API thread inspection is essential for ensuring the performance and safety of oilfield equipment, particularly in OCTG (Oil Country Tubular Goods) applications. Sylvac Plastiform impression materials offer a fast, accurate, and non-destructive solution for evaluating thread integrity on both tubing and casing.
What Is a Thread?
In mechanical engineering, a thread is a helical structure used to convert rotational movement into linear motion or to securely join components. Threads are commonly found on cylindrical parts such as pipes, bolts, and couplings.
In the oil and gas industry (especially in OCTG), threads play a critical role in connecting tubular components like casings and tubings. These threads must withstand high pressure, mechanical stress, and harsh environments while maintaining a tight, leak-proof seal.
Because of their importance in maintaining well integrity, threads must be precisely machined and regularly inspected for wear, damage, and dimensional accuracy.
The Role of Threads in Oil and Gas Equipment
Threads on tubular products serve two primary purposes:
-
Securely assemble pipes that must endure high mechanical stresses.
-
Prevent fluid leaks or the entry of unwanted substances during drilling or production.
Over time, machining tools can wear down, causing surface defects and dimensional deviations in the threads. This reduces mechanical strength and may lead to operational failures if not properly inspected.
Why Thread Inspection Matters
Thread inspection is performed at two key stages:
-
In the manufacturing plant: using statistical sampling and precision tools to ensure dimensional compliance.
-
In the field: through Visual Thread Inspection (VTI) to detect wear, damage, or corrosion
This dual-stage inspection ensures both accuracy and reliability of the thread throughout its lifecycle.
Using Plastiform for API Thread Inspection
What is Plastiform?
Sylvac Plastiform (SRD) is a two-component impression material that creates micron-accurate molds of thread profiles, both internal and external. The process takes less than 6 minutes and enables detailed dimensional and visual analysis.
Application Methods:
1. Manual: 2-component malleable putty (hand-mixed)
2. Injection: Bi-component cartridge system with a dispensing gun
In-Plant Inspection Procedure
Here is how Sylvac Plastiform is typically used during manufacturing inspections:
Step-by-Step:
1. Clean the Surface
Use a Plastiform-approved degreaser to remove oil, dirt, and residue.
2. Take the Impression
Follow the technical instructions. Apply Sylvac Plastiform and allow it to cure fully before removal.
3. Cut the Mold
Use the Plastiform Double Blade Cutter to create a clean cross-section of the thread.
4. Inspect the Profile
Use an optical microscope or profile projector to analyze the mold.
5. Measure Key Thread Features
Plastiform impressions allow for measurement of:
-
Crest angle
-
Thread pitch
-
Thread height
-
Thread angle and root angle
-
Seal and shoulder dimensions
Field Inspection with Plastiform
Visual Thread Inspection (VTI)
In the field, Plastiform impressions are used for non-destructive testing (NDT) of thread conditions. This helps technicians assess if a thread can be reused, needs repair, or must be discarded. Common Defects Identified:
-
Galling
-
Scratches or burrs
-
Mashed or deformed threads
-
Rust, corrosion, or pitting
Plastiform helps detect and quantify these defects quickly and accurately, making it ideal for on-site inspections.
Compatible Thread Types (API Standards)
Plastiform is compatible with a wide range of API thread types, including:
-
EUE (External Upset Tubing)
-
NUE (Non-Upset Tubing)
-
BTC (Buttress Thread Casing)
-
LTC (Long Thread Casing)
-
STC (Short Thread Casing)
Sylvac Plastiform Distributor in Singapore
LFC PTE LTD is the authorized distributor of Sylvac Plastiform in Singapore. Our expert team can assist you in selecting the ideal Sylvac Plastiform to meet your specific measurement needs.
Stay updated on Sylvac products and other measuring tools by following LFC PTE LTD on social media. You can find us on Facebook, Instagram, YouTube, and LinkedIn.
