American Petroleum Institute

Specification for Drilling and Production Hoisting Equipment - Thirteenth Edition
 N SPEC 8A ADD 1

Annotation

1 Scope

1.1 DESIGN RATING BASIS

This specification provides a basis for establishing the ratings of main load carrying components of certain hoisting equipment used in drilling and production operations as follows:

1.1.1 Maximum Load Rating

This is a calculated maximum load rating using a prescribed design safety factor on the minimum yield strength of the material used in the equipment. This load rating is not intended to fix the expected service life other than by providing a reasonable margin of safety against failure.

CAUTION: The terms safety factor or design safety factor are intended as design criteria and should not under any circumstances be construed as allowing loads in excess of the maximum load rating as established under this specification.

1.1.2 Bearing Load Rating

This is a calculated maximum load main-bearing rating for traveling blocks, and swivels. This bearing rating is intended primarily to achieve consistency of ratings, but is also intended to provide a reasonable service life for such main bearings when used at loads within the equipment rating.

1.1.3 Design Criteria

This specification provides for a method of rating main load carrying components of certain hoisting equipment used in drilling and production operations, predicated on normal field loading in which the following conditions are assumed to exist:

a. The maximum load rating includes all static loads encountered in the operation of the equipment. It should be recognized that dynamic loads exist and if the combined static and dynamic loads exceed the maximum safe working load, the safety factor will be reduced accordingly.