A STRUCTURAL INTEGRITY EVALUATION OF THE TANK FARM WASTE TRANSFER SYSTEM Page: 13 of 86
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WSRC-TR-2005-00532 March, 2006
Page 6 of 69
3.2 Historical Background on Specifications
DuPont Specification 3018 is the original piping specification compiled when the plant
was built in 1951 [21]. It was originally issued in May 1951 and was discontinued on
November 1, 1961. It became apparent that Specification 3018 had become obsolete and
extensive revision was necessary. But to avoid radical changes to Specification 3018 that
would destroy the as-built records of the original piping on the site, DuPont Specification
4482 was created to contain all updated P-codes and additions made after November 1,
1961 [22]. Most of the piping associated with the Type III/IIIA tanks was built according
to this Specification 4482. Specification 4482 was in effect until 1990 when it was
superseded by Westinghouse Engineering Requirements [23]. Currently this document is
referred to as Engineering Guide 15060-G. Transfer lines that were either built or
modified since 1990 were fabricated and erected per Engineering Guide 15060-G [23].
Table 2 shows items from each specification which would have a bearing on the initial
wall thickness, inspections, or actions that would have mitigated concerns with corrosion.
Tables 3 through 5 highlight specific items from each of the P-code requirements for the
given Specification that also impact corrosion concerns. The tables indicate that similar
considerations went into the design, fabrication and installation of all the transfer lines.
The largest exception may be that the latter two specification/standard (4482 and 15060)
had specific requirements to (1) limit contact between stainless steel and chloride bearing
materials [24, 25], (2) require corrosion evaluation [26-28], and (3) control moisture and
residual water levels in the piping during construction and following hydrotesting [29,
30].
A specification for limiting contact between chloride bearing materials (e.g., wrapping
tape, markers, gaskets, thermal insulation, etc.) and stainless steels has been in effect
since 1971 [24]. Thus the requirement limiting the chloride concentration would not
have applied to piping placed earlier under Specification 3018 and 4482 up until 1971. It
should be noted that this specification does not place limits on the concentration of
chloride in a liquid in contact with stainless steel, but rather places a limit on the amount
of chloride in a solid material or ink in contact with the stainless steel. The chloride
concentration limit for these materials is 250 ppm. Materials with chloride
concentrations greater than 250 ppm may be utilized, however, if the temperature of the
environment is less than 40 C. As will be discussed later in the report, there were cases
prior to 1971 where chlorides from materials in contact with stainless steel did cause
stress corrosion cracking.
Corrosion evaluation is a series of screening tests that determines whether a material is
susceptible to intergranular attack. Historical documents indicate that the corrosion
evaluation specification was first issued in 1965 [26]. Prior to that time, Specifications
3018 and 4482 required the stainless steel to be in the solution annealed condition [31] in
order to minimize the potential for intergranular attack (see discussion in Section 4.1.3
for further discussion of solution annealing). Therefore, if the pipe was welded into
place, a heat treatment to return the pipe to the solution annealed condition was required
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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/m1/13/: accessed July 16, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.