BOILERS HEAT UP THE GRIDIRON - At Cleveland Browns Stadium - Rehau
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Technical Journal of The National Board of Boiler and Pressure Vessel Inspectors FALL 2010 BOILERS HEAT UP THE GRIDIRON At Cleveland Browns Stadium Browns Facility Manager Neal Pate and Director of Facilities Bob Schmitz
COVER STORY
Turf Conditioning Systems
A Unique Application of Modern Boiler Technology
PHOTOS BY GREG SAILOR & REHAU
Systems like State-of-the-art turf conditioning systems are in- The goal of natural turf is to provide profes-
Cleveland's give sional athletes safer and softer playing surfaces.
stalled in over 15 NFL stadiums across the United
Turf conditioning systems enable stadiums in cold-
field managers
States. At the heart of the systems are boilers that weather climates to maintain green, healthy fields
control over live
well into late December and January.
turf to ensure safe feed warm fluid through miles of tubing just inches
Stadiums in Germany and other European
playing conditions beneath natural playing surfaces. Heat radiates countries began using turf conditioning systems in
year-round. through the soil to keep fields at desired tempera- the 1980s. North American stadiums picked up the
trend in the mid-1990s. Cleveland Browns Stadium,
tures at the root zone level. This prevents grass from then newly constructed, was one of the first in line
going dormant and extends the growing season. to install the system.
18 NATIONAL BOARD BULLETIN/FALL 2010 www.nationalboard.org
COVER STORY
Courtesy of REHAU
Beneath the Browns’ gridiron is 40 miles of 3/4-inch crosslinked polyethylene (PEX) tubing
Cleveland Browns Stadium opened its doors access on their smartphones)—all the way down
in 1999, replacing Cleveland Municipal Stadium, to the very roots in the soil.
which operated from 1946-1995. In keeping with
tradition, the new stadium was built on the same Boilers Behind the Browns
Lake Erie shoreline as its predecessor. The field Beneath the Browns’ gridiron is 40 miles of
still runs east to west and the Dawg Pound re- 3/4-inch crosslinked polyethylene (PEX) tub-
mains on the east side of the stadium. ing. The tubing is fed by nine boilers through 19
If the newly built Browns Stadium was pumps. The system also includes 1,600 feet of
robed in rich tradition, it’s certainly crowned supply/return manifold header piping, 2,460 feet
with 21st century technology—from architec- of distribution tubing, and an advanced controls
tural “gaps” providing soaring views, specially system. The 3/4-inch tubing holds about 0.0189
designed lighting, high-resolution ProStar Vid- gallons per foot—over 4,000 gallons of fluid (a
eoPlus display boards, and a recently installed biodegradable water/propylene glycol solution)
phone substation (providing 70,000 guests fast fill the tubes under the field.
www.nationalboard.org NATIONAL BOARD BULLETIN/FALL 2010 19
COVER STORY
Piping Schematic
ZONE 1 ZONE 2 ZONE 3 ZONE 4
BOILER BOILER BOILER BOILER
Air Separator
Optional Backup Pump
BOILER BOILER BOILER BOILER BOILER
The boiler room is located at field is very good—we have a known unit that
level just inside the tunnel where Browns has been in operation for 47 years now.”
players enter the field. Nine Ajax Ace Terry’s late father, Ed Cancilla, pur-
B15 Series 'G' boilers dominate the space chased the company in 1967. In 1969 he ABOVE: Piping schematic of
like ready linemen. Each boiler is rated patented the innovative self-supporting Browns' boiler system.
at 36 BHP and 1,500,000 Btu/hr, has a copper cone coil, which solved the problem
maximum allowable working pressure of sagging coils and extended the life of coils
(MAWP) of 160 psi, and contains a pat- by decades. Currently, Ajax manufactures
ented, self-supporting copper fin coil. three brands of boilers used for commercial RIGHT: Partial shot of boiler
Safety relief valves are set at 125 psi with and industrial applications. area. Note orange inspection
a relieving capacity of 1,700,000 Btu/hr. The Ajax boilers were installed in stickers and state operating
Jane Terry, president of Ajax Boiler Browns Stadium in 1999 and are still going certificates (foreground). The
Inc. of Santa Ana, California, explains strong. “One interesting thing Bob Schmitz State of Ohio requires an
why this series was the right system for (director of facilities, Cleveland Browns annual inspection.
the job. “The customer specified want- Stadium) told me is that the boilers are
ing commercial grade boilers with a used only part of the year, but they start
long-standing reputation for consistent up like new every time. And that is a good
operations and good value over years of thing,” says Terry— a good thing for Ajax
service. Our reputation for these boilers and the Browns.
20 NATIONAL BOARD BULLETIN/FALL 2010 www.nationalboard.org
COVER STORY www.nationalboard.org NATIONAL BOARD BULLETIN/Fall 2010 21
COVER STORY
LEFT: Installation of PEX
tubing (white) to main
manifold (black) at Browns
Stadium.
RIGHT: Close-up look at the
manifold. Also shown are
the fixing rails.
Photos courtesy
of REHAU
Pure Engineering appear to be the leader in this area,” says Bill
The Browns’ radiant heating system Johansen, business unit manager, building
was designed by REHAU, an internation- technology at REHAU’s North American
al provider of polymer-based innovations headquarters in Leesburg, Virginia. Johansen
and systems in construction, automotive, was directly involved with the Browns’ heat
and industry. REHAU has participated transfer system.
ABOVE: Tubing connections
in more than 160 stadium turf heating “Cleveland Browns Stadium was an in-
to the manifold.
systems in Europe. teresting business and engineering case for us.
“Cleveland was our first stadium We worked with Paul Franks (field contrac-
in North America, although we had tor), Populous (design group formerly known
done different types of turf conditioning as HOK Sport Venue Event), and others to
(greenhouse applications) prior to that. come up with a properly engineered system.
REHAU Europe has done dozens of We got to know the world of sports turf sci-
German football (soccer) fields and they ence a little better through the process.”
22 NATIONAL BOARD BULLETIN/fall2010 www.nationalboard.org
COVER STORY www.nationalboard.org NATIONAL BOARD BULLETIN/fall 2010 23
COVER STORY
Johansen and staff had several objec- “Working with HOK Sports and the sideline to sideline), 10 inches of sand-
tives to meet. “We had to understand the field contractor, we gained an under- based root zone, and then the sod.
exact expectations for the operation of standing of the soil makeup, the type of It took approximately two weeks
the system, especially desired root zone grass, and the expectations for tempera- to install the tubing using two crews of
temperature and under what operating ture at the root zone. Once we had this four people. The flexible white tubing
conditions. Also, soil make-up had an information, we used an analytical tool was snapped into fixing rails to prevent
enormous impact on performance, and called Finite Element Analysis (FEA). bending and bowing while also keep-
this had to be defined fairly precisely.” This computer tool allowed us to create a ing rows straight and even. REHAU
The Browns’ heating system needed to 3-D model of the field and to define input provided the tubing and fixing rails and
keep the field from freezing but also “boundary” conditions, such as soil, sur- had representatives on hand to oversee
control grass root zone temperatures. face, and tube temperatures; soil thermal the work.
Meeting these objectives hurled Johansen conductivity; and operating parameters, Each zone has four sensors at the
into the competitive and complex realm such as weather and water conditions; 3- to 4-inch soil depth and at the 7- to
of turf science. to help evaluate heat transfer and steady 8-inch soil depth. “The sensors are simple
“We discovered that each type of state condition within the soil.” thermistors that react to temperature
grass, as well as the type of over-seeding The 3-D model also helped Johansen with a control wire that runs back to the
being used, required different design understand how the field would behave mechanical room where temperatures are
temperatures at either the root zone or given specific data and tube conditions carefully monitored,” explains Johansen.
grass canopy level,” Johansen explains. (tube size, depth in the soil, fluid tem- Neal Pate, facility manager at Cleve-
Adding to the challenge, each sports perature in the tubes, etc.). land Browns Stadium, closely monitors
field designer had a different, often “It was interesting to take this data the field. He has cared for it since the sys-
proprietary, soil construction designed back to the turf specialist, who helped tem was installed, which he remembers
to properly protect players, support the point out how our design would either well. “I literally couldn’t look at the field
type of turf being grown, and ensure accommodate their needs or not. For because it was so bright,” he says, recall-
proper drainage of fields. example, in one of our early iterations of ing the glare of the white PEX tubing.
“At that time, the NFL Players As- the field, we achieved proper root zone Pate explains that if a zone doesn’t
sociation pushed for natural turf fields. temperatures, but our tubes were not get enough sunlight, a portion of turf
There was a lot of discussion going on located deep enough to accommodate could freeze. (For example, sunlight
about real turf versus artificial. We were the aerator tines used to condition the doesn’t reach over part of the stadium’s
just heating engineers and we walked turf during the year. This pushed us roof in October.) Pate relies on setpoint
into all of this discussion—the science back to the analytical tool to determine averages to maintain a healthy lawn.
behind turf growth, liability concerns, a better design.” He inputs a desired field tempera-
and more. It was very interesting for ture (the setpoint) into the computer
us from an engineering-manufacturing A Better Design system much like setting a home ther-
point of view. A bunch of worlds came The Browns’ turf conditioning sys- mostat. Software reads the temperatures
together—it was pure engineering and tem is divided into four zones at the at the four 3- to 4-inch soil level sensors,
a lot of fun!” 50-yard line going across and down the adds them up, and divides by four to
Johansen continues. “While the sci- middle. There are 189 loops per zone and get the average actual temperature. It
ence was quite fascinating, it was also a each supply and return circuit is identical compares the average temperature to
new area for us. To help, we relied on our in length to ensure even temperature dis- the setpoint. In the boiler room, each
own knowledge and engineering expe- tribution throughout the field. Over 1,500 zone has its own pump. If the average
rience with heat transfer, but we could connectors are located at the manifolds. temperature is below the setpoint, the
also draw upon our collective experience The fitting system is REHAU’s propri- system opens the mixing valve and adds
from Europe.” etary EVERLOC® system. The fittings more hot water. Likewise, if the average
REHAU applied several analytical are stainless steel and each connection temperature is above the setpoint, the
tools to determine exactly how heat was covered with a specially designed mixing valve closes to restrict hot water
would transfer through the soil and protective barrier. from being added to the system. The
ultimately what root zone temperatures The system was installed in the fol- desired result? Well-balanced, healthy
could be achieved under various weather lowing layers: drain tiles, 4 inches of pea turf that optimizes player safety and
and climatic conditions. gravel, forty miles of PEX tubing (laid performance.
24 NATIONAL BOARD BULLETIN/Fall 2010 www.nationalboard.orgCOVER STORY Three of the four zone piping arrangements with pumps. www.nationalboard.org NATIONAL BOARD BULLETIN/Fall 2010 25
COVER STORY
Safe Turf, Good Cuts type of field (live or artificial), and even The Browns’ turf conditioning sys-
Players need both agility and stabil- weather determine the type of cleat a tem is used only a couple of months each
ity on the field. That’s why turf condition player will use. Shorter studs may be year. The fluid stays in the system year-
is critical. So critical, in fact, that in 1994 used on a hard, dry surface and longer round and doesn’t need to be drained.
the first NFL Players Playing Surfaces studs on a wet, soppier field. In any given “I may kick on the boilers in March and
Opinion Survey was conducted. Astro- game, a player could have five or six dif- slowly bring up the soil temperature to
Turf dominated NFL fields and many ferent pairs of shoes available. jump-start the grass out of dormancy,”
players believed it was an unsafe surface. Longtime kicker Phil Dawson offers says Pate. “I like to get a start over ev-
The survey is given biennially at the most feedback about field conditions. eryone else,” he smiles.
player union meetings in the fall and is “He’s the only player who’s been here Pate and crew must adapt to a chang-
completed by nearly 1,400 active play- for every season since the new stadium ing climate in order to keep the field
ers. The last survey in 2008 showed that was built in 1999. We’ve gotten to know healthy and resilient year-round, but es-
84.4% of athletes agreed artificial infilled him pretty well. And kickers have their pecially in frigid conditions. “The system
surfaces were more likely to contribute routines—footing is extremely important tricks grass into thinking it's nicer weather
to injury than natural grass fields. An to them,” Pate shares. “But if we don’t during cold months,” Pate says. “It also
overwhelming 91% agreed artificial hear anything from players and the front helps keep the field from freezing.”
turf caused more soreness and fatigue. office, it’s good.” Anytime it rains or snows three to
Of the 31 NFL teams represented on the Systems like Cleveland’s give field four days before a game, tarps are pulled
survey, 18 teams used grass fields and managers control over live turf to ensure out across the field. But tarps can also pull
13 artificial. safe, year-round training and playing moisture out of the ground. On extremely
“Beyond anything—beyond the conditions. Pate and Schmitz can’t control cold mornings this can pose a problem.
way the field looks—safety is our number the weather or the type of cleats players “There have been mornings when we’ve
one priority,” says Pate, glancing at the will use, but they do everything they can pulled back the tarps and the field looks
Browns’ field. “I want to make sure our to provide an optimal playing field for the like it’s covered in snow,” he says.
players can get their feet in the turf and Browns and visiting teams. “Sometimes people wonder why
make good cuts.” there is still snow on the field (during a
Vibrant green grass looks good to Field Goals snowy game day) but they don’t under-
thousands of fans watching from the The Browns’ field is a Kentucky stand all that goes into finding the right
stands or on TV, but Pate knows field bluegrass irrigated field with a sand soil balance. Players need to get their cleats
conditions equate to player safety. root. “The bluegrass is durable and stays into the field,” Pate adds. “They would
“The field gave them what they green, but it doesn’t grow very fast,” rather play in snow than in mud. They
needed to play the game on Saturday—it says Schmitz, “so we supplement it with can get better footing and balance.”
gave good cuts,” Pate says, referring to ryegrass.” Turf can’t be too soft or too hard, and
the August 7 practice game. Director of Pate nods. “We constantly seed the maintaining that balance from week to
Facilities Bob Schmitz agrees. “We want field with ryegrass after each game. It’s week is both science and art. Johansen
the turf to be soft enough so spikes grab used as a supplement to add density to agrees. “A lot of science goes into run-
into the ground, but not so soft that the bluegrass and fill in any thin areas ning a field."
they’ll slide.” on the field,” he explains. Pate re-sods With over 40 miles of tubing buried
Schmitz says two common ways patches of turf on an as-needed basis. The beneath the field, detecting problems
players sustain injury are directly related section between the hash marks and goal (such as leaks) is tricky. Pate can measure
to field conditions. “If the field is too hard lines is replaced mid-season. fluid levels with the sensor system and
and a player makes a quick stop, there’s According to Pate, after a Sunday narrow a problem down to a specific
a chance his spike won’t grab and he can game the field looks “beaten up” until zone, but pinpointing the exact location
slip. If the grass is too soft and gives way about Wednesday. That’s when new is a matter of good guesswork—and dig-
when he stops, there can be injury.” grass begins to spring up. “The bluegrass ging. Tubing is accessed only by stripping
Turf and cleats go hand in hand. doesn’t like this heat. This has been the back the sod and digging through 10
“The players have jars of cleats, all dif- longest recovery we’ve had in quite a inches of root zone soil.
ferent sizes, to choose from. Each player while,” he says, referring to sweltering A leak was detected after the first
determines how he wants his shoes,” August heat combined with wear and tear season in the new stadium. “We tried
says Schmitz. The position of the player, from the recent practice game. many ways to locate it. We narrowed it
26 NATIONAL BOARD BULLETIN/Fall 2010 www.nationalboard.orgCOVER STORY
The completed field, ready
for game day.
down to a few areas and literally dug along Players want and prefer the benefits would likely sustain more injuries and
until we found it. Luckily we haven’t had of natural turf, but maintaining a suitable professional football would not be what
any leaks since then,” says Pate. and safe gridiron for professional athletes it is today.
Browns Stadium is multi-functional is a bit more challenging than opening up As technology in turf conditioning
and hosts other sporting events (such as in- pasture for grazing cattle. Professional progresses, Johansen believes advances
ternational soccer), concerts, and more. The playing fields endure hit after heavy hit in turf/soil engineering and in drain-
field is able to bear the loads of forklifts and year-round. Cleveland’s field sustains age of fields will lead the way. Pate
cranes for venue setup. Fifty-ton cranes, such action as the Browns clawing out says “stitching” procedures, a process
two at a time, put down pressed plastic victory, frigid lake-effect conditions, and whereby a machine stitches threads of
flooring for protection. Another reason turf the wear of hundreds of concert-goers artificial field material into the ground
conditioning systems are preferred is they rushing a stage. for added stability, is another option
promote faster grass resilience after the No matter the occasion, the on-field some stadiums use to obtain ideal play-
wear and tear of hosting large-scale events. action may not be as important as what ing surfaces.
is beneath it. Either way, natural playing fields are
Final Score Turf conditioning systems are a here to stay and rely upon the science of
“If a cow cannot eat it, we shouldn’t unique application of modern boiler heat transfer systems fed by robust boil-
be playing on it,” remarked one athlete technology. Without them, grass could ers—and the expertise of dedicated staff
on the 2008 NFL Players Playing Surfaces not repair itself after heavy traffic nor who maintain the turf in support of a safe
Opinion Survey. withstand year-round usage. Players and winning season.
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