Make-Up

Key Takeaways

• API make-up torque specifications for drill pipe, casing, and tubing connections are determined by the thread geometry (taper, pitch, thread form, and number of threads per inch), the pipe body and connection dimensions (OD, wall thickness, and connection OD), and the material yield strength of the pipe, with the minimum, optimum, and maximum torque values calculated to ensure that the connection is tight enough to prevent back-off but not so tight that the threads yield: API Recommended Practice 5C1 (for casing and tubing) and API RP 7G (for drill pipe) provide the standard make-up torque tables for each connection type and pipe weight, with the optimal (target) torque approximately 50 to 75 percent of the theoretical yield torque for standard API connections; premium connections (non-API, proprietary designs from companies including VAM, Tenaris, and Hunting Energy) have their own manufacturer-specified torque requirements that must be used instead of API tables, with the premium thread designs providing higher tensile capacity, gas-tight metal-to-metal seals, and resistance to cross-threading and galling that exceed the capabilities of standard API connections in demanding well environments.
• Thread compound application before make-up is mandatory for all threaded tubular connections in oilfield use, serving as both a lubricant (reducing friction during the make-up rotation so that the applied torque accurately represents the clamping force rather than being partially lost to thread friction) and a sealant (filling microscopic surface irregularities in the thread flanks to prevent gas or fluid leakage through the helical leak path of the connection): API modified thread compounds (approved to API Bulletin 5A2) are lead-free, petroleum-based greases with metallic filler particles (zinc, copper, or tin) that provide both lubrication and gap filling, applied to the pin threads (and optionally the box threads) at the rig floor before make-up; the amount of thread compound applied affects the make-up torque achieved for a given number of turns (insufficient compound increases friction and causes premature torque response before the connection is fully engaged; excessive compound can hydraulically prevent full engagement and trap fluid that is expelled when the connection is pressurized); thread compound selection for sour service (H2S environments) requires verification that the compound does not contain sulfur-bearing additives that could contribute to sulfide stress cracking of the high-strength connection steel.
• Power tong make-up equipment used on the rig floor applies make-up torque to the connection being assembled, using either manual tongs (hydraulic or pneumatic wrenches that grip the pipe body and apply rotational torque through a reaction post on the rig floor) or the iron roughneck (an automated hydraulic unit that combines a spinning wrench for rapid initial turn-up and a torque wrench for precise final torquing to the specified target torque); the make-up torque and turns-to-makeup are recorded by a torque monitoring system (tong gauge, electronic torque sensor, or integrated iron roughneck control system) that generates a torque-turn graph for each connection, showing the torque achieved as a function of the number of turns from initial thread engagement; the shape of the torque-turn curve is a quality indicator for the connection: a smooth, continuously increasing curve indicates proper thread engagement without cross-threading, while an irregular curve with sudden torque spikes or drops indicates damaged threads, inadequate thread compound, or cross-threading that requires breaking out and reinspecting the connection before re-making.
• Casing make-up on the rig requires careful management of connection quality because casing connections in the wellbore are subjected to large tensile loads (from the weight of the casing string in tension), burst loads (from internal pressure during cementing, production, or well control events), and collapse loads (from external mud weight or formation pressure), and a connection that is improperly made up may fail under these loads in the wellbore where remediation is extremely costly: power tong make-up of casing connections at the rig uses a backup tong (anchored to the rig floor through a safety line) and a makeup tong that applies torque to the pin body, with the turns and torque monitored continuously; the standard quality assurance practice for casing make-up includes a thread inspection (visual inspection and ring gauge measurement of the connection geometry before make-up), a thread compound application inspection (confirming that compound covers the full thread length), a torque-turn record for each joint (confirming that the target torque was achieved and that the torque-turn curve shape was normal), and a post-makeup thread count verification (counting the make-up length from the coupling face to the pipe body shoulder to confirm that the specified engagement has been achieved).
• Make-up problems and defects that require immediate remediation include cross-threading (the pin thread starts engagement at an incorrect angle, crossing rather than following the thread helix, producing a high early torque response and visible thread damage when the connection is broken out), galling (metallic adhesion of the contacting thread surfaces due to insufficient lubrication or excessive surface roughness, causing torn metal rather than smooth thread sliding and permanently damaging one or both thread surfaces), incorrect final make-up position (too few or too many turns, indicating either a damaged connection, wrong compound application, or measurement error), and visible connection damage (chipped, cracked, or bent threads identified during inspection before make-up that should have prevented the connection from being made up at all); the decision to break out and re-make a connection versus accepting a questionable torque-turn record requires judgment about the probability that the connection will perform satisfactorily in the wellbore under the loads it will experience, and the cost of a dropped string or leaking connection if the judgment is wrong.