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Description / Abstract:
This practice covers the procedure for locating, by the use of a
solution of copper sulfate, the thinnest spot in a zinc coating
(hot dipped, electroplated, or sprayed) on iron or steel articles
that are coated after the shape is produced by casting, drawing,
pressing, or other forming methods. Examples are: electrical
metallic tubing and rigid conduit pipe, castings and forgings, and
structural steel; on special hardware, such as poleline, builder's,
and farm implement hardware; bolts, nuts, screws, and other
miscellaneous general hardware.
The use of this practice with zinc coating deposited through
different processes (such as hot dipped, electroplated, or sprayed)
requires caution in interpretation since the end point may vary
considerably between different zinc-coating systems.
Excluded from this practice is sheet steel from hot-dip or
electrocoating lines as the sheet products are normally subject to
additional forming after the coating process. Also excluded from
this practice are all zinc-coated wire and wire products either
continuously or batch coated before or after forming.
Warning—Past research (dating from around 1963)
has indicated that this practice can be influenced by operator
technique. Variations can be due to the difference in hand pressure
used to wipe the sample or the inability of the operator to
recognize the end point.
This technique removes the zinc coating on the surface of the
part being examined. This coating removal makes the part or article
unusable after testing. This technique may not be suitable for
parts fabricated into their final configuration, since they will
not be acceptable after testing.
The results of this practice should not be used to predict the
service life of the galvanized coating. Other factors such as
location of the thinnest spot, orientation of the part in service,
and specific environmental conditions will also affect the service
life.
The values stated in inch-pound units are to be regarded as
standard. The values given in parentheses are mathematical
conversions to SI units that are provided for information only and
are not considered standard.
This standard does not purport to address all of the safety
concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety and
health practices and determine the applicability of regulatory
limitations prior to use.
*A Summary of Changes section appears at the
end of this standard