scope:

ASTM specification A802, together with Adjunct No. 12-108020-02, provides sets of graded reference photographs and descriptions from which purchasers and suppliers may, by mutual agreement, select visual examination standards of surface acceptability. The specification requires the inquiry or order to indicate acceptable limits.

The SCRATA comparators are plastic replicas of actual casting surfaces, each of which is also represented by photograph. The standard suggests designating acceptance criteria on drawings.

MSS SP-55 acceptance criteria have been reviewed against the ASTM and SCRATA standards in order to designate the acceptance criteria of each type which are equivalent to SP-55 acceptance criteria. Comparisons published in this Annex represent MSS interpretation. They are intended to be of assistance to those interpreting the ASTM and SCRATA standards.

PURPOSE

Other societies have published standards illustrating various levels of surface texture and irregularities classified by type. The two standards discussed in this Annex do not identify specific levels as being acceptable, leaving the issue to the product specification or contract.

This Annex has been included for the purpose of showing MSS interpretation as to the levels of discontinuity by type which would be met by castings conforming to SP-55.