Tubing Specifications

EU (external upset) tubing

Since it is always the tubing string in which slickline operations are carried out, it is necessary for the slickline operator to understand the specifications and tubing product options.

Size

Generally identified by the outside diameter of the tube (the nominal description size). The internal diameter of the tubing is generally approximate or rounded up to the nearest full size.

Grade

The tubing grade indicates the strength and type of steel used to make the tubing. It is specified by a letter and number, e.g., H-40, J-55, C-75, L-80, N-80 or P-105. The lower the number, the softer the steel. The number signifies the tensile strength in 1000 psi, i.e., N-80 with a cross-sectional area of one square inch will withstand a load of 80,000 lb.

Weight per Foot

Determines the wall thickness of the tubing. Since the OD is determined by the nominal tubing size, i.e., thicker wall reduces the ID in heavy weight tubing.

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Drift

The drift diameter is a means of ensuring the quality control on the tubing ID. The process involves passing a precisely machined bar through the tubing joint or string. All tubing and completion components run in the well must be drifted.

Threads

Common thread types include:

EU = External upset tubing joints incorporate a collar and an internal recess.

NU = Non-upset, but otherwise same as the EU.

VAM = A premium type thread seal with a collar and no internal recess.

Hydril CS = A premium connection with no collar and incorporating a metal-to-metal, three point seal system and no internal recess.

The following table shows a summary of the common tubing sizes:

Common Tubing Sizes and Drift Diameters