that there are few standards that all black iron pipes adhere to. However, they are all made to handle natural and propane gas, which usually stay below 60psi. The standards that black iron pipe must conform to guarantee a pressure rating of at least 150psi, if installed properly.

Black iron is stronger than any plastic pipe because it is made of metal. This is important, because a gas leak can be deadly. In the case of an earthquake or fire, this extra strength could be what causes potentially deadly gas from leaking throughout a home.

Black Iron Pipe Temperature Rating

Black malleable iron piping is also tough when it comes to its temperature rating. While the melting point of black iron pipe can exceed 1000F (538C), the teflon tape that holds the joints together can start failing around 500F (260C). When the sealant tape fails, the strength of the pipe doesn't matter, as gas will start leaking through the joints.

Luckily, teflon tape is plenty strong enough to withstand any temperatures caused by weather. The main risk of failing comes if there is a fire. But in that case, any occupants of a home or business should already be outside by the time gas lines fail.

How to Install Black Iron Piping

One of the primary advantages of black iron piping is its malleability. This means it can be threaded without much trouble. Threaded piping is easy to work with because it can be screwed into fittings instead of having to be welded. Like any system with threaded connections, black iron pipe and fittings require teflon sealant tape to make an airtight seal. Luckily, sealing tape and pipe dope are inexpensive and easy to apply!

Putting together black iron gas systems require a little bit of skill and a lot of preparation. Sometimes pipe comes pre-threaded in specific lengths, but other times cutting and threading must be done by hand. To do this, you must hold lengths of pipe in a vise, cut them to length with a pipe cutter, and create threads on the end with a pipe threader. Use plenty of thread cutting oil to avoid damaging threads.

When connecting lengths of pipe, you must use some type of sealant to fill the gaps between threads. The two methods of thread sealant are thread tape and pipe dope.

How to Use Thread Tape

Thread tape (commonly referred to as "teflon tape" or "PTFE tape") is a simple way to seal joints without making a mess. Applying only takes a few seconds. Wrap thread tape around the pipe's male threads. If you are looking at the end of the pipe, wrap clockwise. If you wrap counter-clockwise, the act of screwing on a fitting could push the tape out of place.

Wrap tape 3 or 4 times around the male threads, then screw the pieces together as tightly as you can by hand. Use a pipe wrench (or a set of pipe wrenches) to tighten at least one full turn more. Once you have fully tightened the pipe and fitting, they should be able to withstand at least 150psi of pressure.


How to Use Pipe Dope

Pipe dope (otherwise known as "joint compound") is a liquid sealant that oozes between threads to maintain a tight seal. Pipe dope is great because it never fully dries, allowing joints to be unscrewed for maintenance and repairs. One downside is how messy it can be, but usually pipe dope is too thick to drip much.

Pipe dope typically comes with a brush or some other type of applicator. Use this to completely cover the male threads in an even coating of the sealant. Do not apply to female threads. Once the male threads are totally covered, screw pipe and fitting together just as you would with thread tape, using pipe wrenches to finish tightening.

Some plumbers recommend thread tape with a layer of pipe dope on top, so that is worth a shot if you can't decide which you like more! For more details on installing black iron piping, read this article.


Black Iron Fittings

In this article, we have focused on black iron pipe, but fittings are an important part of any black pipe gas system. PVC Fittings Online sells a wide range of black malleable fittings and nipples (short, pre-cut, pre-threaded pipe lengths) at great prices!