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Here you will find
our frequently asked questions. If you don't find the
answer to your question, please feel free to
contact us.
Why do accidentally frozen pipes break?
So why won't Cryostop™ International's process cause an expansion break?
Don't the extremely cold temperatures cause
damage to my pipe or alter it in some bad way metallurgically?
Its just a chunk of ice. Why won't it blow out when we cut the pipe?
How much pressure will the Cryostop™
freeze plug hold?
If this is so safe, why won't Cryostop™ International
Cryostop™ freeze plug
over a joint weld or simple dent?
What aspect of Cryostop™ freeze plug makes pipe defects a concern?
So what are the mechanical hazards?
Why such an involved job procedure and rigorous safety monitoring?
Why do accidentally frozen pipes break?
Numerous scientific studies have proven that frozen pipes break
when ice is uncontrollably formed inside the pipe near to a
dead-end or closed valve. As the ice forms, it seals off the
pipe I.D., and then expands longitudinally, along the center
axis of the pipe, pushing on the trapped water. This push causes
the pressure to rise in the entrapped unfrozen water area until
it reaches a level that the pipe can no longer hold. The pipe
then sometimes breaks. Highly involved testing has shown that
radial expansion of the ice plug does not come close to exerting
enough stress on normal piping systems to cause failure.
So why won't Cryostop International's process
cause an expansion break?
CRYOSTOP International doesn't freeze plug up against a dead-end
and if necessary we install pressure relief equipment to monitor
and control the internal pressure of the fluid.
Don't the extremely cold temperatures
cause damage to my pipe or alter it in some bad way
metallurgically?
No. In fact there are types of steel that are "heat treated"
to improve their performance properties by cryogenically
quenching them. Extensive strain gauge, metallurgical and
mechanical measurement studies by independent laboratories have
shown that no permanent damage or deformation occurs with
Cryostop™ freeze plugging.
Its just a chunk of ice. Why won't it
blow out when we cut the pipe?
First, ice has an amazingly high adhesion to steel (you've
witnessed that if you've ever tried to chip ice from steel
surfaces in the winter). This, combined with friction of the
long ice plug inside the irregular surface of the pipe would be
enough to assure the plug isn't going anywhere. Additionally,
Cryostop™ freeze plugs lock themselves in place due to a
phenomenon known as "hour-glassing". As the Cryostop™ freeze
plug begins forming, the pipe cylinder being chilled temporarily
elastically reduces in diameter at a localized area inside our
equipment. The Cryostop™ freeze plug then conforms to this
shape, having large ends on either side of a narrower middle.
This dimensional change of the pipe is small and only lasts as
long as CRYOSTOP International maintains the Cryostop™ freeze
plug. It is one of the reasons why Cryostop™ freeze plugs can be
used to hold back thousands of pounds of line pressure.
How much pressure will the Cryostop™
freeze plugs hold?
How much pressure will your pipe hold? A "high pressure"
Cryostop™ freeze plug will hold even when pressure behind it is
raised to cause stresses greater than 100% SMYS of the pipe. In
fact, full scale laboratory tests even discovered that the
Cryostop™ freeze plug locked into a severely damaged pipe held
these over-stresses, for reasons that are just now being
understood.
If this is so safe, why won't CRYOSTOP
International freeze plugs over a joint weld or simple dent?
Cryostop International is a safety-driven company. We know
that Cryostop™ freeze plugs are a well engineered procedure with
large safety factors built into it. We don't want to use up any
safety factor unnecessarily. Welds, dents, gouges, scrapes,
corrosion pits and the like often hide dangerously weakened
spots in pipe -- these are the spots where leaks occur. That's
why CRYOSTOP International's pre-job inspection of your pipe is
so important. We will work with customers that absolutely must
Cryostop™ freeze plug over a welded joint or known defect, but
it won't be easy and the customer should consider a mechanical
line stop offered by our sister company, Proactive Maintenance
Industrial Services.
What aspect of Cryostop™ freeze
plugging makes pipe defects a concern?
Although Cryostop™ freeze plugs may temporarily increase the
tensile and yield strength of your pipe by as much as 100%, the
pipe is quite brittle inside the Cryostop™ freeze chamber during
the procedure. If your pipe is damaged enough so that it's just
about to fail at room temperature, while its being worked on
there is an unknown degree of hazard.
So what are the mechanical hazards?
Impact, water hammer, pounding on or jerking the pipe around
at the Cryostop™ freeze plug location. Again, these are not
quantifiable hazards but it is obvious that temporarily
super-cooled pipe shouldn't be abused with impacting stresses.
This is why CRYOSTOP International insists on things like: (a)
locating the Cryostop™ freeze chambers back away from your work
location; (b) absolute securing of the pipe if its going to be
opened or cut, and; (c) if feasible separate bell holes for the
Cryostop™ freeze plugs and your work site if the job is on
underground piping.
Why such an involved job procedure and
rigorous safety monitoring?
It's that safety-driven CRYOSTOP International philosophy
again. Perfect execution of a job equals perfect and safe
results. CRYOSTOP International knows the hazards of handling
cryogenic liquefied refrigerants and we take prudent precautions
to assure a safe jobsite. That's why we insist on such a large
safety perimeter on a jobsite. We're concerned about your safety
too.
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