Nomograph
The Nomograph and Table 4 below may be applied in calculating wall thickness. The following example demonstrates the use of the nomograph in a typical problem situation.
Problem: To find maximum operating pressure of a thermowell, 304 stainless steel material, with a .385 inch bore and .750 minimum outside diameter whose maximum operating temperature will be 700°F.
Solution: Maximum allowable stress (Table 4) 10,500 PSI.Wall thickness (Min.) = .182.
A) Align 10,500 on right scale with .182 on wall thickness scale and mark intersection on pivot line.
B) Align pivot point intersection with correct outside diameter.
C) Read maximum pressure on left scale (5100 PSIG).
Table 4 – Allowable Stress Values (PSI)1
| Material | Temperature °F | ||||||
| 0 | 300 | 500 | 700 | 900 | 1100 | 1300 | |
| Aluminum (1100)
Aluminum (6061-T6) Nickel Steel2 304 S. Stl. 316 S. Stl. 310 S. StI . 321 – 347 S. Stl. 410 S. StI . 446 S. Stl. A182-F11 A182-F22 Copper Admiralty Brass Monel 400 Inconel 600 Incoloy 8003 Hastelloy B4 Hastelloy X5 |
2,350
6,000 10,000 11,250 18,750 18,750 18,750 18,750 15,000 17,500 16,150 17,500 6,000 10,000 16,600 20,000 15,600 25,000 23,350 |
1,850
5,000 10,000 11,000 13,750 16,400 14,600 15,300 13,800 16,100 16,150 17,500 5,000 10,000 13,600 18,800 12,100 24,750 18,850 |
–
– 9,500 10,250 11,400 15,500 12,600 13,500 12,850 15,000 16,150 17,500 – – 13,100 18,500 10,400 21,450 16,000 |
–
– – 9,000 10,500 15,100 11,300 12,200 12,050 – 16,150 17,500 – – 13,100 18,500 9,600 – 15,500 |
–
– – 7,750 10,000 11,650 10,300 11,300 9,650 – 13,100 14,000 – – 8,000 16,000 9,100 – 15,500 |
–
– – 6,500 8,250 8,500 9,450 9,100 2,900 – 4,000 4,200 – – – 3,000 8,800 – 15,500 |
–
– – – 3,400 3,500 4,000 2,200 – – – – – – – – 4,150 – 9,500 |
- Values from ASME Boiler and Pressure Vessel Code Section VlIl – Unfired Pressure Vessels,1965.
- ASME Spec. Min. Tensile = 45,000 PSI
- ASME Code (See Note 1), Case 1325 (special ruling)
- ASME Code (See Note 1), Case 1323 (special ruling)
- ASME Code (See Note 1), Case 1321 (special ruling)
