Absolutely — here's a clearer, more detailed explanation of both Taper Tap and Die Overshot (Die Collar) in simple, easy-to-understand terms with examples.
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🔩 1. Die Overshot (Die Collar)
✅ What It Is:
A Die Overshot, also called a Die Collar, is a fishing tool used to grab stuck pipe or tools from the outside when drilling. It is used when the top of the broken pipe is too rough or damaged to grip using normal tools.
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⚙️ How It Works:
The inside of the Die Collar has sharp cutting threads.
You lower it over the top of the broken pipe (called the “fish”).
As you rotate it, the threads cut into the outside of the pipe and grip it firmly.
Once it's tight, you pull the pipe out of the wellbore.
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📏 Inch Sizes (Outer Diameter Match):
You select the Die Overshot based on the outer diameter (OD) of the stuck pipe:
Pipe OD (Outside Diameter) Die Overshot Size
2 3/8″ 2 3/8″ collar
2 7/8″ 2 7/8″ collar
3 1/2″ 3 1/2″ collar
4 1/2″ 4 1/2″ collar
6 5/8″ 6 5/8″ collar
🟡 Important: It is external — it does not go inside the pipe.
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🖼️ Image of Die Overshot:
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🔩 2. Taper Tap
✅ What It Is:
A Taper Tap is another fishing tool, but it grabs the fish from the inside. It is used when the broken pipe has an open, smooth inner hole, and you can’t reach it from the outside.
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⚙️ How It Works:
The taper tap looks like a cone or bolt with threads.
You lower it inside the broken pipe.
As you turn (rotate) it, the threads cut into the inner wall of the pipe (like screwing into wood).
The more you rotate, the tighter it grips.
Once it’s fully engaged, you pull the fish out.
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📏 Inch Sizes (Inner Diameter Match):
You select the taper tap based on the inner diameter (ID) of the stuck pipe:
Pipe OD (Outer Diameter) Pipe ID (Inner Diameter) Taper Tap Size
2 3/8″ ~1.9″ 1.9″ tap
2 7/8″ ~2.3″ 2.3″ tap
3 1/2″ ~2.9″ 2.9″ tap
4 1/2″ ~3.8″ 3.8″ tap
🔵 Important: It is internal — it goes inside the fish.
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🖼️ Image of Taper Tap:
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🧠 Main Differences (Quick Comparison)
Feature Die Overshot (Die Collar) Taper Tap
Grabs From Outside of the pipe Inside of the pipe
Thread Type External biting threads Internal cutting threads
Works When... Top is rough but accessible Pipe is open and smooth inside
Pipe Condition No clean inside Has a clear inner bore
Size Match Outer Diameter (OD) Inner Diameter (ID)
Common Use Tubing, casing, drill pipe Tubing, casing, drill pipe
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🏪 Where to Find Them
Online: Aliexpress, Drillingsupplystore.com, Made-in-China
In Ethiopia: Check with:
Oilfield tool suppliers in Addis Ababa (Merkato or Kality areas)
Chinese/Ethiopian drilling contractors
Industrial importers of mining/drilling tools
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