Tubing Casing Thread Training

THREAD GAUGING TECHNIQUES

API Tubing and Casing Threads

Connection Thread Styles Straight Threads

API Tubing and Casing Tapered Threads

API Tubing and Casing Tapered Threads

API Connection Names 

EUE – External Upset Tubing

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STC – Short Thread Casing

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NUE – Non-Upset Tubing

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LTC – Long Thread Casing

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BTC – Buttress Casing

Datum

API Tubing and Casing Tapered Threads

What are Tubing & Casing Threads 

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

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API Specification 5B covers all Tubing and Casing dimensions

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There are two types of pipe sizes ◦ Tubing sizes: 1” – 4½” ◦ Casing sizes: 4½” – 20”

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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

API Tubing and Casing Tapered Threads

How Threads Lock Up and Seal 

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

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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.

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

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

API Tubing and Casing Tapered Threads

8R Thread Form

API Tubing and Casing Tapered Threads

What is a “Datum Plane”? 

Datum Plane- a starting point or reference location. Also referred to as the face or end of pipe. Datu Datum A

Datum B m

API Tubing and Casing Tapered Threads

How do we get started? 

Request the product thread drawing

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Verify the thread form is correct

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Verify the threading insert is correct for the thread on the drawing

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Request a gage set up report

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List all the gage serial numbers used to inspect the part

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Verify the ball contact sizes are correct

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Set the gages to a zero on a calibrated standard

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Thread the part and start the inspection

API Tubing and Casing Tapered Threads

TDWIN TAPER Drawing 7” LTC Pin

API Tubing and Casing Tapered Threads

Thread Lead Inspection with an LG-5002

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

Set using a Standard  Double-check your zero setting  Measure the part  Compare the standard to the machined lead 

1.Place the fixed ball contact in the first full depth thread. 2. Move the fixed ball back one thread and check again. 3.

Record your measurement for comparison.

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

API Tubing and Casing Tapered Threads

Thread Height Inspection 

Set using a setting standard

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Double check your zero setting

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Measure the part

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.

8 Round thread height = .072125” 10 Round thread height = .05560” Buttress ¾”TPF thread height = .0620” Buttress 1”TPF thread height = .0620”

API Tubing and Casing Tapered Threads

Pin Taper Inspection with an ET-7000

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

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

API Tubing and Casing Tapered Threads

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

“B”

While The MRP holding Shoe the makes gage contact against with theuse theof Standard MRP-2001 is preset to size by the crest part cone sweep left and right to find “A” &face, “B” Rod Standards the largest indicator value. Then, The MIC TRAC can be used instead of the rotate the gage 90° and repeat standards

“A” Standard

API Tubing and Casing Tapered Threads

What do you do with the MRP readings? 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.

Ovality

Average Cone Diameter

How egg-shaped or out of round the pipe is

The diameter of the part would be, if it were round (Largest Diameter - Smallest Diameter) = ACD 2

LARGE READING

Largest Diameter - Smallest Diameter = Ovality

SMALL READING

Largest Diameter

Smallest Diameter

Averaged Diameter

Largest Diameter

Smallest Diameter

Ovality

+.005

‑.010

‑.0025

+.005

‑.010

.015

Largest Diameter

Smallest Diameter

Averaged Diameter

Largest Diameter

Smallest Diameter

Ovality

-.005

‑.010

‑.0075

-.005

‑.010

.005

Largest Diameter

Smallest Diameter

Averaged Diameter

Largest Diameter

Smallest Diameter

Ovality

-.015

+.001

‑.007

-.015

+.001

.016

API Tubing and Casing Tapered Threads

Average Cone Diameter 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. Largest Diameter

Smallest Diameter

Averaged Diameter

Largest Diameter

Smallest Diameter

Averaged Diameter

+.005

‑.010

‑.0025

+.005

‑.005

.000

LARGE READING

SMALL READING

API Tubing and Casing Tapered Threads

Thread Ovality 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). Largest Diameter

Smallest Diameter

Total Ovality

Largest Diameter

Smallest Diameter

Total Ovality

+.005

‑.010

.015

+.005

‑.005

.010

LARGE READING

SMALL READING

API Tubing and Casing Tapered Threads

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

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

Pin Length Inspection

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. L2 L4

L4=Last scratch length.

API Tubing and Casing Tapered Threads

15 Minute Break API Tubing and Casing Tapered Threads

Datum A

Coupling Threads

Datum B

API Tubing and Casing Tapered Threads

How do we get started? 

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

API Tubing and Casing Tapered Threads

TDWIN TAPER Drawing 7” LTC Coupling

API Tubing and Casing Tapered Threads

Coupling Thread Lead Inspection with an LG-5002 

Set to zero using a standard

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Double check your zero setting

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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. 3.Record your measurement for comparison.

Remember: Each different taper requires a different lead setting standard

API Tubing and Casing Tapered Threads

Coupling Thread Height Inspection with a TH-3006 

Set to zero using a standard

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Double check your zero setting

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Measure the part

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. Thread Heights: 8-Round = .0721” Buttress = .0620” API Tubing and Casing Tapered Threads

Coupling Taper Inspection with an IT-6000

Zero the dial on the first thread. Do not lock the bezel clamp! To inspect, move the gage down the taper 1” or: Note the radial location of the gage 8 threads for 8-round to the part or chuck. 5 threads for Buttress (6 or 12 o’clock is best) After moving 1” down the taper, double check your radial position of the gage to the part or chuck.

API Tubing and Casing Tapered Threads

Coupling PD Inspection with an MRP-2002 (Crest Cone Diameter Inspection) “B” Standard

While MRP-2002 holdingisthe preset gagetoagainst size with the the use part of face, “A” & sweep “B” Rodleft Standards & right to find the largest indicator value The MIC TRAC can be used instead of rod standards. Rotate the gage 90° and repeat

“A” Standard

API Tubing and Casing Tapered Threads

MRP Reading Refresher 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 Ovality How egg-shaped or out of round the pipe is

Average Cone Diameter The diameter the pipe would be, if it were round

LARGE READING

SMALL READING

(Largest Diameter - Smallest Diameter) = ACD 2

Largest Diameter - Smallest Diameter = Ovality

API Tubing and Casing Tapered Threads

Coupling Length Inspection 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 Coupling Length (NL)

NL/2 = ½ the coupling length. NL = Length of coupling.

API Tubing and Casing Tapered Threads

API Tubing and Casing Tapered Threads

Gagemaker Thread Inspection

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