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MANDATORY APPENDIX FEXTRUDED HEADERS AND WELDED BRANCH CONNECTIONS1

F-1 EXTRUDED HEADERS

Definitions and limitations applicable to Figs. F-1through F-4 are as follows:

D p outside diameter of run, in. (mm)Dc p corroded internal diameter of run, in. (mm)Do p corroded internal diameter of extruded outlet

measured at the level of the outside surface ofrun, in. (mm)

L p height of the reinforcement zone, in. (mm)p 0.7dT0

Tb p

actual thickness of branch wall, not includingcorrosion allowance, in. (mm)Tr p actual thickness of the run wall, not including

the corrosion allowance, in. (mm)To p corroded finished thickness of extruded outlet

measured at a height equal to ro above theoutside surface of the run, in. (mm)

d p outside diameter of branch pipe, in. (mm)dc p corroded internal diameter of branch pipe,

in. (mm)ho p height of the extruded lip. This must be equal

to or greater than ro, except as shown in limita-tion (b) ofro below, in. (mm).

rl p half width of reinforcement zone (equal to Do),

in. (mm)ro p radius of curvature of external contoured por-

tion of outlet measured in the plane containingthe axes of the run and branch, in. (mm). Thisis subject to the following limitations:

(a) Minimum Radius. This dimension shallnot be less than 0.05d (1.27d), except that onbranch diameters larger than 30 in. (762 mm),it need not exceed 1.50 in. (38.1 mm).

(b) Maximum Radius. For outlet pipe sizesNPS 8 (DN 200) and larger, this dimension shallnot exceed 0.10d + 0.50 in. (2.54d + 12.7 mm).For outlet pipe sizes smaller than NPS 8(DN 200), this dimension shall not be greaterthan 1.25 in. (31.75 mm).

(c) When the external contour contains morethan one radius, the radius on any arc sectorof approximately 45 deg shall meet the require-ments of (a) and (b) above.

(d) Machining shall not be employed to meetthe above requirements.

1 See para. 831.6.

136

tb p required thickness of branch pipe according tothe steel pipe design formula of para. 841.1.1,but not including any thickness for corrosion,in. (mm)

tr p required thickness of the run according to thesteel pipe design formula para. 841.1.1, but notincluding any allowance for corrosion orunder-thickness tolerance, in. (mm)

F-2 EXAMPLES ILLUSTRATING THE APPLICATION

OF THE RULES FOR REINFORCEMENT OFWELDED BRANCH CONNECTIONS

F-2.1 Example 1

An NPS 8 outlet is welded to an NPS 24 header. Theheader material is API 5LX 46 with a 0.312-in. wall. Theoutlet is API 5L Grade B (Seamless) Schedule 40 with a0.322-in. wall. The working pressure is 650 psig. Thefabrication is in Location Class 1. Using para. 841.1, thejoint efficiency is 1.00. The temperature is 100F. Designfactors F p 0.60, E p 1.00, and Tp 1.00. For dimensions,see Fig. F-5.

F-2.1.1 Header. Nominal wall thickness required:

t pPD

2 SFET p

650 242 46,000 0.60 1.00 1.00

p 0.283 in.

Excess thickness in header wall:

H t p 0.312 0.283 p 0.029 in.

F-2.1.2 Outlet. Nominal wall thickness required:

tb p650 8.625

2 35,000 0.60 1.00 1.00

p 0.133 in.

Excess thickness in outlet wall:

B t b p 0.322 0.133 p 0.189 in.

d p inside diameter of opening p 8.625 2 0.322

p 7.981 in.

F-2.1.3 Reinforcement Required

AR p dt p 7.981 0.283 p 2.259 in.2

F-2.1.4 Reinforcement Provided by Header

A1 p (H t) d p 0.029 7.981 p 0.231 in.2

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F-2.1.5 Effective Area in Outlet

Height L p 21/2B +M (assume 1/4-in. pad)

p (21/2 0.322) + 0.25 p 1.055 in.

or L p 21/2Hp 2.5 0.312 p 0.780 in. Use L p 0.780 in.

A2 p 2 (B tb) L p 2 0.189 0.780

p 0.295 in.2

This must be multiplied by 35,000/46,000 [seepara. 831.4.1(f)].

Effective A 2 p 0.295 35,000

46,000p 0.224 in.2

Required area:

A3 p AR A1 A2

p 2.259 0.231 0.224 p 1.804 in.2

Use a reinforced plate that is 0.250 in. thick (minimumpracticable) 15.5 in. in diameter.

Area p (15.500 8.625) 0.250 p 1.719 in.2

Fillet welds (assuming two 14-in. welds each side):

1/2(0.25 0.25) 4 p 0.125 in.2

Total A 3 provided p 1.844 in.2

See also Fig. F-6.

F-2.1M Example 1M

A DN 200 outlet is welded to a DN 600 header. Theheader material is 317.2 MPa with a 7.92-mm wall. Theoutlet is 241.3 MPa (Seamless) with a 8.18 mm wall.The working pressure is 4.48 MPa. The fabrication is inLocation Class 1. Using para. 841.1, the joint efficiencyis 1.00. The temperature is 37.8C. Design factors F p0.60, Ep 1.00, and Tp1.00. For dimensions, seeFig. F-5.

F-2.1.1M Header. Nominal wall thickness required:

t pPD

2SFET p

4.48 609.6

2 317.16 0.60 1.00 1.00

p 7.178 mm


H t p 7.925 7.178 p 0.747 mm

F-2.1.2M Outlet. Nominal wall thickness required:

tb p4.48 219.1

2 241.32 0.60 1.00 1.00

p 3.390 mm


B tb p 8.179 3.390 p 4.788 mm

137

d p inside diameter of opening p 219.08 2 8.179

p 202.72 mm

F-2.1.3M Reinforcement Required

AR p dt p 202.72 7.178 p 1 455.2 mm2

F-2.1.4M Reinforcement Provided by Header

A1 p (H t) d p 0.747 202.72 p 151.34 mm2

F-2.1.5M Effective Area in Outlet

Height L p 21/2 B +M (assume 6.35 mm pad)

p (21/2 8.179) + 6.35 p 26.797 mm

or L p 21/2H p 2.5 7.92 p 19.812 mm. Use L p19.812 mm

A2 p 2 (B tb) L p 2 4.788 19.812

p 189.73 mm2

This must be multiplied by 241.3/317.2 [separa. 831.4.1(f)].

Effective A2 p 189.73 241.3

317.2p 144.36 mm2

Required area:

A3 p AR A1 A 2

p 1 455.2 151.34 144.36 p 1 159.5 mm2

Use a reinforced platethat is 6.35 mm thick(minimumpracticable) 393.7 mm in diameter.

Area p (393.7 219.1) 6.35 p 1 108.9 mm2

Fillet welds (assuming two 6.35 mm welds each side

1/2(6.35 6.35) 4 p 80.65 mm2

Total A3 provided p 1 189.5 mm2

See also Fig. F-6.

F-2.2 Example 2

An NPS 16 outlet is welded to an NPS 24 header. Thheader material is API 5LX 46 with a 0.312-in. wall. Thoutlet is API 5L Grade B (Seamless) Schedule 20 with

0.312-in. wall. The working pressure is 650 psig. Thfabrication is in Location Class 1. By para. 831.4.2, threinforcement must be of the complete encirclementype. Using para. 841.1, the joint efficiency is 1.00. Thtemperature is 100F. Design factors F p 0.60, E p 1.0and T p 1.00. For dimensions, see Fig. F-7.

F-2.2.1 Header. Nominal wall thickness required

t pPD

2 SFETp

650 24

2 46,000 0.60 1.00 1.00

p 0.283 in.

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H t p 0.312 0.283 p 0.029 in.

F-2.2.2 Outlet. Nominal wall thickness required:

tbp650 16

2 35,000 0.60 1.00 1.00p 0.248 in.


B tb p 0.312 0.248 p 0.064 in.

dp inside diameter of opening p 16.000 2 0.312

p 15.376 in.

F-2.2.3 Reinforcement Required

AR p dt p 15.376 0.283 p 4.351 in.2

F-2.2.4 Reinforcement Provided

A1 p (H t) d p 0.029 15.376 p 0.446 in.2

F-2.2.5 Effective Area in Outlet

HeightL p 21/2 B + M (assume 5/16-in. plate)

p (2.5 0.312) + 0.312 p 1.092 in.

or

L p 21/2Hp 2.5 0.312 p 0.780 in. Use L p 0.780 in.

A2p 2 (B t b) L p 2 0.064 0.780

p 0.100 in.2

This must be multiplied by 35,000/46,000 [seepara. 831.4.1(f)].

EffectiveA 2 p 0.100 35,000/46,000 p 0.076 in.2

Required area:

A3pAR A1 A 2

p 4.351 0.446 0.076 p 3.829 in.2

Approximate required thickness of reinforcement:

3.829 (30 16) p 0.274 in.

Use a 0.312-in. plate minimum required length(neglecting welds):

3.829 0.312 p 12.272 in.

16 + 12.272 p 29 in. (rounded to the next higher whole

number)

Use a plate that is 29 in. long:

Area p 0.312 (29 16) p 4.056 in.2

138

Two 14-in. welds to outlet:

1/2 (0.25 0.25) 2 p 0.063 in.2

Total A 3provided p 4.119 in.2

The use of end welds is optional (see Fig. I-3).

F-2.2M Example 2M

An DN 400 outlet is welded to an DN 600 header.The header material is 317.2 MPa with a 7.92 mm wall.The outlet is 241.3 MPa (Seamless) with a 7.92 mm wall.The working pressure is 4.48 MPa. The fabrication is inLocation Class 1. By para. 841.4.2, the reinforcementmust be of the complete encirclement type. Using para.841.1, the joint efficiency is 1.00. The temperature is37.8C. Design factorsFp 0.60,Ep 1.00, andTp 1.00.For dimensions, see Fig. F-7.

F-2.2.1M Header. Nominal wall thickness required:

tp PD2 SFET

p4.48 609.6

2 317.16 0.60 1.00 1.00

p 7.178 mm


H t p 7.925 7.178 p 0.747 mm

F-2.2.2M Outlet. Nominal wall thickness required:

tbp4.48 406.4

2 241.32 0.60 1.00 1.00

p 6.290 mm


B t b p 7.925 6.290 p 1.635 mm

dp inside diameter of opening p 406.4 2 7.925

p 390.55 mm

F-2.2.3M Reinforcement Required

AR p dt p 390.55 7.178 p 2 803.5 mm2

F-2.2.4M Reinforcement Provided

A1 p (H t) d p 0.747 390.55 p 291.56 mm2

F-2.2.5M Effective Area in Outlet

HeightL p 21/2 B + M (assume 7.94 mm plate)p (2.5 7.92) + 7.94 p 27.75 mm

or

L p 21/2Hp 2.5 7.92 p 19.812 mm. Use L p 19.812 in.

A2p 2 (B t b) L p 2 1.635 19.812

p 64.80 mm2

This must be multiplied by 241.3/317.2 [seepara. 831.4.1(f)].

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EffectiveA2 p 64.80 241.3/317.2 p 49.30 mm2

Required area:

A3p AR A1 A 2

p 2 803.5 291.56 49.30 p 2 462.6 mm2

Approximate required thickness of reinforcement:

2 462.6 (762 406.4) p 6.925 mm

Use a 7.92 mm plate minimum required length(neglecting welds):

3.829 0.312 p 12.272 in.

139

406.4 + 310.75 p 736.6 mm (rounded to the next higher

whole number in customary

units, i.e., equivalent to 29 in.

Use a plate that is 736.6 mm long:

Areap

7.92

(736.6 406.4)p

2616.8 mm

2

Two 6.35 mm welds to outlet:

1/2 (0.25 0.25) 2 p 40.32 mm2

Total A3 provided p 2 657.1 mm2

The use of end welds is optional (see Fig. I-3).

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Fig. F-1

Fig. F-2

GENERAL NOTE: Sketch to show method of establishing To when the taper encroaches on the crotch radius.

Fig. F-3

140

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Fig. F-5 Rules for Reinforcement of Welded Branch Connections

142

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Fig. F-6

Fig. F-7

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B31.8 REINF