Wisconsin Administrative Code › Department of Safety and Professional Services › SPS 301-399 - Safety, Buildings, and Environment › SPS 326-360 - General, Part II › Chapter SPS 341 - Boilers And Pressure Vessels › Appendix A - EXCERPTS FROM: ASME BOILER AND PRESSURE VESSEL CODE

Current through June 24, 2024
SECTION I - POWER BOILERS
2010 EDITION
INTRODUCTION
This Code covers rules for construction of power boilers 1,
					 electric boilers2, miniature boilers3, high-temperature water boilers4, heat
					 recovery steam generators5, and certain fired pressure vessels6 to be used in
					 stationary service and includes those power boilers used in locomotive,
					 portable, and traction service. Reference to a paragraph includes all the
					 subparagraphs and subdivisions under that paragraph. - See PDF for table
1 Power boiler - a boiler in
					 which steam or other vapor is generated at a pressure of more than 15 psi (100
					 kPa) for use external to itself.
2 Electric boiler - a power
					 boiler or a high-temperature water boiler in which the source of heat is
					 electricity.
3 Miniature boiler - a power
					 boiler or a high-temperature water boiler in which the limits specified in
					 PMB-2 are not exceeded.
4 High-temperature water boiler
					 - a water boiler intended for operation at pressures in excess of 160 psi (1.1
					 MPa) and/or temperatures in excess of 250°F (120°C).
5 Heat recovery steam generator
					 (HRSG) - a boiler that has as its principal source of thermal energy a hot gas
					 steam having high-ramp rates and temperatures such as the exhaust of a gas
					 turbine.
6 Fired pressure vessel -
					 reheaters, isolable superheaters, and nonintegral separately fired
					 superheaters.
The Code does not contain rules to cover all details of
					 design and construction. Where complete details are not given, it is intended
					 that the manufacturer, subject to the acceptance of the Authorized Inspector,
					 shall provide details of design and construction which will be as safe as
					 otherwise provided by the rules in the Code.
The scope of jurisdiction of Section I applies to the
					 boiler proper and to the boiler external piping.
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.
Boiler external piping shall be considered as that piping
					 which begins where the boiler proper or isolable superheater, or isolable
					 economizer terminates at:
(a) the first circumferential joint for welding end
					 connections; or
(b) the face of the first flange in bolted flanged
					 connections; or
(c) the first threaded joint in that type of connection;
					 and which extends up to and including the valve or valves required by this
					 Code.
ASME Code Certification (including Data Forms and Code
					 Symbol Stamping), and/or inspection by the Authorized Inspector,when required
					 by this Code, is required for the boiler proper and the boiler external
					 piping.
Construction rules for materials, design, fabrication,
					 installation, and testing of the boiler external piping are contained in ASME
					 B3l.l, Power Piping. Piping beyond the valve or valves required by Section I is
					 not within the scope of Section I, and it is not the intent that the Code
					 Symbol Stamp be applied to such piping or any other piping.
The material for forced-circulation boilers, boilers with
					 no fixed steam and water line, and high-temperature water boilers shall conform
					 to the requirements of the Code. All other requirements shall also be met
					 except where they relate to special features of construction made necessary in
					 boilers of these types, and to accessories that are manifestly not needed or
					 used in connection with such boilers, such as water gages and water
					 columns.
Reheaters receiving steam which has passed through part of
					 a turbine or other prime mover and separately fired steam superheaters which
					 are not integral with the boiler are considered fired pressure vessels and
					 their construction shall comply with Code requirements for superheaters,
					 including safety devices. Piping between the reheater connections and the
					 turbine or other prime mover is not within the scope of the Code. Steam piping
					 to the inlet connections and from the outlet connections of nonintegral
					 separately fired superheaters is not within the scope of the Code.
A pressure vessel in which steam is generated by the
					 application of heat resulting from the combustion of fuel (solid, liquid, or
					 gaseous) shall be classed as a fired steam boiler.
Unfired pressure vessels in which steam is generated shall
					 be classed as unfired steam boilers with the following exceptions:
(a) vessels known as evaporators or heat exchangers
(b) vessels in which steam is generated by the use of heat
					 resulting from operation of a processing system containing a number of pressure
					 vessels such as used in the manufacture of chemical and petroleum
					 products
Unfired steam boilers shall be constructed under the
					 provisions of Section I or Section VIII.
Expansion tanks connected to high-temperature water boilers
					 without intervening valves shall be constructed to the requirements of Section
					 I or Section VIII.
A pressure vessel in which an organic fluid is vaporized by
					 the application of heat resulting from the combustion of fuel (solid, liquid,
					 or gaseous) shall be constructed under the provisions of Section I. Vessels in
					 which vapor is generated incidental to the operation of a processing system,
					 containing a number of pressure vessels such as used in chemical and petroleum
					 manufacture, are not covered by the rules of Section I.
PART PG
GENERAL REQUIREMENTS FOR ALL
METHODS OF CONSTRUCTION
GENERAL
PG-1 SCOPE
The requirements of Part PG apply to power boilers and high
					 pressure, high-temperature water boilers and to parts and appurtenances thereto
					 and shall be used in conjunction with the specific requirements in the
					 applicable Parts of this Section that pertain to the methods of construction
					 used.
PG-2 SERVICE LIMITATIONS
PG-2.1
The rules of this Section are
					 applicable to the following services:
(a) boilers in which steam or other vapor is generated at a
					 pressure of more than 15 psig (100kPa)
(b) high-temperature water boilers intended for operation
					 at pressures exceeding 160 psig (1.1 MPa) and/or temperatures exceeding
					 250°F (120°C)
PG-2.2
For services below those specified in
					 PG-2.1 it is intended that rules of Section IV apply; however, boilers for such
					 services may be constructed and stamped in accordance with this Section
					 provided all applicable requirements are met.
PG-2.3
Coil-type hot water boilers where the
					 water can flash into steam when released directly to the atmosphere through a
					 manually operated nozzle may be exempted from the rules of this Section
					 provided the following conditions are met:
(a) There is no drum, header, or other steam space.
(b) No steam is generated within the coil.
(c) Tubing outside diameter does not exceed 1 in. (25
					 mm).
(d) Pipe size does not exceed NPS ¾ (DN 20).
(e) Nominal water capacity does not exceed 6 gal (23
					 L).
(f) Water temperature does not exceed 350°F
					 (175°C).
(g) Adequate safety relief valves and controls are
					 provided.
PG-3 REFERENCED STANDARDS
Specific editions of standards referenced in this Section
					 are shown in A-360.
PG-4 UNITS
Either U.S. Customary units or SI units may be used for
					 compliance with all requirements of this edition, but one system shall be used
					 consistently throughout for all phases of construction.
Either the U.S. Customary units or SI units that are listed
					 in Mandatory Appendix II are identified in the text, or are identified in the
					 nomenclature for equations, shall be used consistently for all phases of
					 construction (e.g., materials, design, fabrication, and reports). Since values
					 in the two systems are not exact equivalents, each system shall be used
					 independently of the other without mixing U.S. Customary units and SI
					 units.
When SI units are selected, U.S. Customary values in
					 referenced specifications that do not contain SI units shall be converted to SI
					 values to at least three significant figures for use in calculations and other
					 aspects of construction.
MATERIALS
PG-5 GENERAL
PG-5.1
Except as otherwise permitted in
					 PG-8.2, PG-8.3, PG-10, and PG-11, material subject to stress due to pressure
					 shall conform to one of the specifications given in Section II and shall be
					 limited to those that are listed in the Tables of Section II, Part D. The
					 manufacturer shall ensure that the correct material has been received and is
					 properly identified before proceeding with construction (see A-302.4).
					 Materials shall not be used at temperatures above those for which stress values
					 are limited, for Section I construction, in the Tables of Section II, Part D.
					 Specific additional requirements described in PG-5 through PG-13 shall be met
					 as applicable.
PG-5.2
Material covered by specifications in
					 Section II is not restricted as to the method of production unless so stated in
					 the specification, and as long as the product complies with the requirements of
					 the specification.
PG-5.3
If, in the development of the art of
					 boiler construction, it is desired to use materials other than those herein
					 described, data should be submitted to the Boiler and Pressure Vessel Committee
					 in accordance with the requirements of Appendix 5 of Section II, Part D.
					 Material not completely identified with any approved Code specifications may be
					 used in the construction of boilers under the conditions outlined in
					 PG-10.
PG-5.4 Size Limits and Tolerances
PG-5.4.1
Materials outside the limits of size
					 or thickness given in the title or scope clause of any specification in Section
					 II may be used if the material is in compliance with the other requirements of
					 the specification, and no similar limitation is given in the rules for
					 construction.
PG-5.4.2
Pipe having a tolerance of
					 ±1% on either the O.D. or the I.D. rather than the tolerance specified
					 in the material specification, may be used, provided the material complies with
					 all other requirements of the specifications. When used under external
					 pressure, such pipe shall be limited to a maximum of 24 in. (600 mm) in
					 diameter. The pipe shall include the designation 1% O.D. or 1% I.D., as
					 appropriate, in any required documentation and marking of the material.
PG-5.5
The use of austenitic alloy steel is
					 permitted for boiler pressure parts that are steam touched in normal operation.
					 Except as specifically provided in PG-9.1.1, PG-12, and PEB-5.3, the use of
					 such austenitic alloys for boiler pressure parts that are water wetted in
					 normal service is prohibited.7 - See PDF for
					 table
7 Austenitic alloys are
					 susceptible to intergranular corrosion and stress corrosion cracking when used
					 in boiler applications in water wetted service. Factors that affect the
					 sensitivity to these metallurgical phenomena are applied or residual stress and
					 water chemistry. Susceptibility to attack is usually enhanced by using the
					 material in a stressed condition with a concentration of corrosive agents
					 (e.g., chlorides, caustic, or reduced sulfur species). For successful operation
					 in water environments, residual and applied stresses must be minimized and
					 careful attention must be paid to continuous control of water chemistry.
PG-5.6 P-No. 15E, Group 1 Materials
PG-5.6.1
If during any phase of manufacturing
					 or erection any portion of the component that does not contain a weld is heated
					 to a temperature greater than 1,470°F (800°C), one of the following
					 actions shall be performed:
(a) The component shall be reaustenitized and retempered
					 in its entirety in accordance with the specification requirements.
(b) That portion of the component heated above 1,470°F
					 (800°C), including the heat-affected zone created by the local heating,
					 must be replaced or must be removed, reaustenitized, and retempered in
					 accordance with the specification requirements and then replaced in the
					 component.
(c) If the allowable stress values to be used are less
					 than or equal to those provided in Table 1A of Section II, Part D for Grade 9
					 (e.g., SA-213 T9, SA-335 P9, or equivalent product specifications) at the
					 design temperature, then the requirements stated above may be waived, provided
					 that the portion of the component heated above 1,470°F (800°C) is
					 retempered in accordance with the specification requirements. The use of this
					 provision shall be noted on the Manufacturer's Data Report.
PG-5.6.2
If during any phase of manufacturing
					 or erection of the component, any portion that does contain a weld is heated
					 above 1,425°F (775°C), then the requirements of Notes (3) and (4) of
					 Table PW-39 for P-No. 15E, Group 1 Materials, shall apply for reheat treatment.
PG-6 PLATE
PG-6.1
Steel plates for any part of a boiler
					 subject to pressure, whether or not exposed to the fire or products of
					 combustion shall be of pressure vessel quality in accordance with one of the
					 following specifications:
SA-202 Pressure Vessel Plates, Alloy Steel,
					 Chromium-Manganese-Silicon
SA-204 Pressure Vessel Plates, Alloy Steel, Molybdenum
SA-240 (Type 405 only) Pressure Vessel Plates, Alloy Steel
					 (Ferritic Stainless), Chromium
SA-285 Pressure Vessel Plates, Carbon Steel, Low-and
					 Intermediate-Tensile Strength
SA-299 Pressure Vessel Plates, Carbon Steel,
					 Manganese-Silicon
SA-302 Pressure Vessel Plates, Alloy Steel,
					 Manganese-Molybdenum and Manganese-Molybdenum-Nickel
SA-387 Pressure Vessel Plates, Alloy Steel,
					 Chromium-Molybdenum
SA-515 Pressure Vessel Plates, Carbon Steel, for
					 Intermediate- and Higher-Temperature Service
SA-516 Pressure Vessel Plates, Carbon Steel, for Moderate-
					 and Lower-Temperature Service
SA/AS 1548 Steel Plates for Pressure Equipment
SA/EN-10028-2 Flat Products Made of Steels for Pressure
					 Purposes
SA/JIS G3118 Carbon Steel Plates for Pressure Vessels for
					 Intermediate and Moderate Temperature Service
PG-55 SUPPORTS AND ATTACHMENT LUGS
PG-55.1
Lugs or hangers when used to support a
					 boiler of any type shall be properly fitted to the surfaces to which they are
					 attached.
PG-55.2
Lugs, hangers, or brackets may be
					 attached by fusion welding provided the welding meets the requirements of Part
					 PW, including stress relieving but omitting volumetric examination and provided
					 they are attached by full penetration welds, combination groove and fillet
					 welds, or by fillet welds along the entire periphery or contact edges. Some
					 acceptable forms of welds for lugs, hangers, or brackets are shown in Fig.
					 PW-16.2. The materials for lugs, hangers, or brackets are not limited to those
					 listed in Tables 1A and 1B of Section II, Part D, but shall be of weldable
					 quality. The allowable load on the fillet welds shall equal the product of the
					 weld area based on minimum leg dimension, the allowable stress value in tension
					 of the material being welded, and the factor 0.55. When using welded pipe, the
					 stress values given in Table 1A of Section II, Part D, may be increased to that
					 of the basic material by eliminating the stated weld efficiencies.
See PDF for
					 diagram
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					 diagram
BOILER EXTERNAL PIPING AND BOILER PROPER
					 CONNECTIONS
PG-58 OUTLETS AND EXTERNAL PIPING
PG-58.1 General.
The rules of this
					 subparagraph apply to the boiler external piping as defined in the
					 Preamble.
PG-58.2 Boiler External Piping Connections to
					 Boilers.
All boiler external piping connected to a boiler for any
					 purpose shall be attached to one of the types of joints listed in PG-59.1.1.1,
					 PG-59.1.1.2, and PG-59.1.1.3.
PG-58.3 Boiler External Piping.
The following
					 defines the Code Jurisdictional Limits of the boiler external piping systems,
					 including general requirements, valves, and inspection. The limits are also
					 shown in Figs. PG-58.3.1 and PG-58.3.2. The materials, design, fabrication,
					 installation, and testing shall be in accordance with ASME B31.1, Power
					 Piping.
PG-58.3.1.
The steam piping connected to the
					 boiler drum or to the superheater outlet header shall extend up to and
					 including the first stop valve in each connection, except as required by
					 PG-58.3.2. In the case of a single boiler and prime mover installation, the
					 stop valve required herein may be omitted provided the prime mover throttle
					 valve is equipped with an indicator to show whether the valve is open or closed
					 and is designed to withstand the required hydrostatic pressure test of the
					 boiler.
For an isolable or separately fired superheater which
					 discharges steam directly to a process stream, the stop valve required by this
					 paragraph and the safety valve(s) required by PG-68 may be omitted provided the
					 following conditions are satisfied:
(a) The boiler is a drum-type boiler in a single-boiler
					 installation.
(b) The steam discharge passes through the process stream
					 to the atmosphere with no intervening valves.
(c) The system shall be designed so that the process stream
					 through which the steam discharge passes cannot be obstructed in such a way as
					 to cause the pressure in the superheater to exceed that permitted by PG-67.2,
					 with maximum steam flow from the boiler to the superheater. Flow and pressure
					 calculations demonstrating that the superheater will not be overpressurized
					 under any steam flow conditions shall be documented and made available to the
					 Inspector. These calculations shall be certified by a Professional Engineer
					 experienced in the mechanical design of power plants.
(d) There is no valve on the discharge side of the
					 superheater.
(e) Section I jurisdiction shall include the pressure parts
					 between the superheater inlet and the outlet at:
(1) the first circumferential joint for welding end
					 connections; or
(2) the face of the first flange in bolted flange
					 connections; or
(3) the first threaded joint in that type of
					 connection.
PG-58.3.2
When two or more boilers are
					 connected to a common steam header, or when a single boiler is connected to a
					 header having another steam source (e.g., a turbine extraction line), the
					 connection from each boiler having a manhole opening shall be fitted with two
					 stop valves having an ample free-blow drain between them. The boiler external
					 piping includes all piping from the boiler proper up to and including the
					 second stop valve and the free-blow drain valve.
PG-58.3.3
The feedwater piping for all
					 boilers, except high-temperature water boilers and forced-flow steam generators
					 complying with PG-58.3.5, shall extend through the required stop valve and up
					 to and including the check valve except as required by PG-58.3.4. On a single
					 boiler-turbine unit installation the boiler feed shutoff valve may be located
					 upstream from the boiler feed check valve.
If a feedwater heater or heaters meeting the requirements
					 of Part PFH are installed between the required stop valve and the boiler, and
					 are fitted with isolation and bypass valves, provisions must be made to prevent
					 the feedwater pressure from exceeding the maximum allowable working pressure of
					 the piping or feedwater heater, whichever is less. Control and interlock
					 systems are permitted in order to prevent overpressure.
PG-58.3.4
When two or more boilers are fed
					 from a common source, the piping shall be up to and including a globe or
					 regulating valve located between the check valve required in PG-58.3.3 and the
					 source of supply. If the regulating valve is equipped with an isolation valve
					 and a bypass valve, the piping shall be up to and including both the isolation
					 valve downstream from the regulating valve and the shutoff valve in the
					 bypass.
PG-58.3.5
The feedwater piping for a
					 forced-flow steam generator with no fixed steam and waterline may terminate up
					 to and including the stop valve near the boiler and omitting the check valve
					 near the boiler, provided that a check valve having a pressure rating no less
					 than the boiler inlet design pressure is installed at the discharge of the
					 boiler feed pump or elsewhere in the feedline between the feed pump and the
					 feed stop valve. If the feedwater heater(s) is fitted with isolation and bypass
					 valves, the applicable requirements of PG-58.3.3 must be met.
PG-58.3.6
The blowoff piping for all boilers,
					 except forced-flow steam generators with no fixed steam and waterline,
					 high-temperature water boilers, and those used for traction and/or portable
					 purposes, when the maximum allowable working pressure exceeds 100 psi (700kPa)
					 shall extend through and including the second valve. The blowoff piping for all
					 traction and/or portable boilers and for forced circulation and electric
					 boilers having a normal water content not exceeding 100 gal (380 L) are
					 required to extend through only one valve.
PG-58.3.7
The miscellaneous piping shall
					 include the piping for such items as drains, vents, surface-blow-off, steam and
					 water piping for water columns, gage glasses and pressure gages, and the
					 recirculation return line for a high-temperature water boiler. When a drain is
					 not intended for blowoff purposes (when the boiler is under pressure) a single
					 valve is acceptable, otherwise two valves in series are required except as
					 permitted by PG-58.3.6.
PG-58.3.8
Welded piping in PG-58.3.1,
					 PG-58.3.2, PG-58.3.3, PG-58.3.4, PG-58.3.5, PG-58.3.6, and PG-58.3.7 is also
					 subject to the requirements of PG-104 for proper Code certification.
See PDF for
					 diagram
PG-59 APPLICATION REQUIREMENTS FOR THE BOILER
					 PROPER
PG-59.1 Common to Steam, Feedwater, Blowoff, and
					 Drain Systems
PG-59.1.1
Outlets of a boiler to which piping
					 is to be attached for any purpose, and which piping comes within the Code
					 requirements, shall meet the requirements of PG-39 and shall be:
PG-59.1.1.1
A tapped opening.
PG-59.1.1.2
Bolted flanged joints including
					 those of the Van Stone type.
PG-59.1.1.3
Welding ends of the butt or socket
					 welding type.
PG-59.1.1.
Piping within the boiler proper may
					 be expanded into grooved holes, seal welded if desired. Blowoff piping of
					 firetube boilers shall be attached by threading into a tapped opening with a
					 threaded fitting or valve at the other end if exposed to products of
					 combustion, or by PG-59.1.1.1 or PG-59.1.1.2 if not so exposed (see
					 PFT-49).
PG-59.1.2 Steam Mains.
Provisions shall be
					 made for the expansion and contraction of steam mains connected to boilers, by
					 providing substantial anchorage at suitable points, so that there shall be no
					 undue strain transmitted to the boiler. Steam reservoirs shall be used on steam
					 mains when heavy pulsations of the steam currents cause vibration of the boiler
					 shell plates.
PG-59.1.3
Figure PG-59.1 illustrates a typical
					 form of connection for use on boiler shells for passing through piping such as
					 feed, surface blowoff connections, etc., and which permits the pipes' being
					 threaded in solid from both sides in addition to the reinforcing of the opening
					 of the shell. The pipes shall be attached as provided in PG-59.1.1. In these
					 and other types of boilers where both internal and external pipes making a
					 continuous passage are employed, the boiler bushing or its equivalent shall be
					 used.
PG-59.2 Requirements for Feedwater
					 Connections.
The feedwater shall be introduced into a boiler in such a
					 manner that the water will not be discharged directly against surfaces exposed
					 to gases of high temperature or to direct radiation from the fire. For
					 pressures of 400 psi (3 MPa) or over, the feedwater inlet through the drum
					 shall be fitted with shields, sleeves, or other suitable means to reduce the
					 effects of temperature differentials in the shell or head. Feedwater, other
					 than condensate returns as provided for in PG-59.3.6, shall not be introduced
					 through the blowoff.
PG-59.3 Requirements for Blowoffs
PG-59.3.1
A blowoff as required herein is
					 defined as a pipe connection provided with valves located in the external
					 piping through which the water in the boiler may be blown out under pressure,
					 excepting drains such as are used on water columns, gage glasses, or piping to
					 feedwater regulators, etc., used for the purpose of determining the operating
					 condition of such equipment. Piping connections used primarily for continuous
					 operation, such as deconcentrators on continuous blowdown systems, are not
					 classed as blowoffs but the pipe connections and all fittings up to and
					 including the first shutoff valve shall be equal at least to the pressure
					 requirements for the lowest set pressure of any safety valve on the boiler drum
					 and with the corresponding saturated-steam temperature.
PG-59.3.2
A surface blowoff connection shall
					 not exceed NPS 2 ½ (DN 65), and the internal pipe and the terminal
					 connection for the external pipe, when used, shall form a continuous passage,
					 but with clearance between their ends and arranged so that the removal of
					 either will not disturb the other. A properly designed steel bushing, similar
					 to or the equivalent of those shown in Fig. PG-59.1, or a flanged connection
					 shall be used.
PG-59.3.3
Each boiler except forced-flow steam
					 generators with no fixed steam and waterline and high-temperature water boilers
					 shall have a bottom blowoff outlet in direct connection with the lowest water
					 space practicable for external piping conforming to PG-58.3.6.
PG-59.3.4
All waterwalls and water screens
					 that do not drain back into the boiler, and all integral economizers, shall be
					 equipped with outlet connections for a blowoff or drain line and conform to the
					 requirements of PG-58.3.6 or PG-58.3.7.
PG-59.3.5
Except as permitted for miniature
					 boilers in Part PMB, the minimum size of blowoff connections shall be NPS 1 (DN
					 25), and the maximum size shall be NPS 2 ½ (DN 65), except that for
					 boilers with 100 ft2 (9.3 m2) of heating surface or less, the minimum size of
					 blowoff connections may be NPS ¾ (DN 20).
PG-59.3.6
Condensate return connections of the
					 same size or larger than the size herein specified may be used, and the blowoff
					 may be connected to them. In such case the blowoff shall be so located that the
					 connection may be completely drained.
PG-59.3.7
A bottom blowoff pipe when exposed
					 to direct furnace heat shall be protected by firebrick or other heat resisting
					 material that is so arranged that the pipe may be inspected.
PG-59.3.8
An opening in the boiler setting for
					 a blowoff pipe shall be arranged to provide free expansion and
					 contraction.
PG-59.4 Requirements for Drains
PG-59.4.1
Ample drain connections shall be
					 provided where required to permit complete drainage of all piping,
					 superheaters, waterwalls, water screens, integral economizers, high-temperature
					 water boilers, and all other boiler components in which water may collect.
					 Piping shall conform to the requirements of PG-58.3.6 or PG-58.3.7.
PG-59.4.1.1
Each superheater shall be equipped
					 with at least one drain connection so located as to most effectively provide
					 for the proper operation of the apparatus.
PG-59.4.1.2
Each high-temperature water boiler
					 shall have a bottom drain connection of at least NPS 1 (DN 25) in direct
					 connection with the lowest water space practical for external piping conforming
					 to PG-58.3.7.
PG-59.5 Requirements for Valves and Fittings
.
					 The following requirements apply to the use of valves and fittings in the
					 boiler proper.
PG-59.5.1 Steam Stop Valves
PG-59.5.1.1
If a shutoff valve is used between
					 the boiler and its superheater, the safety valve capacity on the boiler shall
					 comply with the requirements of PG-67.2 and PG-70, except as provided for in
					 PG-59.5.1.2, no credit being taken for the safety valve on the superheater, and
					 the superheater must be equipped with safety valve capacity as required by
					 PG-68. A stop valve is not required at the inlet or the outlet of a reheater or
					 separately fired superheater.
PG-59.5.1.2
When stop valves are installed in
					 the water-steam flow path between any two sections of a forced-flow steam
					 generator with no fixed steam and waterline, the safety valves shall satisfy
					 the requirements of PG-67.4.4.
DESIGN AND APPLICATION
PG-60 REQUIREMENTS FOR MISCELLANEOUS PIPE, VALVES,
					 AND FITTINGS
Piping referred to in this paragraph shall be designed in
					 accordance with the applicable requirements of ASME B31.1.
PG-60.1 Water Level Indicators.
All boilers
					 having a fixed water level (steam and water interface) shall have at least one
					 gage glass (a transparent device that permits visual determination of the water
					 level). Boilers not having a fixed water level, such as forced-flow steam
					 generators and high-temperature water boilers of the forced circulation type,
					 are not required to have a gage glass. The lowest visible water level in a gage
					 glass shall be at least 2 in. (50 mm) above the lowest permissible water level,
					 as determined by the boiler Manufacturer. Electrode-type electric boilers are
					 required to have only one gage glass, regardless of MAWP.
Gage glasses having multiple tubular sections shall have a
					 minimum of 1 in. (25 mm) overlap of the sections in which the water level may
					 be visible. Segmented gage glasses, such as ported or end-connected strip
					 gages, shall be equipped to provide obvious visual discrimination between water
					 and vapor in the individual sections.
PG-60.1.1
Boilers having a maximum allowable
					 working pressure exceeding 400 psi (3 MPa) shall have two gage glasses. Instead
					 of one of the two required gage glasses, two independent remote water level
					 indicators (two discrete systems that continuously measure, transmit, and
					 display water level) may be provided.
PG-60.1.1.1
When the water level in at least
					 one gage glass is not readily visible to the operator in the area where control
					 actions are initiated, either a fiber optic cable (with no electrical
					 modification of the optical signal) or mirrors shall be provided to transfer
					 the optical image of the water level to the control area. Alternatively, any
					 combination of two of the following shall be provided:
(a) an independent remote water level indicator
(b) an independent continuous transmission and display of
					 an image of the water level in a gage glass.
PG-60.1.1.2
When two independent remote water
					 level indicators are in reliable operation (continuously indicating water
					 level), the one required gage glass may be shut off, but shall be maintained in
					 the serviceable condition.
PG-60.1.1.3
The display of a remote water
					 level indicator shall have a clearly marked minimum water level reference at
					 least 2 in. (50 mm) above the lowest permissible water level, as determined by
					 the Manufacturer.
PG-60.1.6
Each gage glass shall be fitted with
					 a drain cock or valve having an unrestricted drain opening of not less than
					 ¼ in. (6 mm) diameter to facilitate cleaning. When the boiler MAWP
					 exceeds 100 psi (700 kPa), the gage glass shall be furnished with a connection
					 to install a valved drain to a point of safe discharge.
Each gage glass shall be equipped with a top and a bottom
					 shutoff valve of such through-flow construction as to prevent stoppage by
					 deposits of sediments. If the bottom valve is more than 7 ft (2 m) above the
					 floor or platform from which it is operated, the operating mechanism shall
					 indicate by its position whether the valve is open or closed. The
					 pressure-temperature rating of valves, fittings, and piping shall be at least
					 equal to the boiler MAWP and the corresponding saturated-steam
					 temperature.
Straight-run globe valves shall not be used on such
					 connections. Automatic shutoff valves, if permitted to be used, shall conform
					 to the requirements given in A-18.
PG-60.2 Water Columns
PG-60.2.1
A water column shall be so mounted
					 that it will be correctly positioned, relative to the normal water level under
					 operating conditions.
PG-60.2.3
Each water column shall be furnished
					 with a connection of at least NPS ¾ (DN 20) to install a valved drain to
					 a safe point of discharge.
PG-60.2.4
The design and material of a water
					 column shall comply with the requirements of PG-8.2, PG-8.3, and PG-42.
PG-60.3 Connections.
PG-60.3.1
Gage glasses that are required by
					 PG-60.1 shall be connected directly to the shell or drum of the boiler or to an
					 intervening water column. When two gage glasses are required, both may be
					 connected to a single water column.
PG-60.3.2
The lower edge of the steam
					 connection between a water column or gage glass in the boiler shall not be
					 below the highest visible water level in the gage glass. There shall be no sag
					 or offset in the piping that will permit the accumulation of water.
PG-60.3.3
The upper edge of the water
					 connection between a water column or gage glass and the boiler shall not be
					 above the lowest visible water level in the gage glass. No part of this pipe
					 connection shall be above the point of connection at the water column.
PG-60.3.4
Connections from the boiler to the
					 water column shall be at least NPS 1 (DN 25). Connections for gage glasses
					 connected directly to the boiler or to an intervening water column shall be at
					 least NPS ½ (DN 15). Connections from the boiler to the remote level
					 indicator shall be at least NPS ¾ (DN 20) to and including the isolation
					 valve and from there to the remote level indicator at least ½ in. (13
					 mm) O.D. tubing.
PG-60.3.5
When the boiler MAWP exceeds 400 psi
					 (3 MPa), lower connections to drums for water columns and remote level
					 indicators shall be provided with shields, sleeves, or other suitable means to
					 reduce the effect of temperature differentials in the shells or heads.
PG-60.3.6
The steam and water connections to
					 a water column or a gage glass shall be readily accessible for internal
					 inspection and cleaning. Some acceptable methods of meeting this requirement
					 are by providing a cross or fitting with a back outlet at each right-angle turn
					 to permit inspection and cleaning in both directions, or by using pipe bends or
					 fittings of a type that does not leave an internal shoulder or pocket in the
					 pipe connection and with a radius of curvature that will permit the passage of
					 a rotary cleaner. Screwed plug closures using threaded connections as allowed
					 by PG-39.5.3 are acceptable means of access for this inspection and cleaning.
					 When the boiler MAWP exceeds 400 psig (3 MPa), socket-welded plugs may be used
					 for this purpose in lieu of screwed plugs. If the water connection to the water
					 column has a rising bend or pocket that cannot be drained by means of the
					 water-column drain, an additional drain shall be placed on this connection so
					 that it may be blown off to clear any sediment from the pipe.
See PDF for
					 diagram
PG-60.3.7
Shutoff valves, if provided in the
					 pipe connections between a boiler and a water column or between a boiler and
					 the shutoff valves required for the gage glass (PG-60.1.6), shall be of such
					 through-flow construction as to prevent stoppage by deposits of sediment and
					 shall indicate whether they are in open or closed position of the operating
					 mechanism.
Some examples of acceptable valves are:
(a) outside-screw-and-yoke type gate valve
(b) lever-lifting-type gate valve with permanently fastened
					 lever
(c) stopcock with the plug held in place by a guard or
					 gland
(d) ball valve
Such valves shall be locked or sealed open except under the
					 following additional conditions:
(1) The boiler MAWP shall not exceed 250 psig (1.7
					 MPa).
(2) The boiler shall not be hand fired or fired with solid
					 fuel not in suspension.
(3) Interlocks between the valve and the burner control
					 system shall stop fuel supply and prevent firing whenever the valve between the
					 drum and the water column is not in the fully open position.
(4) The minimum valve size shall be NPS 1 (DN 25).
PG-60.3.8
Except for control devices such as
					 damper regulators and feedwater regulators, drains, steam pressure gages, or
					 apparatus of such form as does not permit the escape of an appreciable amount
					 of steam or water therefrom, no outlet connections shall be placed on the
					 piping connecting a water column or gage glass to a boiler. No outlet
					 connections shall be placed on the piping connecting a remote level indicator
					 to the boiler or to a water column for any function other than water level
					 indication.
PG-60.3.9
An acceptable arrangement is shown
					 in Fig. PG-60.3.9
See PDF for
					 diagram
PG-60.4 Gage Cocks.
Not required.
PG-60.5 Water Fronts.
Each boiler fitted with
					 a water jacketed boiler-furnace mouth protector, or similar appliance having
					 valves on the pipes connecting them to the boiler shall have these valves
					 locked or sealed open. Such valves, when used, shall be of the straightway
					 type.
PG-60.6 Pressure Gages
PG-60.6.1
Each boiler shall have a pressure
					 gage so located that it is easily readable. The pressure gage shall be
					 installed so that it shall at all times indicate the pressure in the boiler.
					 Each steam boiler shall have the pressure gage connected to the steam space or
					 to the water column or its steam connection. A valve or cock shall be placed in
					 the gage connection adjacent to the gage. An additional valve or cock may be
					 located near the boiler providing it is locked or sealed in the open position.
					 No other shutoff valves shall be located between the gage and the boiler. The
					 pipe connection shall be of ample size and arranged so that it may be cleared
					 by blowing out. For a steam boiler the gage or connection shall contain a
					 syphon or equivalent device that will develop and maintain a water seal that
					 will prevent steam from entering the gage tube. Pressure gage connections shall
					 be suitable for the maximum allowable working pressure and temperature, but if
					 the temperature exceeds 406°F (208 °C), brass or copper pipe or tubing
					 shall not be used. The connections to the boiler, except the syphon, if used,
					 shall not be less than NPS ¼ (DN 8) but where steel or wrought iron pipe
					 or tubing is used, they shall not be less than ½ in. (13 mm) inside
					 diameter. The minimum size of a syphon, if used, shall be ¼ in. (6 mm)
					 inside diameter. The dial of the pressure gage shall be graduated to
					 approximately double the pressure at which the safety valve is set, but in no
					 case to less than 1 ½ times this pressure.
PG-60.6.2
Each forced-flow steam generator
					 with no fixed steam and waterline shall be equipped with pressure gages or
					 other pressure measuring devices located as follows:
PG-60.6.2.1
At the boiler or superheater
					 outlet (following the last section which involves absorption of heat), and
PG-60.6.2.2
At the boiler or economizer inlet
					 (preceding any section that involves absorption of heat), and
PG-60.6.2.3
Upstream of any shutoff valve that
					 may be used between any two sections of the heat absorbing surface.
PG-60.6.3
Each boiler shall be provided with a
					 valve connection at least NPS ¼ (DN 8) for the exclusive purpose of
					 attaching a test gage when the boiler is in service, so that the accuracy of
					 the boiler pressure gage can be ascertained.
PG-60.6.4
Each high-temperature water boiler
					 shall have a temperature gage so located and connected that it shall be easily
					 readable. The temperature gage shall be installed so that it at all times
					 indicates the temperature in degrees Fahrenheit (Celsius) of the water in the
					 boiler, at or near the outlet connection.
PG-61 FEEDWATER SUPPLY
PG-61.1
Except as provided for in PG-61.2 and
					 PG-61.4, boilers having more than 500 ft2 (47 m2) of water-heating surface
					 shall have at least two means of feeding water. Except as provided for in
					 PG-61.3, PG-61.4, and PG-61.5, each source of feeding shall be capable of
					 supplying water to the boiler at a pressure of 3% higher than the highest
					 setting of any safety valve on the boiler. For boilers that are fired with
					 solid fuel not in suspension, and for boilers whose setting or heat source can
					 continue to supply sufficient heat to cause damage to the boiler if the feed
					 supply is interrupted, one such means of feeding shall not be susceptible to
					 the same interruption as the other, and each shall provide sufficient water to
					 prevent damage to the boiler.
PG-61.2
Except as provided for in PG-61.1, a
					 boiler fired by gaseous, liquid, or solid fuel in suspension, or heated by
					 combustion turbine engine exhaust, may be equipped with a single means of
					 feeding water, provided means are furnished for the shutting off of its heat
					 input prior to the water level reaching the lowest permissible level
					 established by PG-60.
PG-61.3
For boilers having a water-heating
					 surface of not more than 100 ft2 (9.3 m2) the feed connection to the boiler
					 shall not be smaller than NPS ½ (DN 15). For boilers having a
					 water-heating surface more than 100 ft2 (9.3 m2) the feed connection to the
					 boiler shall not be less than NPS ¾ (DN 20).
PG-61.4
High-temperature water boilers shall
					 be provided with means of adding water to the boiler or system while under
					 pressure.
PG-61.5
A forced-flow steam generator with no
					 fixed steam and waterline shall be provided with a source of feeding capable of
					 supplying water to the boiler at a pressure not less than the expected maximum
					 sustained pressure at the boiler inlet, as determined by the boiler
					 Manufacturer, corresponding to operation at maximum designed steaming capacity
					 with maximum allowable working pressure at the superheater outlet.
OVERPRESSURE PROTECTION REQUIREMENTS
PG-67 BOILER
PG-67.1
Each boiler shall have at least one
					 pressure relief valve and if it has more than 500 ft2 (47 m2) of bare tube
					 water-heating surface, or if an electric boiler has a power input more than
					 1,100 kW, it shall have two or more pressure relief valves. For a boiler with
					 combined bare tube and extended water-heating surface exceeding 500 ft2 (47
					 m2), two or more pressure relief valves are required only if the design steam
					 generating capacity of the boiler exceeds 4,000 lb/hr (1 800 kg/hr). Organic
					 fluid vaporizer generators require special consideration as given in Part
					 PVG.
PG-67.2
The pressure relief valve capacity for
					 each boiler (except as noted in PG-67.4) shall be such that the pressure relief
					 valve, or valves will discharge all the steam that can be generated by the
					 boiler without allowing the pressure to rise more than 6% above the highest
					 pressure at which any valve is set and in no case to more than 6% above the
					 maximum allowable working pressure.
PG-67.2.1
The minimum required relieving
					 capacity of the pressure relief valves for all types of boilers shall be not
					 less than the maximum designed steaming capacity at the MAWP of the boiler, as
					 determined by the Manufacturer and shall be based on the capacity of all the
					 fuel burning equipment as limited by other boiler functions.
PG-67.2.2
The minimum required relieving
					 capacity for a waste heat boiler shall be determined by the Manufacturer. When
					 auxiliary firing is to be used in combination with waste heat recovery, the
					 maximum output as determined by the boiler Manufacturer shall include the
					 effect of such firing in the total required capacity. When auxiliary firing is'
					 to be used in place of waste heat recovery, the minimum required relieving
					 capacity shall be based on auxiliary firing or waste heat recovery, whichever
					 is higher.
PG-67.2.3
The minimum required relieving
					 capacity for electric boilers shall be in accordance with PEB-15.
PG-67.2.4
The minimum required relieving
					 capacity in lb/hr (kg/hr) for a high-temperature water boiler shall be
					 determined by dividing the maximum output in Btu/hr (W) at the boiler nozzle,
					 produced by the highest heating value fuel for which the boiler is designed, by
					 1,000 (646).
PG-67.2.5
The minimum required relieving
					 capacity for organic fluid vaporizers shall be in accordance with PVG-12. The
					 minimum required relieving capacity for miniature boilers shall be in
					 accordance with PMB-15.
PG-67.2.6
Any economizer that may be shut off
					 from the boiler, thereby permitting the economizer to become a fired pressure
					 vessel, shall have one or more pressure relief valves with a total discharge
					 capacity, in lb/hr (kg/hr), calculated from the maximum expected heat
					 absorption in Btu/hr (W), as determined by the Manufacturer, divided by 1,000
					 (646). This absorption s shall be stated in the stamping (PG-106.4). For
					 overpressure conditions where the fluid relieved is water, the discharge
					 capacity of the pressure relief valve, or valves shall be sufficient to prevent
					 the pressure from exceeding the limits of PG-67.2.
PG-67.2.7
The steam generated when all
					 pressure relief valves are relieving at full lift on a boiler that has a
					 steam-generating surface located downstream in the gas stream of a superheater
					 and/or reheater surface may exceed the maximum designed steaming capacity at
					 the MA WP of the boiler. The Manufacturer shall address this by one of the
					 following methods:
PG-67.2.7.1
The minimum required relieving
					 capacity of the pressure relief valves shall not be less than the steam that
					 may be generated with all pressure relief valves relieving at full lift. For
					 boilers that use auxiliary firing in combination with the primary heat source,
					 the Manufacturer shall include the effect of such firing in the total required
					 capacity.
PG-67.2.7.2
The minimum required relieving
					 capacity of the pressure relief valves shall not be less than the maximum
					 designed steaming capacity at the MAWP of the boiler, and the boiler shall be
					 provided with controls responsive to steam pressure, which include not less
					 than the following:
(a) a control that reduces that total heat input to the
					 boiler such that the steam generated does not exceed the maximum designed
					 steaming capacity at the MAWP of the boiler
(b) a control that trips the heat input to the boiler if
					 the pressure reaches 106% of the MAWP of the boiler.
PG-67.3
One or more pressure relief valves on
					 the boiler proper shall be set at or below the maximum allowable working
					 pressure (except as noted in PG-67.4). If additional valves are used the
					 highest pressure setting shall not exceed the maximum allowable working
					 pressure by more than 3%. The complete range of pressure settings of all the
					 saturated-steam pressure relief valves on a boiler shall not exceed 10% of the
					 highest pressure to which any valve is set. Pressure setting of pressure relief
					 valves on high-temperature water boilers8 may exceed this 10% range. Economizer
					 pressure relief devices required by PG-67.2.6 shall be set as above using the
					 MAWP of the economizer.
8 Pressure relief valves in hot
					 water service are more susceptible to damage and subsequent leakage, than
					 pressure relief valves relieving steam. It is recom - mended that the maximum
					 allowable working pressure of the boiler and the pres - sure relief valve
					 setting for high-temperature water boilers be selected substan - tially higher
					 than the desired operating pressure so as to minimize the times the pressure
					 relief valve must lift.
See PDF for
					 diagram
PG-67.4
For a forced-flow steam generator
					 with no fixed steam and waterline (Fig. PG-6704), equipped with automatic
					 controls and protective interlocks responsive to steam pressure, pressure
					 relief valves may be provided in accordance with the above paragraphs or the
					 following protection against overpressure shall be provided:
PG-67.4.1
One or more power-actuated pressure
					 relieving valves9  shall be provided in direct
					 communication with the boiler when the boiler is under pressure and shall
					 receive a control impulse to open when the maximum allowable working pressure
					 at the superheater outlet, as shown in the master stamping (PG-106.3), is
					 exceeded. The total combined relieving capacity of the power-actuated relieving
					 valves shall be not less than 10% of the maximum design steaming capacity of
					 the boiler under any operating condition as determined by the Manufacturer. The
					 valve or valves shall be located in the pressure part system where they will
					 relieve the overpressure.
9 The power-actuated pressure
					 relieving valve is one whose movements to open or close are fully controlled by
					 a source of power (electricity , air , steam, or hydraulic). The valve may
					 dischar ge to atmosphere or to a container at lower pressure. The discharge
					 capacity may be af fected by the downstream conditions, and such ef fects shall
					 be taken into account. If the power-actuated pressure relieving valves are also
					 positioned in response to other control signals, the con - trol impulse to
					 prevent overpressure shall be responsive only to pressure and shall override
					 any other control function
An isolating stop valve of the outside-screw-and-yoke or
					 ball type may be installed between the power-actuated pressure relieving valve
					 and the boiler to permit repairs provided an alternate power-actuated pressure
					 relieving valve of the same capacity is so installed as to be in direct
					 communication with the boiler in accordance with the requirements of this
					 paragraph.
The isolating stop valve port area shall at least equal the
					 area of the inlet of the power-actuated pressure relieving valve. If the
					 isolating stop valve is of the ball type, the valve shall include a means to
					 clearly identify whether the valve is in the open or closed position. If the
					 isolating stop valve is power actuated (air, motor, hydraulic, etc.), a manual
					 override mechanism shall be provided.
Power-actuated pressure relieving valves discharging to
					 intermediate pressure and incorporated into bypass and/or startup circuits by
					 the boiler Manufacturer need not be capacity certified. Instead, they shall be
					 marked by the valve manufacturer with a capacity rating at a set of specified
					 inlet pressure and temperature conditions. Power-actuated pressure relieving
					 valves discharging directly to atmosphere shall be capacity certified. This
					 capacity certification shall be conducted in accordance with the provisions of
					 PG-69.3. The valves shall be marked in accordance with the provisions of
					 PG-69.4.
PG-67.4.2
Pressure relief valves shall be
					 provided, having a total combined relieving capacity, including that of the
					 power-actuated pressure relieving capacity installed under PG-67.4.l, of not
					 less than 100% of the maximum designed steaming capacity of the boiler, as
					 determined by the Manufacturer, except the alternate provisions of PG-67.4.3
					 are satisfied. In this total, no credit in excess of 30% of the total required
					 relieving capacity shall be allowed for the power-actuated pressure relieving
					 valves actually installed. Any or all of the pressure relief valves may be set
					 above the maximum allowable working pressure of the parts to which they are
					 connected, but the set pressures shall be such that when all of these valves
					 (together with the power-actuated pressure relieving valves)are in operation
					 the pressure will not rise more than 20% above the maximum allowable working
					 pressure of any part of the boiler, except for the steam piping between the
					 boiler and the prime mover.
PG-67.4.3
The total installed capacity of
					 spring loaded safety valves may be less than the requirements of PG-67.4.2
					 provided all of the following conditions are met.
PG-67.4.3.1
The boiler shall be of no less
					 steaming capacity than 1,000,000 lb/hr (450 000 kg/hr) and installed in a unit
					 system for power generation (i.e., a single boiler supplying a single
					 turbine-generator unit).
PG-67.4.3.2
The boiler shall be provided with
					 automatic devices, responsive to variations in steam pressure, which include
					 not less than all the following:
PG-67.4.3.2.1
A control capable of
					 maintaining steam pressure at the desired operating level and of modulating
					 firing rates and feedwater flow in proportion to a variable steam
					 output.
PG-67.4.3.2.2
A control that overrides
					 PG-67.4.3.2.1 by reducing the fuel rate and feedwater flow when the steam
					 pressure exceeds the maximum allowable working pressure as shown in the master
					 stamping (PG-106.3) by 10%; and
PG-67.4.3.2.3
A direct-acting
					 overpressure-trip-actuating mechanism, using an independent pressure sensing
					 device, that will stop the flow of fuel and feedwater to the boiler, at a
					 pressure higher than the set pressure of PG-67.4.3.2.2, but less than 20% above
					 the maximum allowable working pressure as shown in the master stamping
					 (PG-106.3).
PG-67.4.3.3
There shall be not less than two
					 pressure relief valves and the total rated relieving capacity of the pressure
					 relief valves shall be not less than 10% of the maximum designed steaming
					 capacity of the boiler as determined by the Manufacturer. These pressure relief
					 valves may be set above the maximum allowable working pressure of the parts to
					 which they are connected but shall be set such that the valves will lift at a
					 pressure no higher than 20% above the maximum allowable working pressure as
					 shown in the master stamping (PG-106.3).
PG-67.4.3.4
At least two of these pressure
					 relief valves shall be equipped with a device that directly transmits the valve
					 stem lift action to controls that will stop the flow of fuel and feedwater to
					 the boiler. The control circuitry to accomplish this shall be arranged in a
					 "fail-safe" manner (see Note).
NOTES:
"Fail-safe" shall mean a circuitry
					 arranged as either of the following:
(a)
Energize to trip:
There shall be at
					 least two separate and independent trip circuits served by two power sources,
					 to initiate and perform the trip action. One power source shall be a
					 continuously charged DC battery. The second source shall be an AC-to-DC
					 converter connected to the DC system to charge the battery and capable of
					 performing the trip action. The trip circuits shall be continuously monitored
					 for availability.
It is not mandatory to duplicate the mechanism that
					 actually stops the flow of fuel and feedwater.
(b)
De-energize to trip:
If the circuits
					 are arranged in such a way that a continuous supply of power is required to
					 keep the circuits closed and operating and such that any interruption of power
					 supply will actuate the trip mechanism, then a single trip circuit and single
					 power supply will be enough to meet the requirements of this subparagraph.
PG-67.4.3.5
The power supply for all controls
					 and devices required by PG-67.4.3 shall include at least one source contained
					 within the same plant as the boiler and which is arranged to actuate the
					 controls and devices continuously in the event of failure or interruption of
					 any other power sources.
PG-67.4.4
When stop valves are installed in
					 the water-steam flow path between any two sections of a forced-flow steam
					 generator with no fixed steam and waterline:
PG-67.4.4.1
The power-actuated pressure
					 relieving valve(s) required by PG-67.4.1 shall also receive a control impulse
					 to open when the maximum allowable working pressure of the component, having
					 the lowest pressure upstream to the stop valve, is exceeded; and
PG-67.4.4.2
The pressure relief valves shall
					 be located to provide the pressure protection requirements in PG-67.4.2 or
					 PG-67.4.3.
PG-67.4.5
A reliable pressure-recording device
					 shall always be in service and records kept to provide evidence of conformity
					 to the above requirements.
PG-67.5
The coefficient of discharge of
					 pressure relief valves shall be determined by actual steam flow measurements at
					 a pressure not more than 3% above the pressure at which the valve is set to
					 relieve and when adjusted for blowdown in accordance with PG-69.1.4. The valves
					 shall be credited with capacities as determined by the provisions of PG-69.2.
Pressure relief valves may be used that give any opening up
					 to the full discharge capacity of the area of the opening of the inlet of the
					 valve, provided the movement of a steam pressure relief valve is such as not to
					 induce lifting of water in the boiler.
For high-temperature water boilers pressure relief valves
					 shall be used. Such valves shall have a closed bonnet. In addition the pressure
					 relief valves shall be capable of satisfactory operation when relieving water
					 at the saturation temperature corresponding to the pressure at which the valve
					 is set to blow.
PG-68 SUPERHEATER AND REHEATER
PG-68.1
Except as permitted in PG-58.3.1,
					 every attached superheater shall have one or more pressure relief valves in the
					 steam flow path between the superheater outlet and the first stop valve. The
					 location shall be suitable for the service intended and shall provide the
					 overpressure protection required. The pressure drop upstream of each pressure
					 relief valve shall be considered in the determination of set pressure and
					 relieving capacity of that valve. If the superheater outlet header has a full,
					 free steam passage from end to end and is so constructed that steam is supplied
					 to it at practically equal intervals throughout its length so that there is a
					 uniform flow of steam through the superheater tubes and the header, the
					 pressure relief valve, or valves, may be located anywhere in the length of the
					 header.
PG-68.2
The discharge capacity of the
					 pressure relief valve, or valves, on an attached superheater may be included in
					 determining the number and size of the pressure relief valves for the boiler,
					 provided there are no intervening valves between the superheater pressure
					 relief valve and the boiler, and provided the discharge capacity of the
					 pressure relief valve, or valves, on the boiler, as distinct from the
					 superheater is at least 75% of the aggregate valve capacity required.
PG-68.3
Every isolable superheater that may
					 be shut off from the boiler and permit the superheater to become a fired
					 pressure vessel and all nonintegral separately fired superheaters shall have
					 one or more pressure relief valves having a discharge capacity equal to 6
					 lb/ft2 (29 kg/m2) of steam per hour, using the superheater surface measured on
					 the side exposed to the hot gases. As an alternative the Manufacturer may also
					 calculate the minimum pressure relief valve discharge capacity in lb (kg) of
					 steam per hour from the maximum expected heat absorption (as determined by the
					 Manufacturer) in Btu/hr (W), divided by 1,000 (646). In the case of
					 electrically heated superheaters, the pressure relief valve capacity shall be
					 based upon 3 ½ lb (1.6 kg)/hr/kW input. The number of pressure relief
					 valves installed shall be such that the total capacity is at least equal to
					 that required. Pressure relief valves for separately fired superheaters shall
					 be located in accordance with the rules of PG-68.1 and the mounting rules of
					 PG-71.
PG-68.4
Every reheater shall have one or more
					 pressure relief valves, such that the total relieving capacity is at least
					 equal to the maximum steam flow for which the heater is designed. The capacity
					 of the reheater pressure relief valves shall not be included in the required
					 relieving capacity for the boiler and superheater.
One or more pressure relief valves with a combined
					 relieving capacity not less than 15% of the required total shall be located
					 along the steam flow path between the reheater outlet and the first stop valve.
					 The pressure drop upstream of the pressure relief valves on the outlet side of
					 the reheater shall be considered in determining their set pressure.
PG-68.5
A soot blower connection may be
					 attached to the same outlet from the superheater or reheater that is used for
					 the pressure relief valve connection.
PG-68.6
Every pressure relief valve used on a
					 superheater or reheater discharging superheated steam at a temperature over
					 450°F (230°C) shall have a casing, including the base, body, and, if
					 applicable, bonnet and spindle, of steel, steel alloy, or equivalent
					 heat-resisting material.
The pressure relief valve shall have a flanged inlet
					 connection, or a weld-end inlet connection. It shall have the seat and disk of
					 suitable heat erosive and corrosive resisting material, and the spring of
					 direct spring-loaded safety valves shall be fully exposed outside of the valve
					 casing so that it shall be protected from contact with the escaping
					 steam.
PG-68.7
The capacity of a pressure relief
					 valve on superheated steam shall be calculated by multiplying the capacity
					 determined in accordance with PG-69.2 by the appropriate superheat correction
					 factor K
sh
, from Table PG-68.7.
TABLE PG- 68.7
SUPERHEAT CORRECTION FACTOR,
Ksh
Click here
					 to view image
TABLE PG- 68.7M
SUPERHEAT CORRECTION FACTOR,
Ksh
Click here
					 to view image
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PG-69 CERTIFICATION OF CAPACITY OF PRESSURE RELIEF
					 VALVES
PG-69.1
Before the Code symbol is applied td
					 any pressure relief valve or power-actuated pressure relieving valve, the valve
					 manufacturer shall have the relieving capacity of his pressure relief valves
					 certified in accordance with the provisions of this paragraph.
PG-69.1.1
Capacity certification tests shall
					 be conducted using dry saturated steam. The limits for test purposes shall be
					 98% minimum quality and 20°F (l0°C) maximum superheat. Correction from
					 within these limits may be made to the dry saturated condition.
PG-69.1.2
Tests shall be conducted at a place
					 that meets the requirements of A-312.
PG-69.1.3
Capacity test data reports for each
					 pressure relief valve design and size, signed by the manufacturer and
					 Authorized Observer witnessing the tests, together with drawings showing the
					 valve construction, shall be submitted to the ASME designee for review and
					 acceptance.10
10 Valve capacities are
					 published in "Pressure Relief Device Certifications." This publication may be
					 obtained from the National Board of Boiler and Pressure Vessel Inspectors, 1055
					 Crupper Ave., Columbus, OH 43299.
PG-69.1.4
Capacity certification tests shall
					 be conducted at a pressure that does not exceed the set pressure by 3% or 2 psi
					 (15 kPa), whichever is greater. Pressure relief valves shall be adjusted so
					 that the blowdown does not exceed 4% of the set pressure. For pressure relief
					 valves set at or below 100 psi (700 kPa), the blowdown shall be adjusted so as
					 not to exceed 4 psi (30 kPa). Pressure relief valves used on forced-flow steam
					 generators with no fixed steam and waterline, and pressure relief valves used
					 on high-temperature water boilers shall be adjusted so that the blow down does
					 not exceed 10% of the set pressure. The res eating pressure shall be noted and
					 recorded.
PG-69.1.5
Capacity certification of pilot
					 operated pressure relief valves may be based on tests without the pilot valves
					 installed, provided prior to capacity tests it has been demonstrated by test to
					 the satisfaction of the Authorized Observer that the pilot valve will cause the
					 main valve to open fully at a pressure which does not exceed the set pressure
					 by more than 3% or 2 psi (15 kPa), whichever is greater, and that the pilot
					 valve in combination with the main valve will meet all of the requirements of
					 this Section.
PG-69.1.6
Pressure relief valves for
					 economizer service shall also be capacity certified using water at a
					 temperature between 40°F and 125°F (4°C and 50°C). The pressure
					 relief valves shall be tested without change to the adjustments established in
					 PG-69.1.1 to PG-69.1.4.
PG-69.2
Relieving capacities shall be
					 determined using one of the following methods.
PG-69.2.1
Three Valve Method.
A
					 capacity certification test is required on a set of three pressure relief
					 valves for each combination of size, design, and pressure setting. The capacity
					 of each valve of the set shall fall within a range of ±5% of the average
					 capacity. If one of the three pressure relief valves tested falls outside this
					 range, it shall be replaced by two valves, and a new average shall be
					 calculated based on all four valves, excluding the replaced valve. Failure of
					 any of the four capacities to fall within a range of ±5% of the new
					 average shall be cause to refuse certification of that particular valve
					 design.
The rated relieving capacity for each combination of
					 design, size, and test pressure shall be 90% of the average capacity.
TABLE PG- 69.2.3
SUPERHEAT CORRECTION FACTOR,
Ksc
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PG-69.2.2 Slope Method.
If a Manufacturer
					 wishes to apply the Code Symbol to a design of pressure relief valves, four
					 valves of each combination of pipe size and orifice size shall be tested. These
					 four valves shall be set at pressures that cover the approximate range of
					 pressures for which the valve will be used or covering the range available at
					 the certified test facility that shall conduct the tests. The capacities based
					 on these four tests shall be as follows:
(a) The slope WIP of the actual measured capacity versus
					 the flow pressure for each test point shall be calculated and averaged
For steam
See PDF for
					 diagram
All values derived from the testing must fall within
					 ±5% of the average value:
minimum slope = 0.95 x average slope
maximum slope = 1.05 x average slope
If the values derived from the testing do not fall between
					 the minimum and maximum slope values, the Authorized Observer shall require
					 that additional valves be tested at the rate of two for each valve beyond the
					 maximum and minimum values with a limit of four additional valves.
For steam applications the relieving capacity to be stamped
					 on the valve shall not exceed 90% of the average slope times the absolute
					 accumulation pressure
rated slope = 0.90 x average slope
For water applications the relieving capacity shall not
					 exceed 90% of the average slope multiplied by the square root of the difference
					 between the flow rating pressure and the valve discharge pressure.
See PDF for
					 diagram
(U.S. Customary Units)
stamped capacity [LESS THAN IS EQUAL TO ] rated slope (1.03
					 x set pressure + 14.7) or (set pressure + 2 psi + 14.7), whichever is
					 greater
(SI Units)
stamped capacity [LESS THAN IS EQUAL TO ] rated slope (1.03
					 x set pressure + 0.101) or (set pressure + 0.015 MPa + 0.101), whichever is
					 greater
TABLE PG- 69.2.3M
SUPERHEAT CORRECTION FACTOR,
					 K
sc
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PG-69.2.3 Coefficient of Discharge Method.
A
					 coefficient of discharge for the design,
K
, may be established
					 for a specific valve design according to the following procedure:
(a) For each design, the pressure relief valve manufacturer
					 shall submit for test at least three valves for each of three different sizes
					 (a total of nine valves). Each valve of a given size shall be set at a
					 different pressure, covering the range of pressures for which the valve will be
					 used or the range available at the facility where the tests are
					 conducted.
For each valve design where the coefficient of discharge
					 has been determined that is intended to be restricted in lift, the Manufacturer
					 shall have capacity tests conducted on three valves of different sizes. Each
					 size valve shall be tested for capacity at the minimum lift for which
					 certification is required, and at two intermediate lift points between the full
					 rated lift and minimum lift certification points. Each of the three test valves
					 shall be set at a different pressure.
For each valve tested, it shall be verified that actual
					 measured capacity at restricted lift will equal or exceed the rated capacity at
					 full rated lift multiplied by the ratio of measured restricted lift to full
					 rated lift.
(b) Tests shall be made on each pressure relief valve to
					 determine its lift at capacity, popping, and blowdown pressures, and actual
					 relieving capacity. An individual coefficient,
K
D
, shall be
					 established for each valve as follows:
See PDF for
					 diagram
Where actual flow is determined by test and theoretical
					 flow,
W
T
is calculated by one of the
					 following equations:
For tests with dry saturated steam
For 45 deg seat
(U.S. Customary Units)
W
T
= 51.5 x p
DLP
x 0.707
(SI Units)
W
T
= 5.25 x p
DLP
x 0.707
For flat seat
(U.S. Customary Units)
W
T
= 51.5 x p
DLP
(SI Units)
W
T
= 5.25 x p
DLP
For nozzle
(U.S. Customary Units)
W
T
= 51.5
AP
(SI Units)
W
T
= 5.25
AP
For tests with water
For 45 deg seat
(U.S. Customary Units)
See PDF for
					 diagram
where
A = nozzle throat area, in.2
					 (mm2)
D = seat diameter, in. (mm)
L = lift at pressure
P
, in. (mm)
P = (1.03 X set pressure + 14.7), psia, or
= (set pressure + 2 + 14.7), psia, whichever is
					 greater
= (1.03 X set pressure + 0.101), MPa, or
= (set pressure + 0.014 + 0.101), MPa, whichever is
					 greater
P d = pressure at discharge of the valve, psia (MPa)
WT = theoretical flow, lb/hr (kg/hr)
w = specific weight of water at inlet conditions,
					 lb/ft3  (kg/m3)
To convert lb/hr of water to gal/min of water, multiply the
					 capacity in lb/hr by 1/500, To convert kg/hr of water to liter/min of water,
					 multiply the capacity in liter/min by 1/60.
The average of the coefficients
K
D
of the nine tests
					 required shall be multiplied by 0.90, and this product shall be taken as the
					 coefficient
K
of that design. All individual coefficients of
					 discharge,
K
D
, shall
					 fall within a range of ±5% of the average coefficient found. If a valve
					 fails to meet this requirement, the Authorized Observer shall require two
					 additional valves to be tested as replacements for each valve having an
					 individual coefficient,
K
D
, outside the
					 ±5% range, with a limit of four additional valves. Failure of a
					 coefficient,
K
D
, to
					 fall within ±5% of the new average value, excluding the replaced
					 valve(s), shall be cause to refuse certification of that particular valve
					 design.
The rated relieving capacity of all sizes and set pressures
					 of a given design, for which
K
has been established under the
					 provision of this paragraph, shall be determined by the equation:
W [LESS THAN IS EQUAL TO ] WT x
					 K
where
K = coefficient of discharge for the design
W = rated relieving capacity, lb/hr (kg/hr)
WT = theoretical flow, defined by
					 the same equation used to determine KD, lb/hr (kg/hr)
The coefficient of discharge for the design shall be not
					 greater Than 0.878 (the product of 0.9 x 0.975). The coefficient shall not be
					 applied to valves whose beta ratio (ratio of valve throat to inlet diameter)
					 lies outside the range of 0.15 to 0.75, unless tests have demonstrated that the
					 individual coefficient of discharge,
K
D
, for valves at the
					 extreme ends of a larger range, is within ±5% of the average
					 coefficient,
K
D
.
For designs where the lift is used to determine the flow
					 area, all valves shall have the same nominal lift to seat diameter ratio
					 (
L
/
D
).
For pressures over 1,500 psig (10.3 MPa) and up to 3,200
					 psig (22.1 MPa), the value of
W
shall be multiplied by the
					 correction factor:
(U.S. Customary Units)
0.1906P - 1,000
0.2292P - 1,061
(SI Units)
27.6P - 1 000
33.2P - 1 061
For pressures over 3,200 psig (22.1 MPa), the value of
W
shall be multiplied by the appropriate supercritical
					 correction factor, K
sc
, from Table PG-69.2.3.
PG-69.3
If a manufacturer wishes to apply the
					 Code symbol to a power-actuated pressure relieving valve under PG-67.4.1, one
					 valve of each combination of inlet pipe size and orifice size to be used with
					 that inlet pipe size shall be tested. The valve shall be capacity tested at
					 four different pressures approximately covering the range of the certified test
					 facility on which the tests are conducted. The capacities, as determined by
					 these four tests, shall be plotted against the absolute flow test pressure and
					 a line drawn through these four test points. All points must lie within
					 ±5% in capacity value of the plotted line and must pass through 0-0.
					 From the plotted line, the slope of the line
dW/dP
shall be
					 determined and a factor of (0.90/51.45) x (
dW/dP
) shall be
					 applied to capacity computations in the supercritical region at elevated
					 pressures by means of the isentropic flow equation.
See PDF for
					 diagram
where
dW/dP = rate of change of measured capacity with respect to
					 absolute pressure
P = absolute inlet pressure, psia (MPa)
v = inlet specific volume,
					 ft3/lb (m3/kg)
W = capacity, lb of steam/hr (kg/hr)
NOTES:
The constant 1,135.8 is based on a g
					 factor of 1.30, which is accurate for superheated steam at temperature above
					 approximately 800°F (430°C). In interest of accuracy, other methods of
					 capacity computations must be used at temperatures below 800°F (430°C)
					 at supercritical pressures.
PG-69.4
Power-actuated pressure relieving
					 valves, having capacities certified in accordance with the provision of PG-69.3
					 and computed in accordance with the formula contained therein, shall be marked
					 as required by PG-110 with the computed capacity, corresponding to 3% above the
					 full load operating pressure and temperature conditions at the valve inlet when
					 the valve is operated by the controller, and they shall also be stamped with
					 the set pressure of the controller. When the valve is marked as required by
					 this paragraph, it shall be the guarantee by the manufacturer that the valve
					 also conforms to the details of construction herein specified.
PG-69.6
When changes are made in the design of
					 a safety or safety relief valve in such a manner as to affect the flow path,
					 lift, or performance characteristics of the valve, new tests in accordance with
					 this Section shall be performed.
PG-70 CAPACITY OF PRESSURE RELIEF
					 VALVES
PG-70.1
Subject to the minimum number required
					 by PG-67.1, the number of pressure relief valves required shall be determined
					 on the basis of the maximum designed steaming capacity, as determined by the
					 boiler Manufacturer, and the relieving capacity marked on the valves by the
					 manufacturer.
PG-71 MOUNTING OF PRESSURE RELIEF
					 VALVES
PG-71.1
When two or more pressure relief
					 valves are used on a boiler, they may be mounted either separately or as twin
					 valves made by placing individual valves on Y-bases, or duplex valves having
					 two valves in the same body casing. Twin valves made by placing individual
					 valves on Y-bases, or duplex valves having two valves in the same body, shall
					 be of approximately equal capacity.
When not more than two valves of different sizes are
					 mounted singly the relieving capacity of the smaller valve shall be not less
					 than 50% of that of the larger valve.
PG-71.2
The pressure relief valve or valves
					 shall be connected to the boiler independent of any other connection, and
					 attached as close as possible to the boiler or the normal steam flow path,
					 without any unnecessary intervening pipe or fitting. Such intervening pipe or
					 fitting shall be not longer than the face-to-face dimension of the
					 corresponding tee fitting of the same diameter and pressure under the
					 applicable ASME Standard listed in PG-42 and shall also comply with PG-8 and
					 PG-39. Every pressure relief valve shall be connected so as to stand in an
					 upright position, with spindle vertical. On high-temperature water boilers of
					 the watertube forced-circulation type, the valve shall be located at the boiler
					 outlet.
PG-71.3
The opening or connection between the
					 boiler and the pressure relief valve shall have at least the area of the valve
					 inlet. No valve of any description shall be placed between the required
					 pressure relief valve or valves and the boiler, nor on the discharge pipe
					 between the pressure relief valve and the atmosphere. When a discharge pipe is
					 used, the cross-sectional area shall be not less than the full area of the
					 valve outlet or of the total of the areas of the valve outlets, discharging
					 thereinto. It shall be as short and straight as possible and so arranged as to
					 avoid undue stresses on the valve or valves.
All pressure relief valve discharges shall be so located or
					 piped as to be carried clear from running boards or platforms. Ample provision
					 for gravity drain shall be made in the discharge pipe at or near each pressure
					 relief valve, and where water of condensation may collect. Each valve shall
					 have an open gravity drain through the casing below the level of the valve
					 seat. For iron- and steel-bodied valves exceeding NPS 2 ½ (DN 65), the
					 drain hole shall be tapped not less than NPS 3/8 (DN 10).
Discharge piping from pressure relief valves on high
					 temperature water boilers shall be provided with adequate provisions for water
					 drainage as well as the steam venting.
The installation of cast iron bodied pressure relief valves
					 for high-temperature water boilers is prohibited.
PG-71.4
If a muffler is used on a pressure
					 relief valve, it shall have sufficient outlet area to prevent back pressure
					 from interfering with the proper operation and discharge capacity of the valve.
					 The muffler plates or other devices shall be so constructed as to avoid a
					 possibility of restriction of the steam passages due to deposit. Mufflers shall
					 not be used on high-temperature water boiler pressure relief valves.
When a pressure relief valve is exposed to outdoor elements
					 that may affect operation of the valve, it is permissible to shield the valve
					 with a satisfactory cover. The shield or cover shall be properly vented and
					 arranged to permit servicing and normal operation of the valve.
PG-71.5
When a boiler is fitted with two or
					 more pressure relief valves on one connection, this connection to the boiler
					 shall have a cross-sectional area not less than the combined areas of inlet
					 connections of all the pressure relief valves with which it connects and shall
					 also meet the requirements of PG-71.3.
PG-71.6
Pressure relief valves may be attached
					 to drums or headers by welding provided the welding is done in accordance with
					 Code requirements.
PG-71.7
Every boiler shall have proper outlet
					 connections for the required pressure relief valve, or valves, independent of
					 any other outside steam connection,. the area of opening to be at least equal
					 to the aggregate areas of inlet connections of all of the pressure relief
					 valves to be attached thereto. An internal collecting pipe, splash plate, or
					 pan may be used, provided the total area for inlet of steam thereto is not less
					 than twice the aggregate areas of the inlet connections of the attached
					 pressure relief valves. The holes in such collecting pipes shall be at least
					 ¼ in. (6 mm) in diameter and the least dimension in any other form of
					 opening for inlet of steam shall be ¼ in. (6 mm).
Such dimensional limitations to operation for steam need
					 not apply to steam scrubbers or driers provided the net free steam inlet area
					 of the scrubber or drier is at least 10 times the total area of the boiler
					 outlets for the pressure relief valves.
PG-71.8
If pressure relief valves are attached
					 to a separate steam drum or dome, the opening between the boiler proper and the
					 steam drum or dome shall be not less than required by PG-71.7.
PG-72 OPERATION OF PRESSURE RELIEF
					 VALVES
PG-72.1
Pressure relief valves shall be
					 designed and constructed to operate without chattering, with a minimum blowdown
					 of 2 psi (15 kPa) or 2% of the set pressure, whichever is greater, and to
					 attain full lift at a pressure not greater than 3% above their set
					 pressure.
Pressure relief valves used on forced-flow steam generators
					 with no fixed steam and waterline, and pressure relief valves used on
					 high-temperature water boilers must be marked for these special services by the
					 valve Manufacturer or Assembler.
PG-72.2
The set pressure tolerance plus or
					 minus shall not exceed that specified in the following table:
Set Pressure, psi (MPa)
Tolerance, Plus or Minus From Set Pressure
370 (0.5)
2 psi (15 kPa)
> 70 (0.5) and 3300 (2.1)
3% of set pressure
> 300 (2.1) and 31,000 (7.0)
10 psi (70 kPa)
> 1,000 (7.0)
1% of set pressure
PG-72.3
The spring in a pressure relief valve
					 shall not be reset for any pressure more than 5% above or below that for which
					 the valve is marked unless the new setting is within the spring design range
					 established by the manufacturer or is determined to be acceptable to the
					 manufacturer.
If the set pressure is to be adjusted within the limits
					 specified above, the adjustment shall be performed by the manufacturer, his
					 authorized representative, or an assembler. An additional valve data tag
					 identifying the new set pressure, capacity, and date shall be furnished and
					 installed, and the valve shall be resealed.
PG-72.4
If the set pressure of a valve is
					 changed so as to require a new spring, the spring shall be acceptable to the
					 manufacturer. The spring installation and valve adjustment shall be performed
					 by the manufacturer, his authorized representative, or an assembler. A new
					 nameplate as described in PG-110 shall be furnished and installed, and the
					 valve shall be resealed.
PG-73 MINIMUM REQUIREMENTS FOR PRESSURE RELIEF
					 VALVES
PG-73.1 Permissible Pressure Relief
					 Valves
PG-73.1.1
Pressure relief valves shall be
					 either direct spring-loaded safety valves, direct spring-loaded safety relief
					 valves, or pilot-operated pressure relief valves.
PG-73.1.2
Power-actuated pressure relieving
					 valves shall only be used for applications specified in PG-67.4.1.
PG-73.1.3
Deadweight or weighted lever safety
					 valves or safety relief valves shall not be used.
PG-73.1.4
Unless otherwise defined, the
					 definitions relating to pressure relief devices in ASME PTC 25 shall
					 apply.
PG-73.2 Minimum Requirements
PG-73.2.1
All pressure relief valves shall be
					 so constructed that the failure of any part cannot obstruct the free and full
					 discharge of steam and water from the valve. Pressure relief valves shall have
					 the seat inclined at any angle between 45 deg and 90 deg, inclusive, to the
					 centerline of the disk.
PG-73.2.2
The design shall incorporate guiding
					 arrangements necessary to insure consistent operation and tightness.
PG-73.2.3
The spring shall be designed so that
					 the full lift spring compression shall be no greater than 80% of the nominal
					 solid deflection. The permanent set of the spring (defined as the difference
					 between the free height and height measured 10 min after the spring has been
					 compressed solid three additional times after presetting at room temperature)
					 shall not exceed 0.5% of the free height.
PG-73.2.4
To provide a means for verifying
					 whether it is free, each safety valve or safety relief valve shall have a
					 substantial lifting device, which when activated will release the seating force
					 on the disk when the valve is subjected to pressure of at least 75% of the set
					 pressure. The lifting device shall be such that it cannot lock or hold the
					 valve disk in lifted position when the exterior lifting force is released.
					 Disks of pressure relief valves used on high-temperature water boilers shall
					 not be lifted while the temperature of the water exceeds 200°F (93°C).
					 If it is desired to lift the valve disk to assure that it is free, this shall
					 be done when the valve is subjected to a pressure of at least 75% of the set
					 pressure. Pilot-operated pressure relief valves shall be provided with either a
					 lifting device as described above or means for connecting and applying pressure
					 to the pilot adequate to verify that the moving parts critical to proper
					 operations are free to move. For high-temperature water boilers, the lifting
					 mechanism shall be sealed against leakage.
PG-73.2.5
The seat of a pressure relief valve
					 shall be fastened to the body of the valve in such a way that there is no
					 possibility of the seat lifting.
PG-73.2.6
A body drain below seat level shall
					 be provided in the valve and this drain shall not be plugged during or after
					 field installation. For valves exceeding NPS 2 ½ (DN 65), the drain hole
					 or holes shall be tapped not less than NPS 3/8 (DN 10). For valves of NPS 2
					 ½ (DN 65) or smaller, the drain hole shall not be less than ¼ in.
					 (6 mm) in diameter.
PG-73.2.7
In the design of the body of the
					 valve, consideration shall be given to minimizing the effects of water
					 deposits.
PG-73.2.8
Valves having screwed inlet or
					 outlet connections shall be provided with wrenching surfaces to allow for
					 normal installation without damaging operating parts.
PG-73.2.9
Means shall be provided in the
					 design of all valves for use under this Section, for sealing all external
					 adjustments. Seals shall be installed by the manufacturer, his authorized
					 representative, or an assembler at the time of the initial adjustment. After
					 spring replacement and/or subsequent adjustment, the valve shall be resealed.
					 Seals shall be installed in such a manner as to prevent changing the adjustment
					 without breaking the seal and, in addition, shall serve as a means of
					 identifying the manufacturer, his authorized representative, or the assembler
					 making the adjustment.
PG-73.2.10
Valve capacity may be restricted by
					 restricting the lift of a valve provided the following requirements are
					 met:
(a) The valve size shall be NPS ¾ (DN 20) or
					 larger.
(b) No changes shall be made in the design of the valve
					 except to change the valve lift by use of a lift restraining device described
					 in (c) below.
(c) The restriction of valve capacity shall be permitted
					 only by the use of a lift restraining device which shall limit valve lift and
					 shall not otherwise interfere with flow through the valve. The design of the
					 lift restraining device shall be subject to review by an ASME designee.
(d) The lift restraining device shall be designed so that,
					 if adjustable, the adjustable feature can be sealed. Seals shall be installed
					 by the valve Manufacturer or Assembler at the time of initial
					 adjustment.
(e) Valves shall not have their lifts restricted to a value
					 less than 30% of full rated lift, or 0.080 in. (2 mm).
(f) When sizing and selecting valves, the restricted lift
					 nameplate capacity shall be determined by multiplying the capacity at full
					 rated lift by the ratio of the restricted lift to the full rated lift.
PG-73.2.11
A pressure relief valve over NPS 3
					 (DN 80), used for pressure greater than 15 psig (100 kPa), shall have a flanged
					 inlet connection or a welded inlet connection. The dimensions of the flanges
					 subjected to boiler pressure shall conform to the applicable ASME standards as
					 given in PG-42. The facing shall be similar to those illustrated in the
					 standard.
PG-73.2.12
The pilot sensing line of
					 pilot-operated pressure relief valves shall be adequately protected from
					 freezing.
PG-73.3 Material Selections
PG-73.3.1
Cast iron seats and disks are not
					 permitted.
PG-73.3.2
Adjacent sliding surfaces such as
					 guides and disks or disk holders shall both be of corrosion-resistant material.
					 Springs of corrosion-resistant material or having a corrosion-resistant coating
					 are required. The seats and disks of pressure relief valves shall be of
					 suitable material to resist corrosion by the lading fluid.
NOTES:
The degree of corrosion resistance,
					 appropriate to the intended service, shall be a matter of agreement between the
					 manufacturer and the purchaser.
PG-73.3.3
Materials used in bodies and bonnets
					 or yokes shall be listed in Section II, Parts A and B, and identified in Tables
					 1A and 1B of Section II Part D, as permitted for Section I construction.
					 Materials used in body to bonnet or body to yoke bolting shall be listed in
					 ASME B16.34. Materials used in all other parts required for the pressure
					 relieving or retaining function shall be
(a) listed in ASME Section II
(b) listed in ASTM Specifications (see Note below)
					 or
(c) controlled by the manufacturer of the pressure relief
					 valve by a specification ensuring control of chemical and physical properties
					 and quality at least equivalent to ASTM Standards (see Note below)
PG-73.3.4
Pressure relief valves may have
					 bronze parts complying with either SB-61, SB-62 or SB-148, provided the maximum
					 allowable stresses and temperatures do not exceed the values given in Table 1B
					 of Section II, Part D, and shall be marked to indicate the class of material
					 used. Such valves shall not be used on superheaters delivering steam at a
					 temperature over 450°F (230°C) for SB-61 and SB-148, and 306°F
					 (I50°C) for SB-62, and shall not be used for high-temperature water
					 boilers.
NOTES:
It shall be the manufacturer's
					 responsibility to ensure that the allowable stresses at temperature meet the
					 requirements of Section II, Part D, Appendix 1, Mandatory Basis for
					 Establishing Stress Values in Tables 1A and 1B.
PG-73.4 Inspection of Manufacturing and/or
					 Assembly
PG-73.4.1
A manufacturer shall demonstrate to
					 the satisfaction of an ASME designee that his manufacturing, production, and
					 test facilities and quality control procedures will ensure close agreement
					 between the performance of random production samples and the performance of
					 those valves submitted for capacity certification.
PG-73.4.2
Manufacturing, assembly, inspection,
					 and test operations including capacity, are subject to inspections at any time
					 by an ASME designee.
PG-73.4.3
A Manufacturer or Assembler may be
					 granted permission to apply the V Code Symbol to production pressure relief
					 valves capacity-certified in accordance with PG-69, provided the following
					 tests are successfully completed. This permission shall expire on the sixth
					 anniversary of the date it is initially granted. This permission may be
					 extended for 6-yr periods if the following tests are successfully repeated
					 within the 6-mo period before expiration.
(a) Two sample production pressure relief valves of a size
					 and capacity within the capability of an ASME accepted laboratory shall be
					 selected by an ASME designee. The maximum blowdown for these samples shall not
					 exceed the value specified in the following table: -
Set Pressure, psi (kPa)
Maximum Blowdown
< 67 (500)
4 psi (30 kPa)
.67 (500) and 3250 (1 700)
6% of set pressure
> 250 (1 700) and <375 (2 500)
15 psi (100 kPa)
. 375 (2 500)
4% of set pressure
The blow down for sample valves designed for use on forced
					 flow steam generators with no fixed steam and waterline or high-temperature
					 water boilers shall not exceed 10% of the set pressure.
(b) Operational and capacity tests shall be conducted in
					 the presence of an ASME designee at an ASME-accepted laboratory. The valve
					 manufacturer or assembler shall be notified of the time of the test and may
					 have representatives present to witness the test.
(c) Should any valve fail to relieve at or above its
					 certified capacity or should it fail to meet performance requirements in PG-72,
					 the test shall be repeated at the rate of two replacement valves, specify a
					 higher test pressure commensurate with the back pressure anticipated in
					 service.
(d) Failure of any of the replacement valves to meet
					 capacity or the performance requirements of this Section shall be cause for
					 revocation within 60 days of the authorization to use the Code symbol on that
					 particular t type of valve. During this period, the Manufacturer or assembler
					 shall demonstrate the cause of such deficiency and the action taken toward
					 against future occurrence.
PG-73.4.4
Use of the Code Symbol Stamp by an
					 assembler indicates the use of original unmodified parts in strict accordance
					 with the instructions of the manufacturer of the valve.
(a) An assembler may transfer original and unmodified
					 pressure relief parts produced by the Manufacturer to other Assemblers,
					 provided the following conditions are met:
(1) both Assemblers have been granted permission to apply
					 the V or UV Code Symbol to the specific valve type in which the parts are to be
					 used
(2) the Quality Control System of the Assembler receiving
					 the pressure relief valve parts shall define the controls for the procurement
					 and acceptance of those parts
(3) the pressure relief valve parts are appropriately
					 packaged, marked, or sealed by the Manufacturer to ensure that the parts are
(a) produced, by the Manufacturer
(b) the parts are original and unmodified
(b) However, an assembler may convert original finished
					 parts by either machining to another finished part or applying a
					 corrosion-resistant coating to valve springs for a specific application under
					 the following conditions:
(1) Conversions shall be specified by the Manufacturer.
					 Drawings and/or written instructions used for part conversion shall be obtained
					 from the Manufacturer and shall include a drawing or description of the
					 converted part before and after the conversion.
(2) The Assembler's quality control system, as accepted by
					 a representative from an ASME-designated organization, must describe in detail
					 the conversion of original parts, provisions for inspection and acceptance,
					 personnel training, and control of current Manufacturer's drawings and/or
					 written instructions.
(3) The Assembler must document each use of a converted
					 part.
(4) The Assembler must demonstrate to the Manufacturer the
					 ability to perform each type of conversion. The Manufacturer shall document all
					 authorizations granted to perform part conversions. The Manufacturer and
					 Assembler shall maintain a file of such authorizations.
(5) For an Assembler to offer restricted lift valves, the
					 Assembler must demonstrate to the satisfaction of the Manufacturer the ability
					 to perform valve lift restrictions. The Manufacturer shall document all
					 authorizations granted to restrict the lift of the valves, and shall maintain
					 records of the lift restrictions made by the Assembler. The Assembler shall
					 maintain a file of such authorizations.
(6) At least annually a review shall be performed by the
					 Manufacturer of an Assembler's system and conversion capabilities. The
					 Manufacturer shall document the results of these reviews. A copy of this
					 documentation shall be kept on file by the Assembler. The review results shall
					 be made available to a representative from an ASME designated organization.
NOTES:
Within the requirements of PG-73.4 and
					 PG-73.5, a manufacturer is defined as a person or organization who is
					 completely responsible for design, material selection, capacity certification,
					 manufacture of all component parts, assembly, testing, sealing, and shipping of
					 pressure relief valves certified under this Section.
An
assembler
is defined as a person or
					 organization who purchases or receives from a manufacturer the necessary
					 component parts or valves and assembles, adjusts, tests, seals, and ships
					 pressure relief valves certified under this Section at a geographical location
					 other than and using facilities other than those used by the manufacturer.
PG-73.5
Testing by Manufacturers or
					 Assemblers
PG-73.5.1
Pressure Testing. Each pressure
					 relief valve to which the Code Symbol Stamp is to be applied shall be subjected
					 to the following tests by the Manufacturer or Assembler:
(a) The pressure-containing parts of each valve shall be
					 hydrostatically tested at a pressure at least 1.5 times the design pressure of
					 the parts. Parts meeting the following criteria shall be exempt from pressure
					 testing:
(1) the applied stress under hydrostatic test conditions
					 does not exceed 50% of the allowable stress; and
(2) the part is not cast or welded.
(b) Alternatively, testing may be performed pneumatically
					 at a pressure 1.25 times the design pressure of the part. Pneumatic testing can
					 be hazardous; it is therefore recommended that special precautions be taken
					 when conducting a pneumatic test.
(c) Testing may be done in the component or assembled
					 condition.
(d) When the valve is designed for discharging directly to
					 atmosphere, the valve components downstream of the valve disk are exempt from
					 pressure testing
(e) Valve components downstream of the disk and fully
					 contained within the body are exempt from pressure testing.
(f) These tests shall be conducted after all machining and
					 welding operations on the parts have been completed.
(g) There shall be no sign of leakage.
PG-73.5.2
Every valve shall be tested with
					 steam by the manufacturer or assembler to demonstrate its set point and
					 pressure-containing integrity. The blowdown control elements of the pressure
					 relief valve shall be set to the Manufacturer's specifications.
PG-73.5.2.1
Tests shall be conducted either
					 on equipment that meets the requirements of PG-73.5.6, or on the boiler, by
					 raising the pressure to demonstrate the set pressure.
PG-73.5.2.2
When the valve is beyond the
					 production test equipment capabilities, an alternative test method presented in
					 PG-73.5.2.2.1 or PG-73.5.2.2.2 may be used, provided all of the following
					 conditions are met:
(a) testing the valve at full pressure may cause damage to
					 the valve, or testing of the valve is impractical due to boiler system
					 operational safety considerations
(b) the valve lift has been mechanically verified to meet
					 or exceed the required lift
(c) the blow down control elements of the safety valve are
					 set to the valve manufacturer's specification
(d) the valve design is compatible with the alternative
					 test method selected
PG-73.5.2.2.1
The valve, with its lift
					 temporarily restricted during the test, if required to prevent valve damage,
					 shall be tested on steam to demonstrate set pressure.
PG-73.5.2.2.2
The valve may be fitted with a
					 hydraulic or pneumatic lift assist device and tested on steam at a pressure
					 less than the valve set pressure. The lift assist device and test procedure
					 shall be calibrated to provide the set pressure setting within the tolerance of
					 PG-72.2.
PG-73.5.3
Leak Test
(a) A seat tightness test shall be conducted at maximum
					 expected operating pressure but at a pressure not exceeding the reseating
					 pressure of the valve. When being tested, a valve exhibiting no sign of leakage
					 shall be considered adequately tight.
(b) Closed bonnet pressure relief valves designed for
					 discharge to a closed system shall be tested with a minimum of 30 psig (200
					 kPa) air or other gas in the secondary pressure zone. There shall be no sign of
					 leakage.11 - See PDF for table PDF
11 The user may specify a higher
					 test pressure commensurate with the back pressure anticipated in service
PG-73.5.4
A manufacturer or assembler shall
					 have a documented program for the application, calibration, and maintenance of
					 test gages.
PG-73.5.
Testing time on steam valves shall be
					 sufficient to assure that test results are repeatable and representative of
					 field performance.
PG-73.5.6
Test fixtures and test drums, where
					 applicable, shall be of adequate size and capacity to assure that the observed
					 set pressure is consistent with the stamped set pressure within the tolerance
					 required by PG-72.2.
PG-73.6 Design Requirements.
At the time of
					 submission of valves for capacity certification or testing in accordance with
					 PG-69, the ASME designee has the authority to review design for conformity with
					 the requirements of this Section and to reject or require modification of
					 designs that do not conform, prior to capacity testing.
PG-73.7 Code Symbol "V" Stamp.
Each pressure
					 relief valve to which the Code "V" symbol (see Fig. PG-105.4) will be applied
					 shall have been fabricated or assembled by a manufacturer or assembler holding
					 a valid Certificate of Authorization (PG-105.2) and c capacity certified in
					 accordance with the requirements of this Section. A Certified Individual (CI)
					 shall provide oversight to assure that each use of the Code "V" symbol on a
					 pressure relief valve is in accordance with the requirements of this Section,
					 and that each use of the Code "V" symbol is documented on a Certificate of
					 Conformance, Form P-8.
PG-73.7.1 Requirements for the Certified Individual
					 (CI).
The CI shall
(a) be an employee of the manufacturer or assembler
(b) be qualified and certified by the manufacturer or
					 assembler. Qualifications shall include as a minimum
(1) knowledge of the requirements of this Section for the
					 application of the Code "V" symbol
(2) knowledge of the manufacturer's or assembler's quality
					 program
(3) training commensurate with the scope, complexity, or
					 special nature of the activities to which oversight is to be provided
(c) have a record, maintained and certified by the
					 manufacturer or assembler, containing objective evidence of the qualifications
					 of the CI and the training program provided
PG-73.7.2 Duties of the Certified Individual
					 (CI).
The CI shall
(a) verify that each item to which the Code "V" symbol is
					 applied has a current capacity certification and meets all applicable
					 requirements of this Section
(b) review documentation for each lot of items to be
					 stamped to verify, for the lot, that requirements of this Section have been
					 completed
(c) sign the Certificate of Conformance, Form P-8, prior to
					 release of control of the pressure relief valves
PG-73.7.3 Certificate of Conformance, Form
					 P-8
(a) The Certificate of Conformance, Form P-8, shall be
					 filled out by the manufacturer or assembler and signed by the Certified
					 Individual. Multiple duplicate pressure relief valves may be recorded as a
					 single entry, provided the valves are identical and are produced in the same
					 lot.
(b) The manufacturer's or assembler's written quality
					 control program shall include requirements for completion of Certificates of
					 Conformance, Form P-8, and retention, by the manufacturer or assembler, for a
					 minimum of 5 years.
FABRICATION
PG-75 GENERAL
The fabrication of boilers and parts thereof shall conform
					 to the general fabrication requirements in the following paragraphs and in
					 addition to the specific requirements for fabrication in the Parts of this
					 Section that pertain to the methods of construction used.
PG-76 CUTTING PLATES AND OTHER STOCK
PG-76.1
Plates may be cut by machining,
					 punching, shearing, or cutting by the electric arc or gas process, providing
					 enough metal is left at any unfinished edges to meet the requirements of
					 PG-79.
PG-76.2
When end faces of nozzle or manhole
					 necks are to remain unwelded in the completed vessel, these end faces shall not
					 be cut by shearing unless at least 1/8 in. (3 mm) of additional metal is
					 removed by any method that will produce a smooth finish.
PG-91 QUALIFICATION OF INSPECTORS
The inspection required by this Section shall be by an
					 Inspector employed by an ASME accredited Authorized Inspection Agency,12 that
					 is, the inspection organization of a state or municipality of the United
					 States, a Canadian province, or of an insurance company authorized to write
					 boiler and pressure vessel insurance. These Inspectors shall have been
					 qualified by written examination under the rules of any state of the United
					 States or province of Canada which has adopted the Code. - See PDF for
					 table
12 Whenever Authorized
					 Inspection Agency or AIA is used in this Code, it shall mean an Authorized
					 Inspection Agency accredited by ASME in accordance with the requirements in the
					 latest edition of ASME QAI-1, Qualification for Authorized Inspection.
PG-93 INSPECTION AND REPAIR OF FLAT PLATE IN CORNER
					 JOINTS
PG-93.1
When flat plate greater than ½
					 in. (13 mm) thickness is welded to other pressure parts to form a corner joint,
					 such as in flat heads [Fig. PG-31, illustrations (g), (i-1), and (i-2)],
					 waterlegs of firebox boilers or combustion chambers of wetback boilers [Fig.
					 A-8, illustrations (l), (m), (n), and (p)], and the exposed edges of the plate
					 are closer to the edge of the weld than a distance equal to the thickness of
					 the plate, the peripheral plate edges and any remaining edges and any remaining
					 exposed surface of the weld joint preparation shall be examined after welding
					 by either the magnetic particle or liquid penetrant method. When the plate is
					 nonmagnetic, only the liquid penetrant method shall be used. The requirements
					 of this paragraph shall not apply to those joints when 80% or more of the
					 pressure load is carried by tubes, stays, or braces, or when the exposed edges
					 of the plate are farther from the edge of the weld than a distance equal to the
					 thickness of the plate.
PG-93.2
Laminations, cracks, or other
					 imperfections found during the examination required by PG-93.1 that would
					 affect the safety of the vessel shall be repaired in accordance with PG-78. The
					 imperfection(s) may be pursued by any suitable method (grinding, chipping,
					 etc.). The repaired area shall be subjected to the same examination that first
					 revealed the imperfection.
PG-93.3
Methods and acceptance criteria for
					 magnetic particle and liquid penetrant examination shall be in accordance with
					 A-260 or A-270, respectively.
PG-99 HYDROSTATIC TEST
Hydrostatic testing of the completed boiler unit shall be
					 conducted in accordance with the following requirements:
After a boiler has been completed (see PG-104), it shall be
					 subjected to pressure tests using water at not less than ambient temperature,
					 but in no case less than 70°F (20°C). Where required, test pressures
					 are specified in this paragraph; whether minimum or maximum pressures, they
					 apply to the highest point of the boiler system. When the boiler is completed
					 in the Manufacturer's shop without boiler external piping, subsequent
					 hydrostatic testing of the boiler external piping shall be the responsibility
					 of any holder of a valid "S," "A," or "PP" stamp. The safety valves need not be
					 included in the hydrostatic test. The tests shall be made in two stages in the
					 following sequence:
PG-99.1
Hydrostatic pressure tests shall be
					 applied by raising the pressure gradually to not less than 1 ½ times the
					 maximum allowable working pressure as shown on the data report to be stamped on
					 the boiler. No part of the boiler shall be subjected to a general membrane
					 stress greater than 90% of its yield strength (0.2% offset) at test
					 temperature. The primary membrane stress to which boiler components are
					 subjected during hydrostatic test shall be taken into account when designing
					 the components. Close visual inspection for leakage is not required during this
					 stage.
PG-99.2
The hydrostatic test pressure may then
					 be reduced to the maximum allowable working pressure, as shown on the Data
					 Report, to be stamped on the boiler and maintained at this pressure while the
					 boiler is carefully examined. The metal temperature shall not exceed 120°F
					 (50°C) during the close examination.
PG-99.3
A completed forced-flow steam
					 generator with no fixed steam and waterline, having pressure parts designed for
					 different pressure levels along the path of water-steam flow, shall be
					 subjected to a hydrostatic pressure test by the above procedure (PG-99.1 and
					 PG-99.2) based upon:
PG-99.3.1
For the first stage test (PG-99.1) a
					 hydrostatic test pressure of not less than 1 ½ times the maximum
					 allowable working pressure at the superheater outlet as shown in the master
					 stamping (PG-106.3) but no less than 1 ¼ times the maximum allowable
					 working pressure of any part of the boiler, excluding the boiler external
					 piping.
PG-99.3.2
For the second stage test (PG-99.2)
					 the hydrostatic test pressure may be reduced to not less than the maximum
					 allowable working pressure at the superheater outlet.
PG-99.4 Test Gages
PG-99.4.1
An indicating gage, visible to the
					 operator controlling the pressure applied, shall be connected to the pressure
					 parts. Hydrostatic head on the gage shall be considered such that the required
					 test pressure is achieved at the top of the boiler.
PG-99.4.2
Dial pressure gages used in testing
					 shall preferably have dials graduated over their entire range of about double
					 the intended maximum test pressure, but in no case shall the range be less than
					 1 ½ times that pressure. The spacing between graduations shall be such
					 that the inspector and the operator controlling the test shall be able to
					 determine when the required test pressure has been applied. Digital pressure
					 gages having a wider range of pressure readings may be used provided the
					 readings give the same or greater degree of accuracy as obtained with dial
					 pressure gages.
PG-100 HYDROSTATIC DEFORMATION TEST
Where no rules are given and it is impossible to calculate
					 with a reasonable degree of accuracy the strength of a boiler structure or any
					 part thereof, a full-sized sample shall be built by the Manufacturer and tested
					 in accordance with the Standard Practice for Making a Hydrostatic Test on a
					 Boiler Pressure Part to Determine the Maximum Allowable Working Pressure, given
					 in A-22 or in such other manner as the Committee may prescribe.
CERTIFICATION BY STAMPING AND DATA
					 REPORTS
PG-101 HEATING SURFACE COMPUTATION
PG-101.1
For the stamping required by PG-106,
					 the heating surface shall be computed as specified in PG-101.1.1 through
					 PG-101.1.3.
PG-101.1.1
Heating surface, as part of a
					 circulating system in contact on one side with water or wet steam being heated
					 and on the other side with gas or refractory being cooled, shall be measured on
					 the side receiving heat.
PG-101.1.2
Boiler heating surface and other
					 equivalent surface outside the furnace shall be measured circumferentially plus
					 any extended surface.
PG-101.1.3
Waterwall heating surface and other
					 equivalent surface within the furnace shall be measured as the projected tube
					 area (diameter x length) plus any extended surface on the furnace side. In
					 computing the heating surface for this purpose, only the tubes, fireboxes,
					 shells, tubesheets, and the projected area of headers need to be considered,
					 except that for vertical firetube steam boilers only that portion of the tube
					 surface up to the middle of the gage glass is to be computed.
PG-104 GENERAL
PG-104.1
The completed boiler unit includes
					 all piping and piping components as defined in the Introduction.
The Manufacturer [see Note (1) below] of any complete
					 boiler unit to be stamped with the Code symbol has the responsibility of
					 assuring through proper Code certification that all work performed by him or
					 others responsible to him complies with all requirements of the Code, including
					 design, construction, materials, and workmanship. With the exception of field
					 installed boiler external piping, when some portions of a complete boiler unit
					 are supplied by, or Code work is performed by others not responsible to the
					 Manufacturer, the Manufacturer has the duty of obtaining from these other
					 organizations their proper Code certification, covering such portions of
					 work.
When the Manufacturer furnishes a shop assembled boiler
					 that is complete except for boiler external piping, and the boiler has been
					 hydrostatically tested in the shop and properly stamped with the Manufacturer's
					 "S" symbol, the subsequent installation in the field of the external piping
					 within the scope of Section I is not by itself considered "field assembly of
					 the boiler" [see Note (2) below].
No Manufacturer or assembler may accept Code responsibility
					 for work that falls within the scope of the Code, that is performed by workmen
					 employed by any other organization, except through proper Code certification.
					 The responsibilities set forth herein relate only to Code compliance and are
					 not to be construed as involving contractual relations or legal
					 liabilities.
NOTES:
(1) Boiler Manufacturer or Manufacturer
					 as used in PG-104 or other paragraphs referenced to this Note may also be an
					 Engineering Contractor organization with or without fabricating facilities, but
					 having the capability of providing a design specification that establishes the
					 pressure and temperature conditions for each component of a complete boiler
					 unit and of assembling the fabricated parts in the field with authorization
					 from the Society to use the Code symbol stamp "S" in accordance with the Code
					 provisions in PG-105.3.
(2) When boiler external piping within the scope of Section
					 I is furnished by other than the boiler Manufacturer, the boiler Manufacturer
					 is not responsible for the Code certification of such piping. The organizations
					 that furnish and that install such external piping by welding shall furnish
					 proper Code certification (PG-104.2) for such piping including Manufacturers'
					 Data Report Form P-4A as required by PG-112.2.5 and PG-112.3.
PG-104.2
Proper Code certification refers to
					 the furnishing of stamping and Data Reports as evidence to establish the
					 following.
PG-104.2.1
The organization that performed
					 that portion of the work held an appropriate Certificate of
					 Authorization.
PG-104.2.2
By signing and furnishing the
					 appropriate data report, that organization certified compliance with Code rules
					 for that portion of the work.
PG-104.2.3
By proper use of the Code symbol
					 stamp, that organization identified the portions of the work covered by its
					 Data Report Form.
PG-104.2.4
By countersignature on the same
					 Data Report a qualified Inspector confirmed that portion of the work complied
					 with applicable Code rules.
PG-105 CODE SYMBOL STAMPS
PG-105.1 Authorization
. Except as permitted in
					 PG-105.5, no organization may assume responsibility for Code construction
					 without having first received from the ASME a Certificate of Authorization to
					 use one of the Code symbol stamps shown in Figs. PG-105.1 through PG-105.4.
					 There are six such stamps, defined as follows:
(a) S - power boiler symbol stamp (see Fig.
					 PG-105.1)
(b) M - miniature boiler symbol stamp (see Fig.
					 PG-105.1)
(c) E - electric boiler symbol stamp (see Fig.
					 PG-105.1)
(d) A - boiler assembly symbol stamp (see Fig.
					 PG-105.2)
(e) PP - pressure piping symbol stamp (see Fig.
					 PG-105.3)
(f) V - safety valve symbol stamp (see Fig.
					 PG-105.4)
Stamps for applying the Code symbol shall be obtained from
					 the Society. Each boiler, superheater, waterwall, economizer, or boiler part to
					 which a Code symbol is to be applied shall be fabricated by a Manufacturer who
					 is in possession of an appropriate Code symbol stamp. A Certificate of
					 Authorization to use the Code symbol "S," "M," "E," "A," "PP," or "V" stamp
					 will be granted by the Society pursuant to the provisions of these
					 paragraphs.
See PDF for
					 diagram
PG-109 STAMPING OF PRESSURE PIPING
PG-109.1
Boiler external piping, as defined in
					 the Introduction, may be fabricated by a manufacturer other than the
					 Manufacturer of the boiler, provided that the manufacturer has been issued a
					 Certificate of Authorization to use the "S" or "PP" symbol stamp. Boiler
					 external piping may be installed by welding by a manufacturer or contractor
					 other than the Manufacturer of the boiler, provided such an organization has
					 been issued a Certificate of Authorization to use the "S," "PP," or "A" symbol
					 stamp. When boiler external piping is installed by welding, the welding,
					 including the qualification of welding procedures, welders, and welding
					 operators, shall be done in accordance with the applicable rules of ASME B31.1.
					 The welding shall be inspected by an Authorized Inspector at such stages of the
					 work as he may elect. The organizations which fabricate or install such piping
					 shall furnish proper code certification (PG-104.2) for it including a
					 Manufacturer's Data Report Form P-4A as required by PG-112.2.5 and
					 PG-112.3.
PG-109.2
Welded boiler external piping
					 included within the scope of this Code, over NPS 2 (DN 50), shall be stamped
					 with a Code symbol, together with the manufacturer's or contractor's name and
					 serial number. Such stamping shall be on the pipe, valve or fitting adjacent to
					 the welded joint farthest from the boiler. For piping operating at temperatures
					 above 800o F (425o C) the symbol may be stamped on a nameplate that is
					 irremovably attached by welding, provided such welding is postweld heat
					 treated, or on a circular metal band at least ¼ in. (6 mm) thick. This
					 band around the pipe shall be secured in such a manner as to prevent it from
					 slipping off during handling and installation.
Welded piping NPS 2 (DN 50) or less included within the
					 scope of this Code shall be marked with an identification acceptable to the
					 Inspector and traceable to the required Data Report. Such marking shall be of a
					 type that will remain visible until the piping has been installed.
PG-109.3
A manufacturer in possession of the
					 pressure piping symbol stamp may
(a) design and fabricate welded piping. Such fabrications
					 shall be stamped and reported on a Form P-4A, Manufacturer's Data Report for
					 Fabricated Piping, as called for in PG-112.2.5.
(b) fabricate other parts of boilers, such as superheater,
					 waterwall, or economizer headers, where complete design requirements are
					 provided by others. Such parts shall be stamped or marked as required by
					 PG-106.8 and reported on a Form P-4, Manufacturer's Partial Data Report, as
					 called for in PG-112.2.4.
PG-109.4
Mechanically assembled boiler
					 external piping which contains no pressure boundary welds does not require
					 stamping, and as such may be assembled by a non-stamp holder. Note that the
					 responsibility for documentation and hydrostatic testing of a mechanically
					 assembled boiler external piping must be assumed by a holder of a valid "S,"
					 "A," or "PP" stamp (see PG-112.2.5).
PG-110 STAMPING OF BOILER PRESSURE
RELIEF VALVES
Each pressure relief valve shall be plainly marked with the
					 required data by the Manufacturer or Assembler (see PG-73.4.4) in such a way
					 that the marking will not be obliterated in service. The marking shall be
					 placed on the valve or on a nameplate securely fastened to the valve. The Code
					 "V" symbol shall be stamped on the valve or nameplate by the Manufacturer or
					 Assembler, as applicable. The other required data may be stamped, etched,
					 impressed, or cast on the valve or nameplate. For units other than those
					 included below, see PG-4. The marking shall include the following:
(a) the name (or an acceptable abbreviation) of the
					 Manufacturer and Assembler, as applicable
(b) Manufacturer's design or type number
(c) NPS (DN) (the nominal pipe size of the valve
					 inlet)
(d) set pressure __ psi (MPa)
(e)
Capacity
(1) capacity __ lb/hr (kg/hr) (for saturated steam service
					 in accordance with PG-69.2) or
(2) capacity __ lb/hr (kg/hr) at __ °F (°C) (for
					 superheated steam service in accordance with PG-68.7 or supercritical steam
					 service in accordance with PG-69.2.3) or
(3) capacity __ gal/min (l/min) at 70 °F (20° C)
					 and lb/hr (kg/hr) steam for economizer service in accordance with
					 PG-69.2
(f) year built, or alternatively, a coding may be marked on
					 the valve such that the valve Manufacturer or Assembler can identify the year
					 the valve was assembled and tested
(g) ASME symbol as shown in Fig. PG-105.4
(h) The pilot of a pilot-operated pressure relief valve
					 shall be plainly marked by the Manufacturer or Assembler showing the name of
					 the Manufacturer, the Manufacturer's design or type number, the set pressure in
					 pounds per square inch (MPa), and the year built, or alternatively, a coding
					 that the Manufacturer can use to identify the year built.
PG-111 LOCATION OF STAMPINGS
The location of the required stampings shall be as listed
					 below. These stampings shall be left uncovered or an easily removable marked
					 cover may be provided over the stamping when a boiler is covered with
					 insulation, or jacketed. No piping, boiler appliance, or other obstructions
					 shall interfere with reading of the stamping.
PG-111.1
Horizontal-return tubular boilers -
					 on the front head above the central rows of tubes.
PG-111.2
Horizontal-flue boilers - on the
					 front head above the flues.
PG-111.3
Traction, portable, or stationary
					 boilers of the locomotive type or Star watertube boilers - on the furnace end
					 above the handhole. Or on traction boilers of the locomotive type - on the left
					 wrapper sheet forward of the driving wheel.
PG-111.4
Vertical firetube and vertical
					 submerged tube boilers - on the shell above the firedoor and handhole
					 opening.
PG-111.5 Watertube Boilers
PG-111.5.1
Drum type - on a head of the steam
					 outlet drum near and above the manhole.
PG-111.5.2
Forced-flow steam generator with no
					 fixed steam and waterline - the master stamping (PG-106.3) shall be located on
					 a major pressure part, located near the main operating floor where readily
					 visible. The Data Report Form shall record the location of the master
					 stamping.
PG-111.6
Scotch marine boilers - on either
					 side of the shell near the normal water level line and as near as practical to
					 the front tubesheet.
PG-111.7
Economic boilers - on the front head,
					 above the center row of tubes.
PG-111.8
Miniature and electric boilers - on
					 some conspicuous and accessible place on the boiler proper, or on a stamping
					 plate at least 3/64 in. (1.2 mm) thick, permanently fastened (adhesives
					 prohibited) to the boiler.
PG-111.9
On any of the above types where there
					 is not sufficient space in the place designated, and for other types and new
					 designs - in a conspicuous place on the boiler proper. The Data Report Form
					 shall record the location of the required stamping.
PG-111.10
Superheaters - on superheater header
					 near the outlet. Other headers shall carry identifying marks.
PG-111.11
Economizers - at a handy location on
					 water inlet header or drums. Other headers shall carry identifying
					 marks.
PG-111.12
Waterwalls - on one end of a lower
					 header. Other headers shall carry identifying marks.
PG-111.13
When required by PG-106.6 and
					 PG-106.7, the Manufacturer [see PG-104, Note (1)] shall furnish a nameplate or
					 plates on which the appropriate Code Symbol and design data for the scope of
					 his responsibility are permanently imprinted. The nameplate shall be securely
					 attached to the front of the boiler, its setting or casing, at a place readily
					 visible from the operating floor or platform.
PG-112 MANUFACTURERS' DATA REPORT FORMS
PG-112.1
Ten types of Manufacturers' Data
					 Report Forms are shown in the Appendix under the heading "Data Report Forms and
					 Guides" at the end of this Section. These forms shall be used by the
					 Manufacturer [see PG-104, Note (1)] to record all the items of a complete
					 boiler unit, in accordance with the provisions of PG-112.2. When the
					 certification of the complete boiler unit is accomplished by more than one Data
					 Report, the principal Data Report (P-2, P-2A, P-3, or P-3A) shall be designated
					 as the Master Data Report (see PG-113).
For forced-flow steam generators with no fixed steam and
					 waterline consisting of groups of pressure parts or components designed at
					 several different pressure levels, a separate Manufacturers' Data Report shall
					 clearly identify the pressure parts at each pressure level and show the maximum
					 allowable working pressure. These several Data Reports shall be attached to a
					 Master Data Report (PG-113) that shall clearly identify each component as part
					 of the complete unit.
PG-112.2 Types of Data Report Forms.
The types
					 of Data Report Forms and the purposes for which they are to be used are
					 specified in PG-112.2.1 through PG-112.2.8.
PG-112.2.1
Form P-2, Manufacturers' Data
					 Report for All Types of Boilers Except Watertube and Electric, shall be used to
					 record all types of boilers other than watertube boiler units and parts
					 thereof, which are included under Form P-3.
PG-112.2.1.1
Form P-2A, Manufacturers' Data
					 Report for All Types of Electric Boilers, shall be used to record all types of
					 electric boilers.
PG-112.2.1.2
Form P-2B, Manufacturers' Data
					 Report for Electric Superheaters and Reheaters, shall be used to record
					 electric superheaters and reheaters installed external to the boiler
					 setting.
PG-112.2.2
Form P-3, Manufacturers' Data
					 Report for Watertube Boilers, Superheaters (except electric), Waterwalls, and
					 Economizers, shall be used to record all of the items comprising a watertube
					 boiler.
The Form P-3 shall also be used to record a superheater,
					 waterwall, or economizer when the design of such an item is certified by a
					 manufacturer other than the boiler Manufacturer, or when such an item is to be
					 added to an existing boiler. The item shall be stamped with the ASME "S" symbol
					 and the additional information, as applicable, shown in PG-106.4.2.
Item 10 on Form P-3 shall be used to record other parts
					 connected at the openings listed in Item 11 if such parts are fabricated of
					 materials or by processes that require Code inspection. If such parts have not
					 been connected prior to the hydrostatic test, a notation shall be made under
					 Item 10 reading: "No parts connected to the openings listed in Item 11 except
					 as noted."
PG-112.2.3
Form P-3A, Engineering-Contractor
					 Data Report for a Complete Boiler Unit, shall be used when such an organization
					 assumes the Manufacturer's Code responsibility as provided for by PG-104, Note
					 (1). This form shall be used to certify Code responsibility for the design
					 specification of the complete boiler unit, of which the components are
					 individually certified by their individual manufacturers in accordance with the
					 Code rules. This form also provides for field assembly certification.
PG-112.2.4
Form P-3A shall not be used by a
					 Manufacturer to provide Code certification for only a portion of the complete
					 boiler unit.
PG-112.2.5
Form P-4A, Manufacturers' Data
					 Report for Fabricated Piping, shall be used to record all shop or field-welded
					 piping that falls within the scope of this Section but is not furnished by the
					 boiler Manufacturer. Form P-4B, Manufacturers' Data Report for Field Installed
					 Mechanically Assembled Piping, shall be used to record all field installed
					 mechanically assembled boiler external piping. Form P-4B shall be used only for
					 piping that contains no joints brazed or welded by the field installer.
PART PFT
REQUIREMENTS FOR FIRETUBE BOILERS
GENERAL
PFT-1 GENERAL
The rules in Part PFT are applicable to firetube boilers
					 and parts thereof and shall be used in conjunction with the general
					 requirements in Part PG as well as with the specific requirements in the
					 applicable Parts of this Section that apply to the method of fabrication
					 used.
MATERIALS
PFT-5 GENERAL
PFT-5.1
Materials used in the construction of
					 pressure parts for firetube boilers shall conform to one of the specifications
					 given in Section II and shall be limited to those for which allowable stress
					 values are given in Tables 1A and 1B of Section II, Part D, or as otherwise
					 specifically permitted in Parts PG and PFT.
PFT-5.2
Waterleg and doorframe rings of
					 vertical firetube boilers and of locomotive and other type boilers shall be of
					 wrought iron or steel, or cast steel as designated in the SA-216. The ogee or
					 other flanged construction may be used as a substitute in any case.
DESIGN
PFT-8 GENERAL
The rules in the following paragraphs apply specifically to
					 the design of firetube boilers and parts thereof and shall be used in
					 conjunction with the general requirements for design in Part PG as well as with
					 the specific requirements for design in the applicable Parts of this Section
					 that apply to the method of fabrication used.
PFT-9 THICKNESS REQUIREMENTS
PFT-9.1 Shell and Dome.
The thickness after
					 forming shall be as determined in accordance with the rules in Part PG.
PFT-9.2 Tubesheet
PFT-9.2.1
The thickness shall be as determined
					 in accordance with Part PG and Part PFT.
PFT-9.2.2
When buttwelded to the shell of a
					 firetube boiler, a formed tubesheet with a straight flange longer than 1
					 ½ times the tubesheet thickness shall have a straight flange thickness
					 not less than that specified in the table in PFT-9.2.1, but in no case less
					 Than 0.75 times the thickness of the shell to which it is attached.
PFT-10 SHELL JOINTS
Longitudinal and circumferential welded joints of a shell
					 or drum shall comply with the rules in Part PW.
PFT-11 ATTACHMENT OF HEADS AND
					 TUBESHEETS
Flat heads and tubesheets of firetube boilers shall be
					 attached by one of the following methods.
PFT-11.2
By flanging and butt welding in
					 accordance with Parts PG and PW.
PFT-11.3
By attaching an outwardly or inwardly
					 flanged tubesheet to the shell by fillet welding provided the following
					 requirements are met.
PFT-11.3.1
The tubesheet is supported by
					 tubes, or stays, or both.
PFT-11.3.2
The joint attaching an outwardly
					 flanged tubesheet is wholly within the shell and forms no part thereof.
PFT-11.3.3
Inwardly flanged tubesheets are
					 full fillet welded inside and outside.
PFT-11.3.4
The throat dimension of the full
					 fillet weld is equal to not less Than 0.7 of the thickness of the head.
PFT-11.3.5
The shell at the welds is not in
					 contact with primary furnace gases.13 - See PDF for
					 table
13 Primary furnace gases are
					 those in a zone where the design temperature of those gases exceeds 850°F
					 (455°C).
PFT-11.3.6
The construction conforms in all
					 other respects to the requirements of this Section, including welding and
					 postweld heat treating, except that volumetric examination is not
					 required.
PFT-11.3.7
This construction shall not be used
					 on the rear head of a horizontal-return tubular boiler and inwardly flanged
					 tubesheets shall not be used on a boiler with an extended shell.
PFT-11.3.8
On inwardly flanged tubesheets, the
					 length of flange shall conform to the requirements of PW-13 and the distance of
					 the outside fillet weld to the point of tangency of the knuckle radius shall be
					 not less than ¼ in. (6 mm).
PFT-11.4
By attaching an unflanged tubesheet
					 to the shell by welding, provided the requirements of PFT-11.4.1 through
					 PFT-11.4.7 are met.
PFT-11.4.1
The tubesheet is supported by
					 tubes, or stays, or both.
PFT-11.4.2
The welded joint may be made
					 through the tubesheet or shell thickness. When the weld joint is made through
					 the shell, a minimum of 80% of the pressure load shall be carried by the tubes,
					 stays, or both.
PFT-11.4.3
The weld is a full penetration weld
					 equal at least to the full thickness of the base metal applied from either or
					 both sides. When the full penetration weld is made through the shell, an
					 external fillet weld with a minimum throat of ¼ in. (6mm) shall be
					 provided, and no weld prep machining shall be performed on the flat tubesheet.
					 The distance from the edge of the completed weld to the peripheral edge of the
					 tubesheet shall not be less than the thickness of the tubesheet.
PFT-11.4.4
The shell or wrapper sheet, where
					 exposed to primary furnace gases14 and not water
					 cooled, does not extend more than 1/8 in. (3 mm) beyond the outside face of the
					 tubesheet. - See PDF for table
14 Primary furnace gases are
					 those in a zone where the design temperature of those gases exceeds 850°F
					 (455°C).
PFT-11.4.5
The weld attaching a furnace or a
					 lower tubesheet of a vertical firetube boiler to the furnace sheet is wholly
					 within the furnace sheet and is ground flush with the upper or water side of
					 the tubesheet.
PFT-11.4.6
The construction conforms in all
					 other aspects to the requirements of this Section including welding, and
					 postweld heat treatment, except that volumetric examination is not
					 required.
PFT-11.4.7
This construction shall not be used
					 on the rear head of a horizontal-return tubular boiler.
PFT-12 TUBES
PFT-12.1 Allowable Working Pressure
PFT-12.1.1
The maximum allowable working
					 pressure of tubes or flues of firetube boilers shall be as given in PFT-50 and
					 PFT-51.
PFT-12.1.2
The maximum allowable working
					 pressure for copper tubes or nipples subjected to internal or external pressure
					 shall not exceed 250 psi (1.7 MPa). The maximum temperature shall not exceed
					 406° F (208° C).
See PDF for
					 diagram
The maximum allowable working pressure for copper clad
					 tubes subjected to external pressure shall be determined by the formula in
					 PFT-51, in which
t
may be increased by one-half the thickness
					 of the cladding.
PFT-12.2 Attachment of Tubes
PFT-12.2.1
Figure PFT-12.1 illustrates some of
					 the acceptable types of tube attachments. Such connections shall be
(a) expanded and beaded as in illustrations (a), (b), and
					 (d)
(b) expanded and beaded and seal welded as in illustration
					 (c)
(c) expanded and seal welded as in illustration (e)
(d) welded, as in illustrations (f) and (g)
Tube ends attached by expanding and welding are subject to
					 the provisions specified in PFT-12.2.1.1 through PFT-12.2.1.3.
PFT-12.2.1.1
Where no bevel or recess is
					 employed, the tube shall extend beyond the tubesheet not less than a distance
					 equal to the tube thickness or 1/8 in. (3 mm), whichever is the greater, nor
					 more than twice the tube thickness or ¼ in. (6 mm), whichever is the
					 lesser [see Fig. PFT-12.1, illustration (e)].
PFT-12.2.1.2
The tubesheet hole may be beveled
					 or recessed. The depth of any bevel or recess shall not be less than the tube
					 thickness or 1/8 in. (3 mm), whichever is greater, nor more than one-third of
					 the tubesheet thickness, except that when tube thicknesses are equal to or
					 greater Than 0.150 in. (4 mm), the bevel or recess may exceed
T
/3. Where the hole is beveled or recessed, the projection of
					 the tube beyond the tubesheet shall not exceed a distance equal to the tube
					 wall thickness [see Fig. PFT-12.1, illustrations (f) and (g)].
PFT-12.2.1.3
On types of welded attachment
					 shown in Fig. PFT-12.1, illustrations (c) and (e), the tubes shall be expanded
					 before and after welding. On types shown in illustrations (f) and (g), the
					 tubes may be expanded.
PFT-12.2.2
Expanding of tubes by the Prosser
					 method may be employed in combination with any beaded or seal welded attachment
					 method [see Fig. PFT-12.1, illustration (b)].
PFT-12.2.3
After seal welding as shown by Fig.
					 PFT-12.1, illustrations (c) and (e), a single hydrostatic test of the boiler
					 shall suffice.
PFT-12.2.4
The inner surface of the tube hole
					 in any form of attachment may be grooved or chamfered.
PFT-12.2.5
The sharp edges of tube holes shall
					 be taken off on both sides of the plate with a file or other tool.
DOORS AND OPENINGS
PFT-40 WELDED DOOR OPENINGS
Arc or gas welding may be used in the fabrication of door
					 holes provided the sheets are stayed around the opening in accordance with the
					 requirements of PFT-27.6 and PFT-27.7.
No calculations need be made to determine the availability
					 of compensation for door openings spanning between the plates of waterlegs. The
					 required thickness of circular access openings shall be determined in
					 accordance with PFT-51. The required thickness of door openings of other than
					 circular shape shall be calculated using eq. (1) of PG-46, using 2.1 or 2.2 for
					 the value of
C
, depending on the plate thickness, and a value
					 of
p
equal to the waterleg inside width. Volumetric
					 examination of the joining welds is not required.
PFT-41 OPENINGS IN WRAPPER SHEETS
Openings located in the curved portion of the wrapper sheet
					 of a locomotive type boiler shall be designed in accordance with the rules in
					 PG-32.
PFT-42 FIRESIDE ACCESS OPENINGS
The minimum size of an access or fire door opening, in
					 which the minimum furnace dimension is 24 in. (600 mm), shall be not less than
					 12 in. x 16 in. (300 mm x 400 mm) or equivalent area, 11 in. (280 mm) to be the
					 least dimension in any case. A circular opening shall be not less than 15 in.
					 (380 mm) in diameter.
For furnace dimensions less than 24 in. (600 mm), the
					 opening should be 2 ¾ in. x 3 ½ in. (70 mm x 89 mm) or larger
					 where possible. In cases where the size or shape of the boiler prohibits an
					 opening of that size, two openings with a minimum size of 1 in. (25 mm) may be
					 used, preferably opposite each other, to permit inspection and cleaning of the
					 furnace. If the burner is removable so as to permit inspection and cleaning
					 through the burner opening, a separate access opening need not be
					 provided.
The bonnet or smoke hood of a vertical flue or tubular
					 boiler shall be provided with an access opening at least 6 in. x 8 in. (150 mm
					 x 200 mm) for the purpose of inspection and cleaning the top head of the
					 boiler.
PFT-43 REQUIREMENTS FOR INSPECTION
					 OPENINGS
All firetube boilers shall have sufficient inspection
					 openings, handholes, or washout plugs with a minimum of four openings to permit
					 inspection of the waterside of the tubesheets, furnaces, and tubes and to
					 permit flushing of loose scale and sediment from the boiler. Except where space
					 restrictions would prohibit entry to the boiler, a manhole shall be provided in
					 the upper portion of the shell. All openings shall meet the requirements of
					 PG-32 through PG-44. Where washout plugs are used, the minimum size shall be
					 NPS 1½ (DN 40), except for boilers 16 in. (400 mm) or less in inside
					 diameter, the minimum size shall be NPS 1 (DN 25).
PFT-44 OPENING BETWEEN BOILER AND SAFETY
					 VALVE
The opening or connection between the boiler and the safety
					 valve shall have at least the area of the valve inlet.
After the boiler Manufacturer provides for the opening
					 required by the Code, a bushing may be inserted in the opening in the shell to
					 suit a pressure relief valve that will have the capacity to relieve all the
					 steam that can be generated in the boiler and which will meet the Code
					 requirements. The minimum size of the connection and opening for the pressure
					 relief valve shall be not less than NPS ½ (DN 15).
No valve of any description shall be placed between the
					 required pressure relief valve or valves and the boiler, or on the discharge
					 pipe between the pressure relief valve and the atmosphere. When a discharge
					 pipe is used, the cross-sectional area shall be not less than the full area of
					 the valve outlet or of the total of the areas of the valve outlets discharging
					 thereinto and shall be as short and straight as possible and so arranged as to
					 avoid undue stresses on the valve or valves.
DOMES
PFT-45 REQUIREMENTS FOR DOMES
PFT-45.1
The longitudinal joint of a dome may
					 be butt welded or the dome may be made without a seam of one piece of steel
					 pressed into shape. The dome flange may be double full fillet lap-welded to the
					 shell if all welding complies fully with the requirements for welding in Part
					 PW. Volumetric examination of the fillet welds may be omitted. The opening
					 shall be reinforced in accordance with PG-32 through PG-44.
PFT-45.3
When a dome is located on the barrel
					 of a locomotive-type boiler or on the shell of a horizontal-return tubular
					 boiler, the outside diameter of the dome shall not exceed six-tenths the inside
					 diameter of the shell or barrel of the boiler unless the portion of the barrel
					 or shell under the dome (the neutral sheet) is stayed to the head or shell of
					 the dome by stays which conform in spacing and size to the requirements given
					 in PG-46 and Table 1A of Section II, Part D. With such stayed construction the
					 outside diameter of a dome located on the barrel or shell of a boiler is
					 limited to eight-tenths of the barrel or shell inside diameter.
PFT-45.4
All domes shall be so arranged that
					 any water can drain back into the boiler.
PFT-45.5
Flanges of domes shall be formed with
					 a corner radius, measured on the inside, of at least twice the thickness of the
					 plate for plates 1 in. (25 mm) in thickness or less, and at least three times
					 the thickness of the plate for plates over 1 in. (25 mm) in thickness.
PFT-45.6
Domes and manhole frames attached to
					 shells or heads of boilers shall be designed in accordance with PG-32 through
					 PG-44.
PART PEB
REQUIREMENTS FOR ELECTRIC BOILERS
GENERAL
PEB-1 GENERAL
The rules in Part PEB are applicable to electric boilers
					 and parts thereof and shall be used in conjunction with the general
					 requirements in Part PG as well as with the special requirements in the
					 applicable Parts of this Section that apply to the method of fabrication
					 used.
PEB-2 SCOPE
PEB-2.1
This part contains special rules for
					 construction of electric boilers, both of the electrode and immersion
					 resistance element type. This Part does not include electric boilers where the
					 heat is applied externally to the boiler pressure vessel by electric resistance
					 heating elements, induction coils, or other electrical means. These types of
					 electric boilers shall be constructed in accordance with other applicable Parts
					 of this Section.
PEB-2.2
Electric boilers and parts thereof
					 that do not exceed the diameter, volume, or pressure limits of PMB-2 may be
					 constructed using the applicable paragraphs of Part PMB in conjunction with
					 this Part.
PEB-2.3
An electrode type boiler is defined as
					 an electric boiler in which heat is generated by the passage of an electric
					 current using water as the conductor.
PEB-2.4
An immersion resistance element type
					 boiler is defined as an electric boiler in which heat is generated by the
					 passage of an electric current through a resistance heating element directly
					 immersed in water, or enclosed in a pipe immersed in water.
PEB-2.5
Electric boilers may be field
					 assembled provided the boiler is manufactured and assembled in compliance with
					 the provisions and requirements of Part PEB and other applicable Parts of this
					 Section.
PEB-3 OPTIONAL REQUIREMENTS FOR THE BOILER PRESSURE
					 VESSEL
The boiler pressure vessel may be constructed in compliance
					 with the ASME Pressure Vessel Code Section VIII, Division 1, rules for unfired
					 steam boilers [UW-2(c)] subject to the conditions specified in PEB-3.1 through
					 PEB-3.4.
PEB-3.1
The Manufacturer who certifies and
					 stamps the completed boiler shall specify to the "U" stamp holder all
					 additional requirements of Part PEB, which are not requirements of Section
					 VIII, Division 1, and shall ensure that these requirements are
					 satisfied.
PEB-3.2
These additional requirements
					 are:
PEB-3.2.1
The materials of construction shall
					 comply with the requirements of PEB-5.1 and PEB-5.3.
PEB-3.2.2
Inspection openings shall comply
					 with the requirements of PEB-10.
PEB-3.3
The boiler pressure vessel shall be
					 stamped with the ASME Code "U" symbol and the letters "UB," and be documented
					 with the ASME U-1 or U-1A Data Report.
PEB-3.4
The master Data Report P-2A for the
					 Electric Boiler shall indicate "Boiler pressure vessel constructed to Section
					 VIII, Division 1 as permitted by Part PEB."
MATERIALS
PEB-5 GENERAL
PEB-5.1
Unless specifically permitted
					 elsewhere in this section, materials used in the construction of pressure parts
					 for electric boilers shall conform to one of the specifications in Section II
					 and shall be limited to those permitted by PG-6, PG-7, PG-8, and PG-9 for which
					 allowable stress values are given in Tables 1A and 1B of Section II, Part D.
					 Miscellaneous pressure parts shall conform to the requirements of PG-11.
PEB-5.2
Seamless or welded shells, plates, or
					 heads of electric boilers shall not be less than 3/16 in. (5 mm) in
					 thickness.
PEB-5.3
Electric boilers of the immersion
					 element type may be fabricated of austenitic stainless steel type 304, 304L,
					 316, 316L, and 347 of any material specification listed in PG-6 and PG-9,
					 provided that a precautionary statement indicating that the boiler shall be
					 operated using only deionized water, having a maximum conductance of 1
					 microSiemen per cm (1 mS/cm) [minimum specific resistivity of 1 megohm per cm
					 (1 M¿/cm)], is clearly marked on the boiler in a visible
					 location.
DESIGN
PEB-8 GENERAL
PEB-8.1
The rules in the following paragraphs
					 apply specifically to the design of electric boilers and parts thereof. They
					 shall be used in conjunction with the general requirements for design in Part
					 PG, any applicable requirements in Part PMB for miniature boilers, and with the
					 specific requirements for design in applicable Parts of this Section that apply
					 to the method of fabrication used.
PEB-8.2
Responsibility of design of electric
					 boilers to be marked with the "E" symbol shall be that of the holder of the "E"
					 stamp.
PEB-9 WELDING
Electric boilers may be constructed by fusion welding in
					 accordance with all the requirements of this Section except that postweld heat
					 treatment, volumetric examination of the welded joints, and the nondestructive
					 examinations described in PG-93.1 are not required when the limitations in
					 PMB-2.1 are not exceeded.
PEB-10 INSPECTION OPENINGS
PEB-10.1
Electric boilers of a design
					 employing a removable cover, or removable internal electric heating elements
					 that will permit access for inspection, and cleaning and having an internal
					 volume (exclusive of casing and insulation) of not more than 5 ft3 (0.14 m3)
					 need not be fitted with washout or inspection openings.
PEB-10.2
Electric boilers of more than 5 ft3
					 (0.14 m3) not provided with a manhole, shall have an inspection opening or
					 handhole located in the lower portion of the shell or head. The inspection
					 opening shall not be smaller than NPS 3 (DN 80). In addition, electric boilers
					 of the resistance heating element type designed for steam service shall have an
					 inspection opening or handhole at or near the normal waterline.
PEB-11 FEEDWATER SUPPLY
PEB-11.1
The feedwater source to electric
					 boilers shall be capable of meeting the applicable requirements of PG-61.
					 Feedwater connections to an electric boiler shall not be smaller than NPS
					 ½ (DN 15), except as permitted by PMB-11.
PEB-11.2
Electric boilers that do not exceed
					 the diameter, volume, or pressure limits of PMB-2, may have the feedwater
					 delivered through the blowoff opening if desired.
PEB-12 BLOWOFF
PEB-12.1
The blowoff piping for each electric
					 boiler pressure vessel having a normal water content not exceeding 100 gal (380
					 L) is required to extend through only one valve.
PEB-12.2
The minimum size of blowoff pipes and
					 fittings shall be NPS 1 (DN 25), except that for boilers of 200 kW input or
					 less the minimum size of pipe and fittings may be NPS ¾ (DN 20).
					 Electric boilers that do not exceed the diameter, volume, or pressure limits of
					 PMB-2 may have blowoff connections in accordance with PMB-12.
PEB-13 WATER LEVEL INDICATORS
PEB-13.1
Electric boilers of the electrode
					 type shall have at least one gage glass. The gage glass shall be located as to
					 indicate the water levels both at startup and under maximum steam load
					 conditions as established by the Manufacturer.
PEB-13.2
Electric boilers of the resistance
					 element type shall have at least one gage glass. The lowest visible water level
					 in the gage glass shall be at least 1 in. (25 mm) above the lowest permissible
					 water level as determined by the Manufacturer. Each electric boiler of this
					 type shall also be equipped with an automatic low-water cutoff on each boiler
					 pressure vessel so located as to automatically cut off the power supply to the
					 heating elements before the surface of the water falls below the visible level
					 in the gage glass.
PEB-13.3
Tubular gage glasses on electric
					 boilers shall be equipped with protective rods or shields.
PEB-14 PRESSURE GAGES
Pressure gages shall meet the requirements of
					 PG-60.6.
PEB-15 PRESSURE RELIEF VALVES
PEB-15.1
Each electric boiler shall have at
					 least one pressure relief valve. Electric boilers with a power input more than
					 1,100 kW shall have two or more pressure relief valves.
PEB-15.2
The minimum pressure relief valve
					 relieving capacity for electric boilers shall be 3 ½ lb/hr/kW (1.6
					 kg/hr/kW) input. The pressure setting shall not be higher than the MAWP stamped
					 on the completed boiler (see PEB-18.3.2).
PEB-15.3
Pressure relief valves shall be
					 mounted in accordance with PG-71.2 with the spindle vertical. Electric boilers
					 that do not exceed the diameter, volume, or pressure limits of PMB-2, may have
					 a pressure relief valve(s) installed in other than the vertical position,
					 provided that
(a) the valve design is satisfactory for such
					 position
(b) the valve is not larger than NPS ¾ (DN
					 20)
(c) the maximum angle of deviation from vertical does not
					 exceed 30 deg
(d) the nozzle location is such that no material that could
					 interfere with the operation of the valve can accumulate at the valve
					 inlet
(e) the discharge opening of the valve body and discharge
					 piping is oriented so that drainage is adequate
PEB-16 AUTOMATIC DEVICES
Electric boilers shall be provided with pressure and/or
					 temperature controls and an automatic low-water fuel cutoff. No low-water
					 cutoff is required for electrode type boilers.
PEB-17 HYDROSTATIC TEST
PEB-17.1
Each electric boiler pressure vessel
					 shall be hydrostatically tested at completion of fabrication in accordance with
					 PG-99 or PMB-21, as applicable.
PEB-17.2
In addition to the above, after
					 assembly of the boiler pressure vessel and the mechanically assembled boiler
					 external piping and trim, the completed electric boiler shall be given a final
					 hydrostatic test at a pressure not less than 1 ½ times the MAWP of the
					 pressure vessel. Miniature electric boilers that are trimmed to operate at less
					 than the MAWP of the pressure vessel shall be given a hydrostatic test at a
					 pressure not less than the safety valve setting.
PEB-17.3
When the electric boiler is to be
					 marked with the "E" symbol, the symbol shall be applied after completion of the
					 hydrostatic test of PEB-17.2.
PEB-18 INSPECTION AND STAMPING OF
					 BOILERS
PEB-18.1
Inspection of electric boilers shall
					 be as required by PG-90.1 and PG-90.3. Witness by the Authorized Inspector of
					 the hydrotest required in PEB-17.2 for the completed boiler may be omitted for
					 electric boilers that meet all the following limitations:
(a) 800 kW maximum per vessel
(b) 600 V maximum
(c) mechanically assembled boiler external piping (BEP)
					 only
When the Authorized Inspector does not perform a final
					 inspection of the completed boiler, the Manufacturer or Assembler shall make an
					 equivalent examination. The equivalent examination shall be in accordance with
					 a quality control procedure meeting the requirements of PEB-18.2 and
					 PEB-18.5.
PEB-18.1.1
Electric boilers exceeding the size
					 limitations specified in PEB-18.1, and having only mechanically assembled
					 external piping (BEP) and trim, shall have a final inspection by the Authorized
					 Inspector, who shall also witness the hydrostatic test called for in
					 PEB-17.2.
PEB-18.1.2
For electric boilers having welded
					 or brazed boiler external piping (BEP) or trim, the inspection requirements of
					 PG-90.1 and the hydrostatic test requirements of PG-99 apply.
PEB-18.2
Each electric boiler Manufacturer
					 shall comply with the applicable requirements of PG-104 and PG-105.
PEB-18.2.1
An electric boiler Manufacturer or
					 Assembler applying for or renewing the "E" stamp shall have its facilities and
					 organizations subject to a joint review by its Authorized Inspection Agency and
					 the legal jurisdiction involved (see last paragraph of PG-105.4).
PEB-18.2.2
A Manufacturer or Assembler holding
					 an "E" stamp and assembling units where the final shop inspection is not
					 mandatory (see PEB-18.1), shall be subject to periodic review by its Authorized
					 Inspection Agency. The review shall be conducted on a quarterly basis or more
					 frequently if deemed necessary by the Authorized Inspection Agency. The
					 frequency of this review may be reduced subject to written agreement between
					 the Manufacturer or Assembler and its inspection agency and the written
					 approval of the appropriate legal jurisdiction. However, in no case shall the
					 review be less than once every 6 months.
PEB-18.3
The stamping of electric boilers
					 shall conform to the requirements of PG-106. Completed electric boilers shall
					 be marked with the "S" or "M" symbol by the Manufacturer of the boiler pressure
					 vessel except when the boiler pressure vessel is constructed under the
					 provisions of PEB-3 (see PEB-18.4). When the trim, fixtures and fittings (such
					 as valves), threaded boiler external piping, and appurtenances are connected to
					 an electric boiler by a Manufacturer or Assembler not authorized to apply the
					 "S" or "M" stamp, the boiler assembler shall apply an "E" stamp to the
					 completed assembly. "E" stamp holders are limited to the use of assembly
					 methods that do not require welding or brazing.
PEB-18.3.1
The stamping of the boiler pressure
					 vessel shall be located as called for in PG-111.8 and need not indicate the kW
					 input or the maximum designed steaming capacity.
PEB-18.3.2
The stamping of the complete
					 electric boiler shall be on a separate metallic plate and shall be in
					 accordance with PG-106.4. The MAWP shall be that established by the completed
					 boiler assembler holding the "S," "M," or "E" stamp, but in no case higher than
					 the MAWP stamped on the boiler shell. The MAWP shall be listed on Part II of
					 Form P-2A, Manufacturers' Data Report for All Types of Electric Boilers. This
					 plate shall be located on the assembly so that it is readily visible from the
					 operating floor.
PEB-18.3.3
The stamping required by PEB-18.3.2
					 need not be done in the presence of the Authorized Inspector for electric
					 boilers that do not receive final inspection by the Authorized Inspector (see
					 PEB-18.1).
PEB-18.4
For boiler pressure vessels
					 constructed under the provisions of PEB-3, the inspection and stamping
					 requirements of Section VIII, Division 1, UG-116(c) for special service
					 pressure vessels (UB), shall be followed.
PEB-18.5
Those Manufacturers and Assemblers
					 providing an equivalent examination of completed electric boilers when final
					 inspection is not witnessed by the Authorized Inspector (see PEB-18.1), shall
					 provide oversight by a Certified Individual (CI).
PEB-18.5.1
A Certified Individual (CI) shall
					 be an employee of the Manufacturer or Assembler and shall be qualified and
					 certified by the Manufacturer or Assembler. Qualifications shall include as a
					 minimum
(a) knowledge of the requirements of this Section for the
					 application of Code symbols
(b) knowledge of the Manufacturer's quality program
(c) training commensurate with the scope, complexity, or
					 special nature of the activities to which oversight is to be provided
The Manufacturer or Assembler shall maintain a record
					 containing objective evidence of the Certified Individual's qualifications,
					 training and certification.
PEB-18.5.2
The duties of a Certified
					 Individual (CI) shall be to assure that each use of the Code symbol as
					 permitted in PEB-18.3.3 is in accordance with the requirements of this Section
					 and is documented on the Certificate of Conformance on Form P-2A,
					 Manufacturers' Data Report for All Types of Electric Boilers. The CI shall
					 also
(a) verify that each electric boiler, to which a Code
					 symbol is applied, meets all applicable requirements of this Section
(b) sign the Certificate of Conformance, Form P-2A, prior
					 to release of control of the boiler
PEB-19 MANUFACTURERS' DATA REPORT FOR ELECTRIC
					 BOILERS
PEB-19.1
This form consists of two parts. Part
					 I is to be completed by the Manufacturer of the boiler pressure vessel who is
					 the holder of the "S" or "M" stamp and his inspection agency. Part II is to be
					 completed by the Manufacturer or Assembler responsible for the completed
					 electric boiler who shall be authorized to use any of the "S," "M," or "E"
					 stamps.
PEB-19.2
When the boiler pressure vessel is
					 constructed by a "U" stamp holder and certified on a U-1 or U-1A Data Report,
					 Part 1 shall be completed by the "S," "M," or "E" stamp holder to the extent
					 indicated in Guide A-351.1.