12 Allowable Pipe Span Formulas and Tables

12 Allowable Pipe Span Formulas and Tables

Pipe-Span Stress Limits

M 5 WL2 Sa=-= z 4Z

In order to have a workable set of pipe-span tables or to find an allowable span that will require a minimum of manual calculations, the limit for dead load stresses is set at Sh/2. This eliminates the need for checking the sum of the longitudinal pressure stresses plus dead load stress. (Sh = allowable stress at maximum temperature, ASA Code B31.1 and B31.3.) The formula used to determine the maximum spans in the tables (Tables 12-1 through 12-9) is a mean between a uniformly loaded beam simply supported at both ends and a uniformly loaded beam with both ends fixed. This mean formula most nearly depicts the conditions actually existing in a refinery. (See Figure 12-1.) By inspection, if the two moment diagrams in Figure 12-1 are superimposed, the point of the maximum bending moment will still be at mid-span.

or

L

Maximum allowable pipe deflection between supports must not exceed 1 in. or 1/2 the nominal pipe diameter. whichever is the smaller. This is the basic piping practice: however, it is subject to compliance with the customer's specification. The formula used to determine the deflections in Tables 12-1 through 12-9 is a mean between a uniformly loaded beam simply supported at both ends and a uniformly loaded beam with both ends fixed. (See Figure 12-2.) In order to maintain homogeneous units, " Lh must be in in. and "W" must be in lbs/ in ., however, for ease of handling we wish to have " L" in ft and "W" in lb/ft, which we must now convert to inch units. The preceding equation becomes:

+ -wu) (wu 8 24

A safety factor of 1.25 is required because of the discrepancy between theoretical assumption and the actual field situation. 5WU 48

In order to maintain homogeneous units, "L" must be in lb/in.; however, for ease of handling we wish to have " L" in feet and "W" in lb/ft, which we must now convert to inch units. Thus the preceding equation becomes:

swv

M = -48

=

w

Pipe-Span Deflection Limits

Mean = M = 112 -

wv 5 M=--X12 4

~ ~0.8 Z f,

""

5WU 4

6

WL4 13.5WL4 = -- = 128EI EI

6

=

13.5WU EI (Text continued on page 320

314

Allowable Pipe Span Formulas and Tables

Fixed Ends

Simply Supported

a~:=:~~~-L.~IIIII ~ ___. :___. . .,___~ - .~

Load

-.

.,.>

_j_ !---~..,.....--- . . - -

>

..LL.---~~--,.­ >

L 2

Shear

_j_

,I

Moment

Fixed Ends

Simply Supported

V = WL

V = WL 2

Mmax =

2 WL2

WL2

S

24

Figure 12-1 . Diagram showing how stress limits are determined by figuring the mean between a uniformly loaded beam supported at both ends and a uniformly loaded beam with both ends fixed .

Fixed Ends

Simply Supported

~ 1 = 5WL

4

.:12 =

384EI Mean:

=

~1

+ ~2 2

=

WL4 384EI

3WL4 384EI

Figure 12-2. Diagram showing how deflection limits are determined by figuring the mean between a uniformly loaded beam supported at both ends and a uniformly loaded beam with both ends fixed .

315

Piping Stress Handbook

316

Table 12-1 Piping Spans Based on the Following Carbon Steel Materials: Seamless A53 Gr. A, A106 Gr. A, API SL Gr. A; Welded A53 Gr. B, API SL Gr. B, A1 55 C55 Class 2 201"F-600"F with Commodity • (f, 6,175 psi)

;;, 200" F with Water, No Insulation (f, = 7,650 psi)

Pipe Size

3/4" I

1-1 /2 " 2" 2'

3" 4" 6" B' 10" 10" 12" 12" i4' 14" .!.§'

! tl" 18 18" 20"

SCH.

80 80 80 40 8U 40 40 40 40 20 _40

20 STD . JO STD. 10 SJ!J. 10 STD. 10

Maximum Span

17 ' - 6" 20 -0" 24 ' -0" 26' -0' 2~ -6" 31 -6. 34 -6" 4U - 6" 4~ - 0" 45 -0" 49 -6 47 - 0" !lZ -0" 47 -6" 53 -6' 48 -6' 5~' - 0 49 - 6" 5b - b'

50 -6"

=

Recommended Span

Defl .

1-13 16"* 1- 131 '16"* 1-13, '16"* 1-3, I" * * 1-~ -3 4" * 1-4 '16" .. 1-l rz· * 1- '16" ... 8" *

-- ( IJ'

- 3 '16" - 1/4"

* * *

..

-1/4" * /8" -1/B" * 13/16" - 1/16" .. 3 4.

12' -0" 14 -6" 19' -0" 23 -0" 23'-0 27 -6' 31 -0" 3/ -0" 41 -6" 44 ' -0" 4l>' -:-0' 45 ' -6" 44 ' -0" 46 -b" 51 -0" 46 ' -6"

Defl.

3/8" 1/ 2' l/4" I"

26'-6 29 -6" J5 - 0" 39 ' - 6" 39 ' -C

1" l"

~.· -

j_

40 -c 45 -6

1" 1" 1{8

1" .. 3/4"

J

47 -6" 55 - 6" 47' -6 '

14' -0" 15 -b' 19 -6" 21 - 0"

E-

1 1"

53 ':'tl'

Maximum Span

11 /1 6" 1"

~8

4!.

Weight of Water, Minimum Insulation

Recommended Span

Defl.

7/8" * 7/8" * 1" 7/8'

11 ' -0" 13 -6 ' 18 -0' 20 -0"

..

__£]

1" 1" / I!'

'8" 8' jf~

5 '8" 1 / 16"

-b'

';)f.l!"

4b'-6" 42 -6" 48 -0' 43 - 6" 49 -6" ..'!_4 ' - 0'

3/4" 1/2" 3 ' 4' 1 ( 2" 5/ 8" l ' 2'

-

25 ' -6" 27 -6' 33 -0" 39 -o· 36 ' -6" 40 -b' 56 -6 " 43 -0" 37 - 6" 44' -0" 38 ' -0" 45 -0" 39 -6'

Defl.

3/8" 1/2 " 3/4' 3/ 4' / 8' 1/ 8" 3/ 4" 3/ 4" 7/B" 9/16" /16' 1/16' 11/16" 7/ 16" ~/ 8"

3/ 8" 9/16' 3/ 8"

4~--6 "

1!2''

41'-D"

3/ 8"

!I • Exceeds maximu m deflec tion.

Courtesy of Power Piping Company.

Table 12-2 Piping Spans Based on the Following Stainless Steel Pipe Materials: Seamless A3 12 TP316, A312 TP317, A430 FP316H , A376 TP317 201 " F-600° F with Commodity (f, = 8.550 PSI)

;;, 200"F wit h Water, No Insulation (f, 9,375 psl)

=

Pipe Size

SCH.

Maximum Span

Defl.

Recommended Span

Defl.

..

Maximum Span

Weight o f Water, Minimum Insulation

Recommended Span

De fl.

.. 1"

.. *

•..

• Exceeds maximum deflection .

Courtesy of Power Piping Company.

Defl .

.

7/ 8"

Allowable Pipe Span Formulas and Tables

Table 12-3 Piping Spans Based on the Following Stainless Steel Pipe Materials: Seamless A213 TP304L, A312 TP304L, A376 TP304, A430 FP304H " 200" F with Water, No Insulation (f, = 7,650 psi)

Pipe Size SCH.

Maximum Span

Defl.

Recommended Span

201"F-600°F with Commodity (f, = 5,800 p si)

Defl.

Maximum Span

Defl.

Weight of Water, Minimum Insulation

Recommended Span

Defl.

----------~----------------~--------------------~--------------------~------------

2-1!16" 2-1 /16' 1

12'-0" 14 1 -0"

14' -0

11

22 ' -6"

3/8"

l/2 11

3/4" 1"

15'-0"11

3/4" * 7/8 11 *

20' -0"

13/16"

12'-6"

l8 ' -6

7/B" * 15/16"

11 /16"

10' - 6"

13' -0"

17 1 -6" 14' - 0" 20' - 0" 21 I -6"

10"

12'' 12"

14 11

• Excee ds maximum deflection.

Courtesy of Power Piping Company.

Table 12-4 Piping Spans Based on the Following Stainless Steel Pipe Materials: Seamless A213 TP304L, A312 TP304L ~ 200"F

with Water, No Insulation (f, = 7,650 p si)

Pipe Size

SCH.

Maximum Span

• Exceeds maximum deflection.

Courtesy of Power Piping Company.

Defl.

201"F-600°F w ith Commodity (f, = 4,500 psi)

Recommended Span Defl.

Maximum Span

Weight of Water, Minimum Insulation

Defl.

Recommended Span

Defl.

317

Piping Stress Handbook

318

Table 12-5 Piping Spans Based on the Following Nickel Pipe Material: Seamless B161 Annealed i!:200"F with Water, No Insulation (1, 4 ,000 psi)

201"F-450 "F with Co mmodity • (f, • 1,000 psi)

=

Pipe Size 3/4" 1" 1-1 /2"

z

2 3" 4" b'' 8" 10" 10" 12' 12" 14" _li'' 1b' 16" 18" _II!" 20'

20" 24" £4' 30"

SCH. 80 80 80 40 80 40 '10 40 40 20 40 20

Maximum Span 12 '-0" 13 -6" 6 -0" 17 -b' 18 -0" 21 -6" 2~

STD

10 10 STD

10

:SID 10 20 10 2L 55

10'0" 12 -6" 15 -6" lb' -b' 16 -6"

1/2" 1/2" 1/2" 1/Z'

/2" '2"

~~·

-IJ'

I(>"

28' -0" 3 -6" 3 -6" 34 -b' 32 -b' .. 31

16' /8" 5 '16"

-,

j,

__:,_1_0

Recommended Span

Defl.

--

_3 }" 3• 33'-6" !::>' - o· _39' -6" 35' -b" 40'-6" 36'-6" _42_ -_u· 37 -6"

-b'

_2_2 -0 2b' ~o· 29' -6" 29' - 6" _3~ -b' 3 1 ~o· 34 - 6" 31 -6" ~:,· - 6 32 -6' 36'-6" 33' - 0" _38 -0 34' ~o · 39' - 0 35' -0" 40' -0 Jb ' - 0.

r'_l!''

lb" /8" 3/8" ~·

4 16" 4" 'I(>"

/4" 5/16" 3.'16" /4' 3/16"

Maximum Span

Deft. 3 8" 1.'2" 1.12" ljZ_ 112" '2" lb' ' I(>'

8" 5/16" ~{8'

!l/lb' 3, 8" 5/16" _318 1/4" 5 '16" 1 14" ' If)

114' 5/16' 3/16" '4' 3/ l b'

10'-0" 12 -0" 15 - 0" _16 ~o· 17 -0" 20' -o· 2J' -0 21 -0" 37'-0" 38'-0" 33 -o· 31 -!)' 35 ' -0" 32 -0" !b' -0' 33' -o· 17 -6' 34' -0" ;sa -6' 34' ~6' 39 ' -6" 35 -6" 4•

-

37 -0"

Weight of Water, Minimum Insulation

Recommended Span

Dell.

9' - 6" 11 - 6. _14 - 0" 1:, -o· 16 -0" ·~ -6' 22 :U" 26 -o• 28 -0' 28 -0' 3 1 - o" 29 - 0" 33 ' - 0' 30 -0" 34 -()' 31 -0" 35 - 6" J2 -0" 37 -ll' 33 -o· 38 - 0" 34 - 0" 39 ' - o· 35' -o·

3/8" 3/8' 7/16 lf8'

7!16" lb' I~

3/ B' 3/8" 5/16" 3/B' _I 14' 318 " 14" ' 16 14" '16 " 1.14" :l/ 1b' 114' 114" 3 '16" 14' 16"

De fl. 3/8" 3/8" If 6"

6" 16" 6' 8" 3 8' 5/16" 3 8' I ' 4" 3 8" 1 14 ' ' 16' 1 14" 5 '16" 1 14 ..

' If>' lf4' 1 14 .. 3 16" 14'' 1b"

Courtesy of Power Piping Company.

Table 12-6 Piping Spans Based on the Following Aluminum Pipe Material: Seamless B241 Gr. 3003 H112 ' ~4 ' -6" 29 -0" Z:> -b' 29 -(>' 25' -0" _29 -6" 25 I -0II

Courtesy of Power Piping Company.

.~

18" Ill'

zu·-

3 8" 7.'16" 3/8"

:,/If>" 3/8" 5 '16" lb'

22 -0" 24' -0" zz_ -6 25' -0" 23' -0" 25 -U" 23' - 0"

z

Maximum Span

Dell.

-

2 2!l 23 ~5 - 0"

114" 1 14" '!_b_'

1/4" 1 13" 18 liB" 8 Ill'

'16" 18"

~~~ · -

8 ' 16" 118"

•

~5

6' -6" 8 -0" 10 - 0" 10 ' -b" 11 -6" 13 -0" 14 -b' II' -0' 18 -6" J7 -b' 20 ' - 6" 18' -0" 21 -u· 18'-0" -6" -b'

:_1)_"

-0" 25 -0" I 24 -0

•

6" /8" II

1/8" I 8" 118" I 8 1 18" Ill' Ill' I 8

16" 6 16" 16" ' lb" '16"

~0"

-6" 22'-0" ~~·

~4

Dell.

-u·

_2_2_' ~· 19' -0' 23'-0" 19 I -6 II

5"

6" b' ,fl"

6' '16" 1/16 II

Recommended Span 6'-6" 7 -6" 9 ' -6" 10' -u· 1 -0" 3 -0" 14' -u· 16 -0 17 -6" 1b' -b' 19 -6' 17 -0" 2ll 17 -0" 0 -6" -b' ~I -0 I B ' -0" 21 -6" Ill ~·

-

18 - (}''_ 22' -0' 18 I -6 II

Dell. 1 8" I 18 " 1 18" 8" 1 18' 1 8' Ill' r'_l!''

'16' '16" 1 16" '16" 16" I ' l b' '16' lb' II_(>' I ' lb'

'16" '16" lb' ')_(>'

16" II

Allowable Pipe Span Formulas and Tables

Table 12-7 Piping Spans Based on the Following Aluminum Pipe Material: Seamless 8241 Gr. 6061 T6 201 ' F-400"F with Commodity :a Weight of Water, Minimum Insulation (f, = 2,000 p si)

;;. 200"F with Water, No Insulation (f, = 3,000 p si)

Pipe Size

SCH.

Maximum Span

Recommended Span

Defl.

Defl.

Maximum Span

Recommended Span

Defl.

9'-6"

3/4"

3 8"

1/ ..

11' -6" 14' -0 11 14' -0" 18' -6" 20' -6" 24'-0"

3"

Defl.

1!2"

7/ l6" l/2"

1/2" 7/16" 3/8" 1/4" 3/8' 1

8"

1011 10"

~~::

• Exceeds maximum deflection.

Courtesy of Power Piping Company.

Table 12·8 Piping Spans Based on the Following Aluminum Pipe Materials: Seamless 8210, 8234, and 8235 Gr. 6061 T4, 8241 Gr. 3003 H18 « 200" F with Water, No Insulation

201"F-600"F with Commodity (f, 2 950 psi)

(f, = 4,500 psi)

Pipe Size

3/4"

1"

J-1/2" 2:: 3" 4"

SCH.

80 80

~~

40 40 40 40

2o

40 20 STD

nolO

Maximum Span

17'-0" 19'-0"

n::~:: 26 -6" 1

28'-6" 32 1 -6"

35'-6" 33:-0" 38 -6" 33 1 -6"11 39 ' -6 34'-6"

~~: =~::

Defl.

Recommended Span Defl.

1-3/4" * 1-3/4" *

3/8" 1/2"

9'-0"

11'-0 11

n:=z::

15 ' -6 11 18' -0" 20'-0" 23'-6 11 25' -0 11

l-1/4" * 1-3/16"* 1"

15/16"

9/1611 3/4 1/2 "

Maximum Span

~~: =~::

24'-6" 28'-6" 24'-6"

11

~k~::

= Weight of Water, Minimum Insu lation

Recommended Span

Defl.

5/16" 3/8"

s·-6"

7/16" 3/S"

5/16"

14'-6" 17 ' -0" 19' -0 11 22'-0" 23'-6"

3/16" 174" 3/16 11

23'-011 27'-0 11 25'-0"

~~a:: 3;8"

5/16''

m~

.

m~~~

10' -6"

g:=~::

~2:-f 6II

g:=z::

20

1::4''

24"

20

30"

~s

-

41'-6" 35'-0" _11_