THREAD GAUGING TECHNIQUES

API Tubing and Casing Threads

2014 Gagemaker, LP

Connection Thread Styles

API Tubing and Casing Tapered Threads

API Tubing and Casing Tapered Threads

Pin (External)

Coupling (Internal)

2014 Gagemaker, LP

EUE External Upset Tubing

NUE Non-Upset Tubing

BTC Buttress Casing

API Connection Names

API Tubing and Casing Tapered Threads

STC Short Thread Casing

LTC Long Thread Casing

Datum

2014 Gagemaker, LP

Purpose: Join two pieces of pipe together to produce a gas tight seal

API Specification 5B covers all Tubing and Casing dimensions

There are two types of pipe sizes

Tubing sizes: 1 4

Casing sizes: 4 20

There are two cone angles or tapers

All 8-round threads are Taper Per Foot (TPF)

Buttress sizes 4- 13 are TPF

Buttress sizes 16- 20 are 1 TPF

API Tubing and Casing Tapered Threads

What are Tubing & Casing Threads

2014 Gagemaker, LP

There are no lock washers or jam nuts on tapered threads to lock them together

The pin and box tapered threads interfere and allow them to form a seal when torqued together as the flanks of the threads compress against each other.

However, a clearance remains between the crests and roots of the threads, resulting in a helical leak path

Thread compounds or pipe dope plug up this helical path to produce a seal under high pressures

API Tubing and Casing Tapered Threads

How Threads Lock Up and Seal

2014 Gagemaker, LP

API Tubing and Casing Tapered Threads

8R Thread Form

2014 Gagemaker, LP

Datum

Pin Threads

API Tubing and Casing Tapered Threads

2014 Gagemaker, LP

Unlike straight threads where the pitch diameter is the same along the axis, a tapered thread changes in diameter along its axis.

The Datum Plane is a starting point or reference location on a part. All diameters are dimensioned at a distance from this location. Example L1, L2 & L4. Locate these on your TDWIN TAPER drawing.

Also, it is referred to as the face or end of pipe.

API Tubing and Casing Tapered Threads

What is a Datum Plane?

Please see the following pages for illustrations.

2014 Gagemaker, LP

Datum

API Tubing and Casing Tapered Threads

Datum Plane on a Pin

2014 Gagemaker, LP

API Tubing and Casing Tapered Threads

Datum Planes on a Coupling Datum A Datum B

2014 Gagemaker, LP

Request a product drawing on the threads.

Verify which thread form is required.

Request the threading insert called out on the drawing.

Request a gage Set-Up Sheet.

List all the gage serial # used to inspect the part.

Verify the ball contacts are the right size.

Set your gages to a zero value on a standard.

Now thread the part and start the inspection.

API Tubing and Casing Tapered Threads

What is the first step?

2014 Gagemaker, LP

API Tubing and Casing Tapered Threads

External Inspection

2014 Gagemaker, LP

API Tubing and Casing Tapered Threads

TDWIN TAPER Drawing- 7 LTC Pin

2014 Gagemaker, LP

Set the LG-5002 on Setting Standard* and zero the dial. After locking the bezel clamp, always double check your zero setting. Now, measure the part and compare the standard to the machined lead.

*Every different TPF requires a different lead setting standard.

Thread Lead Inspection with an LG-5002

API Tubing and Casing Tapered Threads

API Tubing and Casing Tapered Threads

The LG-5002 is used the same way on the part as on the standard. Place the fixed ball contact in the first full depth thread. Move the fixed ball back one thread and check again. Record your measurement.

Thread Lead Inspection with an LG-5002

Thread Height Inspection with a TH-3002

Set the TH-3002 on Setting Standard and tilt the base back and forth to obtain the lowest reading. After locking the bezel clamp, always double-check you zero setting. Now, measure the part and compare the standard to the machined thread groove.

API Tubing and Casing Tapered Threads

8 Round = .072125 10 Round = .05560 Buttress TPF = .0620 Buttress 1TPF = .0620

Thread Heights:

API Tubing and Casing Tapered Threads

Thread Height Inspection with a TH-3002

The TH-3002 is used the same way on the part as on the standard. Measure only within the perfect thread length. (On your thread drawing, this length dimension is called L2) Align the base parallel to the thread axis and tilt the base back and forth to obtain the lowest reading. Record your measurement.

2014 Gagemaker, LP

API Tubing and Casing Tapered Threads

Zero the dial on the first thread. Do not lock the bezel clamp! Note the radial location of the gage to the part or chuck. Move the gage up the taper 1 (8 R = 8 threads, Buttress = 5 threads). Place your index finger on top of the indicator stem to hold the ball contact into the thread groove.

Pin Taper Inspection with an ET-7000

2014 Gagemaker, LP

Pin Taper Inspection with an ET-7000

API Tubing and Casing Tapered Threads

After moving back 1 up the taper double check your radial position of the gage to the part or chuck. Failure to stay in the same radial position will induce errors caused by the thread helical path. If the gage rotated, the ball contacts will move up or down the taper. You are checking the change in diameter about a radial location or plane. On a 8R TPF connection, every 45 rotation of the gage = .00097 change in diameter.

2014 Gagemaker, LP

API Tubing and Casing Tapered Threads

MRP-2001 is set to a connection size by the use of A & B Rod Standards. The rod standards position the gage to measure the Crest Cone diameter at a known location from the datum plane or face. B standard sets the distance off the face. Hold light pressure between the shoe and wear pad and tighten both black knobs. A standard sets the crest cone diameter. Sweep the standard until the lowest indicator reading is obtained and zero the dial. Double- check the zero after locking the bezel clamp.

Pin PD Inspection with the MRP-2001 (Crest Cone Diameter Inspection)

B Standard

A Standard

2014 Gagemaker, LP

Pin PD Inspection with the MRP-2001 (Crest Cone Diameter Inspection)

API Tubing and Casing Tapered Threads

*Can preset with MIC TRAC

The MRP Shoe makes contact with the crest cone within the L2 perfect length. Gagemaker calculated the crest cone diameter from the Spec 5Bs pitch diameter. The shoe swivels so the taper tolerance will not effect the diameter reading. Using a shave gage the distance from the crest cone to the pitch diameter can be measured. As the threading insert wears the pitch diameter plane moves closer to the crest cone. The connection makes up on the thread flanks and not the crest cone.

2014 Gagemaker, LP

API Tubing and Casing Tapered Threads

Pin PD Inspection with the MRP-2001 (Crest Cone Diameter Inspection)

While holding the gage against the part face, sweep left & right to find the largest indicator value. Then, rotate the gage 90 and repeat. If the indicator value changes, this indicates Ovality or out of roundness. Take multiple readings around the part to find the largest and smallest values. Write these High and Low values down on your inspection report.

2014 Gagemaker, LP

Largest and smallest indicator readings provide the data for calculating Average Cone Diameter and Thread Ovality. They both use the same data but calculate the readings in different ways.

LARGEREADING

SMALLREADING

(Largest Diameter + Smallest Diameter) = Diameter 2 Largest Diameter - Smallest Diameter = Ovality

Largest Diameter

Smallest Diameter Ovality

+.005 -.010 .015

Largest Diameter

Smallest Diameter

Averaged Diameter

+.005 -.010 -.0025

Ovality Average Cone Diameter

Largest Diameter

Smallest Diameter Ovality

-.005 -.010 .005 Largest

Diameter Smallest Diameter Ovality

-.015 +.001 .016

Largest Diameter

Smallest Diameter

Averaged Diameter

-.005 -.010 -.0075 Largest

Diameter Smallest Diameter

Averaged Diameter

-.015 +.001 -.007

Ovality is how egg or out of round it is. Ovality is the amount of out-of-roundness in a piece of pipe or a coupling. Determining ovality requires locating the largest and the smallest diameter readings on the part and subtracting the smallest reading from the largest reading. Ovality readings are always positive (no sign attached).

What do you do with the high and low indicator values?

Average Cone Diameter is the size, it would be, if it were round. Determining the round diameter of a connector requires locating the largest and the smallest diameter readings on the part and taking the average of the two readings, as shown in the following formula:

API Tubing and Casing Tapered Threads

2014 Gagemaker, LP

LARGEREADING

SMALLREADING

Largest Diameter

Smallest Diameter

Averaged Diameter

+.005 -.010 -.0025

Largest Diameter

Smallest Diameter

Averaged Diameter

+.005 -.005 .000

Average Cone Diameter is the distance across the face of the pipe or coupling. Determining the round diameter of a connector requires locating the largest and the smallest diameter readings on the part and taking the average of these two readings.

API Tubing and Casing Tapered Threads

Average Cone Diameter

2014 Gagemaker, LP

LARGEREADING

SMALLREADING

Largest Diameter

Smallest Diameter

Total Ovality

+.005 -.010 .015

Largest Diameter

Smallest Diameter

Total Ovality

+.005 -.005 .010

Ovality is the amount of out-of-roundness in a piece of pipe or a coupling. Determining ovality requires locating the largest and the smallest diameter readings on the part and adding the smallest reading to the largest reading, as shown in the following formula. Ovality readings are always positive (no sign attached).

API Tubing and Casing Tapered Threads

Ovality

2014 Gagemaker, LP

Pin Thread Form Inspection

TP-8R Profile inspecting a pin thread. Always check the first starting thread.

When deburring the thread with a flapper wheel, burrs can be rolled into the thread groove. This will cause gauling when the connections are made up on the rig.

2014 Gagemaker, LP

API Tubing and Casing Tapered Threads

Pin Length Inspection

L2 L4

Always keep the scale parallel to the pipe axis. A digital depth gage can be used in place of a scale.

L2=Perfect thread length. Crest of thread must have a full radius top. L4=Last scratch length.

2014 Gagemaker, LP

Coupling Inspection

2014 Gagemaker, LP

Coupling Threads

API Tubing and Casing Tapered Threads

Datum A Datum B

2014 Gagemaker, LP

Request a product drawing on the threads. Verify which thread form is required. Request the threading insert called out on the drawing. Request a gage Set-Up Sheet. List all the gage serial #s used to inspect the part. Verify the ball contacts are the right size. Set your gages to a zero value on a standard. Now, thread the part and start the inspection.

What is the first step?

API Tubing and Casing Tapered Threads

2014 Gagemaker, LP

API Tubing and Casing Tapered Threads

TDWIN TAPER Drawing 7 LTC Coupling

2014 Gagemaker, LP

Set the LG-5002 on Setting Standard* and zero the dial. After locking the bezel clamp, always double-check your zero setting. Now, measure the part and compare the standard to the machined lead.

*Every TPF connection requires a different lead setting standard. We will discuss setting standard design in the next class.

Coupling Thread Lead Inspection with an LG-5002

API Tubing and Casing Tapered Threads

2014 Gagemaker, LP

LG-5002 Inspecting Coupling

Coupling Thread Lead Inspection with an LG-5002

API Tubing and Casing Tapered Threads

The LG-5002 is used the same way on the part as on the standard. Place the fixed ball contact in the first full depth thread. Move the fixed ball back one thread and check again. Record your measurement.

2014 Gagemaker, LP

Coupling Thread Height Inspection with a TH-3006

API Tubing and Casing Tapered Threads

Set the TH-3006 on Setting Standard and tilt the standard back and forth to obtain the lowest reading. After locking the bezel clamp, always double-check your zero setting. Now, measure the part and compare the standard to the machined thread groove.

Thread Heights: 8 Round = .072125, Buttress = .0620

2014 Gagemaker, LP

Coupling Thread Height Inspection with a TH-3006

API Tubing and Casing Tapered Threads

The TH-3006 is used the same way on the part as on the standard. Align the gage parallel to the thread axis and lift up and down to obtain the lowest reading. Record your measurement.

2014 Gagemaker, LP

Coupling Taper Inspection with an IT-6000

Zeroed on Coupling

API Tubing and Casing Tapered Threads

Zero the dial on the first thread. Do not lock the bezel clamp!

Note the radial location of the gage to the part or chuck. (6 or 12 oclock is best.)

Move the gage down the taper 1 (8 threads for 8R or 5 threads for Buttress).

2014 Gagemaker, LP

Inspecting Coupling

Coupling Taper Inspection with an IT-6000

API Tubing and Casing Tapered Threads

Failure to stay in the same radial position will induce errors caused by the thread helical path. If the gage rotated, the ball contacts will move up or down the taper.

After moving 1 down the taper, double-check your radial position of the gage to the part or chuck.

You are checking the change in diameter about a radial location or plane.

2014 Gagemaker, LP

MRP-2002 is set to a connection size by the use of A & B Rod Standards. The rod standards position the gage to measure the Crest Cone diameter at a known location from the datum plane or face. B standard sets the distance off the face. Hold light pressure between the shoe and wear pad and tighten both black knobs. A standard sets the crest cone diameter. Sweep the standard until the lowest indicator reading is obtained and zero the dial. Double- check the zero after locking the bezel clamp.

Coupling PD Inspection with an MRP-2002 (Crest Cone Diameter Inspection)

API Tubing and Casing Tapered Threads

B Standard

A Standard

2014 Gagemaker, LP

Inspecting Coupling

Coupling PD Inspection with a MRP-2002 (Crest Cone Diameter Inspection)

While holding the gage against the part face, sweep left & right to find the largest indicator value. Then, rotate the gage 90 and repeat. If the indicator value changes, this indicates Ovality or out of roundness. Take multiple readings around the part to find the largest and smallest values. Write these values down on your inspection report.

API Tubing and Casing Tapered Threads

2014 Gagemaker, LP

LARGEREADING

SMALLREADING

Largest and smallest indicator readings provide the data for calculating Average Cone Diameter and Thread Ovality. They both use the same data but calculate the readings in different ways.

(Largest Diameter+Smallest Diameter) = Diameter 2 Largest Diameter - Smallest Diameter = Ovality

Largest Diameter

Smallest Diameter Ovality

+.005 -.010 .015

Largest Diameter

Smallest Diameter

Averaged Diameter

+.005 -.010 -.0025

Ovality Average Cone Diameter

Largest Diameter

Smallest Diameter Ovality

-.005 -.010 .005 Largest

Diameter Smallest Diameter Ovality

-.015 +.001 .016

Largest Diameter

Smallest Diameter

Averaged Diameter

-.005 -.010 -.0075 Largest

Diameter Smallest Diameter

Averaged Diameter

-.015 +.001 -.007

Ovality is how egg-shaped or out of round it is. Ovality is the amount of out-of-roundness in a piece of pipe or a coupling. Determining ovality requires locating the largest and the smallest diameter readings on the part and subtracting the smallest reading from the largest reading, as shown in the following formula. Ovality readings are always positive (no sign attached).

What do you do with the high and low indicator values?

Average Cone Diameter is the size, it would be, if it were round. Determining the round diameter of a connector requires locating the largest and the smallest diameter readings on the part and taking the average of the two readings, as shown in the following formula:

API Tubing and Casing Tapered Threads

2014 Gagemaker, LP

LARGEREADING

SMALLREADING

Largest Diameter

Smallest Diameter

Averaged Diameter

+.005 -.010 -.0025

Largest Diameter

Smallest Diameter

Averaged Diameter

+.005 -.005 .000

Average Cone Diameter is the distance across the face of the pipe or coupling. Determining the round diameter of a connector requires locating the largest and the smallest diameter readings on the part and taking the average of these two readings.

API Tubing and Casing Tapered Threads

Average Cone Diameter

2014 Gagemaker, LP

LARGEREADING

SMALLREADING

Largest Diameter

Smallest Diameter

Total Ovality

+.005 -.010 .015

Largest Diameter

Smallest Diameter

Total Ovality

+.005 -.005 .010

Ovality is the amount of out-of-roundness in a piece of pipe or a coupling. Determining ovality requires locating the largest and the smallest diameter readings on the part and adding the smallest reading to the largest reading. Ovality readings are always positive (no sign attached).

API Tubing and Casing Tapered Threads

Ovality

2014 Gagemaker, LP

Coupling Thread Form Inspection

TP-8R Profile inspecting a pin thread. Always check the first starting thread.

When deburring the thread with a flapper wheel, burrs can be rolled into the thread groove. This will cause gauling when the connections are made up on the rig.

2014 Gagemaker, LP

Coupling Length Inspection

API Tubing and Casing Tapered Threads

Coupling Length (NL)

NL/2

Q Q is measured from the coupling face to the start of the 35 chamfer.

Always keep the scale parallel to the coupling axis.

NL/2 = the coupling length. NL = Length of coupling.

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