For fixed orifice double regulating valves, a minimum of 5 pipe diameters of straight pipe (without intrusion) should be installed upstream of the orifice plate, and a minimum of 2 pipe diameters of straight pipe are required downstream of the valve
Minimum corrosion allowance for stainless steels is 0.8 mm
Minimum corrosion allowance of 1.5 mm shall be provided for carbon steel material
Stainless steels may be classified by their crystalline structure into four main types: austenitic, ferritic, martensitic and duplex
Difference between 304 and 316 stainless steel?
The simple answer is 304 contains 18% chromium and 8% nickel while 316 contains 16% chromium, 10% nickel and 2% molybdenum. The molybdenum is added to help resist corrosion to chlorides (like sea water and deicing salts)
Stress Analysis
- Permissible load variation is determined as the ratio of (Travel x Spring rate / Load ) based on max. operating condition.
- Cold Load = Hot Load + Movement x Spring Rate (For pipe movement up)
- Cold Load = Hot Load – Movement x Spring Rate (For pipe movement down)
- the load variability shall be up to 25% throughout the total travel. However, for critical systems such as piping connected to pumps, compressors, reboilers, etc. lesser load variation is required to meet the allowable load requirements.
- if the load variation exceeds the allowed value, in the same load range selects a spring with lower spring rate. Else, select higher size spring.
Strainers
- If the application requires that the system has to run continuously and cannot be shut down, then the only real choice is a duplex basket strainer.
- If a vertical installation is planned, a Y-Strainer is the one that will work. Y-Strainers can be installed either vertically or horizontally. A basket strainer must be installed horizontally.
For Cold Service Bolting torque to develop 70% Bolt Yield Stress at Nut Factor, K=0.16 (Nut Factor based on lubricant used)
Bolting torque to develop 50% Bolt Yield Stress at Nut Factor, K=0.16 (Nut Factor based on lubricant used)
if the vessel is protected by multiple relief devices, then one relief device must be set no higher than the MAWP but the others can be set as high as 105% of the MAWP.
Relief Valves
– The required relief area for two-phase flow is typically two to ten times the area for single-phase flow.
– For spring-operated relief valves, small amounts of leakage start to occur at 92–95% of the set pressure.
– A relief devices over-pressure is the pressure increase over its set pressure, usually expressed as a percentage of the set pressure. Pop-acting relief valves do not immediately open completely (to 100% lift). Sufficient over pressure is necessary to achieve full lift.
– if the vessel is protected by multiple relief devices, then one relief device must be set no higher than the MAWP but the others can be set as high as 105% of the MAWP.
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.
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
