make-and-break cycles with no loss of seal integrity
250 °C
temperature resistance of the polymer ring
15,000 psi
maximum working pressure
The problem
The weak point of a tubing string is the thread connection
It is inside the coupling that internal coating breaks off, while the gap at the pipe ends becomes a hotspot of corrosion and failure. Conventional solutions address the problem only partially:
Uneven coating
Epoxy coating is thinner on thread crests and thicker in the roots. Make-up creates local overloads and chipping.
Micro-cracks during make-up
Thread stresses are uneven. Micro-cracks appear and let the corrosive fluid in.
Rapid coating failure
After 3–6 make-and-break cycles the coating breaks down. Bare steel becomes a site of intense corrosion.
Poor J-area protection
The most vulnerable spot is the pipe end. The coating chips and peels, leaving the metal exposed.
Seal extrusion
Ordinary seal rings are extruded by pressure during make-up and do not perform under load.
No make-up torque control
There is no mechanism to control make-up depth and prevent over-torque.
The solution
A polymer ring that closes the gap
M2® is a modification of a standard API / GOST coupling: a barrier polymer ring with tapered edges is installed in its middle section. During make-up the first thread turns cut into the polymer — the connection is sealed and the vulnerable J-area is fully covered.
Asymmetric polymer ring
The special ring geometry compensates for thread tolerances — deviations within GOST and API limits.
J-area protection
Physically covers the pipe end where mill coating typically breaks off. Creates a reliable barrier.
Controlled deformation
The ring deforms within 15–18 % — inside the polymer elasticity range. It fills every micro-gap in the thread.
Load damping
Smooths out the gaps that appear under string tension and cyclic loads.
Repeated make-and-break
8–10+ cycles guaranteed with no loss of seal integrity. Ideal for workover stock.
Make-up torque control
Once optimal deformation is reached, the ring builds up resistance — helping avoid over-torque.
How it works
The M2® ring in operation
01
Tolerance compensation
The asymmetric ring shape distributes load evenly even with thread deviations within GOST and API limits.
02
Gap filling
During make-up the polymer plastically fills every micro-gap in the thread, creating a labyrinth seal.
03
J-area protection
The ring fully covers the pipe end, protecting the most vulnerable spot of the connection from corrosion.
04
Controlled deformation
Deformation is limited to 15–18 % — the ring acts as an elastic damper, not a rigid stop.
05
Dynamic load damping
Under string tension and vibration the polymer compensates micro-movements, preserving the seal.
06
Torque feedback
As the ring deforms, make-up becomes noticeably harder — a natural indicator of correct torque.
Specifications
M2® connection data
Seal material
PTFE / PE-UHMW / PEEK (selected for the well fluid)
Make-and-break cycles
8–10+ with no loss of seal integrity
Operating temperature
−40 °C to +150 °C (short-term up to +180 °C)
Maximum pressure
up to 10,000–15,000 psi
Compatible tubing sizes
2⅜", 2⅞", 3½", 4½" (API 5CT)
Thread type
API 8rd EUE / BTC and analogues, 8–10-turn GOST threads
Controlled ring deformation
15–18 % (within polymer elasticity)
J-area protection
Full coverage of the pipe end
Applicability
External-upset tubing, including internally coated and lined pipe
Benefits
What the operator gains
8–10+ make-and-break cycles
Significantly more than standard coated couplings. More well interventions without replacing the tubing string — ideal for workover operations.
Reliable J-area protection
Physical coverage of the connection’s most vulnerable spot. Corrosion does not start at the pipe end.
Tolerance compensation
Asymmetric geometry and polymer plasticity level out API and GOST thread imperfections.
Load resistance
Damps vibration and cyclic loads. Reduces the risk of thread fatigue failure.
Easy adoption
No changes to processes, equipment or crew skills. Runs like a regular coupling.
Lower OPEX
Fewer tubing replacements, fewer emergency workovers, longer run life. Effective with CO₂, H₂S and high salinity.
Comparison
M2® vs standard solutions
Parameter
Standard coupling
M2® coupling
Repeated make-and-break
3–6 cycles
8–10+ cycles
J-area protection
Poor — coating chips and fails
Full — the ring covers the pipe end
Thread tolerance compensation
Low
High — asymmetric ring
Gap filling under load
None
Effective — damping action
Make-up torque control
None
Natural torque feedback
Corrosive environments
Limited
High resistance
Ring materials
Three materials to match well conditions
The seal ring material is selected for the transported fluid, temperature and pressure of the specific well.
PE-UHMW
up to 90 °C
Ultra-high-molecular-weight polyethylene
An engineering thermoplastic for extreme service. Self-lubricating material with extremely low moisture absorption.
high resistance to aggressive chemicals
15× more abrasion-resistant than carbon steel
high impact toughness and strength
very low friction coefficient
PTFE
up to 260 °C
Polytetrafluoroethylene
A fluoropolymer with outstanding chemical resistance, including oxidizing acids. The primary material of the M2® connection.
extremely high chemical resistance
high thermal stability
flame-resistant, self-extinguishing compound
no stress cracking under load
PEEK
gas wells
Polyetheretherketone
Protection technology for gas wells: the PEEK ring prevents PTFE ring movement at high temperatures and during rapid gas bleed-off.
for wells with elevated bottomhole pressure
high-temperature service
eliminates the need for drift runs
suitable for internally coated pipe
Applications
Where M2® delivers the most
Workover stock and well intervention
More operations without replacing the tubing string — 8–10+ make-and-break cycles.
Challenging wells
High water cut, CO₂ and H₂S presence. Effective protection in corrosive environments.
Mature fields
Frequent workovers and re-makes. Substantially lower pipe replacement costs.
Injection wells
Corrosion protection when injecting produced water, CO₂ and aggressive agents.
Price / performance balance
For operators unwilling to pay premium-connection prices yet wanting more than a standard coating.
High downtime-cost assets
Where minimizing tubing replacements and unplanned workovers is critical.
Track record
Field results
M2® performance is proven by operation on real assets in corrosive environments.
Karasu Operating Company
Mishovdag field, Azerbaijan
delivery — October 2019
PE-UHMW seal ring. Positive results on producing assets; performance in corrosive environments confirmed.
Azneft / SOCAR
Bibi-Heybat field, Azerbaijan
delivery — February 2017
PTFE seal ring for service under extreme chemical exposure.
RN-Vankor (Rosneft)
Pilot field trials
ongoing
Pilot field trials are underway. First results confirm the efficiency of the connection.
Next generation
M2® Smart Connect
In development
We are developing a next-generation coupling — a high-integrity tubing connection with digital identification. An RFID tag records the full lifecycle of the coupling and pipe, while the digital passport feeds data into ERP, maintenance and AI systems.
combined ring made of corrosion-resistant alloy (CRA)
