At the U.S. Department of Energy/National Nuclear Security Administration’s (DoE/NNSA’s) Pantex Plant near Amarillo, Texas, a leak in the water piping can be a matter of large-scale life or death.
Melvin Suttle, the high-pressure fire loop system engineer at BWXT Pantex, the plant’s management and operating contractor, noticed pipe breaks due to corrosion of the cast and ductile iron system (first installed in the late 1940s). The 24,079-m (79,000-ft) long high-pressure fire loop is a dedicated water distributor feeding fire suppression systems, which can be seriously compromised by a bad break.
In August 2001, he specified 18.3 m (60 ft) of high-density polyethylene pipe for extending a system requiring 19 m3 (5000 gal) per minute and 18 kg (40 lb) of residual pressure.
“Back then, the product was brand new to us,” Suttle said. “It’s performing very well. And knowing what I know about HDPE pipe now, I’m sure we’ll never have to see that 60-foot section of pipe again.”
Today, Pantex has about 1189 m (3900 ft) of HDPE installed for the high-pressure fire loop, and a phased plan to replace an additional 15,240 m (50,000 ft) with the material. However, the transition required numerous steps and hurdles before Suttle received his approvals.
“My impression is HDPE pipe was viewed by some site engineers as low-quality material to be used for temporary service,” he says. “I worked with my management to have vendor demonstrations on site. This was no small task due to site security. I also collected all the vendor data I could find using the Internet extensively, conducted visits to municipalities and observed [other materials] and talked to several installers.”
Since the high-pressure fire loop is considered ‘safety-class,’ any proposed changes must be defined, described, and proven to meet the operating requirements of the system. In fact, a DoE engineer objected to the use of HDPE pipe before Suttle proved the material was listed in National Fire Protection Association (NFPA) 24, Standard for the Installation of Private Fire Service Mains and their Appurtenances.
Suttle was also able to successfully argue the HDPE pipe material would be a strong environmental choice, as its fused joints minimize the possibility of contaminants leaching into the water supply. HDPE was also ideally suited to the horizontal directional drilling (HDD) installation needed to run the pipe under two railroad tracks, a roadway, and a security corridor.