High pressure may result from the failure of a control valve, a reaction that is out of control, thermal expansion of a liquid, or even an external fire.
by increase the flange class inner diameter and diameter of the raised face at all the same; but outside diameter, bolt circle and diameter of bolt holes become larger in each higher pressure class.
| ASTM Group 2-1.1 Materials | ASTM Group 2-2.3 Materials | |||||||
| Nominal | Forgings | Castings | Plates | Nominal | Forgings | Castings | Plates | |
| Designation | Designation | |||||||
| C-Si | A105(1) | A216 | A515 | 16Cr 12Ni 2Mo | A182 | … | A240 | |
| Gr.WCB(1) | Gr.70(1) | Gr.F316L | Gr.316L | |||||
| C Mn Si | A350 | … | A516 | 18Cr 13Ni 3Mo | A182 | … | … | |
| Gr.LF2(1) | Gr.70(1),(2) | Gr.F317L | ||||||
| C Mn Si V | A350 | … | A537 | 18Cr 8Ni | A182 | … | A240 | |
| Gr.LF6 Cl 1(3) | Cl.1(4) | Gr.F304L(1) | Gr.304L(1) | |||||
| 3.1/2Ni | A350 | … | … | |||||
| Gr.LF3 | ||||||||
| Notes: | Note: | |||||||
| (1) Do not use over 425°C. | ||||||||
| (1) Upon prolonged exposure to temperatures above 425°C, the carbide phase of steel may be converted to graphite. Permissible but not recommended for prolonged use above 425°C. | ||||||||
| (2) Do not use over 455°C. | ||||||||
| (3) Do not use over 260°C. | ||||||||
| (4) Do not use over 370°C. | ||||||||
| Pressure-Temperature Ratings for ASTM Group 2-1.1 Materials | |||||||
| Working pressure by Classes, BAR | |||||||
| Temp °C | 150 | 300 | 400 | 600 | 900 | 1500 | 2500 |
| -29 to 38 | 19.6 | 51.1 | 68.1 | 102.1 | 153.2 | 255.3 | 425.5 |
| 50 | 19.2 | 50.1 | 66.8 | 100.2 | 150.4 | 250.6 | 417.7 |
| 100 | 17.7 | 46.6 | 62.1 | 93.2 | 139.8 | 233 | 388.3 |
| 150 | 15.8 | 45.1 | 60.1 | 90.2 | 135.2 | 225.4 | 375.6 |
| 200 | 13.8 | 43.8 | 58.4 | 87.6 | 131.4 | 219 | 365 |
| 250 | 12.1 | 41.9 | 55.9 | 83.9 | 125.8 | 209.7 | 349.5 |
| 300 | 10.2 | 39.8 | 53.1 | 79.6 | 119.5 | 199.1 | 331.8 |
| 325 | 9.3 | 38.7 | 51.6 | 77.4 | 116.1 | 193.6 | 322.6 |
| 350 | 8.4 | 37.6 | 50.1 | 75.1 | 112.7 | 187.8 | 313 |
| 375 | 7.4 | 36.4 | 48.5 | 72.7 | 109.1 | 181.8 | 303.1 |
| 400 | 6.5 | 34.7 | 46.3 | 69.4 | 104.2 | 173.6 | 289.3 |
| 425 | 5.5 | 28.8 | 38.4 | 57.5 | 86.3 | 143.8 | 239.7 |
| 450 | 4.6 | 23 | 30.7 | 46 | 69 | 115 | 191.7 |
| 475 | 3.7 | 17.4 | 23.2 | 34.9 | 52.3 | 87.2 | 145.3 |
| 500 | 2.8 | 11.8 | 15.7 | 23.5 | 35.3 | 58.8 | 97.9 |
| 538 | 1.4 | 5.9 | 7.9 | 11.8 | 17.7 | 29.5 | 49.2 |
| Pressure-Temperature Ratings for ASTM Group 2-2.3 Materials | |||||||
| Working pressure by Classes, BAR | |||||||
| Temp °C | 150 | 300 | 400 | 600 | 900 | 1500 | 2500 |
| -29 to 38 | 15.9 | 41.4 | 55.2 | 82.7 | 124.1 | 206.8 | 344.7 |
| 50 | 15.3 | 40 | 53.4 | 80 | 120.1 | 200.1 | 333.5 |
| 100 | 13.3 | 34.8 | 46.4 | 69.6 | 104.4 | 173.9 | 289.9 |
| 150 | 12 | 31.4 | 41.9 | 62.8 | 94.2 | 157 | 261.6 |
| 200 | 11.2 | 29.2 | 38.9 | 58.3 | 87.5 | 145.8 | 243 |
| 250 | 10.5 | 27.5 | 36.6 | 54.9 | 82.4 | 137.3 | 228.9 |
| 300 | 10 | 26.1 | 34.8 | 52.1 | 78.2 | 130.3 | 217.2 |
| 325 | 9.3 | 25.5 | 34 | 51 | 76.4 | 127.4 | 212.3 |
| 350 | 8.4 | 25.1 | 33.4 | 50.1 | 75.2 | 125.4 | 208.9 |
| 375 | 7.4 | 24.8 | 33 | 49.5 | 74.3 | 123.8 | 206.3 |
| 400 | 6.5 | 24.3 | 32.4 | 48.6 | 72.9 | 121.5 | 202.5 |
| 425 | 5.5 | 23.9 | 31.8 | 47.7 | 71.6 | 119.3 | 198.8 |
| 450 | 4.6 | 23.4 | 31.2 | 46.8 | 70.2 | 117.1 | 195.1 |
Flanges can withstand different pressures at different temperatures. As temperature increases, the pressure rating of the flange decreases
Slug Flow is typical two phase flow where a wave is picked up periodically by the rapidly moving gas to form a frothy slug, which passes along the pipe at a greater velocity than the average liquid velocity.
Data required for flexibility calculations
1. Code of Practice
2. Basic Material of Construction of Pipe
3. Ambient / Installation temperature
4. Number of Thermal Cases
5. Flexibility Temperature (See Note)
6. Design Pressure
7. Outside diameter of Pipe
8. Type of construction of pipe
9. Nominal Thickness of Pipe
10. Manufacturing tolerance
11. Corrosion allowance
12. Pipe Weight
13. Insulation Weight
14. Specific Gravity of Contents
15. Young’s Modulus at Ambient/Installation Temperature
16. Young’s Modulus at Flexibility Temperature
17. Thermal Expansion at Flexibility Temperature
18. Allowable stress at Ambient/ Installation temperature
19. Allowable stress at flexibility temperature
20. Bend radius and type of bend
21. Branch connection type
22. Weight of attachments – Valves and Specialties
23. Terminal movements with directions
Types of fluid service according to B31.3
(a) Category D Fluid Service: a fluid service in which all the following apply:
(1) the fluid handled is nonflammable, nontoxic, and not damaging to human tissues as defined in para.300.2;
(2) the design gage pressure does not exceed 1035 kPA (150 psi);
(3) the design temperature is from −29°C (−20°F) through 186°C (366°F).
(b) Category M Fluid Service: a fluid service in which the potential for personnel exposure is judged to be significant and in which a single exposure to a
very small quantity of a toxic fluid, caused by leakage, can produce serious irreversible harm to persons on breathing or bodily contact, even when prompt restorative
measures are taken
(c) High Pressure Fluid Service: a fluid service for which the owner specifies the use of Chapter IX for piping design and construction; see also para. K300
(d) Normal Fluid Service: a fluid service pertaining to most piping covered by this Code, i.e., not subject to the rules for Category D, Category M, or High
Pressure Fluid Service
Pressure gauge normally indicates the difference between the measured pressure (absolute pressure) and atmospheric pressure.
On the long term negative effects of rusting on steel valves will reduce the structural integrity of the valve, since rust has different physical characteristics than steel
Zinc, aluminum and magnesium are more electronegative than steel they are increasingly able to supply electrons to the more electropositive steel when in electrical contact in water,
Cathodic protection may be achieved in either of two ways. By the use of an impressed current from an electrical source, or by the use of sacrificial anodes (galvanic action).
1. Identify Application Requirements
-
- Service Conditions: Determine the operating temperature, pressure, and medium (e.g., gas, liquid, corrosive chemicals) the gasket will be exposed to.
-
- Flange Type: Identify the flange design (e.g., raised face, flat face, ring-type joint) per standards like ASME B16.5 or B16.47.
-
- Piping or Vessel Code: Confirm the applicable ASME code (e.g., ASME B31.3 for process piping or ASME Section VIII for pressure vessels).
2. Select Gasket Material
-
- Compatibility: Choose a material compatible with the process fluid to avoid degradation (e.g., rubber, PTFE, graphite, or metallic materials like stainless steel).
-
- Temperature and Pressure Limits: Ensure the material can withstand the maximum temperature and pressure of the system. ASME standards provide guidance on material performance under these conditions.
-
- Corrosion Resistance: Consider the environment and potential galvanic corrosion between the gasket and flange materials.
3. Determine Gasket Type
-
- Non-Metallic Gaskets (ASME B16.21): Soft gaskets (e.g., rubber, PTFE, compressed fiber) for low-pressure, non-critical applications.
-
- Metallic Gaskets (ASME B16.20): Spiral-wound, ring-type joint (RTJ), or solid metal gaskets for high-pressure, high-temperature, or critical services.
-
- Semi-Metallic Gaskets: Combination of metal and filler (e.g., spiral-wound with graphite) for versatility in moderate to severe conditions.
4. Size and Dimensions
-
- Match the gasket dimensions to the flange size, adhering to ASME B16.20 (metallic gaskets) or B16.21 (non-metallic gaskets). This includes inner diameter (ID), outer diameter (OD), and thickness.
-
- Ensure proper fit to avoid overhang or insufficient coverage of the sealing surface.
5. Evaluate Gasket Performance Factors
-
- Seating Stress: Calculate the minimum and maximum seating stress required to achieve a seal, using ASME Section VIII, Division 1, Appendix 2. This involves gasket factors “m” (maintenance factor) and “y” (yield factor).
-
- m: Ensures the gasket maintains a seal under operating pressure.
-
- y: Ensures sufficient initial compression during bolt tightening.
-
- Seating Stress: Calculate the minimum and maximum seating stress required to achieve a seal, using ASME Section VIII, Division 1, Appendix 2. This involves gasket factors “m” (maintenance factor) and “y” (yield factor).
-
- Bolt Load: Confirm the bolt load is adequate to compress the gasket without exceeding flange or gasket limits.
6. Consider Design and Installation
- Flange Surface Finish: Verify the flange surface roughness aligns with gasket type (e.g., smoother finish for soft gaskets, specific serrations for spiral-wound).
You can protect piping which in contact with the ground or routinely contains fuel by one of the following methods
-
made of a non-corrodible material (such as fiberglass or flexible plastic)
-
made of steel and coated and cathodically protected
-
made of steel and cathodically protected
-
isolated from contacting the earth by being inside some form of secondary containment that is made of a non-corrodible material
The fluid flow velocities in water systems should not exceed certain limits to avoid noise and damaging wear and tear of pipes and fittings. The table below can be used as guidance to maximum velocities:
Featured Posts
-
Weight of pipe filled with water
Categories: Calculations
-
Categories: Articles
-
-
Categories: Articles
-
Categories: Articles