Tubing Casing Thread Training

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THREAD GAUGING TECHNIQUES

API Tubing and Casing

Threads

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Connection Thread Styles

Straight Threads

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

EUE – External Upset Tubing



NUE – Non-Upset Tubing



BTC – Buttress Casing

API Connection Names



STC – Short Thread Casing



LTC – Long Thread Casing

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 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” – 4½” ◦ Casing sizes: 4½” – 20”

 There are two cone angles or tapers

◦ All 8-round threads are ¾” Taper Per Foot (TPF) ◦ Buttress sizes 4½”- 13⅜” are 1” TPF

◦ Buttress sizes 16”- 20” are 1” TPF

What are Tubing & Casing Threads

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 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

How Threads Lock Up and Seal

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8R Thread Form

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Datu m

Datum A Datum BDatu_m

What is a “Datum Plane”?

 Datum Plane- a starting point or reference location. Also referred to as

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 Request the product thread drawing  Verify the thread form is correct

 Verify the threading insert is correct for the thread on the drawing  Request a gage set up report

 List all the gage serial numbers used to inspect the part  Verify the ball contact sizes are correct

 Set the gages to a zero on a calibrated standard  Thread the part and start the inspection

How do we get started?

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TDWIN TAPER Drawing 7” LTC Pin

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 Set using a Standard

 Double-check your zero setting  Measure the part

 Compare the standard to the machined lead

Thread Lead Inspection with an LG-5002

Note: Lead setting standards designs are based on the taper of the connection.

Measuring the part

The LG-5002 measures the same way on the part as on the standard.

1.Place the fixed ball contact in the first full depth thread.

2. Move the fixed ball back one thread and check again.

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Thread Height Inspection

 Set using a setting standard

8 Round thread height = .072125” 10 Round thread height = .05560”

Buttress ¾”TPF thread height = .0620” Buttress 1”TPF thread height = .0620”

The TH-3002 is used the same way on the part as on the

standard.

1.Measure only within the perfect thread length. Perfect thread length is labeled “L2” on the product drawing.

2.Align the gage base parallel to the thread axis and tilt the base back and forth to obtain the lowest reading.

3. Record your measurement.

 Double check your zero setting

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Zero the dial on the first thread.

Do not lock the bezel clamp!

Pin Taper Inspection with an ET-7000

To inspect, move the gage up the taper 1” (8-round = 8 threads, Buttress = 5 threads)

After moving back 1” up the taper, double-check your radial position of the gage to the part or chuck

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MRP-2001 is preset to size by the use of “A” & “B” Rod Standards

The MIC TRAC can be used instead of the standards

Pin PD Inspection with the MRP-2001

(Crest Cone Diameter Inspection)

“B” Standard

“A” Standard

The MRP Shoe makes contact with the crest cone

While holding the gage against the part face, sweep left and right to find the largest indicator value. Then, rotate the gage 90° and repeat

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LARGE READING

SMALL READING

Largest and smallest indicator readings provide data for calculating Average Cone

Diameter (ACD) and Thread Ovality. They both use the same data but calculate

the readings in different ways.

(Largest Diameter - Smallest Diameter) = ACD 2

Largest Diameter - Smallest Diameter = Ovality

Largest

Diameter Diameter Smallest Ovality

+.005 ‑.010 .015

Largest

Diameter Diameter Smallest Averaged Diameter

+.005 ‑.010 ‑.0025

Largest

-.005 ‑.010 .005

Largest

-.015 +.001 .016

Largest

-.005 ‑.010 ‑.0075

Largest

-.015 +.001 ‑.007

Ovality

How egg-shaped or out of round the pipe is

What do you do with the MRP readings?

Average Cone Diameter

The diameter of the part would be, if it were round

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LARGE READING SMALL READING

Largest

+.005 ‑.010 ‑.0025

Largest

+.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.

Average Cone Diameter

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LARGE READING SMALL READING

Largest

Diameter Diameter Smallest OvalityTotal

+.005 ‑.010 .015

Largest

Diameter Diameter Smallest OvalityTotal

+.005 ‑.005 .010

Thread 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. The ovality is the difference between these values. Ovality readings are always positive (no sign

attached).

Thread Ovality

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Thread Form Inspection

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

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Pin Length Inspection

L2 L4

Always keep the scale parallel to the pipe axis.

(Note: 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.

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15 Minute

Break

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Coupling Threads

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 Request the product thread drawing  Verify the thread form is correct

 Verify the threading insert is correct for the thread on the drawing  Request a gage set up report

 List all the gage serial numbers used to inspect the part  Verify the ball contact sizes are correct

 Set the gages to a zero on a calibrated standard  Thread the part and start the inspection

How do we get started?

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TDWIN TAPER Drawing 7” LTC Coupling

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Coupling Thread Lead Inspection with an LG-5002

 Set to zero using a standard

 Measure the part

The LG-5002 measures the same way on the part as on the standard.

1.Place the fixed ball contact in the first full depth thread.

2.Move the fixed ball back one thread and check again.

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Coupling Thread Height Inspection with a TH-3006

Thread Heights: 8-Round = .0721”

 Set to zero using a standard

The TH-3006 is used the same way on the part as on the standard.

1. Align the gage parallel to the thread axis. 2. Lift up and down to obtain the lowest reading. 3. Record your measurement.

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Coupling Taper Inspection with an IT-6000

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 o’clock is best)

To inspect, move the gage down the taper 1” or:

8 threads for 8-round 5 threads for Buttress

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

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MRP-2002 is preset to size with the use of “A” & “B” Rod Standards

The MIC TRAC can be used instead of rod standards.

Coupling PD Inspection with an MRP-2002

(Crest Cone Diameter Inspection)

“B” Standard

“A” Standard

While holding the gage against the part face, sweep left & right to find the largest indicator value

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The Average Cone Diameter and Thread Ovality are calculated the same for the coupling as for the pin

Refer to the previous slides for more detail

LARGE READING

SMALL READING

(Largest Diameter - Smallest Diameter) = ACD

2 Largest Diameter - Smallest Diameter = Ovality

Ovality

How egg-shaped or out of round the pipe is

MRP Reading Refresher

Average Cone Diameter

The diameter the pipe would be, if it were round

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Coupling Length Inspection

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 = ½ the coupling length.

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Gage Manuals and Posters

Training Videos