5.5.1
Erection equipment
Winches, gin poles and other erection equipment, together with wire ropes, shall be re-certified on a six monthly basis and visually inspected prior to use. A record shall be kept of the inspections. Ensure that the loads are within the safe working load of the slings and other equipment in use.
5.5.2
Derrick and mast inspection
Derricks and masts shall be thoroughly inspected after erection and before lowering to verify that no members are distorted and all bolts are tightly in place and equipped with suitable lock washers. This inspection should ensure that no member has been installed in a manner that will impair the safety of the derrick. Telescoping masts shall be inspected to verify that all the locking devices are in place before transferring the load from the raising system. During inspection use should be made of the 'Report of Visual Field Inspection of Derrick or Mast and Substructure' (Ref. 26).
5.5.3
Derrick loading
Eccentric loading of a derrick should be avoided. If, because of unequal settling of derrick corners, the centre of the water table when drilling with rotary tools, does not line up with the centre of the well, the condition should be corrected by inserting shims at the low corners of the derrick. A crown block shall never be shifted off centre to correct for derrick misalignment unless such movement is small and due care is taken to determine the effect it will have in reducing the safe working load of the derrick. Eccentric application of loads reduces the rating of the derrick and may ultimately result in derrick failure. To balance further derrick and mast loading, the dead line and fast line should be on opposing sides.
5.5.4
Foundations
The bearing capacity of all soils decreases as the moisture content increases. Proper drainage should be provided and the foundation inspected after heavy rains to ensure that derrick corners have not settled unequally, thereby causing the derrick to be out of plumb. Civil engineering advice should always be sought and matting or concrete pads will generally be used.
5.5.5
Masts
Written procedures shall be provided and enforced by the contractor when raising or lowering a mast. The type of weight indicator used shall indicate the correct number of lines strung to the block.
Lock pins, or other locking devices for holding the upper sections of a telescopic mast in place, shall be inspected to ensure that they are seated before any additional work on the structure if performed. Any
alteration to the securing pins or positive locking mechanisms shall be made only after authorisation by the manufacturer and application of change control procedures.
No other work should be performed underneath the derrick while it is being erected or dismantled, or under the mast while it is being raised or lowered. The cellar should be completely covered during these operations. Wells within the mast radius shall be closed-in and isolated prior to mast raising or lowering operations.
5.5.6
Guy lines
Guy lines shall be used to support the mast as recommended by the manufacturer. The strength of the guy lines and auxiliary equipment shall be in accordance with the manufacturer's specification. If guying requirements are not mentioned in the operating procedures or are not known, the mast should be guyed according to 'Specification for Drilling and Well Servicing Structures' (Ref. 27). Guy lines shall never be used for aligning the mast.
Guy lines shall never be removed during operations and shall be subjected to the same inspection procedures as other wire rope devices.
5.5.7
Escape line and slide
On each operating rig a derrickman's escape line shall be provided, with one end secured to the derrick or mast near the derrickman's platform and the other end anchored at a point one mast length away from the well bore, in a clear area, where a derrickman can make a safe landing by way of the line. (If possible the line should be strung-out into the prevailing wind).
5.5.8
Crown protection
Every rig shall have a crown-o-matic or other similar emergency stop device to prevent hoisting the travelling block against the crown block. If timber blocks are used as shock absorbing devices, ensure that they are secured in such a way that impact does not dislodge them. There exists a real hazard to the Driller from the rapid downward movement of the brake handle when the crown safety device is activated. Jumper bars to prevent drilling line from jumping out of the crown sheaves shall be installed so that no section more than 100° of arc is unprotected.
5.5.9
Deadline anchor/weight indicator
Deadline anchors for hoisting lines shall be constructed and installed (bolted/welded) such that their strength equals or exceeds the working strength of the hoisting line. Avoid systems which rely on bolts in tension, the system should be designed such that a bolt failure does not result in the anchor flying. Regular checks for cracks and significant corrosion shall be made to ascertain proper functioning and structural integrity of the equipment. Precontract and major inspections shall include detailed inspection of the anchor assembly.
Failure of the welding of the drilling deadline anchor has occurred during jarring operations. Critical welds or other securing devices shall be regularly inspected.
A weight indicator shall be installed on every drilling and workover rig and it shall be maintained such that it registers an accurate indication of the hook load suspended (within 5 per cent at maximum hook load). The weight indicator shall be checked regularly for calibration by comparing its reading with the
calculated drill pipe or tubing string weight. The load cell gap should be checked every shift. A closed load cell will not indicate additional loading.
5.5.10 Stabbing board
Prior to running casing or any other job requiring the stabbing board, it shall be inspected and tested to ensure safe operation. The following points should be checked or observed:
• a safety harness, attached to a derrick member above the stabber, shall be worn on the stabbing board at all times
• inspect hoisting system
• inspect safety stops
• check emergency brake system
• ensure no loose objects are left on the board
• never test stabbing board during other drill floor operations
• good communication (visual) is required at all times between Driller and stabber.
The stabbing board shall be regarded, for the purpose of inspection and testing, as lifting equipment. It shall be subjected to the same rigorous inspection and certification process as other hoisting equipment, with particular attention to its man riding function. Stabbing boards shall have a positive mechanical locking device in case of hoist failure. Friction devices alone are not acceptable. Stabbing boards shall be included in the rig's preventive maintenance procedures.
Controls of the stabbing board winch shall be fail-safe and of the dead-man type of action.
Any maintenance work done on the stabbing board shall be concluded by a complete system function test to verify that all controls work correctly. The function testing should be done under the permit-to-work system.
Some rigs are equipped with a so called 'cherry picker' which is a mechanised pipe handling tool. This and other types of mechanised systems shall be included in the preventive maintenance procedures and be additionally subjected to pre-job safety checks.