The types of insulation are broken down per their temperature ranges. In general, high temperature supports use different types of insulation than the low temperature supports. Cryogenic means that this particular support should be used on cold pipelines.
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When the temperature is very low then the normal piping system is not able to hold the processing gases in the form of liquid. Cryogenic piping is the concept of low-temperature piping where material type, support, and valve have different requirements than a normal piping system.
In this article, we will give a briefly described knowledge of the following things:
More to Read: Heat Tracing in Piping: Types, Working, Use, Installation, Comparison (Steam Tracing vs Electrical Tracing)
What is Cryogenic Piping?Cryogenic piping refers to a special kind of system that is used in industrial applications which require processing at very low temperatures. Normally around -150°C. Because of this, This much low-temperature material of pipes faces different types of corrosion and deterioration issues.
Cryogenics is part of physics that deal with the property of materials at very low temperature. Very cold and extremely cold temperature changes the chemical and physical properties of materials. Because of this reason, Normally used materials for pipes are not suitable for process application in cryogenic piping.
A process fluid to be called cryogen, Vapor to liquid volume ratio should be 175. Cryogenic Piping is used in many industrial applications including the following:
More Resources: A brief on the Difference between PSV and PRV (PSV vs PRV)
Common Natural Cryogenic materialIn general, Cryogenic materials are odorless, tasteless, and colorless when not in liquid states. Cryogenic liquids need to be handled carefully as they cause cold burns and frostbites. In below table, there is a list of some cryogenic liquid temperatures and liquid to gas expansion ratio:
Cryogenic materials are odorless, tasteless, and colorless when vaporized. Cryogenic liquids need to be carefully handled as they may cause skin burns and frostbite. Table-1 below lists down the liquid temperatures and the liquid to the gas expansion ratio of some of the common cryogenic materials:Cryogenic MaterialTemperature (in liquid state, °C )Liquid to Gas Expansion RatioOxygen-:860Nitrogen-:696Methane-:579Helium-:757Argon-:847Hydrogen-:851Fluorine-:888
Key Challenges of Cryogenic Piping DesignCryogenic piping is a different set of piping items combined together to process for an Industrial application. From Material of pipe to Support type and even types of valve are different in cryogenic piping from Normal process piping.
Design for Fabrication and Installation of Cryogenic Piping must be done with stability to withstand stress and material deformation because of low temperature and thermal forces. Accountability for various constraints like piping layout, space limitations, support location, and Insulation must take into consideration. Some other key challenges for cryogenic piping are as follows:
Cryogenic Globe ValveMore Resources: Piping Supports as Per Insulation System: Hot insulated, Cold Insulated, Non-Insulated
Cryogenic Piping MaterialsMetal shows different properties with different temperatures. Because of that, we can not use the same material type for every range of cryogenic piping. Materials show different properties at different levels of cold temperature because of their crystalline structure, grain size, and heat treatment properties.
Some metals are ductile at room temperature but lose the ductile property when the temperature goes down below its threshold limit. The selection of material as per cryogenic temperature is briefed in further sections.
Properties of Cryogenic materialWith the decrease in temperature, the material becomes brittle, and impact test requirements as per codes and standards need to be verified. Various properties required for a cryogenic piping material are as follows:
This temperature range can be found in natural environmental operations. Many industries especially chemical industries process their product in this temperature range. But common construction Steel is not suitable for this range of lower temperatures.
Pipes used for 0°C to -45°C are commonly made of Copper or Nikel alloy with some specified heat treatment as per design requirement. Alloys of Aluminum and titanium are also used for the piping systems at this temperature.
PH steel, i.e. Precipitation Hardening stainless steel is not suitable for operation in this temperature range because of embrittlement and crack development during the process.
Cryogenic Piping material for Temperature up to -75°CSome steels like low allow, quenched and tempered steels or ferrite nickel steel are suitable for piping operation in this temperature. Most low carbon steel with carbon percentages between 0.20%-0.35% is reliable. Many alloys of manganese, nickel, chromium, molybdenum, and vanadium are suitable for Piping operational work.
Cryogenic Piping material for Temperature up to -100°CLow carbon steel with 3.5% of nickel is often used in liquid gas storage tank fabrication. This steel can handle temperatures as low as -100°C. Many aluminum, nickel, and titanium alloys are also found to be suitable for pipes at these temperatures. Aluminium -T6 can also be used up to -128°C but not for critical operations.
Cryogenic Piping material for Temperature up to -196°CFor more cryogenic pipe supportsinformation, please contact us. We will provide professional answers.
Authentic steel of 300 series is most suitable for working effectively in this temperature range. Maraging steel with nickel (20%-25%) with the addition of cobalt, molybdenum, Titanium, Aluminium, and Niobium are also suitable for Piping application at this temperature. All Nickel-based alloys are almost crack-resistant up to -196°C.
Cryogenic Piping Material for temperature below -196°CThis low range of temperature has a special interest for the storage of Hydrogen and Helium. These gases are promising sources of energy for nuclear fusion plants. Among all type of steel only High alloy authentic stainless steel are suitable for these low-temperature ranges. These alloys contain 18%-21% of chromium and 9%-14% of Nickel.
Cryogenic piping InsulationIn the world of piping, insulation has an important role to save heat loss for effective working and processing of the piping systems. To minimize heat leaks from pipes and equipment high-performance materials are required to provide an efficient level of insulation. A good cryogenic insulation effect on the efficiency of fluid processing in Industries and also low maintenance of cryogenic lines
There are mainly 03 types of cryogenic Insulation that are frequently used in Industries:
Details of each type of cryogenic insulation are described in the following sections.
Expanded foam insulationThis type of insulation is normally considered a mixture of solids and gases with lots of voids. These voids are filled with gases that help to provide a temperature resistance barrier to the pipe or equipment in which this is applied. In this type of insulation heat loss is normally by conduction only as heat loss because convection and radiation are negligible.
Expanded foam insulation is a lightweight, rigid, and closed-cell insulation. this type of insulation is available in several compressive strengths to withstand a load of pipe. Expanded foam insulation has a cellular structure that is formed because of gas intrusion in the foam during manufacturing. Some examples of foam insulation are:
The thermal conductivity of insulation foam depends on the gases that are used during the manufacturing process and also on internal radiant heat transfer when foam becomes solid. Because of the closed-cell structure of foam insulation, it provides minimal water absorption and low vapor permanence. Gases that are generally used are CO2 or Freon. Thermal conductivity and density of different materials of expanded foam insulation are as follows:Foam TypeDensity (Kg/m3)Thermal conductivity (mW or mK)PolyurethanePolystyreneRubberSilicaGlass
The primary method of insulation in gas-filled power or fibrous material is to reduce or eliminate the convection of heat because of the small size of the void within foaming material. A gas-filled power reduces the gas convection as the distance between powder particles in the insulation is much smaller than the gas mean free path.
As a result, the regular gaseous conduction process shifts towards free molecular conduction. This helps to decrease the thermal conductivity. The commonly used insulation material for Gas-filled powder and fibrous material are:
The thermal conductivity and density of the above materials are as follows:Material TypeDensity (Kg/m3)Thermal conductivity (mW or mK)PerliteSilica AerogelFiberglassRockwool
Vacuum jacketed cryogenic insulation is just like steam jacket piping where there are 02 concentric parallel pipes running together. The inner pipe is called the core while the outer pipe is called the jacket. The Vacuum jacketed insulation is the most effective cryogenic piping method for insulation in terms of safety, reliability, and durability of cryogenic fluid transfer.
A well-designed vacuum jacketed insulation for a cryogenic piping system includes the following accessories to control the flow of fluid, efficient connection, and maintain the vacuum space.
In the vacuum jacketed Cryogenic insulation inner pipe that carries the cryogenic fluid is wrapped with multiple layers of super insulation materials. The insulating layer is made up of radiant heat barrier material and non-conductive spacer material and the space between the two lines is evacuated. there are two types of vacuum jacketed insulation:
More Resources: SOP for jacketed piping: Types, General requirement, Fabrication, Erection, Testing
Cryogenic Pipe SizingAn accurate size for cryogenic service is an important factor for saving the complete piping system from thermal force and heat loss. You can simply understand by this example: If the size of a pipe is bigger than its surface area will be more and heat loss per unit area will be more and its other terms, if the size will be less than the required size for precessing than excessive hoop stress, will be there on the pipe that can reduce the lifespan of the piping system.
Choosing an exact pipe size for cryogenic piping normally depends on 04 factors:
Working in extremely low temperatures has many different hazards like a cold burn, Skin freezing. Some of the cryogenic hazards are as follows:
Cryogenics is a branch of physic that deal with change in the chemical or physical property of material because of very low or extremely low temperature. So, the material used for cryogenic piping could not be the same as normal piping. Even types of support, Insulation, and valve are different from general piping.
Some of the key points of the article are as follows:
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