10/18/23, 10:22 AM
ASME B31.1 (Power Piping) VS ASME B31.3 (Process Piping)
Meena Rezkallah, P.Eng.
ASME B31.1 (Power Piping) VS ASME B31.3 (Process
Piping)
If you are searching for differences between ASME B31.1 (Power Piping) and ASME B31.3 (Process Piping), your
search have been successful. As we have skilled professional piping engineers with vast experience in a variety of
projects over more than 15 years, we decided to list the main differences between ASME B31.1 and ASME B31.3.
ASME B31.1
ASME B31.3
ASME B31.3, Process Piping, is an American Society
ASME B31.1 is an American Society of Mechanical
of Mechanical Engineers (ASME) standard that
Engineers (ASME) standard that covers the
provides requirements for piping typically found in
requirements for the design, fabrication, installation,
petroleum refineries, chemical, pharmaceutical, and
inspection, and testing of power piping systems. It is
other process plants. The standard covers materials,
applicable to all piping systems operating at
design, fabrication, assembly, erection, examination,
temperatures between -20 and 800°F (-29 and 427°C).
inspection, and testing of piping.
The document outlines the requirements for
ASME B31.3 is a code that applies to the design,
materials, welding, and brazing, as well as
construction, fabrication, assembly, erection,
requirements for pressure design and safety. It also
examination, inspection, and testing of piping. It
outlines requirements for valve installation, pipe
establishes requirements for materials, components,
supports, and other safety-related topics. The
design, fabrication, assembly, erection, examination,
standard also includes requirements for testing and
inspection, and testing of piping that is used to
inspection, as well as acceptance criteria for use in
transport fluids in process plants and other industrial
the field.
facilities. The requirements of ASME B31.3 are
ASME B31.1 is a code of practice for the design,
organized into several sections, including:
fabrication, installation, inspection, testing and
• General Requirements
maintenance of power boilers. The Code covers rules
• Materials
for construction of power boilers, electric boilers,
• Design
miniature boilers, and high temperature water
• Fabrication
boilers. The code also outlines requirements for
• Assembly
safety valves, pressure relief devices, and other safety
• Erection
related items. In addition, ASME B31.1 provides
• Examination, Inspection, and Testing
requirements for materials, welding, non-destructive
• Repairs and Alternations
testing, and erection of power boilers.
• Pressure Testing
• Piping System Components
• Nonmetallic Piping
• Special Piping Components
• Process Piping
• Flanged Fittings
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10/18/23, 10:22 AM
ASME B31.1 (Power Piping) VS ASME B31.3 (Process Piping)
• Threaded Fittings
• Welded Fittings
• Valves
• Flexible Hose Connectors
• Connectors
• Supports
• Special Piping Components
• Nonmetallic Piping
• Thermal Expansion
• Expansion Joints
• Identification and Marking
• Quality Control
• Quality Assurance
• Inspection and Testing
• Repairs and Alterations
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10/18/23, 10:22 AM
ASME B31.1 (Power Piping) VS ASME B31.3 (Process Piping)
ASME B31.1 (Power Piping) VS ASME B31.3 (Process Piping)
Item:
ASME B31.1
ASME B31.3
Scope:
ASME B31.1: Provides Rules for Power
Plant Piping. It deals with Power Plant
Piping typically found in Electric Power
Generating Stations, Geothermal Heating
System and Central & District Heating and
Cooling System.
ASME B31.1: Factor of safety is considered
as 4 (ref. cl. no. K of C2), so thickness is
more & less risk is involved. Normal
designed life of the plant is approx. 40 - 45
years.
ASME B31.1: As per ASME B31.1, there is
no limitation in Power Piping wail thickness
calculation. However, there is a limitation
of maximum design pressure.
ASME B31.1: Basic allowable material
stress is lower. For example: Allowable
stress value of ASTM A106 Gr.B Pipe is 17.1
Ksi at 500 Deg. F temperature.
ASME B31.1: Clearly specifies the allowable
sagging as 2.5mm in sustained condition
(Ref. Table 121.5, Note-c). ASME B31.1,
Table 121.5 provides suggested pipe
support span.
ASME B31.3: Provides Rules for Process &
Chemical Plant Piping. It deals with piping
typically found in Process Plants like - Petroleum
Refineries, Chemical, Pharmaceutical, Textile,
Paper and Cryogenic Plants
Factor of Safety &
Plant Life:
Equation for Pipe
Wall Thickness
Calculation:
Basic Allowable
Material Stress:
Support Span and
Allowable Sagging:
Stress
Intensification
Factor (SIF):
Section Modulus (Z)
for Sustained and
Occasional Stresses:
Max. Value of Cyclic
Stress Range Factor
(f):
SA =
f(1.25Sc+1.25Sh-SL)
ASME B31.1: ASME B31.1 uses a SIF up to
1.9 (max) for butt welded joints and SIF of
2 for reducers in stress calculation (ref.
Table-Dl). ASME B31.1 uses a single SIF.
ASME B31.1: ASME B31.1, calculates
section modulus (Z) using nominal
thickness. Thickness is not reduced by
corrosion and other allowances.
ASME B31.1: As per ASME B31.1, maximum
Value of Cyclic Stress Range Factor (f) is 1.0
ASME B31.3: Factor of safety is considered as 3
(ref. cl. no. X302.1.1), so thickness is less & more
risk is involved. Normal designed life of the plant
is approx. 20 - 30 years.
ASME B31.3: As per ASME B31.3, the equation
for pipe wall thickness calculation is valid for
thickness less than D/6. Where D is outer
diameter of pipe
ASME B31.3: Basic allowable material stress is
higher. For example: Allowable stress value of
ASTM A106 Gr.B Pipe is 19 Ksi at 500 Deg. F
temperature.
ASME B31.3: Does not specifically says about any
limit of allowable sagging in sustained condition.
An allowable sagging of up to 15mm is
acceptable in general in sustained condition.
ASME B31.3 does not provide suggested pipe
support span.
ASME B31.3: ASME B31.3 uses a SIF = 1.0 for
butt welded joints and for reducers in stress
calculation (ref Appendix-D). ASME B31.3 uses a
complex in-plane and out-of-plane SIF.
ASME B31.3: ASME B31.3, calculates section
modulus (Z) reducing the thickness by corrosion
and other allowances.
ASME B31.3: As per ASME B31.3, maximum
Value of Cyclic Stress Range Factor (f) is 1.2
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ASME B31.1 (Power Piping) VS ASME B31.3 (Process Piping)
ASME B31.1 (Power Piping) VS ASME B31.3 (Process Piping)
Item:
ASME B31.1
ASME B31.3
Allowance for
Pressure
Temperature
Variation:
ASME B31.1: As per ASME B31.1, cl. no.
102.2.4, occasional pressure temperature
variation can exceed the allowable by
ASME B31.3: As per ASME B31.3, cl. no. 302.2.4,
occasional pressure temperature variation can
exceed the allowable by
a. 15% if the event duration occurs for
no more than 8 hours at any time
and not more than 800 hours per
year OR
a. 33% for no more than 10 hours at any
time and no more than 100 hours per year
OR
b. 20% for no more than 50 hours at any one
time and no more than 500 hours per
year.
b. 20% if the event duration occurs for
not more than 1 hour at any one
time and not more than 80 hours
per year.
Rules for material
usage below (-) 29
Deg. C:
PSV Reaction Force:
Fabrication
(Preheating &
Post Weld Heat
Treatment:
Inspection &
Examination:
ASME B31.1: ASME B31.1 does not provide
any such rules for use of piping materials
below (-) 29 Deg. C.
ASME B31.1: ASME B31.1 provides specific
equations for PSV reaction force
calculation.
ASME B31.1: ASME B31.1 requires
preheating to 200 Deg. F (95 Deg. C) or
Post Weld Heat Treatment for Carbon Steel
having thickness less than or equal to 3/4"
(19mm).
ASME B31.1: ASME B3X.1 does not include
the concept of random with progressive
examination, either 100% or none.
ASME R31.3: ASME B31.3 provides extensive
rules for use of piping materials below (-) 29 Deg.
C.
ASME B31.3: ASME B31.3 does not provide
specific equations for PSV reaction force
calculation.
ASME B31.3: ASME B31.3 requires neither
preheating nor Post Weld Heat Treatment for
same thickness range
ASME B31.3: ASME B31.3 includes the concept
of random with progressive examination.
1. For Category D Fluid (utility): Visual only.
1. For temp, above 400 Deg. C & all
pressure: Magnetic Particle or
Liquid Penetrant test up to 2" and
100% Radiography for above 2" size.
2. For Normal Process Fluid: Visual plus 5%
Radiography.
3. For Category M Fluid: Visual plus 20%
Radiography.
2. For temp. 175 to 400 Deg. C &
pressure above 70 bar: Visual plus
100% Radiography for thickness
above 3/4" (19mm) & only visual for
thickness 3/4" (19mm) or less.
4. For Elevated Temperature (creep range)
Fluid: Visual plus 5% Radiography, 100%
Magnetic Particle or Liquid Penetrant test
of fillet welds.
5. For High Pressure (above 100 Mpa): Visual
+ 100% RT.
Leak Testing:
ASME B31.1: Hydraulic test at 1.5 times
design pressure. Pneumatic test at 1.2 to
1.5 times design pressure.
ASME B31.3: Hydraulic test at 1.5 times design
pressure corrected for temperature. Pneumatic
test at 1.1 to 1.33 times design pressure.
Category D Fluid: may be initially service leak
tested. Other Fluids: require hydrostatic or
pneumatic testing. Category M Fluid: requires a
sensitive leak test in addition to hydrostatic or
pneumatic test.
Read more:
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10/18/23, 10:22 AM
ASME B31.1 (Power Piping) VS ASME B31.3 (Process Piping)
1. ASME B31.8 VS CSA Z662
2. ASME B31.4 VS CSA Z662
3. ASME B 31.1 & ASME B 31.3 CODE COMPARISON
4. ASME B31.3 (Power Piping) VS ASME B31.3 (Process Piping)
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