piping thermal insulation calculation – What Is Piping: All about Piping Engineering

Thermal Insulation is very important for saving energy costs and maintaining the process fluid temperature at the required level. In case, thermal Insulation is appropriately chosen and used so that it is: Non-complainingMaintenance-freePatient workhouse It looks after the economy with tremendous savings in energy costs, the safety of personnel and smoother process control. On the other hand, insufficient or poor insulation can be a cause of huge energy loss. So most of the time, thermal Insulation is defined as, “A major tool in improving energy availability”. The basic objective of thermal insulation is to retard the flow of heat: From a hot surface to a cold environment orFrom a warm environment to a cold surface Insulated Pipes Energy Loss from Hot Surface Without Thermal Insulation: Fig. 1: Example showing Heat Loss from Hot Surfaces Economic Reasons for Thermal Insulation: Reduces fuel consumption, and hence overall operational cost so day to day economic benefits.Reduces capacity requirements for heating/cooling systems (boiler, refrigeration unit, etc)Savings in Capital costs Even though the basic requirement for providing thermal insulation is Economic, still it is not the sole criterion. The process requirement controls the usage of thermal insulation. Process Reasons for using thermal Insulation: Reduces temperature a drop of fluid in a heated systemReduces temperature gain of fluid in the refrigerated system.Reduces boil-off rate in a volatile liquid storage systemAssist in maintaining thermal balance in the reaction systemIn the heated system, it lowers temp. of exposed surfaces-protects workmen from burn hazardProvides fire protection for plant, equipment & pipingReduces capacity requirements for heating/cooling systems (boiler, refrigeration unit, etc) Economic Thickness for Thermal Insulation (Fig.2): Fig. 2: Determination of Economic Thickness By virtue, Insulation shall resist heat transfer by: RadiationConvectionConduction Types of Thermal Insulation: Mass type insulation: Based on interposing a mass of material with a built-in capacity to retard heat flowReflective Insulation: Based on providing a series of the reflective surface with the intervening space s evacuatedMicroporous Insulation: Based on a combination of Mass & Reflective technologies. Physical Properties of Thermal Insulation Materials: Significant physical parameters of thermal insulating materials can be divided into: Thermal PropertiesChemical PropertiesCommercial Factors Thermal Properties: Basic thermal parameters that thermal insulation materials should possess are: Temperature resistanceThermal conductivityThermal diffusivity, andThermal shock resistance Chemical Properties of Insulating Material: Major Chemical properties of insulating materials are: Compatibility with the metal surfaceCompatibility with environmental mediaDeterioration arising out of the chemical actionLife of insulation material Points to remember while selecting thermal insulating materials: Alkalinity (pH) or acidityChemical Reactivity / passivityCoefficient of Expansion / ContractionCompressive Strength & Breaking LoadAbrasion ResistanceCombustibilityMost importantly, THERMAL CONDUCTIVITY Thermal Conductivity Vs Density (Fig. 3): Fig. 3: A curve showing the relation between Thermal Conductivity and Density Widely used Hot Insulating Material: Mineral Wool: e.g Rockloyd by Llyod InsulationCeramic Fibre: e,g Supercera range by Llyod InsulationCalcium Silicate Widely used Cold Insulating Materials: Expanded Polystyrene Foam (EPS)Extruded Polystyrene Foam (XPS)Polyurethane Foam (PUF)Poly-isocyanurate Foam (PIR)Foam glassPhenolic Foam Among the above-listed materials, Polyurethane and Polyisocyanurate have assumed the highest importance because these possess many superiorities as compared to others. Both of these materials can be used as Preformed shapes or installed in-situ-by Pouring or by spray. Insulation Finishes: The outer part of insulation is normally provided with: Weather barriers-claddingsWeather and Vapor retarder, Indoor coverings, and finishes All of these have only one basic function that is to protect the insulation material from the severe external exposure media. Insulating System Design: Insulation system should perform to the expected level, undiminished over its life. This needs full data on material behavior under all conditions of exposure.In particular, we need to know what would make a material lose its properties. Thermal calculations need a representative value of Thermal Conductivity for design Standard materials like Rockwool and Calcium Silicate have well-established Design ‘k’ values.Limiting Service Temperature of useIn pipe applications, weight becomes critical. Abrasion is also a major problem with some materials. Some more resouces for you:Piping insulation: Important Considerations for Piping EngineerCorrosion under insulation: A Presentation References: https://www.sciencedirect.com/science/article/pii/S0950061819332180https://www.thermaxxjackets.com/difference-between-hot-and-cold-insulation-materials/