Unit 5 Flow Through Pipes PDF

Unit:5 FLOW THROUGH PIPES 1) Pipe Size Selection and Several Criteria of Pipe Size Pipe Size Criteria for Single Phase Liquid Lines 1) Pipe size criteria based on ISO 13703 Single phase liquid lines shall be sized base on flow velocity primarily If transportation from o...

Unit:5 FLOW THROUGH PIPES 1) Pipe Size Selection and Several Criteria of Pipe Size Pipe Size Criteria for Single Phase Liquid Lines 1) Pipe size criteria based on ISO 13703 Single phase liquid lines shall be sized base on flow velocity primarily If transportation from one vessel to another vessel is conducted by differential pressure, maximum velocity should not exceed 5 m/s at maximum flow rate Flow velocity should not be less than 1 m/s to minimize sand deposition Table below can be used as preliminary criteria for sizing suction and discharge of pump 2) Pipe size criteria based on API 14E 3) Pipe size criteria based on Norsok Standard 4) Pipe size criteria based on BS MA-18 British Standard Marine Series 18 (BSMA-18) provides specification for salt water piping systems in ship. The standard stated maximum velocities of seawater pipeline as a function of pipe bore. For pipe with bore equal to and more than 100 mm, maximum velocity are (for continuous flow basis): 5 m/s for cast iron 4 m/s for CuNi 70/30 3.5 m/s for CuNi 90/10 3 m/s for steel galvanize Pipe Size Criteria for Single Phase Gas Line 1) Pipe size criteria based on ISO 13703 2) Pipe size criteria based on API 14E 3) Pipe size criteria based on Norsok Standard 2) MOODY CHART A moody chart (or moody diagram) is used to estimate the friction factor for fluid flow in a pipe. The chart represents friction factor as a function of reynolds number and the ratio between internal pipe roughness and pipe diameter, or relative roughness, ε/d. The Darcy Weisbach equation is commonly used for calculating pressure drop in a pipe due to friction, otherwise known as major losses. One of the terms in the equation is the Darcy friction factor. 3) Water hammer effect: Water hammer is a phenomenon that can occur in any piping system where valves are used to control the flow of liquids or steam. Water hammer is the result of a pressure surge, or high- pressure shockwave that propagates through a piping system when a fluid in motion is forced to change direction or stop abruptly. This shockwave is also commonly referred to as a hydraulic shock or hydraulic surge, and may be characterized by a marked banging or knocking sound on the pipes immediately after shutoff. Water hammer can occur when an open valve suddenly closes, causing the water to slam into it, or when a pump suddenly shuts down and the flow reverses direction back to the pump. Since water is incompressible, the impact of the water results in a shock wave that propagates at the speed of sound between the valve and the next elbow in the piping system or within the column of water after the pump.