Connecting Assembly, SK type

Connecting assembly of SK type is applied in tool assemblies when performing works using coil tubing (CT) in tubing strings with a diameter of 73÷89 mm.

CA connecting assembly consists of the four units:

I – circulation diaphragm valve is designed to provide fluid circulation when pulling the downhole equipment as well as for emergency depressurization in CT, if necessary.

II – emergency disconnector is designed to release CT from the downhole equipment or object being pulled if the force generated by the injector is insufficient for releasing of stuck pipes.

III – back-pressure clappet valve is designed to prevent reverse fluid flowing in CT.

IV – connecting crossover is designed to connect CT with connecting assembly. Connecting assembly set may also include a matrix of MGT 38 type designed to prepare CT for connection with SK–54 case.

The connecting assemblies manufactured have 45 and 54 mm nominal diameters.

Basic parameters and dimensions:

Parameter Value
SK–45 SK-54
Rated string size, tubing string, mm 60; 73; 89 73; 89
Coil tubing nominal diameter, mm 38.1
Working pressure, MPa 10
Shear pressure of pins after positioning the ball in the seat of the disconnected section or circulation valve seat, MPa, not greater than 15
Diaphragm fracture pressure (unit I), MPa, not greater than:

– inner choke No. 1 (with one screwdriver slot) o11 mm

– inner choke No. 2 (with two screwdriver slots) o10.5 mm



Bore minimum diameter, mm, not less than 12 15
Connecting assembly length, mm, not greater than 1,015 1,210
Outer diameter, mm 45 54
Weight, kg, not greater than 10 13.8
Working fluid Drilling fluid, oil, water
Fluid temperature, °С, not greater than 100
Connecting thread dimensions as per GOST 24705-81, 8724-81, 9150-81 М х 42 М х 42
Posted in Wireline and coiled tubing downhole tools.