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5/24/2018 Applying ASME Boiler Code to Steam Generation Systems
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CHEMICAL ENGINEERING WWW.CHE.COM JANUARY 2013 49
The 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 ofMechanical Engineers), is a well-es-tablished standard for the design and
fabrication of boilers and pressure ves-sels. ASME code-symbol stamps showcompliance with the requirements ofthe standard, but code stamping ofsteam systems in ethylene and otherlarge heaters can be controversial.
Much of the challenge for those inthe chemical process industries (CPI)stems from the fact that the main focusof the code is on power boilers, ratherthan on petroleum refinery or petro-chemical heaters, so definitions aresometimes not clear. Furthermore, itcan be difficult to define which author-ity has jurisdiction over steam genera-tion systems in the CPI. Even in theU.S., state boiler codes vary among thestates. In other countries, adherence to
ASME standards may or may not berequired, thus leaving it up to the own-ers of the asset to decide. This articleprovides guidance on the requirementsfor stamping within the ASME codeand explains how state boiler codes canaffect the requirements.
Steam-generation systemsWhen it comes to steam-generationsystems, safety is the primary con-
cern for both the owners of the systemand for the authorities that have ju-risdiction over them. All parties wantsafe and reliable equipment designedfor the intended purpose. Section 1 ofthe ASME BPVC contains the rulesfor construction of power boilers [1].
Power boilers are defined as boilersthat generate steam at pressures inexcess of 15 psig, for external use.Most designers and owners of steam-
generation systems from fired heat-ers agree that ASME Code Section 1is the appropriate design code for thesteam system.
Steam systems in fired heaters typi-cally consist of the following: steamdrum; relief valves; boiler-feedwater
preheat tubes; steam-generation tubes;steam superheating tubes; an end-stageor interstage de-superheater; startup
vent and silencer; interconnecting pip-
Engineering Practice
Martha Choroszy, David Ballow andAli BourjiWorleyParsons
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
Radiant
section
Steam drum
Transferline
exchanger
Interstage
desuperheater
Economizer
Boiler feed water
Produced steam
Saturated steam
Watercirculation
Steamcirculation
Superheated steam
Convection
sec
tion
Preheated
boiler feed
water
Radiant
section
Steam drum
Economizer
Boiler feed water
Saturated steam
Watercirculation
Saturatedsteam
Superheated steam
Convection
section
Steamgeneration
coils
Superheatercoils
FIGURE 1.Most operatorsagree that Sec-tion 1 of theASME Boilerand PressureVessel code isthe most appro-
priate standardfor steam-generationsystems, suchas the morecommon natu-ral-circulationtype (above)and the forced-circulation type(below)
Applying ASME Boiler Code to
Steam Generation Systems
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5/24/2018 Applying ASME Boiler Code to Steam Generation Systems
Engineering Practice
50 CHEMICAL ENGINEERING WWW.CHE.COM JANUARY 2013
ing; inline instruments;and, for ethylene heaters,a primary transfer line ex-changer (TLE) as shown in
Figure 1. The steam gener-ation system can be one oftwo types: either naturalcirculation or forced circu-lation. The natural circula-tion type is more common.Figure 1 (bottom) shows atypical set-up for a forced-circulation system.
ASME jurisdictionThe jurisdictional limits of
ASME from Section 1 of the
BPVC are shown in Figure2. The figure, Code Juris-dictional Limits for Pip-ing Drum Type Boilers,was adapted from ASME2010 BPVC Section 1, withpermission of ASME [2].
The ASME BPVC de-scribes three areas oftechnical responsibil-ity: the boiler proper, theboiler external piping and
joint, and non-boiler ex-
ternal piping and joint.The boiler proper fallsunder the administrative
jurisdiction and technicalresponsibility of Section 1of the ASME BPVC. Theboiler proper and boilerexternal piping and jointfall under the administrative juris-diction of ASME BPVC and requiremandatory certification, along withcode stamping, ASME data forms andauthorized inspection.
Technical responsibility for boilerexternal piping is assigned to the
ASME section committee of B31.1.Non-boiler external piping and jointis not considered to be within the ju-risdiction of ASME BPVC section 1,and those components are usuallydesigned according to B31.1 in utilityapplications or B31.3 in chemical orrefinery plant applications.
Even the application of the CodeJurisdictional Limits for Piping
Drum Type Boilers to steam systemsin ethylene heaters can be problem-atic, because the language of the sec-tion is clearly intended for a conven-
tional boiler. Most engineers agree,and several U.S. state boiler codesrequire that the steam drum be de-signed to ASME Section 1. In non-codestates, the drum may be designed toSection VIII.
Steam superheat tubes, economizertubes and steam generation tubes arealso designed to meet the require-ments of ASME Section 1.
Stamp requirementsThe ASME BPVC clearly requires allequipment considered to be boilerproper and boiler external pipingand joint to be stamped. Steam sys-tems for ethylene heaters are typi-
cally manufactured by multiple ven-dors and assembled in the field by adifferent contractor. The particular
ASME stamp and partial data re-
port produced depends on the type ofmanufacturer. Table 1 shows a com-mon setup, where multiple vendorsprovide the various components of thesteam system.
Master stampIf compliance with ASME BPVC Sec-tion 1 is required by law, a masterstamp is required. For a forced-flowsteam-generation unit, the code isclear manufacturers of forced-flowsystems must provide a master stamp.For field-assembled boilers, a masterstamp is clearly required.
The master stamp must be providedby whoever has responsibility for the
entire boiler unit. In cases where themanufacturer is not the assembler, themanufacturer or engineering contrac-tor may provide partial data reports to
Single installation
Multiple installation
Drain
Drain
Drain
Drain
CommonheaderDrain
Main steam
Vent
Vents andinstrumentation
Vent
Vent
Control device
PG-58.3.1
PG-58.3.7
Single boiler
Part PFH
Boiler no. 1
Boiler no. 1
Boiler no. 2
Boiler no. 2
Single boiler
Regulating valves
Two or moreboilers fed froma common source
Two or moreboilers fedfrom a com-mon source
PG-68.1
PG-68.2
Soot blowers PG-68.5
Soot blowers PG-68.5
Single installation
Multiple installationPG-58.3.1
PG-58.3.2
PG-58.3.7
Feedwatersystems
PG-58.3.3
PG-58.3.6
Blow-offsingle and multipleinstallations
Administrative jurisdiction and technical responsibility
Non-boiler external piping and joint Not section jurisdiction (see applicable ASME B31 code).
Boiler proper the ASME boiler and pressure vessel code (ASME BPVC) has total
administrative jurisdiction and technical responsibility (refer to section I preamble)Boiler external piping and joint the ASME BPVC has total administrative jurisdiction (mandatorycertification by code symbol stamping, ASME data forms, and authorized inspection) of boiler exter-nal piping and joint. The ASME section committee B31.1 has been assigned technical responsibility
PG-71
Level indicators PG-60
Surface blow
Continuous blow
Chemical feed
Drum sample
Water drum
Inlet header(if used)
Integral
superheater
(if used)
Integral
economizer(if used)
PG-58.3.2
PG-60
Common
headerSteam drum
FIGURE 2. The ASME BPVC describes three areas of technical responsibility: boiler proper;boiler external piping and joint; and non-boiler external piping and joint
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the assembler, and the assembler mayaffix the stamp jointly with the manu-facturer, according to the rules of sec-tion PG-106 in ASME BPVC Section1. In this case, both the engineeringcontractor and the authorized inspec-tor must sign the P-3A forms providedby the assembler.
The question that arises for steam-generation units on ethylene heatersis this: When adherence to ASMEBPVC Section 1 is voluntary, is a mas-ter stamp required? The answer is no.If compliance is voluntary, the ownerof the system may opt to comply withsome parts of the code, but not others.
Owner requirementsAlmost all owner specifications requirethat the steam drum, primary trans-fer line heat exchanger (TLE; steamside), and boiler proper piping are de-signed according to ASME BPVC Sec-tion 1, and stamped by the supplier.
Few owners require a master stampunless a stamp is required by the localauthority having jurisdiction.
Owner specifications for steam
systems can sometimes be confusing,and at other times do not address thesubject at all. Statements such as thesteam system shall be in accordancewith ASME section 1 can be difficultto interpret.
State boiler code requirementsIn the U.S., the individual statesregulate boilers. There is no federalboiler code that applies to all statesand territories. Not all 50 states haveboiler codes. Most states that do haveboiler codes require compliance with
ASME BPVC Section 1. Some statesgo further and require National BoardRegistration and inspection. A sam-pling of three state boiler-code lawsfollows. While the language containedin the codes for both Mississippi andTexas are clear, the language of otherstates is not.
Mississippi State Boiler Code commonly known as Title 15, Sec-
tion III, part 76 clearly definesany vessel that generates steam atover 15 psig as a power boiler [3]. Itgoes on to say that Boilers and un-
fired pressure vessels to be installedfor operation in Mississippi shallbe designed, constructed, inspected,stamped and installed in accordancewith the applicable ASME Boilerand Pressure Vessel Code, and theserules and regulations.
Texas State Boiler Code, commonlyknown as 16 TAC 65, requires thatany heating boiler, nuclear boiler,power boiler, unfired steam boiler orprocess steam generator that is in-stalled in Texas must be inspected,installed and stamped in conformitywith the applicable section of the
ASME BPVC. Such boilers must beregistered with the National Boardof Boiler and Pressure Vessel Inspec-tors. Exceptions include reinstalledboilers, as well as those exemptedby the Health and Safety Code,755.022 [4].
New Jersey Boiler Code is com-monly called NJAC 12 subchapter
4. In New Jersey, the term boilermeans a closed vessel in which wateris heated, steam is generated, steamis superheated, or any combination
TABLE 1. MULTIPLE VENDORS SUPPLY VARIOUS STEAM-SYSTEM COMPONENTS
Component name Category ASME CodeCode stamp(by vendor)
Code stamp re-quirement(by field assem-bler)
AssemblerStamp(by field as-sembler)
Stamptype
ASMEpartialdatareport
Stamptype
ASMEpartialdatareport
Stamptype
ASMEpartialdatareport
1 Boiler feed water (BFW) feed
piping to pre-heater
Piping ASME B31.1 PP P-4A
A P-3A
2 BFW feed piping tode-superheater
Piping ASME B31.1 PP P-4A
3 BFW pre-heater Equipment ASME SEC. I S P-4A
4 BFW piping to steam drum Piping ASME B31.1 PP P-4A
5 Steam drum Equipment ASME SEC. I S P-4A
6 Pressure-reducing de-superheat-ing stations (PRDs) on steamdrums
Pressure reliefvalve
ASME SEC 1 V P-7
7 Riser and downcomer Vendor piping ASME SEC. I S P-4A S P-4A
8 Primary transfer-line heat ex-changer (TLE), steam-side
Equipment ASME SEC. I S P-4A
9 Primary TLE blowdown Piping ASME B31.1 PP P-4A
10 Super high-pressure (SHP) pip-ing from steam drum
Piping ASME B31.1 PP P-4A
11 Upper steam superheater(USSH)
Equipment ASME SEC. I S P-4A
12 De-superheater Equipment ASME SEC. I S P-4A
13 De-superheater piping Vendor piping ASME SEC. I S P-4A S P-4A
14 Lower steam superheater (LSSH) Equipment ASME SEC. I S P-4A
15 SHP export piping Piping ASME B31.1 PP P-4A
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52 CHEMICAL ENGINEERING WWW.CHE.COM JANUARY 2013
thereof, under pressure or vacuum,for external use by the direct applica-tion of heat [5]. The term boilershallinclude fired or waste-heat units for
heating or vaporizing liquids otherthan water where these units areseparate from processing systemsand are complete within themselves.New Jersey requires compliance with
ASME BPVC Section 1 and NationalBoard rules.
Concluding remarksWhile safety remains of the utmostconcern, economics, more than engi-neering, play a great role in defining
the boundaries where the ASME codemay apply. Unless a more specific codeis developed for ethylene units, thedebate about boundaries will continueamong owners, engineering contrac-tors, technology providers and otherstakeholders. In general, more strin-
gent requirements of ASME are ap-plied for ethylene plants in the U.S.,compared to other places in the world.
Edited by Scott Jenkins
AuthorsMartha Choroszyis a chiefprocess engineer at Worley-Parsons (6330 West LoopSouth, Bellaire, Tex. 77401;Phone: 713-407-5000; Email:martha.choroszy@worley-
parsons.com). She receiveda B.S.Ch.E. degree from theMassachusetts Institute ofTechnology and an MBA fromTulane University. She is a li-censed professional engineer
in Texas and a member of AIChE and NFPA.She is the author of numerous publications, a re-cipient of Tulanes Allen Vorholt award and hasserved as a Blue Ribbon Panel Member to definethe National Agenda for the U.S. Core Combus-tion Research Program.
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References
1. ASME Section 1, Boiler and Pressure VesselCode, ASME, July 1, 2010.
2. Reprinted from ASME 2010 BPVC, Section 1,by permission of The ASME (American Society
of Mechanical Engineers.) All rights reserved.3. Mississippi Department of Health, Title 15, Part
III Office of Health Protection, 76 Boiler andPressure Vessel Safety, July 1, 1975.
4. Texas Boiler Administrative Rules 16 TexasAdministrative Code, January 1, 2008.
5. New Jersey Administrative Code(N.J.A.C.) Boilers, Pressure Vessels &Refrigeration,October 6, 2008.
David Ballow is a principalprocess engineer at Worley-Parsons in Houston (Email:[email protected]) and is a professional en-gineer. He received a B.S.Ch.E.degree from Louisiana TechUniversity and is a memberof AIChE.
Ali Bourji is a senior tech-nical director at WorleyPar-sons in Houston (Email: ali.
[email protected]).Bourji received his B.S. andM.S. degrees in chemical en-gineering from the Universityof Houston, and a doctoratedegree from Lamar Univer-sity. He is a professional engi-neer and a member of AIChEand AFPM. Dr. Bourji is the
author of numerous publications and serves onthe Chemical Engineering PhD Advisory Councilat Lamar University.