When measuring a manhole seat with a feeler gauge, what is the maximum taper allowed?

The maximum taper allowed when measuring a manhole seat with a feeler gauge is .012. This specification is essential because it ensures a proper sealing surface for the gasket, which must be maintained to prevent leakage. If the taper exceeds this limit, it could lead to improper sealing, resulting in operational issues and potential safety hazards.

In the context of machinery maintenance and operation, a tight and flat seating surface for manholes is critical to maintain system integrity and efficiency. Each of the other measurements represents a greater tolerance for taper, which does not align with the established guidelines that prioritize a tighter fit to ensure adequate sealing performance. The .012 taper provides a balance between manufacturability and operational reliability within the engineering design standards.