manager, Chalmers and Kubeck, says.
However, sometimes the damage isn’t
visible. Also, McCoy warns that cast-iron
bodies may be strong, but they are not
immune, even when the temperature gets
nowhere close to the melting point. “In
real hot fires the cast iron and ductile
iron need to be replaced because they are
going to be brittle,” says Bohannon.
Also, if water hits it, the iron may crystallize.
Meanwhile, valves with steel bodies
will require Brinell hardness testing to
determine the stress relieving exposure
that may have been experienced. If they
pass the test, they can usually be reused,
and while repair work is going on in the
shop, cast iron hand wheels and yokes
can be replaced.
As with floods, actuators caught in
fires tend to sustain more damage than
valves, and will usually need to be
replaced. Again, visual inspection can
provide a rough estimate of the temperature exposure. For example, if the positioner is an aluminum body with some
plastic on it and “the plastic’s melted but
BLAST DAMAGE
A sufficiently large explosion takes out
everything, including the valve and the
actuator and can have some pretty
astounding effects. For example. “I’ve
seen big … 4x6 relief valves that have
just been sliced in half from the sheer
force of the blast,” says Roubik. In cases
like that, he says, “Engineering usually
comes in and redesigns or reconfigures
that part of the plant. They just haul it off
for scrap and rebuild it.”
In a smaller explosion, “you’re proba-
bly going to have broken yokes and bent
stems. There may not be any other dam-
age; the valve body itself is probably
going to be in pretty good shape,” Roubik
comments. Such situations require a
physical inspection of those devices to see
if there’s any damage with line stresses.
“If the piping has been blown away or
bent, then chances are your valve is pos-
MSS Publishes Comprehensive Pipe Hanger Standard AdCompFA 12/16/09 10:47AM Page 1
the aluminum is still there, you can know
you’re within a certain temperature
range,” Bohannon says.
stresses [and] the bolting stresses,” he
says.
RESOLUTION
One could make a pretty good argument
that a flood is worse, economically, than
an explosion or fire. While less likely to
cause injuries or death, floods generally
affect an entire region, which means
wider competition for people to repair the
damage. And a flood is likely to affect an
entire plant, not just the parts under
water.
What’s more, “If it catches [plant
operators] by surprise,” says Bohannon,
“then they’re going to have issues other
than the stuff that’s been exposed to ris-
ing water—upsets in their process, relief
valves that are blowing, flares that are
flaring. They will be trying to get [the
plant] shut down in a safe manner with-
out blowing the whole facility up.”
Another difference is the time it
takes to resolve matters, Bohannon
adds. Fires and explosions trigger inves-
tigations, which take time. “A large
explosion will have an investigation
The Manufacturers Standardization Society of the Valve & Fitting Industry
SP-58-2009,“Pipe Hangers and Supports- Materials, Design, Manufacture, Selection, Application and Installation”, has recently been published by MSS. This comprehensive Standard Practice combines all of the content of five Pipe Hanger and Support standards into a single document. MSS SP-58-2009 will serve as a “complete guide” for pipe hanger and support design, manufacture, selection, and installation.
The document includes all of the information from ANSI/MSS SP- 69,“Selection and Application”; MSS SP-77,“Guidelines for Pipe Support Contractual Relations”; MSS SP-89,“Fabrication and Installation Practices”; and MSS SP-90,“Guidelines on Terminology for Pipe Hangers and Supports”.
For further information on MSS standards, contact MSS at 703/281-6613, or visit the MSS website at www.mss-hq.com.
