API RP 4G
Recommended Practice for Maintenance and Use of Drilling and Well Servicing Structures
|Publication Date:||1 January 1992|
These recommendations should be considered as supplemental to, and not as a substitute for. the manufacturer's instructions and the recommendations in the most current edition of API RP 54. Recommended Practices for Occupational Safety and Health for Oil and Gas Well Drilling and Servicing Operations.
The manufacturer has used great care in design and selection of materials for his drilling or well servicing structure. The structure should give satisfactory performance when used within the stipulated load capacities and in accordance with instructions. Every crew member should be given instructions and training in erecting, lowering, and using the structure.
The safe operation of drilling and well servicing structures depends on whether the foundation is adequate for the load imposed. The design load for foundation requirements should be the sum of the weight of the drilling or well servicing structure, the weight of the machinery and equipment on it, the maximum hook load of the structure, forces due to external guywire loading, and the maximum setback load. (See Section 7, Foundations for Portable Masts with Guylines).
In the erecting and lowering operations utilizing the rig drawworks, the slowest practical line speed should be used.
Loads due to impact, acceleration, and deceleration may be indicated by fluctuation of the weight indicator and the operator should keep the indicator readings within the name plate hook load capacity.
Some rig designs require that the mast base structure be restrained against uplift from the application of mast hook load. For the requirements of a specific rig, check the manufacturer's operating instructions.
Each part of a bolted structure is designed to carry its share of the load; therefore, parts omitted or improperly placed may contribute to the failure of the structure. In the erection of bolted structures, so far as it can be done safely, the bolts should be tightened only slightly tighter than finger-tight until the erection of the structure is completed, after which all bolts should be drawn tight This procedure permits correct alignment of the structure which will result in proper load distribution.