Wireline Tensile Strength & Ductility Tester Why is The Ductility Wireline Important • We all know that strength of individual strands are important, we calculate our Cable Head strength from that number. But when we pull on that Cable Head or we pump against that head how do we know what the condition of the head is then. We have all seen Cable Heads that were reheaded to a certain weight and when worked for a short time, come apart at a considerably lesser amount. Also we have reheaded other lines, gotten stuck, and worked the line for an equal length of time and pulled out at what we built the head for. Why? ( next page) (continued) • In most cases it is because of fatigue of the wire. Many of you that own or have used a Cable Head Testing Machine have noticed that when using the Strand Tester on the machine a new . 040 wire strand (sweet line) will lose about 8% of its strength when bent over a cone radius. Older wire can exceed 20% when bent over that same radius. This decline is an indirect function of the lines ductility if the strand remains the same diameter. What is needed is a machine that delivers data that is a direct function of ductility. Description of the Wireline Tensile Strength and Ductility Tester • The previous page show a “T S & D” Tester. It measures 15” long and 2” in diameter. It tests 12” of line between its two wire clamps. On each end are the wire clamps. From left to right the first device is the Rotating Wire Clamp. Next is the Tension Sleeve. Next is the Threaded Union. It is attached to the Pressure Cylinder. On the inside of the Pressure Cylinder is a piston and mandrel. ( the mandrel is bored to allow wire to be placed through it) On the end of the Mandrel is the Non Rotating Wire Clamp. (next page) (continued) • Above the main body of the Tester, from left to right, is The Pressure Transmitter. (This Transmitter is Optional.) Next is the Gauge. The gauge can be 0-600 PSI/lbs as shown or it can be larger or smaller. As shown, this machine is rated to 1500 PSI/ lbs because of the wire clamps. When pulling wire that exceeds 750 lbs an auxiliary hydraulic cylinder pump can be added as shown on the 4th photo. Operation • The previous photo shows a couple of tools that come with the T S & D Tester. The device is best secured in a pipe vise but will work fine in a jaw vise. A strand of wireline is inserted through the Rotating Wire Clamp, through the mandrel bore and clamped in the Non Rotating Wire Clamp. To test the tensile strength of the wire the lever handle (shown on the left side of the photo) is attached to the Rotating Wire Clamp. The Dow Pin Socket Wrench is inserted into one of the multiple bores in the Tension Sleeve. While holding the Rotating Wire Clamp in place the Tension Sleeve is Rotated causing the wire to tighten and pressure to build until the wire fails. Note the pressure and insert (next page) (continued) • another length of the same line and clamp in like manner. Rotate the Tension Sleeve until the pressure / lbs is within 80% of the breaking point of the previous wire piece. Next, Rotate the Rotating Wire Clamp slowly while counting the revolutions until the wire breaks or it reaches 20 turns. If the wire reaches 20 turns rotate the Tension Sleeve until the wire parts. An improved plow steel wire that reaches 20 turns and has to be broken by hydraulic force is considered in excellent shape and will fatigue very slowly. An example of excellent line and poor line is shown in graph form in the graphs at the end of this presentation. The “poor line passed the bend test and made 10 wraps around it’s own diameter before breaking. The difference between this line’s straight line breaking strength and bent over a cone radius was 20%.
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