Chemical Engineering October 2016 - 51

Administration building. The only
piping typically found in an administration
building would be considered
plumbing, which is outside the scope
of the ASME piping codes. Compliance
plumbing codes for such a facility
will be either the International Plumbing
Code or those written or adopted
and codified by the governing jurisdiction
where the facility is located.
Modifications, repairs, retrofits
ASME B31.3 paragraph 300(c)(2)
states the following: " This Code is
not intended to apply to the operation,
examination, inspection, testing,
maintenance, or repair of piping that
has been placed in service. The provisions
of this Code may optionally be
applied for those purposes, although
other considerations may also be
necessary. " In making that statement
the code is, in fact, acknowledging
that while it can be, and most
certainly is used for guidance and
contractual directives for piping that
has been or is in-service, there are
indeed fitness-for-service (FFS) considerations
that need to be assessed
(for instance, corrosion or erosion to
the pipe wall, pitting, under-insulation
corrosion, localized dynamic pressure
impacts, and so on). A topic
such as FFS is too broad to cover
here, but details can be found in API
579-1/ASME FFS-1 - Fitness-forService
standard for guidance.
Before continuing with this topic
it must be understood that this discussion
goes beyond the scope of
B31.3. As with this entire article, any
guidance or stated recommendations
within this brief section are also
those of the author and are not those
of any particular code.
The more complex issue of FFS
aside, explicit code requirements,
when it comes to making modifications,
repairs or retrofits to in-service
piping systems, are not just a little
vague, they are non-existent. Determining
how the more current code
requirements should blend with an
existing system that was designed,
constructed and installed in accordance
with an earlier version of
perhaps the same code is left to
the user. This intentional avoidance
in the code, of providing guidance
or recommendations with regard to
Are there fluid services other than
the following?
Water for heating and cooling
Condensing water
Steam and other condensate
Other nontoxic liquids
Steam
Vacuum
Compressed air
Other nontoxic, nonflammable gases
Combustible liquids, including fuel oil
No
Are there piping materials other
than the following?
Carbon steel: NPS 30 and 0.500 in. wt
Stainless steel: NPS12 and 0.500
in. wt
Aluminum: NPS 12
Brass: NPS 12
Copper: 12.5 in. OD copper tubing
Thermoplastic: NPS 14
Ductile iron: NPS 18
Reinforced thermosetting resin: 14 in.
Materials per B31.9 Chapter III
No
Are there fluid service pressures
that exceed the following?
Steam and condensate: 150 psig
Liquids: 350 psig
Vacuum: 1 atm external pressure
Compressed air and gas: 150 psig
No
Are there fluid service temperatures
that exceed the following?
Steam and condensate: 366oF
Other gases and vapors: 200oF
Other nonflammable liquids: 250oF
Minimum temperature of 0oF
No
Is there boiler external piping that
exceeds the following conditions?
For steam boilers, 15 psig max
For water heating units, 160 psig max,
and 250oF max
No
Consider ASME B31.9
Building Services Piping Code
Consider ASME B31.1
Power Piping Code
FIGURE 7. A decision tree for determining the piping code required
working with or connecting to existing
piping systems, is in keeping
with its scope. The question then
becomes how to properly reconcile
the transitional interface of the old
system with that of the new piping
and equipment while still maintaining
the essential elements of the code.
In other words, it is an attempt to follow,
not the word of the code, but
rather its philosophical intent. That is
therefore the intent of the following.
The first step when modifying, repairing
or retrofitting a processing
system that has been in operation
for a period of time, is in understanding
the following: so long as the operating
or design conditions have not
changed, or the piping modified, the
designated code under which the
original design, fabrication and installation
were performed can remain in
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OCTOBER 2016
effect. Only those segments of piping
to which a tie-in (TI) connection is
made or a piping segment otherwise
modified to the extent that the pressure
containing integrity of that segment
of piping has been altered, will
need to comply with the most current
B31.3 piping code.
In making the assumption in the
following example that all operating
and design conditions will remain
unchanged with regard to a modified
existing piping system, all unchanged
piping will remain under the same
earlier issue of the code under which
it was designed, fabricated and installed.
However, when modifying,
repairing, or otherwise tying into an
existing piping system, the following
guidelines are recommended:
* At the tie-in interface point when
connecting new piping to an
51
Yes
Is there boiler external
piping?
No
Yes
Can design temperatures
be the result of chemical
reaction?
Yes
Yes
Can design pressure be the
result of chemical reaction?
Yes
ASME B31.3
Process Piping Code
Yes
Yes
Can a large percentage of the
fluid services be considered
process chemicals?
Yes
Will a large percentage
of the piping materials be
considered for use in process
chemical service?
Yes
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