Chemical Engineering October 2016 - 45

sign/build of a CPF only if a boiler
installation or modification is part of
the facility design. ASME B31.3, in
paragraph 300.1.3 Exclusions, subparagraph
(b) states that among the
exclusions are, " power boilers in accordance
with BPV Code Section I
and boiler external piping that is required
to conform to B31.1, " making
it clear that boiler external piping is
excluded from the scope of B31.3.
Therefore, if the installation or modification
of boiler external piping is
part of a project, then the rules and
compliance of the B31.1 Power Piping
Code would go into effect, in addition
to that of the B31.3 Process
Piping Code for piping other than
boiler external piping.
Boiler external piping is defined
under ASME B31.1, paragraph
100.1.2(A) as follows: " Boiler external
piping shall be considered as piping
that begins where the boiler proper
terminates at: (1) the first circumferential
joint for welding end connections;
or (2) the face of the first flange
in bolted flanged connections; or (3)
the first threaded joint in that type of
connection; and that extends up to
and including the valve or valves required
by para. 122.1. The terminal
points themselves are considered
part of the boiler external piping. "
In understanding fully the jurisdictional
limits, when the installation or
modification of a boiler and its associated
boiler external piping is at
play, and the points at which one
safety code ends and another begins,
there are two additional terms,
beyond that of " boiler external piping "
defined above, that also need
to be understood. Those terms are
" boiler proper " and " nonboiler external
piping. " These two terms are defined
as follows:
* Boiler proper is clarified in the
Preamble of the BPVC Section
I, in which it states that, " Superheaters,
economizers, and other
pressure parts connected directly
to the boiler without intervening
valves shall be considered as
parts of the boiler proper, and
their construction shall conform to
Section I rules. "
* Nonboiler external piping, in
accordance with B31.1, paragraph
100.1.2(B), " ...includes all
Boiler proper section I
Boiler external piping
section I & B31.1
Nonboiler external piping
B31.1 or B31.3
B31.1
or
B31.3
B31.3
Steam drum
Battery limits
FIGURE 2. Shown here is an example of code jurisdiction and transitioning
the piping covered by this Code
[B31.1] except for that portion defined
above [in Para. 100.1.2(A)]
as boiler external piping. " The
implication can be made that if
B31.3 is in effect for all piping
except boiler external piping, then
nonboiler external piping can also
be covered by B31.3. These are
code boundary limits that need to
be made explicit and definitive in
procedures, guidelines, scopes
of work and drawings that are
followed by those engineers and
constructors that are designing
and constructing CPI facilities.
With the three boiler terms clarified,
we can now discuss code jurisdiction
as it relates to steam generation.
In doing so we will begin at the
" boiler proper, " which, as mentioned
above, is the pressure equipment
plus its interconnecting tubing and
components that make up the boiler
package, whether preassembled or
assembled on-site. Both the administrative
jurisdiction and technical
responsibility of the boiler proper is
governed by Section I of the Boiler
Code. The " boiler external piping "
that connects directly to the " boiler
proper " is an interface or transitional
segment of piping in which the administrative
jurisdiction is governed
by the Section I Boiler Code, but
the technical responsibility is owned
by the B31.1 Power Piping Committee.
Extent of the boiler external
piping includes the joint connection
made at the boiler proper and extends
through the valve or valves as
required by B31.1 Paragraph 122.1.
While the technical responsibility
of boiler external piping is governed
by B31.1, the piping that connects
to the boiler external piping
at a point opposite from that of the
boiler proper connection can either
be accomplished in accordance with
B31.1 or B31.3. If the owner, or their
Central utility plant (CUP)
(Containing steam generation, condensate recovery, chilled water
generation, compressed air generation, and cooling water control and
distribution)
Work on this facility performed under design/build package
Construction boundry match line
Plant distribution pipe rack
FIGURE 3. This schematic shows piping code compliance jurisdiction
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OCTOBER 2016
45
B31.1 compliance
B31.3 compliance
CUP pipe rack
Central utility
plant (CUP)
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Chemical Engineering October 2016

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