CPVC Fire Sprinkler Systems Proven to Outperform Steel When an Earthquake Strikes

A fire sprinkler system offers little or no benefit if it doesn’t remain intact when an earthquake strikes.  This harsh reality has been the basis for a number of states adopting new provisions of the International Building Code (IBC) to address the installation of fire sprinklers in seismic zones.

Now, a new report confirms what field results had previously proven – that a fire sprinkler system made of CPVC is more likely to perform reliably during and after an earthquake than a steel system.   It was Wiss, Janney, Elstner Associates, Inc. (WJE), a nationally renowned engineering, architectural and materials testing company that conducted the test and reported the results.  With more than 50 years in the business, 400+ professionals and 19 offices nationwide, Chicago-based WJE is a recognized leader in both product testing and specification.

Proven Results in the Lab
WJE specifically tested the performance of BlazeMaster® CPVC pipe and fittings and compared it to the performance of steel pipe (1-inch in diameter) using cyclic loading.  Steel schedule 40 fire sprinkler piping was tested separately following the same procedure. 

The test setup consisted of suspending the piping from dimensional lumber connected to steel framing, which was anchored to the structural lab floor.  Pipe support hangers were spaced 6 ft. for each pipe.  The test configuration consisted of installing 1-in. diameter BlazeMaster CPVC pipe in a Z-shape with two 90-degree connections to the test framing.  Steel pipe 1-in. in diameter was assembled independently in the same design configuration. 

The hangers on one side of the framing were positioned and connected to the wood members such that this section of the piping was allowed to slide during loading.  The pipe was filled with water and pressurized to 175 psi before the start of each test.  Displacement of the pipe was controlled using a hydraulic actuator.  A load cell was in-line with the actuator and pipe to measure the force required to move the pipe.

Both types of pipe were displaced a maximum of +3 in., or a total displacement of 6 in, during which time the connections were monitored for water leakage.  The actuator moved at a frequency of 0.04 Hz (or approximately two cycles every 50 seconds) for a period of nearly 20 minutes. 

After 50 cycles, the BlazeMaster CPVC system remained uncompromised.  Failure did not occur at the elbow connections or along the pipe length.  And, the pressure remained at 175 psi throughout the test.

In contrast, the steel pipe failed at a 90-degree elbow after approximately 33 cycles of +3 in. of displacement.  The failure not only created a loss in pressure but also caused water to spray out of the joint connection.   Upon careful analysis, it was determined that a fatigue failure had occurred at the elbow threaded connection.

Proven Results in the Field

Although this was the first time that a BlazeMaster CPVC fire sprinkler system had officially undergone cyclic testing by a third-party organization, it was not the first time that the system had actually been put to the test   Back in 1986, BlazeMaster CPVC was already proving that it could endure significant seismic activity without any type of service interruption.

It was October 10, 1986 at 11:00 AM when San Salvador (El Salvador) suffered a devastating earthquake lasting seven seconds that measured 7.5 on the Richter Scale.  This magnitude qualified it as a “major” earthquake, according to the National Earthquake Information Center (NEIC).   Based on observations documented since 1990, there are roughly 17 such “major” earthquakes that occur across the globe in one year.  Unfortunately for the U.S. embassy located there, the earthquake’s epicenter was in close proximity.

Overall damage was sizable.  There were thousands of casualties.  At least 200 buildings in San Salvadaor were destroyed or severely damaged, including many of the buildings on the U.S. embassy complex.  The five-story chancery was one of the hardest hit and had to be immediately abandoned.  The force of the tremor was so severe that a number of one and one-quarter inch thick steel reinforcement bars embedded in the building’s concrete support columns were bent into the shape of a pretzel.

Despite all the damage, the recently retrofitted BlazeMaster CPVC fire sprinkler did not fail.  Post-earthquake assessment determined that the entire system substantially stayed on-line without any leaks and would have suppressed any fire in the complex caused by the earthquake.  Not only did this mean continued safety for the workers, but it also turned out to be a reliable source of drinking water.  Due to the complete failure of the municipal water supply, the sprinkler water supply became a readily available and convenient source of water for domestic use.
As a result, the U.S. Department of State Embassy Buildings reported that the non-metallic BlazeMaster CPVC sprinkler pipe had performed “admirably” during this major earthquake, especially considering that the main building had suffered severe damage and all other HVAC and plumbing systems were totally destroyed.

Changing Codes
Through the years, building codes have become increasingly more demanding with regard to the installation of fire sprinkler systems in seismic zones.  This is partially due to the fact that the 1990s saw a pronounced increase in both the frequency and intensity of earthquakes compared to earlier decades. 

The NEIC, in fact, estimates that there are literally several million earthquakes that occur in the world each year (although many go undetected because they hit remote areas or they have a small magnitude).  In the U.S. alone, thousands of earthquakes are documented each year.

In response, the 2007 edition of NFPA 13 was changed significantly with regard to earthquake protection.   NFPA 13 has included provisions for the protection of sprinkler systems against earthquakes since 1947, a time when many building codes didn’t even address the subject.

But the greatest code changes have occurred over the past 20 years due to funding provided from the Federal Emergency Management Agency (FEMA).  The objective is to maintain the ability of the sprinkler system to manage post-earthquake fire hazards and prevent significant water damage that can occur from sprinkler-system ruptures in an otherwise undamaged building.

The more significant changes to the 2007 edition include the need for four-way bracing on piping within six feet of both sides of the seismic separation assemblies; limitations on the maximum load per lateral brace; new spacing requirements between the last lateral brace and the end of a pipe being braced; restraint of branch lines; and the need for additional hangers.

These new changes bring the NFPA 13 standard fully in line with the latest thinking of the earthquake experts.  In fact, the 2007 edition of NFPA 13 was unanimously approved as “deemed to comply” with the seismic requirements of ASCE/SEI7 without exception at the IBC Structural Committee Hearings in Orlando in the fall of 2006.

Unfortunately, many of these changes have occurred so quickly and recently that it’s difficult for engineers and AHJs to stay abreast of the most current criteria.  That makes tests such as the one conducted by WJE much more important, although the real test is how the system performs in the real world, such as the scenario in San Salvador back in 1986.

Not only has the BlazeMaster CPVC fire sprinkler system proven itself worthy in both the lab and the field, but it also meets all of the criteria set forth by the 2007 edition of NFPA 13.