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inhibited bags should be saved for returning exposed specimens. Do not handle
specimens directly with fingers since fingerprints can initiate corrosion sites. Record on
the appropriate form the exact location and date of installation.
Return of Specimens. After the specimens have been exposed for the
selected time (30, 60, or 90 calendar days), carefully remove, air dry without disturbing
any deposits, and return them to the original vapor-inhibited bag. Record date of
removal on the appropriate form. Then send the exposed specimens and completed
forms to the supplier for evaluation. After evaluation, the results are presented and
interpreted in a written report.
INSTALLATION OF COUPON-TYPE TEST SPECIMENS
Method of Installation. Coupons are usually installed in pipe "tees" by
means of corrosion test racks which include a 25-millimeter (1-inch) pipe plug, drilled
and tapped to accept a plastic or phenolic rod with a nylon nut and bolt for attaching the
coupon to the rod. A bypass arrangement with 25-millimeter piping, as shown in Figure
C-1, will facilitate installation and removal as well as allow the use of multiple
specimens. Polyvinyl chloride (PVC) will eliminate electrical effects but cannot be used
for hot condensate. A corrosion test rack may be purchased or constructed on site.
Placement of Coupons. For steam and condensate return lines, install
coupons in any convenient location where there are tees. When using a bypass
arrangement, condensate from the outlet is piped back into the system. Bypasses
should be constructed of iron pipe and fittings and installed only where there is sufficient
pressure differential to ensure a continuous flow through the bypass. Direction of flow
should be as shown in Figure C-1 to minimize turbulence around the corrosion test
specimen and ensure that the test rack remains full of water.