It was supposed to be a simple dedication of a $6.7 million firehouse in Tacony, Philadelphia's first in 15 years.
Suikang Zhao had journeyed to the event from New York to explain his artwork, which honors the Fire Department and the Disston Saw Works, the company that built Tacony.
Fourth and fifth graders from Planet Abacus Charter School, wearing red baseball caps identifying them as members of the Junior Fire Patrol, waited for their chance to help push a fire engine into its parking spot, the traditional way of welcoming a new station.
But the rancorous relationship between the city's firefighters and Mayor Nutter soured Tuesday's celebration. Hundreds of firefighters booed city officials and chanted, "Recall! Recall!"
They are angry because Nutter has repeatedly appealed binding arbitration awards he says are too costly.
"Binding is binding. Respect the men and women of the Philadelphia Fire Department, the men and women who go to work each morning not knowing whether they are going to go home at night," said Bill Gault, leader of the Philadelphia firefighters union.
Plans to transfer experienced firefighters to new firehouses also have riled union members.
Each firehouse is like a family, said Amy Smialowski, who is married to a firefighter, and "they are ripping these families apart." Her friend Al Iavecchia carried a sign that used the letters of the mayor's name as inspiration. It read:
Union members glowered at Nutter, walking out when the Rev. Joseph L. Farrell, a priest at St. Leo Roman Catholic Church, began the ceremony with the Our Father. Many protesters said the prayer but stressed "Deliver us from evil," apparently for Nutter's benefit.
Tacony's previous firehouse was knocked down in 2009 to make way for an I-95 ramp. Funds for the new facility for Engine Company 38 came mostly from the city's capital budget, with Pennsylvania contributing $2 million.
It is Philadelphia's first "green" firehouse, with grass on the roof and other environmentally friendly features, and it includes a community room available for public use.
Nutter did not take the firefighters' bait. He thanked union leader Gault and said he respected the right to free speech.
The children from Planet Abacus, he said, got an unexpected lesson in the Constitution.
"This is a very different kind of civics lesson - very participatory," Nutter said.
As history was being made in Tacony Tuesday, Zhao described how he spent weeks researching the pasts of the Fire Department and Disston Saw Works.
His installation includes a fire hydrant, hose, and other truck equipment that he hopes children will play on. Zhao also set several bronze panels into the concrete that depict axes, the original Tacony firehouse, and other department symbols.
As people wind through the concrete path outside the station, they stumble upon pieces of Zhao's work, such as an old model of a Disston blade.
"It's very subtle and it's not monumental. Some stuff you don't see. You have to discover it," Zhao said.
The sculpture that comes closest to a monument is a replica of a Disston saw, with artfully carved wood handle, cutting a log.
"They are so famous for this saw," Zhao said of Disston, founded in Tacony in 1840. At its height, the company employed 8,000 people. Competition eventually hurt Disston. R.A.F. Industries owns it now, operating it as Disston Precision. It employs about two dozen.
But there was a time when Disston was Tacony. Founder Henry Disston built row after row of twins for his workers.
"You see the smaller homes, and then the bigger ones on the corner were for the foremen," said Lt. Peter Garvin, a member of Engine 38, which operated out of another firehouse in the Northeast for three years. He grew up in Tacony but has since moved north.
Zhao, who is from Shanghai, was fascinated by all he learned about Tacony and Philadelphia. Unable to imagine the Chinese government allowing such a demonstration, he shook his head and smiled.
"That," Zhao said, "was such a performance."