Fig. 190: Fabricated Riser Clamp
SERVICE: In situations where the use of a welded lug attachment would create an undesirable crushing effect on the pipe wall, this clamp can transfer the load from the pipe wall to the riser clamp by means of hold-down lugs welded to the pipe.
Clamps may be furnished in either Carbon or Alloy steel with bolting to suit, using an allowable stress of 10,000 PSI. Temperature correction factors listed in “CHART A” are based on allowable stresses listed in MSS-SP-58.
METHODS OF SELECTION:
1. Determine total load to be supported and service temperature of the piping system.
2. Refer to “CHART A (table below)” and determine the temperature correction factor for the clamp material being used.
3. Multiply total load by the correction factor to obtain a corrected load.
4. Refer to “CHART C (below)” and locate the point determined by the intersection of the total load co-ordinate and the pipe size curve. Project this point horizontally until it intersects with the “D” dimension coordinate. Directly above this point is the required stock size.
5. The bolt diameter is obtained by using the uncorrected total load and referring to “CHART B (below)”.
ORDERING: Specify pipe outside diameter, total load, design temperature, material and dimension “D” or center to center of hanger rods.
NOTE: Pipe clamp can be fabricated to any specified material.
| CHART A - STRESS-TEMPERATURE CORRECTION FACTORS | |||||||||||||
| Material Specification | DESIGN TEMPERATURE °F | ||||||||||||
| ASTM | GRADE | 650 | 700 | 750 | 800 | 850 | 900 | 950 | 1000 | 1050 | 1100 | 1150 | 1200 |
| A 36 | - | 0.8 | 0.83 | 0.89 | 1.06 | - | - | - | - | - | - | - | - |
| A . 387 | 11 | 0.66 | 0.66 | 0.66 | 0.66 | 0.69 | 0.76 | 0.91 | 1.53 | - | - | - | - |
| A . 387 | 22 | 0.66 | 0.66 | 0.66 | 0.66 | 0.69 | 0.76 | 0.91 | 1.28 | 1.72 | 2.38 | - | - |
| A . 240 | 304 | 0.94 | 0.95 | 0.96 | 0.97 | 0.99 | 1 | 1.02 | 1.02 | 1.11 | 1.21 | 1.45 | 1.81 |
|
CHART B – CLAMP SPACING AND BOLT SIZES
|
||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
Uncorrected Total Load lb.
|
3,400
|
4,700
|
6,200
|
8,000
|
10,000
|
12,000
|
16,000
|
19,000
|
25,000
|
32,000
|
40,000
|
55,000
|
67,000
|
82,000
|
96,000
|
118,000
|
135,000
|
154,000
|
|
BOLT – B
|
5/8
|
3/4
|
7/8
|
1
|
1 1/8
|
1 1/4
|
1 3/8
|
1 1/2
|
1 3/4
|
2
|
2 1/4
|
2 1/2
|
2 3/4
|
3
|
3 1/4
|
3 1/2
|
3 3/4
|
4
|
|
BOLT – C
|
–
|
–
|
–
|
3/4
|
7/8
|
1
|
1
|
1 1/8
|
1 3/8
|
1 1/2
|
1 3/4
|
2
|
2
|
2 1/4
|
2 1/2
|
2 3/4
|
3
|
3
|
|
SPACE – S
|
7/8
|
1
|
1 1/4
|
1 1/2
|
1 1/2
|
1 3/4
|
1 7/8
|
2 1/4
|
2 1/4
|
2 1/2
|
3
|
3 1/4
|
3 1/2
|
4
|
4
|
4 1/4
|
4 1/2
|
4 3/4
|
