A STRUCTURAL INTEGRITY EVALUATION OF THE TANK FARM WASTE TRANSFER SYSTEM Page: 47 of 86
View a full description of this report.
Extracted Text
The following text was automatically extracted from the image on this page using optical character recognition software:
WSRC-TR-2005-00532 March, 2006
Page 40 of 69
insulation has been relatively low, minimal corrosion of the exterior of the steel jacket is
expected.
However, there have been examples of failures of the carbon steel piping that were buried
in these types of insulation. Poor placement of the insulation such that water is allowed
to penetrate to the jacket surface is usually the cause of corrosion failure. The attack is
usually characterized as pitting over a locally thinned area. Additionally there are
concerns that attack beneath the Gilsotherm insulation is more likely than the Gilsulate
500. Laboratory tests indicate that when the Gilsotherm is heated, the organic
material will harden creating cracks in the insulation [94]. Water penetrating into the
insulation becomes acidic, and could result is severe corrosion of the carbon steel jacket.
Corrosion of several steam lines has been observed where the pipes were buried in
Gilsotherm [36]. In the late 1970s, SRS changed the powdered insulation fill to
Gilsulate 500, an inorganic material that does not harden and crack. Since this change
occurred, the performance of buried carbon steel piping has improved, although there
have been occasional failures (see Section 5.2.3).
While no conclusions are drawn directly from the discussion above, this information is
important in understanding the discussions that follow in sections 5.2.1, 5.2.3, 6.2, 6.2.2,
and 6.3.
5.0 Monitoring and Inspection of Transfer Lines
5.1 Monitoring of Transfer Lines for Through-Wall Penetrations
The transfer line systems, where possible, are monitored to assess leak integrity [95]. A
15 psig air pressure test was developed to detect through-wall penetrations. See Figure
21 for details of an example of a leak detection system that utilizes a leak detection box
(LDB). Note that the same test pressure may also be performed via a jacket vent pipe, a
modified LDB, or a leak probe sleeve (LPS).). In the example, a portable air compressor
delivers air though a portable air delivery system into the LDB via an LDB dip tube. The
air pressurizes the LDB, jacket and jacket drain line, and the jacket vent line. If the
pressure in the line drops 1 psig within 20 minutes, the line is recorded as having failed.
This test is sensitive enough to detect hole diameters of 0.01". This test is performed at
least every two years for frequently used lines and is required for inactive lines before
they can be utilized.
If a loss of pressure is detected, there are two tests utilized to locate the site of the
through-wall penetration: a) soap bubble and b) helium leak test [95]. For the first
method the ground above the transfer line is wetted with soapy water. The ground is then
examined for excessive foaming. If the through-wall penetration is not located by this
method, a helium (He) leak test is utilized. For the He-leak test, the gas is introduced into
the jacket through the LDB dip tube. Air samples are then extracted from soil boreholes
(spaced approximately 10 feet apart along the transfer line) and ventilation exhausts. The
air samples are then analyzed with a modified mass spectrometer for He.
Upcoming Pages
Here’s what’s next.
Search Inside
This report can be searched. Note: Results may vary based on the legibility of text within the document.
Tools / Downloads
Get a copy of this page or view the extracted text.
Citing and Sharing
Basic information for referencing this web page. We also provide extended guidance on usage rights, references, copying or embedding.
Reference the current page of this Report.
Wiersma, B. A STRUCTURAL INTEGRITY EVALUATION OF THE TANK FARM WASTE TRANSFER SYSTEM, report, March 9, 2006; United States. (https://digital.library.unt.edu/ark:/67531/metadc836317/m1/47/: accessed July 16, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.