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    SPREADSHEETS SERIES No. 0009S - 2

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    Emma D
    This document discusses reinforcement requirements for welded branch connections in piping systems. It provides equations to calculate the minimum required reinforcement area and describes how to determine the available reinforcement area from excess pipe thickness and additional reinforcement materials like welds or rings. Reinforcement areas must be within a defined reinforcement zone and considerations are given for multiple closely spaced branches.

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    © All Rights Reserved
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    SPREADSHEETS SERIES No. 0009S - 2

    Uploaded by

    Emma D
    145 views4 pages
    This document discusses reinforcement requirements for welded branch connections in piping systems. It provides equations to calculate the minimum required reinforcement area and describes how to determine the available reinforcement area from excess pipe thickness and additional reinforcement materials like welds or rings. Reinforcement areas must be within a defined reinforcement zone and considerations are given for multiple closely spaced branches.

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    SPREADSHEETS SERIES No. 0009S_2

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    This document discusses reinforcement requirements for welded branch connections in piping systems. It provides equations to calculate the minimum required reinforcement area and describes how to determine the available reinforcement area from excess pipe thickness and additional reinforcement materials like welds or rings. Reinforcement areas must be within a defined reinforcement zone and considerations are given for multiple closely spaced branches.

    Copyright:

    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd
    Download as pdf or txt
    145 views4 pages

    SPREADSHEETS SERIES No. 0009S - 2

    Uploaded by

    Emma D
    This document discusses reinforcement requirements for welded branch connections in piping systems. It provides equations to calculate the minimum required reinforcement area and describes how to determine the available reinforcement area from excess pipe thickness and additional reinforcement materials like welds or rings. Reinforcement areas must be within a defined reinforcement zone and considerations are given for multiple closely spaced branches.

    Copyright:

    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd
    Download as pdf or txt
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    1/18/2021 SPREADSHEETS SERIES No.

    0009S_2

    Discussion and References


    Information about Reinforcement of Welded Branch Connections:
    ASME B31.3 Process Piping, para. 304.3.3

    Tables and Standards


    - Table A-1 Basic Allowable Stresses in Tension for Metals
    - Table A-1M Basic Allowable Stresses in Tension for Metals (Metric)
    - Table A-1B Basic Quality Factors for Longitudinal Weld Joints in Pipes and Tubes, Ej
    - Table 304.1.1 Values of Coefficient Y for t < D/6
    - Table 302.3.5 Weld Joint Strength Reduc on Factor, W
    - ASME B36.10M-Welded and Seamless Wrought Steel Pipe
    - ASME B36.19M-Stainless Steel Pipe
    - Mill Tolerance = 12.5%

    Equations for Wall thickness calculation of straight pipes under internal pressure (304.1):

    For t < D/6, the thickness should be calculated by the equation:

    Select T from ASME B36.10M or B36.19M


    Mill Tolerance = 12.5%. (See ASTM Standards & appendix S of ASME B31.3)
    T = T (1.00-0.125) = T (0.875) Minimum thickness required, considering a mill tolerance of
    12.5%
    Thickness for design
    pressure

    PD (eq. 3a as per par.


    t= 304.1.2)
    2(SEW + PY)

    The parameters in the wall thickness calcula on of straight pipes under internal pressure
    equa ons above are:
    T = Nominal pipe wall thickness, inches (mm) from ASME B36.10M or B36.19M
    T = Minimum thickness considering a mill tolerance of 12.5%, inches (mm)
    tm = Minimum thickness required, inches (mm)
    t = Thickness for design pressure, inches (mm)
    c = Sum of allowance for corrosion, erosion, slots and threads, inches (mm)
    P = Internal design pressure, psig (barg) (1bar = 100 kN/m2)
    D = External diameter, inches (mm)
    E = Quality factor (table A-1B) of ASME B31.3
    S = Allowable stress at the design temperature, psi (Mpa) (table A-1 or A-1M) of ASME B.31.3.
    Y = Coefficient that depends on the material and design temperature (table 304.1.1) of ASME
    B31.3.
    W = Stress reduc on factor of welded joint, paragraph 302.3.5(e) and table 302.3.5 of ASME
    B31.3

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    1/18/2021 SPREADSHEETS SERIES No. 0009S_2

    The formulas below is used in the pressure design of branch connec ons. It is illustrated in Fig.
    304.3.3, which does
    not indicate details for construc on or welding. Some of the terms defined in Appendix J are
    subject to further
    defini ons or varia ons, as follows:

    b = subscript referring to branch & h = subscript referring to run or header


    d1 = effec ve length removed from pipe at branch.
    For branch intersec ons where the branch opening is a projec on of the branch pipe inside
    diameter (e.g., pipe-to-pipe fabricated branch),

    d₁ =[Db ̶ 2(Tb ̶ c)]/sin β

    d2 = “half width” of reinforcement zone

    d₂ = d₁ or (Tb ̶ c) + (Th ̶ d₁
    c)+ 2

    L4 = height of reinforcement zone outside of run pipe

    L₄ = 2.5(Th ̶ c) or 2.5(Tb ̶
    , whichever is less
    c)+Tr
    Tb = branch pipe thickness (measured or minimum in accordance with the purchase
    specifica on) except for branch connec on fi ngs (see para. 300.2). For such connec ons the
    value of Tb for use in calcula ng L4, d2, and A3 is the thickness of the reinforcing barrel
    (minimum per purchase specifica on), provided that the barrel thickness is uniform (see Fig.
    K328.5.4) and extends at least to the L4 limit (see Fig. 304.3.3.)
    Tr = minimum thickness of reinforcing ring or saddle made from pipe (use nominal thickness if
    made from plate)
    = 0, if there is no reinforcing ring or saddle
    t = pressure design thickness of pipe, accordingto the appropriate wall thickness equa on or
    procedure in para. 304.1. For welded pipe, when the branch does not intersect the longitudinal
    weld of the run, the basic allowable stress, S, for the pipe may be used in determining th for
    the purpose of reinforcement calcula on only. When the branch does intersect the
    longitudinal weld of the run, the product SEW (of the stress value, S; the appropriate weld joint
    quality factor, Ej, from Table A-1B; and theweld joint strength reduc on factor, W; see para.
    302.3.5) for the run pipe shall be used in the calcula on. The product SEW of the branch shall
    be used in calcula ng tb.
    β = smaller angle between axes of branch and run.
    Required Reinforcement Area. The reinforcement area, A1, required for a branch connec on
    under internal pressure is:

    A₁ =th d₁ (2 ̶ sin β) (6)

    For a branch connec on under external pressure, area A1 is one-half the area calculated by eq.
    (6), using as th the thickness required for external pressure.

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    1/18/2021 SPREADSHEETS SERIES No. 0009S_2

    Available Area. The area available for reinforcement is defined as

    A₂ +A₃ + A₄ ≥ A₁ (6a)

    These areas are all within the reinforcement zone and are further defined below.
    I.Area A2 is the area resul ng from excess thickness in the run pipe wall

    A₂ = (2d₂ ̶ d₁)(Th ̶ th ̶ c) (7)

    II.Area A3 is the area resul ng from excess thickness in the branch pipe wall

    A₃ = 2L₄(Tb ̶ tb ̶ c)]/sin β (8)

    If the allowable stress for the branch pipe wall is less than that for the run pipe, its calculated
    area must be reduced in the ra o of allowable stress values of the branch to the run in
    determining its contribu ons to area A3.
    III.Area A4 is the area of other metal provided by welds and properly a ached reinforcement.
    [See para. 304.3.3(f).] Weld areas shall be based on the minimum dimensions specified in para.
    328.5.4, except that larger dimensions may be used if the welder has been specifically
    instructed to make the welds to those dimensions.
    In ring

    A₄ = (Tr)(Dr Db
    sin β
    )
    -
    In fillet welds
    Considering all fillet welds are equivalent to 45 deg fillet welds

    A₄ = No. Fillet welds x Aby fillet


    weld

    A₄ = 4 x 1/2 x Leg²
    Reinforcement Zone. The reinforcement zone is a parallelogram whose length extends a
    distance, d2, on each side of the centerline of the branch pipe and whose width starts at the
    inside surface of the run pipe (in its corroded condi on) and extends beyond the outside
    surface of the run pipe a perpendicular distance, L4.
    Mul ple Branches. When two or more branch connec ons are so closely spaced that their
    reinforcement zones overlap, the distance between centers of the openings should be at least
    1- ⁄ mes their average diameter, and the area of reinforcement between any two openings
    shall be not less than 50% of the total that both require.
    Each opening shall have adequate reinforcement in accordance with paras. 304.3.3(b) and (c).
    No part of the metal cross sec on may apply to more than one opening or be evaluated more
    than once in any combined area. (Consult PFI Standard ES-7, Minimum Length and Spacing for
    Branch Connec ons, for detailed recommenda ons on spacing of welded nozzles.)
    Added Reinforcement

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    1/18/2021 SPREADSHEETS SERIES No. 0009S_2

    I.Reinforcement added in the form of a ring or saddle as part of area A4 shall be of reasonably
    constant width.
    II.Material used for reinforcement may differ from that of the run pipe provided it is
    compa ble with run and branch pipes with respect to weldability, heat treatment
    requirements, galvanic corrosion, thermal expansion, etc.
    III.If the allowable stress for the reinforcement material is less than that for the run pipe, its
    calculated area must be reduced in the ra o of allowable stress values in determining its
    contribu on to area A4.
    IV.No addi onal credit may be taken for a material having higher allowable stress value than
    the run pipe.

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