Reinforcing Pad Calculation

0.707 looks suspiciously like (√2)/2, Guv _{(then I am a polooceman and being suspicious comes with the territory)}.

I don't know the standards you are using, not my discipline.

0.707 is (√2)/2. that is the size of the root of the weld, the narrowest part. Normally, a fillet weld nominal size is multiplied by .707 to find the size of the root.

All the required details are there in ASME B 31.3 para 304.3.3. You need to go through and understand. All relevent details are there for your help.

304.3.3 Reinforcement of Welded Branch Connections.

Added reinforcement is required to meet the

criteria in paras. 304.3.3(b) and (c) when it is not

inherent in the components of the branch connection.

Sample problems illustrating the calculations for branch

reinforcement are shown in Appendix H.

(a) Nomenclature.

The nomenclature below is used

in the pressure design of branch connections. It is

illustrated in Fig. 304.3.3, which does not indicate

details for construction or welding. Some of the terms

defined in Appendix J are subject to further definitions

or variations, as follows:

b

p subscript referring to branch

d

1 p effective length removed from pipe at branch.

For branch intersections where the branch

opening is a projection of the branch pipe

inside diameter (e.g., pipe-to-pipe fabricated

branch), d1 p Db − 2 Tb − c ⁄ sin

d

2 p "half width" of reinforcement zone

p d1 or (Tb − c) + (Th − c) + d1/2, whichever

is greater, but in any case not more than Dh

h p subscript referring to run or header

L

4 p height of reinforcement zone outside of run

pipe

p 2.5(Th − c) or 2.5(Tb − c) + Tr , whichever

is less

Tb

p branch pipe thickness (measured or minimum

per purchase specification) except for branch

connection fittings (see para. 300.2). For such

connections the value of Tb for use in calculating

L

4, d2, and A3, is the thickness of the

reinforcing barrel (minimum per purchase

specification) 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

p minimum thickness of reinforcing ring or saddle

made from pipe. (Use nominal thickness

if made from plate.)

p 0, if there is no reinforcing ring or saddle

t

p pressure design thickness of pipe, according

to the appropriate wall thickness equation 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 calculation

only. When the branch does intersect the

longitudinal weld of the run, the product SE

(of the stress value S and the appropriate weld

joint quality factor Ej from Table A-1B) for

the run pipe shall be used in the calculation.

The product SE of the branch shall be used

in calculating tb.

p smaller angle between axes of branch and run

(b) Required Reinforcement Area.

The reinforcement

area A1 required for a branch connection under internal

pressure is

A

1 p thd1 2 − sin (6)

For a branch connection under external pressure, area

A

1 is one-half the area calculated by Eq. (6), using as

th

the thickness required for external pressure.

(c) Available Area.

The area available for reinforcement

is defined as

A

2 + A3 + A4 ≥ A1 (6a)

These areas are all within the reinforcement zone and

are further defined below.

(1)

Area A2 is the area resulting from excess

thickness in the run pipe wall:

A

2 p 2d2 − d1 Th − th − c (7)

(2)

Area A3 is the area resulting from excess

thickness in the branch pipe wall:

A

3 p 2L4 Tb − tb − c ⁄ sin (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 ratio of allowable stress values ofthe

branch to the run in determining its contributions to

area A3.

(3)

Area A4 is the area of other metal provided

by welds and properly attached reinforcement. [See

para. 304.3.3(f).] Weld areas shall be based on the

minimum dimensions specified in para. 328.5.4, exceptthat

larger dimensions may be used if the welder

has been specifically instructed to make the welds to

those dimensions.

(d) Reinforcement Zone.

The reinforcement zone is

a parallelogram whose length extends a distance of d2

on each side of the center line of the branch pipe and

whose width starts at the inside surface of the run pipe

(in its corroded condition) and extends beyond the

outside surface of the run pipe a perpendicular distance

L

4.

(e) Multiple Branches.

When two or more branch

connections are so closely spaced that their reinforcement

zones overlap, the distance between centers of

the openings should be at least 11⁄2 times 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 section may apply to

more than one opening or be evaluated more than once

in any combined area. (Consult PFI Standard ES-7

for detailed recommendations on spacing of welded

nozzles.)

(f) Added Reinforcement

(1)

Reinforcement added in the form of a ring or

saddle as part of area A4 shall be of reasonably constant

width.

(2)

Material used for reinforcement may differ

from that of the run pipe provided it is compatible

with run and branch pipes with respect to weldability,

heat treatment requirements, galvanic corrosion, thermal

expansion, etc.

(3)

If the allowable stress for the reinforcement

material is less than that for the run pipe, its calculated

area must be reduced in the ratio of allowable stress

values in determining its contribution to area A4.

(4)

No additional credit may be taken for a material

having higher allowable stress value than the run pipe.

Thanks

● Area located at ring (reinforcing pad), A41 = (OD - ID) * Thickness T_r * fr = (14 - 8.625) in. * 0.601 in. * (5700 psig / 8000 psig), where factor fr = S_pipe / S_pad

(Where, reinforcing pad thickness (ring), T_r = 0.687 (1-12.5%) = 0.687 (0.875) = 0.601 in.)

● Area of outward nozzle fillet weld, A42 = 2 Triangles = 2 * (1/2 Base * Heigt) = 2 * 1/2 * Leg² = 2 * 1/2 * (0.354 in.)² = 0.1253 in.²

where Leg of fillet weld = √2 * Throat tc (and it is easy mathimatically to proove that)

and from ASME B31.3, Para. 328.5.4(c), tc = lesser of 0.7 Tb or 0.25 in.

0.7 Tb = 0.7 x 0.500 in. = 0.35 in. & 0.25 in.

tc = lesser of (0.35 & 0.25) = 0.25 in.

Leg = √2 * tc = √2 * 0.25 = 0.354 in.

● Area of outer pad fillet weld, A43 = 2 Triangles = 2 * (1/2 Base * Heigt) = 2 * 1/2 * Leg² = 2 * 1/2 * (0.486 in.)² = 0.2362 in.²

where Leg of fillet weld = √2 * Throat (and it is easy mathimatically to proove that)

and from ASME B31.3, Fig. 328.5.4E(4) , the throat = 0.5 Thickness Tr = 0.5 x 0.687 in. = 0.344 in.

and Leg = √2 * throat = √2 * 0.344 = 0.486 in.

● Total area of fillet welds = A42 + A43 = 0.1253 + 0.2362 = 0. 3615 in.² ≈ 0.362 in.²

Notes:

- Run thickness, T_h = 0.687 (1-12.5%) = 0.687 (0.875) = 0.601 in.

- Branch thickness, T_b = 0.500 (1-12.5%) = 0.500 (0.875) = 0.438 in.

Where 12.5% is the mill tolerance as per specification of ASME B31.3

can you do the excerise of one question? So i can have a better understanding.

Dia header 10

Dia branch 4

Material ASTM A53 grade B.

Header & branch schedule is 20

Thanks in advance.