Custom Search
|
|
|
||
 CASE W2 - Acceptance & Inspection Criteria. J. V. Tyrrell
Problem:
Inspection & Acceptance Criteria
Collection of Facts: Often disputes arise over whether or not an item meets
the contract requirements. This is particularly true where performance
specifications are used. However, it also is a problem for contracts where
explicit specifications are used. Some of the common causes are: conflicts or
errors in the plans and specifications, vagueness, insufficient, definition,
reliance on references to standards or codes without knowing enough about
their content, failure to state essential inspection requirements (methods and
timing), failure to specify how acceptance tests will be evaluated and how
deficiencies are to be resolved, deviations from plans or specifications
permitted by field personnel without design consultation.
One example of such a dispute involved welding of a gas cooler for a jet
engine test cell. This unit was designed for both positive and negative
pressure and for temperatures ranging from minus 67 degrees to 3500 degrees
fahrenheit. The specification required radiographic inspection of welding in
accord with Section 8 of the ASTM Pressure Vessel Code.
The referenced code, at that time, required a sampling of welding and,
where defects were found, the sample was to be extended a certain distance
each side of the original sample. Then all the defective areas were to be
removed and rewelded. Under this code, unacceptable defects included cracks,
lack of fusion, and incomplete penetration. There was no standard for
porosity.
When the welds were examined, the laboratory performing the inspection
recommended rejection of 95% of the sampling. Most of the welds contained all
the defects listed, however, about 20% were cited principally for porosity,
undercut, and other things not specifically covered in the referenced code.
On the basis of these results and to avoid delay in construction, the Resident
Officer in Charge of Construction ordered radiographic inspection of the
welding. This resulted in repair of over 90% of the welds.
The contractor subsequently claimed that some welds were rejected that
were actually not unsatisfactory according to the specification. He also
claimed that if the inspection procedure specified had been followed, some
welds containing defects would have been accepted. The government asserted
that it had the right to extend inspection under the general provisions of the
contract and that the rejected welds all failed to show acceptable
workmanship. In the end a compromise settlement was reached, but the
contractor got the lion's share.
Solution: There is no sure way to avoid all the pitfalls which are inherent
in design and construction. It helps to know the content of referenced
material particularly for important, unusual, or complex construction. It
is, of course, necessary to thoroughly check the plans and specifications and
consider the possible need for a constructibility review. Also think about
the things that you do not want as well as those that you intend to have in
the finished product, and how a third party would evaluate the construction
against the contract documents. Always make sure that the acceptance criteria
is clear.
41
|
 
|
|
|
||
