CSST vs. Black Iron Pipe

Schedule 40 black iron pipe is damaged by earthquakes and lighting

For decades, schedule 40 black iron pipe was the default choice for piping gas to furnaces and water heaters. But in the United States, there are about 65 people killed every year in gas explosions. That is why an alternative to black iron pipe was developed—corrugated stainless steel tubing (CSST). First developed in Japan to solve the dangers of broken rigid gas piping in an earthquake, and then brought to the United States by the American Gas Association (AGA) and the Gas Research Institute (GRI) in the United States as an alternative gas piping solution, CSST was developed to eliminate the difficulties and dangers of rigid gas piping.

Rigid pipe presents a variety of problems:

  • Rigid pipe breaks in earthquakes and other natural disasters

  • Multiple joints frequently leak

  • Pipe dope deteriorates over time and leaks when exposed to lightning strikes

  • Black iron pipe is not listed to any national standards for gas piping. CSST piping can withstand the same forces of nature—earthquakes, lightning, tornados—that make black iron pipe crack

  • Most rigid steel pipe is made in Asia—with no quality control

The rigid pipe joints are a well recognized cause of gas leaks and fires. The National Fire Protection Association (NFPA) publishes the Guide for Fire and Explosion Investigations (NFPA 921), and notes in Chapter 9 that joints and fittings in rigid pipe systems are the most common sources of gas leakages and gas fires and explosions:

  • 9.9.4.1 Pipe Junctions. Improper connections between piping elements, such as inadequate threading (not enough turns for gas tightness), improper threading (cross-threading or right-hand threads merged to left-hand threads), or improper use of pipe joint compound (too much or too little) can cause gas leaks. Pipe junctions are also the most common locations that leak as a result of physical damage to fuel gas piping systems.

  • 9.9.4.8 Physical Damage. Physical damage to fuel gas systems can cause leaks. Strain put on gas piping systems may manifest itself at the pipe junctions and unions. Because pipe elbows, T fittings, and couplings are more rigid and stronger than the pipes they connect, and because the threaded ends are weaker than the rest of the pipes, stress damage usually occurs in the threaded portions of the pipes immediately adjacent to the pipe fittings.

Leaking joints in a rigid pipe system can cause an accumulation of fuel gas and a resulting explosion. Alternatively, leaking gas can ignite from an open flame or pilot light or other ignition source.

Financial and Human Costs

Rigid pipe has a number of drawbacks—it is inflexible and it has multiple joints. Working with rigid pipe also involves major handling and material hassles. First, there is the capital cost for equipment and tools required for cutting, threading, and deburring rigid pipe. Then there is the hassle of storing and disposing cutting oil in compliance with environmental regulations.

Adding to these difficulties is the impact on human resources. Workers lugging 21-foot sections of schedule 40 pipe will lead to higher workers' compensation claims. Time is lost training employees on the old practices of rigid pipe installation and leak checking. And finally, material is lost in scrap and rework by new trainees and old pros alike. In contrast, CSST piping removes these material and human-resource hassles. A 250-foot reel of ½" CSST weighs only 40 pounds. CSST needs only two connections—at the beginning and the end—with fittings that are easy to assemble with typical hand tools and that seal leak-tight each and every time.

Advantages of CSST Piping

Twenty years ago, the American National Standards Institute published the first CSST product standard—ANSI LC 1. Since then, over 750 million feet of CSST have been installed in over five million homes in North America.

CSST piping ensures safety and success thanks to:

  • High flexibility and continuous lengths without joints

  • Pulls easily around obstacles like electrical wiring

  • Easy to assemble fittings using typical hand tools with reliable leak tight results

  • Extensively tested and proven to protect against indirect lightning strikes when bonded according to manufacturer's recommendations and local codes

  • ANSI LC 1 compliance for all CSST piping

  • All CSST sold in the USA is made in the USA

With over 750 million feet installed in over 5 million homes, CSST has an outstanding safety record. When you compare CSST to black iron pipe, it is clear that the safest and best gas piping choice is a CSST system.

20 Years of Safety

As the only gas piping technology approved by ANSI and other national standards, Corrugated Stainless Steel Tubing (CSST) has been installed in millions of homes with an outstanding safety record.