Uninsulated line

Simple heat transfer calculations i. e. using sources like Ref [20], indicate that even uninsulated lines are not a severe problem in most spectroscopic applications. With insulated 1/8, 1/16, and 1/32 inch stainless steel and PEEK tubing, with a flow velocity of ca. 0.1-lm s and driving force of 50 °C between... 

The heat leak into the test line from the natural environment could be limited through the use of Styrofoam insulation. In six out of the ten tests reported, data were obtained with uninsulated lines which resulted in higher heat leaks than for the tests in which insulation was used. 

Question by R. E. Fischer, AlResearch Manufacturing Company In determining that the liquid nitrogen loss through an uninsulated line was 2.5 Btu/hr/ft of length, what were the flow rates and over what total line lengths were the tests performed ... 

Transfer of Liquid Hydrogen Through Uninsulated Lines (5) 103 Externally Bonded and Sealed Insulation for Liquid-Hydrogen-Fueled Rocket Tanks (5) 131... 

Transfer of Liquid Hydrogen through Uninsulated Lines (5) 103 Flexibility Considerations for the Design of Cryogenic Transfer Lines (5) 111 LIQUEFIERS [see also COOLING,REFRIGERATORS, REFRIGERATION]... 

Uninsulated lines voltage Minimum distance Alternatives... 

On one 4,000-B/SD crude unit, an energy survey showed 45% of furnace duty was dissipated to ambient heat losses from hot uninsulated lines, manways, etc. 

TABLE 5.56 Typical Recommended Maximum Support Spacing, in Feet, for Thermoplastic Pipe for Continuous Spans and for Uninsulated Lines Conveying Fluids of Specific Gravity up to 1.35... 

Exhibit 11-22 shows how larger lines in a pipe rack are used to support a group of smaller lines that may not be adequately supported because of the bent spacing. The uninsulated line is U-bolted to the supporting steel the insulated line has its shoe welded to the steel The smaller lines then rest on the steel. When an insulated line is used for support, the growth of the line at the proposed support point must be checked. Its growth could become restriaed by this type of... 

Chart based on spacing for continuous spans and for uninsulated lines conveying fluids of specific gravity up to 1.00. 

TRANSFER OF LIQUID HYDROGEN THROUGH UNINSULATED LINES R. J. Richards, W. G. Steward, and R. B. Jacobs... 

Cryogenic transfer lines can be grouped into three major categories (1) uninsulated lines, (2) foam-insulated lines, and (3) vacuum-insulated lines. The latter category can be subdivided into evacuated powder-insulated lines, high vacuum-insulated lines, and MLI-insulated lines. 

Frequently, it is more economical to transport a cryogen through an uninsulated line than to spend the time and money to insulate the line from heat inleak. An uninsulated pipe is generally employed for short transfer distances and for short or infrequent use periods. 

In an uninsulated line, cooldown costs are low and a frost due to sublimed water vapor quickly forms on the pipe to provide some insulation. A heat transfer coefficient exists for the boundary layer between the ambient air and the outer piping surface as well as between the inner surface of the tube and the transported cryogen. Consequently, both the frost and the film effects offer resistance to heat influx. 

The heat transfer into an uninsulated line may be estimated by summing the convective and radiative heat transfer rates as... 

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