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.
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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 gases
14 and not water cooled, does not extend more than 1/8 in. (3 mm) beyond the outside face of the tubesheet.
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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.
