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Tubing Handling and Running Guidelines
NOTE: The information in this section is taken from API RP
5C1,"Recommended Practice for Care and Use of Casing and Tubing", Seventeenth
Edition, November, 1994. It is intended to provide an overview of the field
handling and assembly of tubing products. Other information may be required, and
the user is advised to obtain and review a copy of RP 5C1.
The information is directed primarily at API connections, though some is
applicable to Specialty connection products. In any event, if the tubing is
equipped with Specialty connections, refer to the manufacturer's Recommended
Practice for handling and running.
I UNLOADING
Ensure that the pipe racks are level and properly positioned to allow
transfer of tubing from the rack to the catwalk.
Ensure that thread protectors are in place on all connections before
unloading tubing.
Avoid rough handling of tubing which might dent, bend, or damage in any
fashion the pipe body or connections. Mechanical damage of the pipe is
injurious, and can result in failure of the tubing in service. Particular care
must be taken when handling tubing with an internal plastic coating.
Do not unload tubing by dropping joints onto the racks or by allowing pipe
to tumble from the transport. Maintain control of the tubing at all times by
handling a small number of joints.
Do not place hooks in the ends of the tubing. Joints should be slung from
spreaders, evenly spaced along the joint.
When rolling tubing on the racks, do not allow joints to strike each
other.
Always leave thread protectors in place when the tubing is being moved.
Tubing should be placed on level tumble racks or clean metal or wooden
surfaces, free of any debris.
II PREPARATION AND INSPECTION
All tubing and accessory equipment should be visually inspected before it
is run in the hole. Where possible, the function of accessory pieces should be
confirmed before assembly.
Any joints or accessories with obvious body or connection damage should be
laid aside and not run. Any accessories which are questionable should not be
used.
The basic running order of the tubing and accessories should be determined
early, and the make/model/type of accessories verified.
The size and condition of all related handling equipment should be checked
thoroughly. Particularly, slips or tubing spiders, back-up tongs, elevators,
and power tongs.
III RIG FLOOR EQUIPMENT
While the use of slip-type elevators is preferred for any length of tubing
string, their use is strongly recommended for long or heavy strings, and for
Special Clearance and Specialty Connection equipped tubing.
Check the elevator body, latch mechanism, links, and dies and setting
plate if slip-type elevators are used. The elevators must close completely,
and the latch engage properly for safety.
If slips are used, ensure the dies are clean and sharp, and all of the
same size. Do not mix old or resharpened dies with new dies in either the
slips of the elevators.
If a tubing spider is used, ensure it does not crimp the tubing when
closed, and also that it releases completely to avoid gouging the tubing when
lowering.
Slips and elevators should be cleaned frequently during use to reduce the
risk of slippage, and to ensure their correct function.
The condition of the slip bushing must also be checked to ensure that the
slips will fit properly and engage the tubing evenly.
NOTE: Slip and tong marks are injurious, and can result in failure of the
tubing in service. Properly fitting and well maintained equipment can greatly
reduce the risk of damaging the tubing.
Check that the blocks are centered over the rotary table. If not, make the
crew aware that the misalignment can result in difficulty when stabbing and
spinning up connections.
Check the rig-in of the power tongs, making sure that the tong back-up
line is at right angles to the tongs, the tongs are level, are free to move
and are at the correct height above the floor.
Check the size and rating of the power tongs. The nominal size of the
tongs should not be more than one size larger than the tubing being run (i.e.
do not use 7" tongs to run 3-1/2" tubing) and the tongs must be able to
readily attain the expected maximum torque.
Ensure that the power tongs are equipped with an accurate and reliable
torque gauge - either electronic or hydraulic, possibly equipped with a
pressure activated dump valve.
Check the size and condition of the back-up tongs. They must be sized
properly, have clean and sharp die segments, and be in good repair to avoid
damaging the tubing. The use of pipe wrenches as back-ups is not permissible
under any circumstance. Check that the back-up tongs are level and do not
interfere with the suspension or operation of the power tongs.
IV TUBING PREPARATION
Remove pin and box protectors from tubing and accessory pieces, and
thoroughly clean the connections, removing all previously applied thread or
storage compound.
Inspect all connections, particularly noting any mechanical damage to the
threads. While minor corrosion damage is of little concern, mechanical damage
of the threads can lead to failures in service. If a connection is damaged or
questionable, it should be laid aside.
When inspecting box connections, check to see that the couplings are made
up power tight. On pup joints and accessories, the couplings may be only spun
on by hand, and may not have thread compound applied to the connection
surfaces. On round thread connections, there should be no pin threads
extending beyond the coupling face.
All tubing joints and accessory pieces should be drifted full-length with
a standard API drift mandrel, from the box end to the pin end. While it is
preferable to drift the tubing on the racks, a rabbit may be used instead as
the tubing is pulled up through the V-door.
With the thread protectors removed and the connections cleaned, tally the
tubing by measuring from the face of the coupling to the point on the pin
connection where the coupling stops when the connection is assembled power
tight. The distance from the pin nose to this point is referred to as the
"make-up loss". Alternately, the total length of the joint can be measured,
and the make-up loss subtracted from the overall length. Tallies should be
made to the nearest 0.01m.
The cleaning, inspection and tallying operations are repeated as each tier
of tubing is uncovered.
Before the tubing is moved to the catwalk, clean thread compound should be
applied, and thread protectors must be replaced. Unless specified otherwise,
API 5A2 type thread compounds should be used. Fresh compound should be used,
the applicator brush must be clean and free of any debris, compound must be
mixed well and never thinned.
Note that certain service applications (heavy oil thermal or extremely
high pressure) may require use of a different compound. In no event are rotary
shoulder (drill pipe or drill collar) compounds to be used.
When moving pipe from the racks to the catwalk, ensure that joints are not
dropped or allowed to hit against other tubing or rig equipment. Tubing should
be pulled up to the V-door with a choker, and then elevators used to pull the
tubing joint into the derrick. Thread protectors must be in place on both pin
and box connections any time the pipe or accessories are moved.
If it is impractical to replace all thread protectors, several only can be
cleaned and used repeatedly, being installed on the pipe rack and removed from
the tubing when hung in the derrick.
If a mixed string is to be run (more than one grade and/or weight), ensure
that sufficient pipe of the required type is available, and that it is laid
out on the racks so that it will be accessible when called for in the program.
V RUNNING TUBING
Once the tubing has been pulled into the derrick, the pin end thread
protector can be removed, thread compound applied (if required) and the joint
stabbed.
In stabbing the joint, lower the tubing slowly to avoid connection damage,
and ensure that the connection is aligned before starting rotation. A man on
the stabbing board can be of great assistance, particularly if any
misalignment of the blocks over the rotary exists.
Care should be taken when running tubing in stands of doubles or triples
as the pipe may bow when the connections are stabbed, resulting in
misalignment.
If the tubing does not stab correctly or jams, the pin should be picked up
from the box, both connections cleaned, inspected, and repaired (remove any
filings or wickers), thread compound re-applied, and the connection
re-stabbed.
Once the joint is stabbed, make-up can proceed, with the connection being
spun up slowly initially, ensuring that the connection is not cross-threaded
or jammed.
API Round thread connections are assembled to position; the assembly
torque values provided are representative of the torque range required to
attain the power-tight position based on nominal conditions, and must be used
only as a guide.Torque must relate to the make-up position, and as a result,
the torques used in the field for a given connection can vary from those
listed.
A suggested procedure for tubing make-up is as follows:
As the nominal power tight position for Round thread tubing connections
is two turns past the hand tight position, it is advisable to assemble a
number of connections (at least ten) from each particular manufacturer or
mill lot on location to establish the torque required to attain this
position.The torque required to attain this position may or may not be
Optimum as listed in API RP5C1, and the torque must be within the
Minimum/Maximum range.
During the initial spin up of the connections, watch for any
irregularities in the assembly (torque spikes, heat, etc.) as these may
indicate dirty connections, damaged threads, cross threading, etc., which
can compromise the connection's integrity. If the initial spin up is
erratic, the assembly should be stopped, and the connection broken out,
cleaned, and inspected. If no damage is obvious, the assembly can be
repeated, but if the initial spin up is again erratic, the connection is
suspect and should not be run.To reduce the risk of galling assembly speeds
should be kept below 25 RPM.
As the assembly progresses, watch the position of the pin member last
scratch relative to the coupling face, and monitor the torque.
The Optimum torque value suggested should provide for a complete make-up
to the power tight position under nominal conditions.
If the pin thread last scratch is buried beyond the coupling face and
Minimum torque has not been attained, the connection is suspect and should
not be run. Conversely, if at Maximum torque the pin thread last scratch is
not within two turns of the coupling face, the connection is suspect and
should not be run.
If at Optimum torque several threads are still showing, the torque
should be increased, up to Maximum, to see if the power tight position can
be attained.
Once the ten or more connections are thus assembled a representative
Optimum torque for that particular lot can be determined, and the balance of
the connections run using this Optimum value.
Suspect connections should be broken out and laid down, and not rerun
unless inspected and repaired. The mating box connection should be cleaned
and inspected for damage after break-out.
Note that when assembling the field connection, it is possible that the
mill end of the connection will make up slightly. This does not suggest that
the mill end is too loose, but rather that the field end torque applied is
more than was used to assemble the mill end.
Tubing must be lowered carefully, first to avoid shock loads to the tubing
string, but also to prevent pressure surges which may damage downhole
formations.The slips must not be set until all downward motion of the tubing
string has stopped. Great care should be exercised to ensure that the string
does not spud the bottom of the hole or any downhole equipment - the
compressive loads can cause the string to buckle and/or connections to loosen
with the subsequent risk of failure in service.
Note that often there is a predetermined running order for tubing and
related accessories - due to design criteria or downhole conditions. It is
vital that this order be followed, and in the event that a specific joint of
tubing cannot be identified with respect to its weight or grade, the joint
should not be run.
VI POSSIBLE RUNNING PROBLEMS
Some of the more common causes of problems encountered when running tubing
are:
Inadequate inspection of tubing or connections prior to running.
Improper transportation, storage, and handling practices.
Ignorance of Recommended Practices for handling and running of tubing.
Improper manufacture of accessory or repair facility produced
connections.
Use of improperly manufactured couplings for replacement parts or
additions.
Excessive spin up speeds for initial assembly.
Excessive or inadequate assembly torques applied.
Use of improper thread compound.
Use of poorly maintained equipment (slips, elevators, power tongs,
etc.).
