HYMAX COUPLING – San Francisco bay area (SFWPS)

Falling debris from the sinkhole damaged the cast iron pipe that had been originally installed almost a hundred years ago.

San Francisco Water Power Sewer (SFWPS) is responsible for providing drinking water and sewer services to 2.6 million residents of the greater Bay Area and its associated industries. Service was disrupted when underground repairs on subway tunnels collapsed a road, damaging a 100 year old main pipe.

The pipe had a pressure rating of 300 psi. Repairs required a coupling able to handle this high water pressure. Richard Gonzales supervises construction, maintenance and operations for SFWPS. On behalf of the city’s public utilities commission he oversees the Water Department and High Pressure Fire System.

Incorporating the HYMAX couplings allowed Richard’s team to complete repairs without having to remove and replace six lengths of cast iron pipe. Instead, only damaged lengths were removed and new pipe connected on either side with HYMAX couplings. The alternative, replacing entire sections, could have taken the team weeks. Instead, re-establishing the mains supply and repairing the subway tunnel collapse, was completed in a matter of days.


Instead of having to remove and replace six lengths of cast iron pipe, Gonzales’s crew was able to replace only damaged sections with new sections of pipe connected on either side with HYMAX couplings.

Richard chose the 12” HYMAX coupling because it allowed the team to work efficiently, repairing the mains supply and the street, with minimal costs. The HYMAX coupling provided three major benefits for SFWPS:

– Strength: 12” HYMAX couplings are manufactured to a 350-psi pressure rating. This high pressure tolerance was essential to the project’s     success “No other coupling handles the high water pressure.” said Richard. “Without the HYMAX expenses would have skyrocketed, from     labor to paving material costs, and we might have had to de-energize power lines, disrupting utilities.”

– Dynamic Deflection: The Bay Area is seismically activity. The HYMAX provides four degrees of dynamic deflection on each side,      accommodating pipe movement while maintaining a tight seal and reducing the risk of future breaks.

– Ease of Installation: The HYMAX coupling features two top-facing bolts, giving Richard’s team easy access to tighten the coupling. This was  essential as utility lines for telephone and power ran alongside the pipe. “Without the top-facing bolts,” said Richard, “it would have been impossible to close the coupling with the utility lines running alongside it.”

SFWPS and its customers can be happy with the project outcome: they now have a coupling built to accommodate the high pressure of the mains system; the repairs were completed efficiently with minimal impact on traffic, and utilities; the coupling’s top-facing bolts allowed installation in a space that would have been inaccessible with typical bolt connections; and the dynamic deflection capacity ensures that the installation will last even in the face of seismic activity.