Looking for Spirax Sarco products and services?

Learn about steam

These tutorials explain the principles of steam engineering and heat transfer. They also provide a comprehensive engineering best practice guide covering all aspects of steam and condensate systems; from the boiler house and steam distribution system up to the point of use; through the condensate recovery system and returning to the boiler. Virtually all major applications and products are discussed.

Steam Insights

Our blog on the latest topics and thought leadership on all things steam

  • Steam - the energy fluid

    This introductory tutorial describes the many benefits and uses of steam in industry today.

  • Steam and the organisation

    The benefits of steam are viewed differently by individuals according to their role and priorities. This tutorial explains the issues of most importance to chief executives, managers and operators and how steam can address these issues.

  • The steam and condensate loop

    How is steam generated, distributed, controlled and used? How is the condensate recycled? A basic overview of a steam system.

  • Engineering Units

    An overview of the units of measurement used in the Steam and Condensate Loop including temperature, pressure, density, volume, heat, work and energy.​

  • What is Steam?

    The properties of steam explained here, including the ability of steam under pressure to carry, and then give up, large amounts of energy. Topics include saturated steam tables, dryness fraction and flash steam.

  • Superheated Steam

    An explanation of the properties and uses of superheated steam (such as for electricity generation). Including explanations of the Rankine and Carnot thermodynamic cycles, superheated steam tables and the Mollier (H-S) chart.​

  • Steam Quality

    Steam should be available at the point of use in the correct quantity, at the correct pressure, clean, dry and free from air and other incondensable gases. This tutorial explains why this is necessary, and how steam quality is assured.​

  • Heat Transfer

    Steam is often generated to provide heat transfer to a process. Modes of heat transfer (conduction, convection, radiation) within or between media are explained, together with calculations and other issues such as heat transfer barriers.​

  • Methods of Estimating Steam Consumption

    How to calculate steam requirements for flow and non-flow applications. Including warm-up, heat losses and running loads.

  • Measurement of Steam Consumption

    Methods of measuring steam consumption, from the very basic to sophisticated flow metering, are explained in this tutorial.​

  • Thermal Rating

    Design ratings for items of plant can be both helpful and misleading, as changing any factor can alter the predicted heat output. Also, how to calculate steam load requirements from the kW rating.​

  • Energy Consumption of Tanks and Vats

    The heating of liquids in tanks and vats is an important requirement in process industries. There are many types of tank with different uses. Determination of heat requirements, heat transfer and heat loss calculations are all covered in this tutorial.​

  • Heating with Coils and Jackets

    Indirect heating of fluids is covered in this tutorial including layouts, control and drainage of coils and jackets, and heat transfer calculations.​

  • Heating Vats and Tanks by Steam Injections

    Direct steam injection involves the discharge of steam bubbles into a liquid at a lower temperature to transfer heat. This tutorial explains the process and the methods used, including the relevant heat transfer calculations.

  • Steam Consumption of Pipes and Air Heaters

    Steam will condense and give up its enthalpy of evaporation on the walls of any pipe or tube at a lower temperature. It is not usually possible or necessary to calculate steam consumption exactly. This tutorial allows satisfactory estimates to be made for most practical purposes.​

  • Steam Consumption of Heat Exchangers

    Different types of heat exchanger are explained and compared in this tutorial, together with steam consumption calculations and other issues such as the relevance of the starting load.​​

  • Steam Consumption of Plant Items

    The steam consumption of other common plant items, including heater batteries, calorifiers, drying cylinders, presses and tracer lines.​​​

  • Entropy - a basic understanding

    Entropy is a concept some find difficult to grasp, but in truth it does not deserve such notoriety. Look upon Entropy as a road map that connects thermodynamic situations. This tutorial hopes to shed some light on this subject, by approaching it from first principles.​

  • Entropy - its practical use

    Entropy can be used to understand thermodynamic applications from first principles. This tutorial gives practical examples of how this can be done.​

  • Introduction

    An overview of boiler regulations, with an evaluation of fuel types and comparisons

  • Shell Boilers

    Overview of the different types of shell boiler with layouts, heat and steam release considerations plus pressure and output limitations

  • Water Tube Boilers

    Description of water tube boilers including operation, types and benefits; also, a brief synopsis on how they are applied to combined heat and power generation.

  • Miscellaneous Boiler Types Economisers and Superheaters

    An explanation of specialist boiler types and other specialist features.

  • Boiler Ratings

    This tutorial explains the three most commonly used boiler ratings: The 'From and at' rating for evaporation, the kW rating for heat output, and boiler horsepower.​

  • Boiler Efficiency and Combustion

    A broad overview of the combustion process, including burner types and controls, and heat output and losses.​

  • Boiler Fittings and Mountings

    An overview of the necessary fittings, accessories and controls for a boiler from nameplates and safety valves to gauge glasses and level controls.

  • Steam Headers and Off Takes

    This tutorial looks at steam header arrangements and other design considerations necessary for efficient warm-up, good steam quality and proper steam distribution from the boiler house.​

  • Water Treatment Storage and Blowdown for Steam Boilers

    A look at the chemistry of water supplies including hardness and pH values.​

  • Water for the Boiler

    A steam boiler plant must operate safely, with maximum combustion and heat transfer efficiency. To help achieve this and a long, low-maintenance life, the boiler water can be chemically treated.

  • The Feedtank and Feedwater Conditioning

    All aspects of the design, construction and operation of feedtanks and semi-deaerators, including calculations.​

  • Controlling TDS in the Boiler Water

    The need to measure and control the total dissolved solids (TDS) in the boiler water boiler water, and the methods used to do so, including closed loop electronic control with conductivity sensors.

  • Heat Recovery from Boiler Blowdown TDS Control Only

    Boiler water is blown down to control the amount of total dissolved solids (TDS) in the boiler. This water is pressurised, hot and dirty, creating large volumes of flash steam and possible disposal problems. A heat recovery system can reclaim large amounts of energy during this essential process.

  • Bottom Blowdown

    Factors surrounding the removal of suspended solids from the boiler, including valves, piping and blowdown vessels, with calculations.​

  • Water Levels in Steam Boilers

    The level of water in a steam boiler must be carefully controlled, to ensure good quality steam is produced safely, efficiently and at the correct pressure.​

  • Methods of Detecting Water Level in Steam Boilers

    The application of level controls and alarms, plus an overview of different level detection methods, including float-type controls, conductivity probes and capacitance devices.​

  • Automatic Level Control Systems

    A detailed explanation of on/off, modulating, two and three element automatic level control, with a comparison of pros and cons.​

  • Water Level Alarms

    The function of high and low level alarms. Low-level alarms will draw attention to low boiler water level and, if required, shut down the boiler. High-level alarms protect plant and processes.​

  • Installation of Level Controls

    The pros and cons of direct versus externally mounted level controls.​

  • Testing Requirements in the Boiler House

    Requirements for regular testing will vary according to national regulations, and the type of equipment installed.

  • Pressurised Deaerators

    The need to remove gases from boiler feedwater and the operation of a pressurised deaerator, plus calculations.​

  • Steam Accumulators

    A complete overview of the ne​ed for steam storage to meet peak load demands in specific industries, including the design, construction and operation of a steam accumulator, with calculations.​

  • Fluids and Flow

    Users may wish to measure the flow of steam to help with plant efficiency, energy efficiency, process control or costing purposes. This tutorial considers the characteristics of flowing fluids and the basic requirements for good steam metering practice.

  • Principles of Flowmetering

    A detailed examination of the principles and terminology surrounding the topic of flowmetering, including accuracy, repeatability and turndown. Also included is a basic insight to Bernoulli's Theorem.

  • Types of Steam Flowmeter

    The operation, advantages and limitations of different types of steam flowmeter, including orifice plate, variable area and vortex shedding devices.

  • Instrumentation

    Apparatus for accurate steam flow measurement, including differential pressure cells and data collection & analysis equipment. Also covers special considerations such as the effects of pressure variation, steam dryness fraction and superheat.

  • Installation

    System design, installation and maintenance considerations for steam flowmeters, including the use of strainers, separators and flow straighteners, together with piping layouts. Includes a useful checklist for selecting the correct type of flowmeter for an application.

  • An introduction to controls

    This tutorial provides an introduction to the subject of automatic control, including the basic elements of a control system, different control functions, and relevant terminology, with some emphasis on safety, and stability & accuracy of control.

  • Basic Control Theory

    This tutorial looks at on/off and continuous control modes. It introduces proportional, integral and derivitive control actions and explains some of the terminology.

  • Control loops and dynamics

    An explanation of each component of a control system, including valves, actuators, sensors and controllers; together with an introduction to methods of control and system dynamics, including simple control loops and feedback systems.

  • Choice and Selection of Controls

    This tutorial will concentrate on available automatic control choices (such as self-acting, pneumatic or electric) and the decisions which must be made before selection. Guidance is offered on the basis of the three most important considerations of safety, stability and accuracy.

  • Installation and commissioning of controls

    Practical installation and commissioning advice for valves, actuators, sensors, controllers and more.

  • Computers in Controls

    A look at the more recent developments in control involving the use of information technology.

  • Control Valves

    This tutorial briefly describes the basic components of different types of linear and rotary action control valves available for use in steam and water systems.

  • Control Valve Capacity

    Valves need to be measured on their capacity to pass fluid. To enable fair comparison, valves are sized on a capacity index or flow coefficient. This tutorial explains the different types of flow coefficient in use, how they are established, how they compare, and typical values for different sized valves.

  • Control Valve Sizing For Water Systems

    This tutorial briefly describes how to use flow coefficients to size valves for water systems, the difference between using two-port and three-port valves and the effect of these valves on pressure drop, flow and water system characteristics. Also explained is the importance of valve authority, and the cause and effects of cavitation and flashing under certain conditions.

  • Control Valve Sizing For Steam Systems

    Sizing a control valve for a steam application can be a complex matter. This Module attempts to throw light on the subject by using first principles to explain the relationship between flow and pressure drop. It uses a simple nozzle to explain the phenomenon of critical pressure, and how this can be predicted for steam flow through a control valve. It continues by discussing other properties such as noise, erosion, and how steam is dried or superheated as it passes through a valve, and gives various examples of such calculations. It also briefly compares shell & tube and plate heat exchangers, and shows how to use simple Kv charts to size steam valves.​

  • Control Valve Characteristics

    Various types of flow characteristics are available. This tutorial discusses the three main types used in water and steam flow applications: fast opening, linear, and equal percentage flow; how they compare, and how (and why) they should be matched to the application in which they are used. ​

  • Control Valve Actuators and Positioners

    Control valves need actuators to operate. This tutorial briefly discusses the differences between electric and pneumatic actuators, the relationship between direct acting and reverse acting terminology, and how this affects a valve's controlling influence. The importance of positioners is discussed with regard to what they do and why they are required for many applications.

  • Controllers and Sensors

    Controllers and sensors are important parts of the control system; without information from the sensor, the controller cannot make a decision and instruct the valve to move. This tutorial briefly discusses the different types of controllers and sensors available and how they operate. A brief explanation of digital and analogue control signals is also given.​​

  • Self-acting Temperature Controls

    This tutorial gives a basic introduction to what self-acting temperature control systems are and how they operate. The various different types of valves and controllers are briefly discussed along with typical applications for steam and water systems.​ ​

  • Typical Self-acting Temperature Control Valves and Systems

    Four different types of temperature controllers are considered, including fail-safe high limit protection. Popular applications for self-acting controls are listed for process, heating and cooling systems.​

  • Self-acting Pressure Controls and Applications

    Various types of self-acting pressure controls are examined in this tutorial, including direct acting bellows operated and diaphragm operated valves, and pilot operated valves, with guidelines on how to select and install them correctly. Pressure reducing valves are considered together with pressure maintaining valves and surplussing valves, alongside some typical applications.​

  • Pressure Control Applications

    There are many good reasons for reducing (and sometimes maintaining) steam pressure. This tutorial details common applications for direct operating, pilot operated, pneumatic, electric and electropneumatic pressure control systems, including the advantages and disadvantages of each different control method.​

  • Temperature Control Applications

    Temperature control of the process can be affected using electric, pneumatic, electro-pneumatic and self-acting controls. This Module details some common applications including process vessels, heat exchangers and high temperature fail safe control.​

  • Level Control Applications

    A range of level control systems and methods are used in industry. Systems may be based on the use of floats, probes or even more sophisticated technology. This tutorial studies the use of probes to provide adjustable & non-adjustable on/off control, and modulating control of liquids. Simple flow control applications are also considered. ​

  • Control Installations

    The service life and accuracy of a control system can be influenced by installation factors. This tutorial discusses the basic important considerations including the positioning of equipment and wiring, radio frequency interference, and protection from the environment.​

  • Safety Valves

    Any pressurised system requires safety devices to protect people, processes and property. This tutorial details situations when overpressure may occur, the wide and often confusing types of device on offer, how such devices operate and the many codes, standards and approval authorities to note.​

  • Types of Safety Valve

    A full explanation of the many different types of safety valves available, including operation, materials of construction and accessories.​

  • Safety Valve Selection

    Choosing and commissioning the correct safety valve, including selection considerations, setting, sealing, positioning and the effects of backpressure.​

  • Safety Valve Sizing

    An in-depth study of the sizing process for a range of applications, including sizing equations for AD Merkblatt, DIN , TRD, ASME, API, BS6759 and others. Covers more complex issues such as two-phase flow and superheat.​

  • Safety Valve Installation

    Important installation advice, including handling, plant conditions, pipework configuration, markings and noise considerations.​

  • Alternative Plant Protection Devices and Terminology

    Other methods of relieving excess pressure explained; plus a useful terminology section.​

  • Introduction to Steam Distribution

    An efficient steam distribution system is essential if steam of the right quality and pressure is to be supplied, in the right quantity, to the steam using equipment. This tutorial looks at a typical circuit.

  • Pipes and Pipe Sizing

    Pipe sizing is a crucial aspect of steam system design. This tutorial offers detailed advice on standards, schedules, materials and sizing for various saturated and superheated steam duties.​

  • Steam Mains and Drainage

    Issues surrounding the structure, layout and operation of a steam distribution system, including condensate drain points and branch lines, the avoidance of waterhammer and the use of separators and strainers for steam conditioning.​

  • Pipe Expansion and Support

    Any steam system must be fully supported, able to expand during operation and sufficiently flexible to allow movement as a result. This tutorial includes advice on different methods and full calculations.

  • Air Venting Heat Losses and a Summary of Various Pipe Related Standards

    The venting of air and other incondensable gases from steam systems, and the provision of adequate insulation, are vital to ensure steam plant efficiency, safety and performance.​​

  • Introduction - Why Steam Traps?

    The duty of a steam trap is to discharge condensate, air and other incondensable gases from a steam system while not permitting the escape of live steam. The need for steam traps, considerations surrounding their operation, basic modes of operation and relevant standards are all covered in this tutorial.​

  • Thermostatic Steam Traps

    Thermostatic traps operate in response to the surrounding steam temperature. The operation and benefits of 3 different types are considered here - liquid expansion traps, bimetallic and balanced pressure thermostatic traps. Each operates in a different way and is suited to specific types of application.​

  • Mechanical Steam Traps

    Mechanical steam traps rely on the difference in density between steam and condensate in order to operate. They can continuously pass large volumes of condensate and are suitable for a wide range of process applications. Types include ball float and inverted bucket steam traps. This tutorial considers the operation and benefits of both types.​

  • Thermodynamic Steam Traps

    Thermodynamic steam traps have a unique operating principle which relies on the dynamics of water and flash steam. They are simple, robust and reliable and can operate up to very high temperatures and pressures. Their construction, use and benefits are detailed here.

  • Considerations for Selecting Steam Traps

    Application type, system design and maintenance needs will influence the performance and selection of steam traps. Factors such as waterhammer, dirt, steam locking, group trapping, vacuum conditions and temperature control of processes are discussed in this tutorial.

  • Selecting Steam Traps - Canteen Equipment Oil Transfer Storage Hospital Equipment

    Selection tables and advice on trap selection for a range of different processes are included in this tutorial, including steaming ovens, bulk storage tanks and autoclaves.

  • Selecting Steam Traps - Industrial Dryers

    Selection tables and advice on trap selection for a range of different processes are included in this tutorial, including multi-bank pipe dryers and rotating cylinders.

  • Selecting Steam Traps - Laundries and Presses

    Selection tables and advice on trap selection for a range of different processes are included in this tutorial, including calendars, garment presses, dry cleaning machines and tyre presses.

  • Selecting Steam Traps - Process Equipment

    Selection tables and advice on trap selection for a range of different processes are included in this tutorial, including boiling pans, retorts, digesters, coppers, reboilers, evaporators and vulcanisers.​

  • Selecting Steam Traps - Space Heating Equipment

    Selection tables and advice on trap selection for a range of different processes are included in this tutorial

  • Selecting Steam Traps - Steam Mains Tanks and Vats Pressure Reducing Valves

    Selection tables and advice on trap selection for different types of steam mains, headers and off-takes are included in this tutorial, together with process vats and pressure reducing valve stations.​

  • Air Venting Theory

    The presence of air has a devastating effect on steam systems and processes. The basic theory of air venting is explained in this tutorial, plus advice on air vent location.

  • Air Venting Applications

    Some of the many different applications for air vents are described in this tutorial, including steam mains, bypasses, jacketed vessels and rotating cylinders. Other issues such as venting large volumes of air, group air venting and the substitution of thermostatic steam traps are also considered.​

  • Testing and Maintenance of Steam Traps

    Indiscriminate maintenance of steam traps wastes money. This tutorial considers a planned approach to steam trap testing and maintenance, with recommended methods and equipment.​

  • Energy Losses in Steam Traps

    A large amount of inaccurate and misleading information has been written on this subject. This tutorial gives clear, accurate information regarding the energy consumption of different trap types.​

  • Isolation Valves - Linear Movement

    Isolation valves are used for diverting process media, facilitating maintenance, equipment removal and shutdown. The operation, application and construction of gate, globe, piston and diaphragm valves are studied in this tutorial.

  • Isolation Valves - Rotary Movement

    Isolation valves are used for diverting process media, facilitating maintenance, equipment removal and shutdown. The operation, application and construction of gate, globe, piston and diaphragm valves are studied in this tutorial.

  • Check Valves

    Check (non-return) valves are installed in pipelines to allow flow in one direction only; helping to protect equipment and processes. The operation, benefits, applications and selection of different designs, including lift, disc, swing and wafer check valves are explained in this tutorial.

  • Strainers

    Strainers arrest pipeline debris such as scale, rust, jointing compound and weld metal in pipelines, protecting equipment and processes. This tutorial considers the range of strainer and filter types in use and how to size and select them for different applications.​

  • Separators

    'Wet' steam is a major concern in a steam system as it can cause process and maintenance problems, including lower productivity, erosion and corrosion. Separators are designed to efficiently remove the moisture from steam flow. The application and selection of different types are considered here.​

  • Gauges Sight Glasses Vacuum Breakers

    These small items of equipment have a variety of important applications throughout steam systems and process equipment. The different types available are studied in this tutorial.

  • Introduction to Condensate Recovery

    An introduction to the reasons for condensate recovery and return, including energy costs, water charges, effluent restrictions and water treatment costs. Includes sample calculations for potential savings.

  • Layout of Condensate Return Lines

    Considerations surrounding the design and layout of condensate return pipework, including drain lines to steam traps, discharge lines from traps, common return lines and pumped return lines. Includes the effect of trap types used, the effect of different pressures and discharging condensate into flooded mains.

  • Sizing Condensate Return Lines

    A guide to sizing condensate lines to and from steam traps, including examples and calculations using the condensate pipe sizing chart.​​​

  • Pumping Condensate from Vented Receivers

    A basic introduction to pumping terminology, including vapour pressure and static head. Includes a description of the operation, application and comparable benefits of electrical centrifugal and mechanical condensate pumps, with sizing examples for pumps and pump discharge lines.​

  • Flash Steam

    The benefits of recovering flash steam, how it is done and how flash steam can be applied elsewhere in the plant to maximise overall efficiency.​

  • Lifting Condensate and Contaminated Condensate

    Recommendations for special circumstances, including lifting condensate to a higher level return line, and dealing with contaminated condensate.​

  • Basic Desuperheater Types

    This tutorial introduces the common types of desuperheater in regular use, their limitations and typical applications.​

  • Basic Desuperheating Theory

    Superheated steam has important advantages on certain applications, for example, when used in power stations to drive turbines. For efficient use on heating applications however, the steam must be desuperheated. This tutorial considers basic desuperheating theory and calculations.

  • Other Types of Desuperheater

    Additional desuperheater designs such as the venturi and variable orifice types are covered in this tutorial. A comparison of all types is included at the end.​

  • Typical Installations

    A number of important considerations need to be taken into account when installing desuperheaters. This tutorial covers issues such as water quality and pressure control. A desuperheater selection chart and a list of applications are also included.​