From The Blog

Insights on technology, productivity, programming, and good reads.

Energy Required to Heat Air

Recently I came across this requirement of calculating heat required to heat air (for AHU), I came across two simplified formulas, as follows. Please also note the learning from this workout at the bottom! Learning! for delta T, Centigrade vs Fahrenheit are different! I was thinking, as long as its Delta (Difference between two temperature), […]

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Non Destructive Testing of Welding

So, we have covered Destructive testing in my last post, now something on Non-destructive testing. There are Numerous Non-Destructive tests used to evaluate the base metal to be joined as well as completed welds. However these all NDT shares several common elements, these essential elements are summarized below: o A Source of Probing energy or […]

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Testing of Weldments!

I’ve covered, welding and weld defect in past posts, what I missed completely is the testing of Weldments. One of the purpose of effective quality control program is to determine the suitability of a given base metal or a weld to perform its intended service. When It comes to testing, we have two type of […]

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Effect of Mill undertollerance on Shell thickness calculation

During design of pressure vessel, I came across this issue number of time. Unfortunately, ASME VIII Div.1 doesn’t give a clear picture, whether to add the undertollerance in the min. required thickness as calculated by ASME VIII Div.1 ASME VIII Div. 2, give a clear cut understanding on this issue, can clears all ambiguity. (Clause […]

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Tube Holes in Tubesheet : Point to ne noted while designing heat exchanger

Tube hole finish affects the mechanical strength and leak tightness of an expanded tube-to-tubesheet joint. In general: (1) A rough tube hole provides more mechanical strength than a smooth tube hole. This is influenced by a complex relationship of modulus of elasticity, yield strength and hardness of the materials being used. (2) A smooth tube […]

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Design of heat exchanger step :5 : Parameter Calculations

In the process of evaluation of U, we need to calculate various parameters. Below paragraph mentions few of them. 1. Reynolds number (Re) Reynolds number, which relates inertial forces to viscous forces and thereby characterizes the type of flow regime2. Prandtl number (Pr), which relates the thermal properties of the fluid to the conductivity of […]

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Differences Between The Eighth And Ninth Edition Of The TEMA

Ok, TEMA Ninth edition is here. Other Than complete change in Page Indexing (Page number), Following are note worthy changes from eigth edition : Followings are Prominent Changes and Listed at TEMA website 1. New rules for flexible shell elements (expansion joints), which are based on a Finite Element Analysis (FEA) approach. 2. Tables for […]

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Design of heat exchanger step :4 : Thermal Design

Next step, do a detailing. To Calculate LMTD, we need to understand the flow and type of process (Isothermal or not) Generally we have complication, when either of fluid is showing isothermal characteristics. see the following variation. Two fluids are separated by a heat transfer surface (wall), these fluids ideally do not mix, and there […]

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TEMA Learning -Heat Exchanger nomenclature & Designation:

Heat Exchanger nomenclature & Designation:The name is splited in three portions e.g 23-192-BEM 1st Position : 23 : Defines, ID of Vessel2nd Position : 192 : Defines, Tube length3rd Position : BEM : it further splited in three parts as per fing N-1.2e.g B-E-M, the 1st section, defines the Type of Front head (B for […]

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