 |
DUCTILE
IRON FITTINGS - HOWTO - THRUST ANCHORING |
Thrust
Anchoring
Actual thrust force and factor of safety
of are least 1.5 may be taken in calculation.
Thrust Anchoring at Fittings
Thrust forces in water
mains are created when the pipeline changes directions (at bends and tees), stops (at dead
ends), or changes in size (at reducers). In order to keep the pipeline intact, there are
several methods of restraint available, the most popular of which is the use of thrust
blocks.
Thrust
blocks on Bends
|
Thrust
blocks on Tees
|
Thrust
blocks on Reducers
|
Thrust Force
Caused by Water Pressure at Different Fittings
| 1. |
At bend: P = 2. p.A. Sin F
Where,
A: sectional area of pipe
P: Internal pressure
F: Degree of bend |
| 2. |
At tee: P = p.a
Where,
A: Sectional area of branched pipe |
| 3. |
At reducer: P = p.(A - a)
Where,
A - a: Changed sectional area |
| 4. |
At pipeline End: P = p.A |
Thrust Force in kgf at Fitting at 1
kgf.cm2 Water Pressure
|
Nominal Dia mm |
Dead End Kgf |
900 Bend kgf |
450 Bend kgf |
220 Bend kgf |
110 Bend kgf |
|
80 |
75.4 |
106.7 |
57.7 |
29.4 |
14.8 |
|
100 |
109.4 |
154.7 |
83.7 |
42.7 |
21.4 |
|
150 |
227.0 |
321.0 |
173.7 |
88.6 |
44.5 |
|
200 |
387.1 |
547.4 |
296.3 |
151.0 |
75.9 |
|
250 |
589.6 |
388.9 |
451.3 |
230.1 |
115.6 |
|
300 |
834.7 |
1180.4 |
638.9 |
325.7 |
163.6 |
|
400 |
1445.5 |
2044.2 |
1106.3 |
564.0 |
283.4 |
|
500 |
2222.9 |
3143.6 |
1701.3 |
867.3 |
435.8 |
|
600 |
3166.9 |
4478.7 |
2423.9 |
1235.7 |
620.8 |
|
700 |
4277.6 |
6049.5 |
3274 |
1669 |
838.6 |
|
800 |
5568.2 |
7875.6 |
4261.7 |
2172.6 |
1091.6 |
|
900 |
7013.8 |
9919.0 |
5368.1 |
2736.6 |
1374.9 |
|
1000 |
8626.1 |
12199.1 |
6602.1 |
3365.7 |
1691.0 |
*From the above corresponding thrust
force can be calculated for different pressures. |
