W-31-PERF ABS Perforated Standpipe Home » Products » Specification Drainage Products » Parts » W-31-PERF ABS Perforated Standpipe MIFAB® W-31-PERF, 4″ diameter with N.P.S.M. threads, perforated ABS standpipe with .40″ diameter weep holes. Catalog Catalog List Pricing Current Catalog: MPB-2024 Return to Products