The Complete Guide to Cryogenic Pipe Supports
Cryogenic Pipe Supports, often called Cold Shoes, are a common component of low temperature piping service lines such as those found in liquid natural gas (LNG) processing plants as well as other lines involved in the liquification of other gases
Making Cold Shoes
Designing Cryogenic Pipe Supports
Foam, Shielding and Clamps
Fabricating Cryogenic Pipe Supports
Foam, Shielding and Clamps
Standard Polyurethane Pipe Supports
Guided, Clamped etc.
Special Cryogenic Pipe Supports
Where to Buy Cryogenic Pipe Supports
Selecting Cold Shoe Pipe Supports
In order to assign cryogenic pipe supports to a piping system one must first identify why the pipe needs to insulated in the first place. Next is to identify the environmental conditions in which the pipe exists. Thirdly, selection of appropriate insulation and exterior materials. And lastly perform a heat gain calculation.
In the first step, the planner needs to identify why the LNG pipe is in need of being insulated. The two most common reasons for insulating LNG pipes are to minimize condensation on the outer surface of the insulation system, limit heat input to the LNG within, and control the processes that cause sublimation of the liquid within the piping. A common rule of thumb in the cryogenic pipe support industry is to limit the heat gain by the insulation system to the outer shell area of ≤8 Btu / hrft2 (25 W / m2). There are other possible purposes but most of them are achieved by addressing these two.
[See also Factors Influencing the Likelihood of Surface Condensation on Mechanical Systems Insulation, Jim Young, Insulation Outlook, July and August, 2012. for more information.]
Examples of worst-case climatic conditions that you should choose for a warm, moist oceanfront location are 90 ° F, 85% relative humidity (RH), and a wind speed of 7mph. When designing an insulation system, it is important to know that the worst-case conditions, where the humidity is very high, or even 100%, cannot be selected. As relative humidity approaches 100%, the thickness of insulation required to control condensation rapidly increases to infinity. The rate of increase in the required insulation thickness is very fast at relative humidity levels above 90%, so relative humidity levels in the range 90% are usually chosen as the maximum value for the design.
Next, the designer needs to select the cold shoe insulation and dressing and determine their thermal conductivity curve (insulation) and jacketing. It is recommended that you use the industry standard values for these properties as published in the ASTM standard specifications for the type of insulation or jacket you are using. For commonly used metal sheaths, the emissivity values should be 0.1 and 0.3, respectively.
Finally, the system engineer needs to perform calculations to determine the outer surface temperature of the jacket and the heat gain through the insulation system. These are a function of the design conditions and the thickness of the insulation of the material used. To perform these calculations, engineers use computer programs to outline the industry standards outlined in the ASTM C680 The end product of these calculations are often displayed in a thickness table showing the thickness of insulation required as a function of the pipe size (NPS) and pipe temperature.
Cold Shoe Pipe Support Types
Resting Cold Shoes
Resting cold shoe supports are used if there is no anchor load, guide load, or if constraining the support is unnecessary. It only supports the pipe without harming the insulation.
Anchor-Type Cold Shoes
Anchor-type cold shoe supports are needed if either axial, lateral, or rotational force movement of the pipe needs to be restrained.
Guided Cold Shoes
Guided cold shoe supports are chosen if controlling pipe movement is needed to prevent harm to process equipment.
Pipe Insulation Guides
This type of cold shoe pipe support (sometimes referred to as a Cold Saddle) is for when there is minimal space between the pipe and the supporting structural steel beneath it. and also where pipe must be supported with damage to its insulation.