The 2018 edition of the Power Piping code was issued on 20 July 2018 and will come in effective on 20 January 2019. The next scheduled publication is in 2020.

The following is an extension to the summary of changes from the 2016 edition. I included the changes exactly as they appear in the Summary of Changes in the same format consisting of Page Location Change. To help with scanning for relevant changes and understanding where the change is located, I have included the section title along with the higher level headings. 

The exact text of the Code are defined with a vertical bar to the left and beneath I have included some notes to the changes made. Some that are obvious like a title change, I just included the revised title.

ASME interpretations to this Code and others are published online at https://cstools.asme.org/Interpretation/SearchInterpretation.cfm. As of time of writing 433 records were found for B31.1.

Code cases may be published by the ASME B31 Committee and can be found under here http://go.asme.org/B31committee. At the time of writing there were 3 existing code cases 175, 182 and 183. 

Errata may also be posted on the ASME B31 Committee website. From the page there is an email subscription box if you wish to be notified of any further posts on the page. At the time of writing there were 4 records posted.

Enjoy and happy Power Piping!

Introduction

xii Introduction

(1) Sixth and eighth paragraphs revised

Sixth paragraph has added the operation and maintenance to the  safe design and construction of pressure piping.

Eighth paragraph shortened to a single line that the Code follows a simplified approach.

(2) Ninth and tenth paragraphs added

Ninth paragraph extended the previous eight paragraph in clarifying responsibility of the owner for when a more rigorous approached is taken beyond the simplified approach of the Code. For the design and construction the designer shall get approval from the owner, and the details shall be documented in the engineering design.

The tenth paragraph added specially when a more rigorous approach is taken in operation and maintenance,  the owner shall provide details that the alternative practices are inline with the philosophy of the Code, and such details shall be documented in the operating records and kept for the life of the plant.

Chapter I  Scope and Definitions

100 General

100.1 Scope

1 100.1.1 First paragraph revised

Added the requirement from the ninth paragraph of the Introduction that when outside of the Code the measures are to documented in the engineering design.

1 100.1.2 In subparagraph (a), third and fourth paragraphs revised

Third paragraph editorial revision to the revised figure naming convention. Much better now.

Fourth paragraph changed the ASME Certification Mark from ASME BPVC  Section I to ASME CA-1 Conformity Assessment Requirement.  The quality control system requirements refer to Section I (2016) and added ASME CA-1 and QAI-1 Qualification for Authorized Inspectors shall apply. No further reference to Appendix J as it has been removed.

2 100.1.4 Revised

Added an advisory that the cleaning and purging of flammable gas systems by be subject to the requirements of NFPA Standard 26.

2 100.2

(1) Definitions of austenitizing; heat treatments, subcritical heat treatment; and heat treatments, tempering added

• austenitizing: forming austenite the transformation range.
• subcritical heat treatment: a general heat-treating process where ferritic or martensitic steel is heated to
• a temperature below the temperature at which austenite begins to form.
• Austenite begins to form, and then cooling at any desired rate.
• tempering: reheating a quench-hardened or normalized steel to a temperature below the temperature at which

(2) Definitions of covered piping systems (CPS), failure, heat treatments, reinforcement of weld, repair, and undercut revised

• covered piping systems (CPS) – Removed the statement of the Operating Company may add other piping systems.
• Heat treatments – changed noted above.
• reinforcement of weld – split clause for (external and internal) to the face of the groove.
• Repair – replaced the reference to pressure containing components to basically anything that meet the requirements of the Code.
• Undercut – added weld root to weld toe

3 Figure 100.1.2-1 Title and illustration revised

Figure 100.1.2-1 Code Jurisdictional Limits for Piping – An Example of Forced Flow Steam Generators With No Fixed Steam or Waterline

The diagrams line for Nonboiler External Piping and Joint (NBEP) changed from dashed to solid. I prefer the previous dashed line.

4 Figure 100.1.2-2 Title and illustration revised

Figure 100.1.2-2 Code Jurisdictional Limits for Piping – An Example of Steam Separator Type Forced Flow Steam Generators With No Fixed Steam or Waterline

5 Figure 100.1.2-3 Revised

Figure 100.1.2-3 Code Jurisdictional Limits for Piping – Drum-Type Boilers

Dashed to solid line per above.

Reheater has been removed and rename of the integral superheater and integral economizer

6 Figure 100.1.2-4 Revised

Figure 100.1.2-4 Code Jurisdictional Limits for Piping — Isolable Economizers Located in Feedwater Piping and Isolable Superheaters in Main Steam Piping (Boiler Pressure Relief Valves, Blowoff, and Miscellaneous Piping for Boiler Proper Not Shown for Clarity)

The Isolable economizer has been split out 3 ways. 2 arrangements within Limits of BEP and one Outside the limits of BEP.

7 Figure 100.1.2-5 Title and illustration revised

Figure 100.1.2-5 Code Jurisdictional Limits for Piping – Reheaters and Nonintegral Separately Fired Superheaters

Reheater added to the title as well as to the figure.

The discharge to the relief changed from NBEP to Boiler Proper. Given it is a relief discharge, I would question if possibly they missed then open circle which would indicate a NBEP scope. Might be worthy of a query.

8 Figure 100.1.2-6 Cross-references added to illustration

Figure 100.1.2-6 Code Jurisdictional Limits for Piping – Spray-Type Desuperheater

Reference included to the newly added figure 100.1.2.7 included.

9 Figure 100.1.2-7 Added

Code Jurisdictional Limits for Piping – HRSG – Desuperheater Protection Devices

Chapter II Design

Part 1 Conditions and Criteria

101 Design Conditions

101.1 General

101.7 Thermal Expansion and Contraction Loads

101.7.2 Expansion, Swivel, or Ball Joints, and Flexible Metal Hose Assemblies.

16 101.7.2 Revised

Included the requirement that metallic bellows expansion joints shall be in accordance with Mandatory Appendix P.   The design requirements in the appendix are compatible with standards by the Expansion Joint Manufacturers Association, Inc. (EJMA). The appendix contain 3 sections for General, Piping Designer and Expansion Joint Manufacturer’s Responsibilities.

102 Design Criteria

102.4 Allowances

102.4.5 Bending

19 102.4.5 Subparagraph (b) revised

The minimum required thickness, t_m, of a bend equations now includes the weld strength reduction factor, W. Which is 1 for seamless pipe or seam-welded pipe operating below the creep range or areas of the bend that doesn’t contain a weld.

104 Pressure Design Of Components

104.1 Straight Pipe

104.1.1 Straight Pipe Under Internal Pressure

22 (1) Paragraph 104.1.1 revised

Simplified the paragraph as the equations now include the weld strength reduction factor, W,  so the text previously is no longer required.

104.1.2 Straight Pipe Under Internal Pressure – Seamless, Longitudinal Welded, or Spiral Welded and Operating Below the Creep Range

(a) Minimum Wall Thickness.

22 (2) In subparagraph 104.1.2(a), equations revised, nomenclature alphabetized, and W added

The maximum allowable stress term, SE, now includes the weld strength reduction factor, W, making it SEW in all the equations.

(3) Paragraph 104.1.4 deleted

This section had the equations for SEW, which have now been included in 104.1.2(a).

Figure 104.3.1-1 Reinforcement of Branch Connections

27 Figure 104.3.1-1 In General Note (b), dt corrected by errata to read d1

Required reinforcement area, A7, corrected to d₁ as indicated in the figure.

104.8 Analysis of Piping Components

104.8.2 Stress Due to Occasional Loads

35 104.8.2 Revised

Equation 16 variable P change to P_o, which is the pressure coincident with the occasional load that is being evaluated. Reference made to clause 101.5 dynamic effects (Impact, Wind, Earthquake, Vibration) can be considered as occasional providing they are within the frequency defined in term k.

104.8.4 Moments and Section Modulus

35 104.8.4 Subparagraph (c) revised

(c) for reduced outlet branch with the exception of branch connections extended to include Table D-1.

In my version of electronic file the equation M_A, M_B, M_C = blank. I believe this is typo and should be the square root of the sum of the squared moments about point 3 as per the previous equation and that in 2016 edition.

For Figure 104.8.4-1 Cross Section Resultant Moment Loading, the dashed moment lines of axis have changed to solid lines. I prefer the dashed line as the solid lines clearly indicated the component.

106 Fittings, Bends, and Intersections

106.1 Fittings

36 106.1 Subparagraph (a) punctuation revised

Chapter III Materials

123 General Requirements

123.1.1 Listed Materials

67 123.1.1 Subparagraph (c) revised

The adoption of new material requirements have been included as 2016 referred to Non Mandatory Appendix VI which has been removed from 2018.

124 Limitations On Materials

124.2 Steel

69 124.2

(1) Subparagraphs (a) and (b) revised

Carbon-molybdenum moved from (b) to (a) in this edition.

(2) Subparagraph (e) added

Flow-accelerated corrosion or flow-assisted corrosion discussed.

125 Creep Strength Enhanced Ferritic Materials

125.1 Requirements for ASTM A217, Grade C12A and ASTM A1091, Grade C91 Castings > 125.1.2 Heat Treatment Requirements

70 125.1 Title revised

125.1.2 Heat Treatment Requirements

70 125.1.2 Subparagraphs (a) and (c) revised

ASTM A1091 added.

125.1.3 Weld Repair Requirements

71 125.1.3 Subparagraph (c) revised

ASTM A1091 added.

Table 126.1-1 Specifications and Standards

73 Table 126.1-1

(1) For ASCE/SEI 7 and ASME B31J, titles revised

(2) ASTM A1091/A1091M and Standards of the Expansion Joint Manufacturers Association, Inc. added

(3) FCI 79-1 revised

Chapter V Fabrication, Assembly, and Erection

127 Welding

127.4 Procedure

127.4.2 Girth Butt Welds

Table 127.4.2-1 Reinforcement of Girth and Longitudinal Butt Welds

85 Table 127.4.2-1 Revised

The maximum thickness of reinforcement for design temperature ranges reduced from 3 to 2 covering >700°F (400°C) and <= 700°F (400°C), and the addition of 2 notes.

129 Bending and Forming

129.3 Heat Treatment of Bends and Formed Components

93 129.3.3.1 First paragraph revised

Minor editorial revision.

93 129.3.4 Revised

Added nickel alloys to the clause. I think it should be or Nickel alloys instead of and Nickel alloys.

93 129.3.4.1 First paragraph revised

Added nickel alloys to the clause. I think it should be or and not and.

94 Table 129.3.3.1-1 Title revised

Table 129.3.3.1-1 Post Cold-Forming Strain Limits and Heat-Treatment Requirements for Creep-Strength Enhanced

96 Table 129.3.4.1-1 Title revised

Table 129.3.4.1-1 Post Cold-Forming Strain Limits and Heat-Treatment Requirements for Austenitic Materials and Nickel Alloys

131 Welding Preheat

131.4 Preheat Temperature

Table 131.4.1-1 Preheat Temperatures

97 Table 131.4.1-1 In fifth column, first entry revised

The additional limits on %C for thickness ≤ 1″ (25 mm) removed.

132 Postweld Heat Treatment

Table 132.1.1-1 Postweld Heat Treatment

98 Table 132.1.1-1

(1) In second column, penultimate entry revised

P-No. 15E Group 1 holding temperature range lower limit reduced from 1350°F (730°C) to 1300°F (705°C)

(2) Notes (5) and (6) revised

Note 5: Applies to P-No. 15E Group 1 – A1091, Grade C91 added

Note 6: Applies to P-No. 15E Group 1 – The minimum PWHT holding temperature reduced to 1250 F (675 C).

132.4 Definition of Thicknesses Controlling PWHT

99 132.4 Title revised

Controlling replaces Governing

136 Inspection and Examination

136.1 Inspection

136.1.1 General

104 136.1.1 Revised

Authorized Inspections added.

136.1.2 Verification of Compliance

104 136.1.2 Subparagraph (a) revised

Reference to Appendix J removed as the appendix has been removed in this edition.

136.2 Inspection and Qualification of Authorized Inspector for Boiler External Piping

104 136.2 Revised in its entirety

136.2.1 and 136.2.1.1 – Same intent but just replaced the word inspection with Authorized Inspection.

136.2.2 – Certification requirements of many sections in the BPVC replaced with ASME CA-1 Conformity Assessment Requirements. ASME CA-1 specifies the requirements for accreditation and certification of organizations supplying products and or services that are intended to conform the requirements of ASME standards.

136.3 Examination

136.3.2 Qualification of NDE Personnel

105 136.3.2

(1) Subparagraph (d) revised

Option of an oral examination removed. Written examination must be done.

(2) Last paragraph revised

Clauses T-120(e) or T-120(f) of ASME BPVC Section V specifically referenced.

136.4 Examination Methods of Welds

136.4.6 Ultrasonic Examination

108 136.4.6 Subparagraph (c) added

The fracture mechanics ultrasonic acceptance criteria in Mandatory Appendix O may be used. 

Table A-1 Carbon Steel

118 Table A-1 Note (1) revised

Additional figure added under the statement for material that cannot be used for pressure rated piping.

Mandatory Appendix A Allowable Stress Tables

Table A-2 Low and Intermediate Alloy Steel

130 Table A-2

(1) Under Electric Fusion Welded Pipe — Filler Metal Added, Notes revised for first 12 entries

Note 2 added for A672 L65/L70/L75, A691 CM-65/70/75

(2) Under Castings, A1091 C91 added

(3) Notes (1) and (2) revised

Note 1: Additional figure added under the statement for material that cannot be used for pressure rated piping.

Note 2: Celsius reference added in relation to the statement of conversion to graphite under prolonged exposure to elevated temperatures.

Table A-3 Stainless Steels

142 Table A-3

(1) Under Seamless Pipe and Tube, Austenitic, for both A312 TP321 lines and second TP321H line, Notes revised

Note 30 added

(2) Second group of A312 TP321 and TP321H lines added

Second group of notes 31 added.

(3) Under Ferritic/Austenitic, A789 and A790 S32003 added

S32003 21Cr–3.5Ni–1.75Mo–N added

(4) Under Welded Pipe and Tube — Without Filler Metal, Ferritic/Austenitic, A789 and A790 S32003 added

S32003 21Cr–3.5Ni–1.75Mo–N added

(5) Under Welded Pipe and Tube — Filler Metal Added, Ferritic/Austenitic, for first entry, UNS No. and Specified Minimum Tensile revised

S31803 corrected. Specified Minimum Tensile lowered to 90 ksi (620 MPa). 

(6) Under Pipe, Sheet, and Strip, Ferritic/Austenitic, two A240 S32003 lines added

Should be Under Plate, Sheet and Strip

S32003 21Cr–3.5Ni–1.75Mo–N

(7) Notes (1) and (24) revised

Note 1: Additional figure added under the statement for material that cannot be used for pressure rated piping.

Note: 24: UNS No. S32003 heat treatment requirements added.

(8) Notes (30) and (31) added

The allowable stress values apply to seamless pipe with a wall thickness  ≤  3/8 in. (note 30) or > 3/8 in. (note 31).

Table A-4 Nickel and High Nickel Alloys

176 Table A-4

(1) Note (1) reference deleted from 71 lines

(2) Note (1) revised

Note 1: Additional figure added under the statement for material that cannot be used for pressure rated piping.

Table A-5 Cast Iron

190 Table A-5

(1) For A395 60-40-18, stress value for 600°F corrected by errata to read 9.0

(2) Note (1) revised

Note 1: Additional figure added under the statement for material that cannot be used for pressure rated piping.

Table A-6 Copper and Copper Alloys

194 Table A-6 Note (1) revised

Note 1: Additional figure added under the statement for material that cannot be used for pressure rated piping.

Table A-7 Aluminum and Aluminum Alloys

200 Table A-7 Note (1) revised

Note 1: Additional figure added under the statement for material that cannot be used for pressure rated piping.

Table A-8 Temperatures 1,200°F and Above

216 Table A-8 Note (1) revised

Note 1: Additional figure added under the statement for material that cannot be used for pressure rated piping.

Table A-9 Titanium and Titanium Alloys

220 Table A-9 Note (1) revised

Note 1: Additional figure added under the statement for material that cannot be used for pressure rated piping.

Table A-10 Bolts, Nuts, and Studs

222 Table A-10 Notes (2) and (14) revised

Note 1: Additional figure added under the statement for material that cannot be used for pressure rated piping.

Note 14: Celsius reference added in relation to the statement of conversion to graphite under prolonged exposure to elevated temperatures.

Mandatory Appendix B Thermal Expansion Data

Thankfully they removed the following statement: Begins on next page.

Mandatory Appendix D Flexibility And Stress Intensification Factors

Table D-1 Flexibility and Stress Intensification Factors

247 Table D-1 General Note (b) added

Note b: The design is allowed to use ASME B31J for stress intensification and flexibility factors with conditions.

Mandatory Appendix F Referenced Standards

254 Mandatory Appendix F

(1) Editions revised

(2) ASTM A1091/A1091M; ASME CA-1 and QAI-1; Standards of the EJMA, Inc.; and NFPA 56 added

(3) AISC address updated and EJMA added for s

Mandatory Appendix G Nomenclature

258 Mandatory Appendix G

(1) Last h, ℓ, Po, and last S added

(2) For NPS, reference corrected by errata to read 100.1.2

(3) References for P and W updated

(4) For SE and SE, reference to para. 102.3.2(b) relocated by errata

(5) For SL, reference corrected by errata to read 102.3.2(a)(3)

Mandatory Appendix J Quality Control Requirements For Boiler External Piping (BEP) – DELETED

Mandatory Appendix N Rules for Nonmetallic Piping and Piping Lined With Nonmetals

N-100 General

N-100.2 Definitions and Abbreviations

267 N-100.2.1 Definition of winding angle added

269 Figure N-100.2.1-1 Added

Figure N-100.2.1-1 Winding Angle of Filament-Wound Thermosetting Resin Pipe

N-102.3 Allowable Stresses and Other Limits

N-102.3.1 Allowable Stress Values

271 N-102.3.1 Subparagraphs (b)(3)(-c), (-d), and (-e) added

275 Figure N-102.3.1-1 Added

Figure N-102.3.1-1 Typical Allowable Stress Curve for Filament-Wound Reinforced Thermosetting Resin Pipe

N-127 Bonding Plastic Joints

N-127.7 Thermoplastic Pipe Joints

N-127.7.2 Heat and Fusion Joints

289 N-127.7.2 Subparagraph (b) revised

(b) Procedure – added the requirement of the Fusion Procedure Specification to meet the requirements of ASME BPVC, Section IX, Part QF.

N-127.7.3 Electrofusion Joints

290 N-127.7.3 Subparagraph (b) revised

(b) Procedure – Changed the requirement of the Fusion Procedure Specification to meet the requirements of ASME BPVC, Section IX, Part QF.

Mandatory Appendix O Use Of Alternative Ultrasonic Acceptance Criteria – ADDED

Mandatory Appendix P Metallic Bellows Expansion Joints – ADDED

Nonmandatory Appendix II Rules For The Design Of Safety Valve Installations

304 II-2.2.1

II-2 Loads

II-2.2 Pressure

II-2.2.1 Design Pressure and Velocity for Open Discharge Installation Discharge Elbows and Vent Pipes

(1) Subparagraphs (a)(3)(-a), (a)(3)(-d), (a)(3)(-e), and (b)(4)(-a) revised

Changed to ∑(L/D)

(2) Footnote 2 revised

Changed to ∑(L/D)

Figure II-2.2.1-2 Compressible Flow Analysis

308 Figure II-2.2.1-2 Name of y-axis revised

Changed to ∑(L/D)

II-3 Bending Moment Computations

II-3.4 Earthquake Analysis

311 II-3.4 Second paragraph deleted

Referred to two types of seismic bending moments that occur due to inertia and seismic motions.

II-7 SAMPLE PROBLEM (SEE FIGURE II-7-1 AND FIGURE II-7-2)

II-7.1 Procedure

II-7.1.2 Discharge Elbow Maximum Operating Pressure

317 II-7.1.2 Revised

Changed to ∑(L/D)

Figure II-7-1 Sample Problem Figure 1

318 Figure II-7-1 Sizes for valve discharge elbow and valve vent pipe revised

Revised to NPS.

II-7.1.3 Reaction Force at Discharge Elbow Exit

320 II-7.1.3 In second equation, 103 psig corrected by errata to read 103 psia

II-7.1.7 Calculate the Maximum Operating Pressure for Vent Pipe

321 II-7.1.7 Revised

Changed to ∑(L/D)

II-7.1.8 Check for Blowback From Vent Pipe

322 II-7.1.8 Revised

Changed to ∑(L/D)

II-7.1.10 Conclusion

322 II-7.1.10 Revised

Changed pipe size designation to NPS.

Nonmandatory Appendix V Recommended Practice for Operation, Maintenance, and Modification of Power Piping Systems

V-6 Material Restoration

V-6.2 Inspection Program for Materials With Adverse History

330 V-6.2.2 Revised

Reference has been added to ASME PCC-3 Inspection Planning Using Risk-Based Methods.

Nonmandatory Appendix VI Approval Of New Materials – DELETED

Nonmandatory Appendix VII Procedures For The Design Of Restrained Underground Piping

VII-3 Calculations

VII-3.3 Classification of the Pipe Runs

VII-3.3.3 Locating the Virtual Anchor.

346 VII-3.3.3 Paragraph VII-3.3.4 redesignated as VII-3.3.3

Nonmandatory Appendix VIII Guidelines For Determining If Low-Temperature Service Requirements Apply

Table VIII-2 Material Groupings by Material Specification

355 Table VIII-2 A202 deleted

ASTM A202/A202M Standard Specification for Pressure Vessel Plates, Alloy Steel, Chromium-Manganese-Silicon was Withdrawn 10/09/2003 and Superseded by: No Replacement.

Index – DELETED

Strangely enough this has been dropped without any mention of such. Maybe it was an oversight and will be back in the next revision.