Chemical Engineering January 2013 - 49

Engineering Practice
Applying ASME Boiler Code to
Steam Generation Systems
Determining when and how the
ASME boiler code applies to
steam systems in petrochemical
operations can be difficult.
Guidance on the requirements
for boiler code stamping can help
Martha Choroszy, David Ballow and Ali Bourji
WorleyParsons
T
he ASME Boiler and Pressure
Vessel Code (ASME BPVC),
which is administered by ASME
(New York, N.Y.; www.asme.org;
founded as the American Society of
Mechanical Engineers), is a well-established
standard for the design and
fabrication of boilers and pressure vessels.
ASME code-symbol stamps show
compliance with the requirements of
the standard, but code stamping of
steam systems in ethylene and other
large heaters can be controversial.
Much of the challenge for those in
the chemical process industries (CPI)
stems from the fact that the main focus
of the code is on power boilers, rather
than on petroleum refinery or petrochemical
heaters, so definitions are
sometimes not clear. Furthermore, it
can be difficult to define which authority
has jurisdiction over steam generation
systems in the CPI. Even in the
U.S., state boiler codes vary among the
states. In other countries, adherence to
ASME standards may or may not be
required, thus leaving it up to the owners
of the asset to decide. This article
provides guidance on the requirements
for stamping within the ASME code
and explains how state boiler codes can
affect the requirements.
Steam-generation systems
When it comes to steam-generation
systems, safety is the primary conFIGURE
1.
Most operators
agree that Section
1 of the
ASME Boiler
and Pressure
Vessel code is
the most appropriate
standard
for steamgeneration
systems,
such
as the more
common natural-circulation
type
(above)
and the forcedcirculation
type
(below)
Saturated steam
Steam drum
Preheated
boiler feed
water
Boiler feed water
Economizer
Superheated steam
Interstage
desuperheater
Produced steam
Radiant
section
Saturated steam
Steam drum
Boiler feed water
Economizer
Superheater
coils
Steam
generation
coils
Superheated steam
Convection
section
Radiant
section
cern for both the owners of the system
and for the authorities that have jurisdiction
over them. All parties want
safe and reliable equipment designed
for the intended purpose. Section 1 of
the ASME BPVC contains the rules
for construction of power boilers [1].
Power boilers are defined as boilers
that generate steam at pressures in
excess of 15 psig, for external use.
Most designers and owners of steamgeneration
systems from fired heaters
agree that ASME Code Section 1
is the appropriate design code for the
steam system.
Steam systems in fired heaters typically
consist of the following: steam
drum; relief valves; boiler-feedwater
preheat tubes; steam-generation tubes;
steam superheating tubes; an end-stage
or interstage de-superheater; startup
vent and silencer; interconnecting pipCHEMICAL
ENGINEERING WWW.CHE.COM JANUARY 2013 49
Water circulation
Steam circulation
Saturated steam
Transfer line
exchanger
Water circulation
Convection
section
http://www.asme.org http://WWW.CHE.COM
Chemical Engineering January 2013

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