The ABS has issued a freely available jacking survey guide to establish minimum requirements for the inspection of rack and pinion jacking gear at Special Periodical Survey of Hull for Self-Elevating Drilling Units.
This Guide provides more details regarding the examination of open and closed type jacking systems of a Self-Elevating Drilling Units. The maintenance crew will benefit from understanding the general and design specific survey requirements for a Rack and Pinion jacking gear. This will enable better planning, execution and consistent application of the scope of surveys and inspection during Special Surveys for jacking systems.
The following requirements are to be applied to all units and jacking system designs:
Record Keeping: Number of hours and loading while jacking should be kept for review and used as a reference for the required examinations. These records should include hours jacking under preload, normal loading, pulling stuck legs and jacking in heavy weather. Verification of these records should be performed at each Annual Classification Survey.
Lube Oil Analysis: Lube oil from the gear boxes of systems that are designed as “closed systems” (i.e., planetary drive type) should be retrieved, and analyzed twice each year, as a minimum. When excessive metal content or other conditions that would indicate failure of the gearbox are found the gearbox is to be opened and examined prior to completion of the Special Survey.
Climbing pinions should be closely examined at each Special Survey, tooth profile checked and non-destructively tested as considered necessary.
Rack teeth profiles are to be examined, compared to the tolerances set by the Unit’s designer. Any out of tolerance must be corrected. Areas of the Rack to be examined should be determined from operational records but should include the areas of the leg most highly loaded during jacking operations while going on location.
Shock pads, were fitted, are to be examined, dimensions confirmed to be in accordance with the OEM specifications and found or placed in satisfactory condition.
Leg guide wear plates are to be examined and found or placed in satisfactory condition.
a) Liners are to be confirmed in place
b) Liners are to be examined for cracking or missing retaining welds
c) Liner wear is to be within the OEM’s tolerances
Note: Lower liners are to be examined while the Unit is elevated.
The jacking systems including all auxiliary equipment are to be inspected for damage, wear, or corrosion. This is to include items such as the gearbox and motors, foundations, mounting arrangements, bolting, and connection couplings. Other ancillary equipment such as operating and control, piping and wiring installations along with their supporting structure should also be included.
During any inspection lock-out, tag-out or similar isolation of the jacking system is to be carried out. This included pressure systems, electrical systems, and structural components.
Provision of Safe Access: Due to increased likelihood of survey work being carried out at height or over water, reference is made to the entire text of 1-1-5/7 of the ABS Rules for Conditions of Classification – Offshore Units and Structures (Part 1) and ABS Surveyor’s Safety. In short, ABS Surveyors will conduct surveys, provided the client’s established safety procedures are not less effective than those contained in the ABS Safety Manual and associated procedures.
Any replacement parts are to be manufactured in accordance with the ABS Rule requirements.
Click to read the guide in full: ABS-jacking-survey-guide-2016_11
