After the Federal Aviation Administration (FAA) increased safety requirements across the country, the San Francisco International Airport (SFO) came across several obstacles in moving their runways to comply with the changes. One of the obstacles they encountered - moving their industrial wastewater treatment and storm water pipes - provided an opportunity for the engineer to construct more sustainable infrastructure.
The pressurized industrial wastewater pipe was specified as ductile iron or PVC. All fittings for the project were specified to be epoxy-coated and cement mortar-lined per AWWA C210 and C104 minimum requirements. But the applicator, Mobile Pipe, suggested the life-cycle of the fittings could be extended by lining it with an abrasion- and chemical-resistant coating to withstand the intense pressure of the system. The engineer was presented with the performance criteria of Tnemec’s Series 431 Perma-Shield PL and, after comparing it to an “equivalent” ceramic novolac coal-tar epoxy, decided its superior mechanical properties made it the clear choice for the fittings.
“Mobile Pipe was very excited to get an alternative lining choice,” said Tony Hobbs of TPC Consultants, Inc. “They were confident Perma-shield PL would apply well and perform better than other linings they had used in the past.”
Series 431 is in a league of its own when considering its tensile strength and its abrasion resistance. Its adhesion is also a step up from alternate linings. Plus, Series 431 has been tested extensively in wastewater environments and is formulated to protect ductile iron and steel pipe from MIC and H2S gas permeation.
“Once the engineer decided on Series 431, we shipped the lining directly to Mobile Pipe to be lined in-shop,” explained Hobbs. “There were over 150 ductile iron pieces to be coated, ranging from 4-30 inches.” The fittings of all sizes, including elbows, reducers and tees, were prepared in accordance with NAPF 500-03-05: Abrasive Blast Cleaning of Cast Ductile Iron Fittings, and then the lining was spray-applied using a rotary coater pistol spray gun. Series 431 was applied at 40-50 mils dry film thickness (DFT).
The pipes and fittings for the industrial wastewater line were completely installed by mid-2013. All of the lined fittings were compliant to California’s strict VOC regulations and the airport itself is now within the regulations of the Federal Runway Safety Act (FRSA) and the FAA.
Known as the “Gateway to the Pacific,” SFO is the Bay Area’s largest airport and connects with more than 74 cities in the U.S. and 31 international points. The airport was recently voted gold winner of most “Eco-friendly ‘Green’ Airport” by Travel Weekly and last year was awarded “Best Airport in the Americas” by the readers of Frequent Business Traveler.