Drilling Lines
Drilling Lines(extract)
Recommended Handling Procedures
This section provides recommendations and information on the correct installation and handling of Drilling Lines, to ensure optimum working lives are achieved.
In general all reputable Wire rope producers now manufacture Drilling-Lines to very precise regulations and within high quality control procedures.
As a result of this, it is a proven fact that the majority of unnecessary drilling line wear, damage and premature discard problems arise from incorrect handling and treatment of the rope in service.
With the Drilling Lines now becoming much larger in diameter and often longer in length, making them significantly heavier, the potential for damage is proportionally greater. Therefore it becomes increasingly essential that these ropes are handled
correctly in order to operate safely and optimise the rope working life.
Rope Storage
Unwrap and examine the rope immediately after delivery to site, (whether it’s at the on-shore base warehouse, or out on the rig) to confirm everything is in order.
Select a clean and well ventilated, dry location for storage, where it is not likely to be affected by chemical fumes, steam of corrosive agents.
Mount the reel on timbers or suitable frame to ensure that the rope does not make direct contact with the ground and if stored for extended periods of time ensure the reel in rotated periodically to prevent the migration of lubricants from the rope.
Installation
Prior to installation of the rope (drill-line), ensure that:
A. The drill-line storage reel is properly mounted and free to rotate.
B. The reel is correctly positioned, so that the drill-line will spool off correctly, in the same direction the fast-line will spool onto the draw-work’s drum, i.e. Over-wind to overwind, or under-wind to under-wind.
C. Prior to reeving the drill-line, the following components and equipment must be inspected, to ensure they are compatible with and won’t damage the new drill-line that is to be installed.
i), All sheave groove root profiles are to be gauged, to ensure that they are within acceptable tolerances (as per pictures left). Ideally the groove profile should measure 7.5% above the nominal diameter of the rope.
ii), All sheave grooves are to be checked thoroughly, to ensure that there are no
rope (drill-line) tread wear patterns, indentations or scoring in them.
iii), All sheave bearings must be checked for adjustment, so they are free to rotate efficiently and with the minimum of tractive effort.
Check to ensure that there is no excessive side-movement,
(wobble) which would cause sheave groove enlargement
and the accompanying premature sheave bearing failure,
and undoubtedly contribute to premature drill-line discard.
D. The Travelling Block should be positioned so it is aligned as well as possible with the Crown Cluster Block’s sheaves. It should also be “hung off” and secured to prevent movement, which is essential to ensure that no turn is induced in the rope during installation. On most operational rigs, the travelling-block is hung-off in the derrick , still attached to its guide dolly, so the sheave alignment of both
blocks will be good.
E. The Draw-works drum and it’s flanges need to be inspected to make sure all grooves are in good condition and that they are still compatible with the drill-line size.
(Note: The groove radius and pitch should be checked and measured prior to ordering the new line and the details advised to the rope supplier, to ensure the rope supplied is suitable for the system).
F. The drum flanges, wear and kick-plates should be checked to ensure they are in good condition. (As damage and adverse wear to them can damage the drill-line).
G. The Travelling block must be hung off and secured to prevent movement whilst the new Drill line is being reeved. If any component in the reeving configuration is worn, or damaged, to the extent where it might damage the drill-line, then it should be repaired in situ or changed out prior to reeving the new drill-line.
To leave it in this condition and continue operating, will not only cause premature drill-line discard, but also constitute an unsafe working operation.
Rope Installation
Installation of the new drilling Line is usually undertaken by pulling it through the reeve-up system with the old rope. API 9A, recommends that the two ropes be connected by means of what they call a “swivel stringing grip”, (which is also known as a snake, a Chinese finger, or a sock). This can be a satisfactory procedure with the smaller drill-lines with minimum number of falls. But preferably without a swivel in the reeving hook-up.
(A swivel should never ever be used with Flattened Strand or any
other Langs Lay rope.)
In the case of the much larger diameter drilling lines and multi-fall systems, where the tensions in reeving are much higher, then the use of a stringing grip, or similar, is not a practical or safe way to proceed. The common practice is to directly connect one line to the other. (Splicing is the preferred and safest method).
The prime objective during reeving of the new line is to ensure that no turn is introduced into the new line, either from the old line or by the system.
The possible imposition of rope turn can be checked by attaching a flag or marker at the connection point of the new drill-line and then observed during installation. If any twist is seen to be induced into the rope, then this should be let out before the rope is attached to the drawworks.
Ideally the rope should then be wound onto the Draw-work’s drum at the recommended minimum required fast-line tension , possibly by using a pinch-roller type drill-line tensioner. This rope tension should be applied until the drill-line has the weight of the travelling assembly on it.
The manufacturers recommended minimum number of dead wraps on the Drawworks drum, should where possible be complied with, as any additional or an excessive number of dead wraps, especially any wraps without sufficient tension on them, could lead to rope slackness on the drum with probable
rope crushing damage.
On Rigs with Crown Mounted Compensators, it is recommended that the cylinders be extended, prior to winding the line on to the draw-work’s drum. This ensures that the excessive amount of drill-line that is required for CMC operation when the cylinders are extended, is taken up in the falls between the crown and travelling
blocks as the drill-line is wound onto the drum under tension.
On some draw-works the fast-line’s exit-hole through the drum flange to the clamp may not allow the rope to enter if it has been served (seized). In such a case it is essential to fuse all the wires and strands at the rope end, by weld, to ensure that nothing moves when the serving (seizings) are removed.
Once installed, the rope system should then be lifted and lowered under average working tensions for several cycles, until the rope has bedded in.
Slipping and Cutting
It is essential that before the rope is cut it is securely bound, on both sides of the cut. Failure to properly bind the rope will allow relative movement of the components of the rope – wires and strand – which can cause constructional unbalance and subsequent distortion of the rope in the working rope system.
Distortions or disturbance of the strands within the rope, will result in uneven distribution of the load applied and also surface wear. A condition, that will effect the working life of the rope.
The binding/seizing itself should be of soft or annealed wire or strand (of approximately 0.125” in diameter), wound tightly around the rope at both sides of the cutting position, using a ‘Serving Mallet’ or a ‘Marlin Spike’.
Alternatively a clamp of suitable design, such as a spare drawwork’s drum anchor clamp is ideal for serving (seizing) the drillline prior to cutting and fusing it
For conventional 6 strand preformed ropes the serving (seizing) length, should be no less than twice the diameter of the rope being cut. However in Triangular (Flattened) Strand or other Langs Lay ropes, then two servings (seizings) on either side of the cut would be preferred.
The calculated length of rope to be slipped is critical to ensure that the rope is subject to even wear as the rope progresses through the reeving system. Therefore this length must be measured as accurately as possible, to avoid the rope being
positioned at repeat critical wear positions in the system.
An inaccurate measurement and cut of say half of a single drum wrap, could cause a slip and cut to be inaccurate enough to cause critical wear-spots to move to repeat positions during the slip and cut.
It is of course of paramount importance, after the slip and cut is completed, that the drill-line is wound onto the drawworks at the recommended tension using a pinch-roller type drill-line tensioner until the weight of the travelling assembly is on the drill-line.
One Important Thing To Remember
The main issue that normally dictates/necessitates the need for drill-line handling, whether it’s to do a slip and cut, or to change out a complete drill-line, is the actual rope condition in terms of wear and damage.
Ton.Miles is a conventional method, based upon experience, of calculating the amount of work done by the rope and to then determine the service life of the rope through a slip and cut programme. However it must be emphasised that Ton.Miles is a general guide only and should not be used as the sole criteria for assessing the rope condition, as continual visual monitoring is also essential.
If the visual condition of the drill-line, indicates that the drill-line is showing excess wear and/or damage, or is encroaching on, equal to, or exceeding that described as discard criteria according to ISO 4309, then it should take precedence over
Ton.Mileage as the discard criteria.
Failure to slip and cut, if this sort of excessive drill-line wear occurs, ahead of the scheduled ton-mileage slip and cut, normally results in extremely long slip and cuts in the future and probably an unsafe working condition.
It should be noted, If the rope regularly appears in good condition at the programmed time for slip and cut, and that this good condition can be further confirmed by the Manufacturer, then the Ton.Mile Slip and Cut programme may be extended to increase the rope’s service life.
The above recommendations are offered as a guidance to the handling of Drilling Lines during installation and service. It is essential that the Drilling Line is at all times correctly handled, inspected and slipped through the system, to ensure a safe working operation and an optimum working rope life.
