It is a fast Mechanical Interference Fit (MIF) connection that doesn’t require welding, increase his productivity, reduces hazard and risk and reduces project costs for carbon steel pipeline construction.

A Mechanical Interference Fitting connection is a strong and reliable system that derives from relying on radial compressive elastic and plastic residual stresses and surface friction properties of steel. This is caused by inserting an oversized male carbon steel tube (the “Pin”) into an undersized female carbon steel tube (the “Bell”).

For carbon steel pipeline projects typically associated with hydrocarbon field development, gathering systems and transport pipelines. Put simply it’s good for Oil, Gas and Water high pressure production and water injection pipelines

The Stealth-Lock™ MIF system is applied on API 5L Carbon Steel Line Pipe (or international equivalent specifications). It is compliant to ISO 21329 (International standard governing mechanical connectors).

Our Stealth-Lock™ Hydraulic equipment is designed and manufactured in four different size ranges that cover diameters as low as Nominal Pipe Size (NPS) 2-inches all the way up to NPS 16-inches. The equipment spread models are:
• SL26 (2 to 6-inches diameter)
• SL28 (2 to 8-inches diameter)
• SL410 SL26 (4 to 10-inches diameter)
• SL SL1016 (10 to 16-inches diameter)

Typical applications range from API 5L Grade B through X42, X52, X65 but depending on diameter and wall thicknesses (WT), higher grades of carbon steel pipes can be applied with Stealth-Lock™. The pipe wall thickness we typically quote “from schedule 40 to schedule 80” but again, depending on diameters and pipe grades these parameters can be less than schedule 40 and greater than schedule 80.

Typically, we will be supplied with “free issue” pipes from the client. We refer to the first process as “prepping”. This is where we will clamp one end of each pipe and insert a mandrel to expand that pipe and create “the Bell”. At the other end of the pipe we will either trim a taper or mechanically swage the pipe to form what we call. “the Pin”.

After prepping, the pipes will either be sent for coating applications or as bare pipes directly to the project location. At site, we will utilize our SL Assembly machine and hydraulic power unit to mechanically grip the mating pipes and force fit them together.

Typically, Stealth-Lock™ installation crews can achieve up to 2 km per day onshore. Faster/slower productivity also depends on usual site conditions such as; congestion, topography, and terrain. If you take a typical 6 inch flowline project, in open virgin territory with few obstacles, we would expect to be above 2 km in one 10 hours dayshift. Depending on individual pipe length, we would expect a typical Welding crew to deliver 180 m to 200 m of connected pipeline in the same dayshift.

Stealth-Lock™ performs very well in sour service conditions when applied with internal (ID) coatings such as Fusion Bonded Epoxy (FBE). The technology is also approved for application together with polyethylene (PE) liners, in both tight and loose liner categories. Because FBE is applied after prepping the pipes, Stealth-Lock™ has engineered a special application process for the coating applicator and this results in a holiday free interlocking connection without the need for expensive circumferential Welding sleeves.

Again, as with the ID, the system performs very well with external (OD) coatings such as FBE. Where thicker corrosion or sacrificial barriers are required, the system works very well with, 3-layer polypropylene (3LPP) coated pipes. 3LPP is usually applied in oil fields where the resources are drawn from deep reservoirs and at high temperatures (100°C to 140°C). It is highly abrasion resistant and is generally used where the chances of damage are high such as rocky terrain.

No. For engineering design with corrosion barriers Stealth-Lock™ can be considered as the same or better performance as a welded connection.

Yes. High confidence and pipeline integrity is at the vanguard of our Stealth-Lock™ MIF system. Since 2010, we have worked with independent research and testing laboratories such as Stress Engineering Services based in Houston, Texas. A well renowned leader in mechanical testing of force, load, tension, pressure, fatigue and temperature. Our R&D engineers have worked alongside Stress Engineering in a combined effort to maximise and validate the performance envelopes of the Stealth-Lock™ technology. Stress Engineering test results are completely independent, objective, and trusted by all major oil and gas client operators, worldwide.

In addition to Stress Engineering, we also rely upon specialist expertise that sits with Southwest Research Institute (SwRI), headquartered in San Antonio, Texas. We also credit our Global Value Chain partner; Tenaris (the world’s largest tubular goods manufacturer) who has independently verified Stealth-Lock™ for its application with Tenaris pipes across Latin America to hydrocarbon operators from Argentina to Mexico.

Since 2010, and navigating through many validation and qualification projects for different client operators, the system has been repeatedly independently validated based on the following typical standards and specifications:

• Installation Tests ISO 21329
• Operational Restrained & Unrestrained Tests ISO 21329
• Hydrostatic Pressure Tests ISO 21329
• Limit Load Tests ISO 21329
• Fatigue Tests. BS7608 and DNV C203
• Pressure, Axial Load, Bending ISO 13679:2002(E)
• Electrochemical Impedance Spectroscopy Test (EIS)
• Tensile, Charpy & Hardness Tests API 5L and ISO 3183
• Sulphide Stress Cracking (SSC) NACE TM0177

On occasions since 2010, third-party evaluation validation and reporting has resulted in a high level of confidence for Stealth-Lock™ MIF as being a reliable alternative to standard welded connections across the diameter ranges. Furthermore, Integrity performance as often outperformed welded connections and the generic conclusions of all third-party testing are as follows:

From the testing performed, we can conclude:
• No permanent plastic deformations are done during joining. Once the ends are conformed in the mill, the connection works always in the elastic range.
• The Stealth Lock connection passed satisfactory all the testing done under ISO 21329, that represent conditions that are more severe than the ones found on the field.
• It was proved that structural and seal ability resistance is maintained even under extreme doglegs (up to 79°/100ft).
• In the operational loads, the connection proved its gas seal ability (N2) both on restrained and unrestrained tests.
• In the limit load tests, the connection always failed at values beyond the pipe’s yielding point, withstanding loads that by design the pipe should never be exposed to.
• Tests performed at low temperatures were useful to guarantee

From the analysis performed, we can conclude:
• During assembly, no permanent plastic deformations are generated. Once the ends have been shaped in the mill, the joint will always behave in the elastic range.
• The Stealth Lock connection successfully passed all tests carried out under the guidelines of ISO 21329, which represent more severe loading conditions than those found in the field.
• It was shown that under extreme bending conditions (up to 79 ° / 30m) the joint maintained its structural strength and seal ability.
• In operating load tests, the joint demonstrated gas seal ability (N2) for both, restricted and unrestricted operations.
• In the limit load tests, the connection always failed at values higher than the yield strength of the pipe body, withstanding loads to which the pipeline should never be exposed by design.
• Low temperature tests were useful to ensure that the technology maintains its robustness and is perfectly applicable in environments that reach temperatures down to -20 °C. This is concluded since:
• In impact tests, the joint behaved in a ductile way.
• In the internal pressure tests, the joint always failed having plasticized the pipe body first.