2. Pipe support
Function
• Prevent stresses in excess of permitted stresses.
• Prevent joint leakage.
• Prevent excess forces on equipment to which pipe is
connected.
• Prevent excess stresses in the elements of the support system.
• Avoid resonance from vibrations.
• Avoid interference from the thermal movement with other
pipes or structures.
5. Basic concept
Jika :
F = 10 N
L = 20 m
A = 17
B = 3
Berapakah Fa dan Fb ?
Jawab :
F = Fa + Fb => 10 ton = Fa + Fb. Sehingga
Fb = 10 N – Fa ….(1)
∑Mb = 0, maka
∑Mb = F.b – Fa.20 => 0 = 10 N.3 – Fa.20
atau 30 N = 20Fa;
sehingga Fa = 1.5 N dan Fb = 8.5 N
• berat pipa
• Insulation
• Fluida
• Tekanan
• Peralatan (valve, flange,
dll)
6. Basic concept
Jika :
F = 45KN
L = 3m
a = 2m
b = 1m
EI = 4.16.10^5 Nm2
Berapakah Defleksi
maks (∆max)?
Jawab :
7. Application on pipe system
• Given: A 6 in Sch 40
carbon steel pipe, 10
ft long, anchored at
both ends
• Find: The amount of
force generated by
the expansion of the
pipe from 70°F to
250°F
8. Application on pipe system
• F = Force [lb]
• A = Metal cross-sectional area [in2]
5.581 in2 for 6 in Sch 40 pipe
• E = Young’s Modulus 30 106 lb/in2
• ε =Strain [in/in]
• σ = Stress [lb/in2]
• δ = Displacement due to thermal
growth [in]
• L = Length of pipe [in]
• A = Coefficient of Linear Expansion =
0.000 0065 in/in/°F for carbon steel
• The thermal growth is given by
• L(T) Equation 9.1
• (0.0000065 in/in/°F) (120 in) (250°F
70°F) 0.14 in
Solution ..
10. Application on pipe system
• L= [y.E.I / 22.5.W]¼
L = pipe support spacing, feet,
y = permissible mid-span deflection,
inches
E = modulus of elasticity at design
temperature, lb/in (TABLE C-6(
I = moment of inertia of pipe.
W = weight of supported pipe, including
pipe, contents, insulation, lb/ft
• What is the span of a seamless
ASTM A106 Grade B, 6.625 inch
OD, 0.28 inch wall thick, water
filled pipe with 3 inch of insulation
with a design temperature of 400
F? The specifications limit the mid-
span deflection to 0.25 inch.
Solution:
Pipe = 19.0 lbs per ft
Water = 12.5 lbs per ft
Insulation = 7.6 lbs per ft ( 85 %
Magnesia Calcium
Silicate)
then ,W = 39.1 lb per ft
I = ( π /64)(Do
4 – Di
4)
Do = 6.625, Di = 6.065
I = 28.14 in4
E = 27.7 x 106 psi, Table C-6, C ≤
0.3 at 400°F.
finally, L = [ 0.25x27.7x106 x28.14/(17.
1x39. 1)]1/4
L = 23 feet span
The pipe support spacing would be 23
feet with a mid span deflection of 1/4
inch.
12. Support Selection & Design
• Basic information has to collected before proceeding with
calculations and detailing of pipe supports, as follows;
• A complete set of piping drawings
• A complete set of steel and structural drawings/ data.
• A complete set of drawings showing locations of ventilating ducts, electrical
cable trays, equipment locations (pumps, tanks, etc)
• A complete set of piping specifications and data.
• Insulation specification.
• Movement of all critical equipment connections such as boiler headers, steam
drums, turbine connections, etc..
• The results of stress, flexibility, and movement calculations performed for
critical systems.
14. Application on pipe system
load is calculated as 2500 lbs (1134 kg) at the
position where
• we need a hanger, and it has a movement of 1.2
in. (30.5 mm) at that location.
• We want the difference between the loads to be
less than 600 lbs (272 kg).
• We have a spring hanger that has an acceptable
range within our movement range. It has a spring
rate of 450 lbs/in. (10 kg/mm). Will
• the hanger meet the load difference
requirement?
a) 1.2 × 450 = 540 lbs−−meets the 600-lb
criteria
b) 30.5 × 10 = 350 kg−−does not meet the
600-lb criteria
Solution
a) (hot load/cold load).100 < 25 %; cold
load = 2500 lbs. then (540/2500 ).100=
22 %. OK
b) Because case “b“ doesn’t meet criteria
so the spring rate must be…?
We want the variablity 24% (less than 25%) so
(272/x) = 24%; x = 1134
x
x
Xxx Anchor
Mampu menahan 6 derajat kebebasan
Biasa di pasang di ujung expmjoint dan pipeline underground
Xxx Support hanya menopang pipa saja
a.Rigid hanger no displcmnt y +/-
b. Paling murah dan mudah dipasang
c. Untuk pipa berinsulsi dengn ukuran max 10” , bentuk kaki seperti “T”
d. Untk pipa 12-24”, bntuk kaki “H”
e/h. Memakai trunion atau clamp shoe karena suhu lebih dari 400 calc
f/g. untuk pipa lbih dari 24”
Hanger/spring
1.Jika bergerak kurang dari 4derjt maka horizontal load bisa diabaikan
ara yang paling ekonomis untuk memberikan beban dari sistem perpipaan ke steel structure adalah dengan menggunakan rod hanger. Rod hanger sangat kuat dalam menahan beban tension, namun lemah dalam menahan beban compression. Oleh karenanya, rod harus diletakkan di atas pipa, dan menggantungkan pipa ke steel structure.
For instance, if LB = 0.45LS, then the
allowable LA is 0.16LS.
Ketika suhu meningkat, secara berlahan support di no 30 dan 20 tidak bekerja
Hal ini disebabkan oleh expansi ke atas equipment. Ketika suhu menurun (dari shu max ke ambienti, maka secara berlahan support di node 30 dan 20 mulai bekerja. Penurunan suhu akan membuat pipa kembali pada bentuk awal lebih cepat sebelum kondisi ambient tercapai. Hal ini menyebabkan terjadinya penambahan beban arah Y- pada support dan dapat menyebabkan stress.
Variable Spring Hanger digunakan untuk piping system yang non-critical dan dimana constant hanger tidak diperlukan. Karakteristik Variable Spring adalah gaya supportnya bervariasi dengan berubahnya spring deflection dan spring scale. Vertical expansion dari pipa menyebabkan spring dari hanger mengalami compression atau extension yang selanjutnya menyebabkan perubahan gaya support yang diberikan oleh spring, yang merupakan hasil dari adanya vertical expansion dan spring scale. Maksimum variation pada variable spring hanger adalah 25%.
Constant Spring Hanger digunakan ketika persentase variasi dari cold ke hot condition harus lebih kecil dari 6% ataupun ketika vertical movement dari pipa terlalu besar (lebih dari 2 inchi). Kondisi ini biasanya diperlukan pada daerah yang dekat dengan nozzle equipment yang critical, seperti reciprocating compressor, turbine, boiler, dsb. Karakteristik Constant Spring Hanger ini adalah gaya supportnya konstan tidak peduli berapa- pun vertical movement yang terjadi pada pipa. Gambar di bawah ini adalah salah satu conotoh dari Constant Spring Hanger.