PIPING ENGINEERING TUTORIALS

Piping Specifications are usually in the form of a manual containing the below-listed points, but not limited to             1 )       Pipe Class and Specifications.             2)       Pipe and fittings thickness table for the different class of piping.             3)       P & ID Abbreviations and Symbols.             4)       List of fluids with Design conditions and Pipe Class.             5)       List of Valves and Gaskets.             6)       Table of Branch connections for different Pipe Classes.             7)       Table of Bolt length.             8)       Valve Dimensions.             9)         Piping Scope Limit for instrumentation called as “Hook Up Diagram”.            10)      Special Items list. Licensor transfers the basic piping specification as part of their basic engineering package, it generally includes a)        List of mediums that have to handle with design conditions. b)       Dimensional and material standard o

Piping flexibility analysis as per B31.3code requirements is dealing with two types of stress named as Sustained Stress and Displacement stress .  Both types of stress must be considered separately because sustained stresses are associated with sustained forces while displacement stresses are associated with fixed displacements. SUSTAINED STRESSES: Sustained Stresses are stresses caused by loads that are not relieved as the piping system deflects. See the diagrammatic representation below to get an idea about this.  The weight of the valve placed at the end of the cantilevered pipe induce Stress at the T-Joint. Regardless of the magnitude of the displacement (∆), the magnitude of the load (the weight of the valve) which causes the stress is unchanged.  Therefore, to avoid catastrophic failure, the magnitude of any sustained stress must not exceed the yield strength of the material.  Another example of a sustained stress is the hoop and longitudinal stresses induced by the

Nominal Wall Thickness Calculation Of metallic pipes needs the following information as a Pre-requisite. a) Design Pressure, b) Design Temperature, c) Material Specification, d) Pipe Size e) Applicable Code As Per B 31.3, the required thickness of a Straight Section of Pipe is given by the relation t m =t+c Where , t m =Minimum thickness required including, mechanical corrosion and erosion allowance t=Thickness Required to withstand internal pressure c=Sum of Mechanical Allowance (thread, groove depth) added with corrosion and erosion allowance. Let's Go through each term in the above equation i) Thickness Required to withstand internal pressure [ t ] Nominal wall thickness should be Greater than or equal to the sum of the minimum required thickness and Manufacturer’s Negative tolerance. As per the Code Minimum Thickness t =PD/2(SE+PY) Here, P=Design Pressure (Gauge) D=Outside Diameter of Pipe S=Allowable Stress Value of

Imagine a pipe Element, of which's both ends are closed. An Internal Pressure “P” applies on the internal walls of the pipe. The pressure causes the following Stresses on each element of the pipe. a) Circumferential (Hoop) Stress ( σ H ) b) Longitudinal Stress ( σ L ) c) Radial Stress( σ R )  Graphical Representation of Stress on pipe wall Imagine a condition in which the Pressure "P" Exceeds the Resisting capacity of the wall. The pipe may split as shown below. Splitting of Pipe along the Longitudinal Plane The failure may possible across any line containing diameter and axis of the pipe.Here it's the horizontal plane.Elements which resists this failure experience stress and direction of the same will be along the circumference. Hence it’s called as Circumferential or “Hoop Stress ” Let's try to quantify this  here,                              D=Diamter of the Pipe                              t=Thikn