In the oil and gas industry, a single bolt can be the difference between operational success and catastrophic failure. Especially in critical applications like wellheads, pressure vessels, and offshore platforms, bolting must meet the highest standards of strength, durability, and reliability. That’s where API 20E comes in.
API 20E is the American Petroleum Institute’s standard for carbon and alloy steel bolting intended for use in the petroleum and natural gas industries. It provides guidelines that ensure bolting components are manufactured with exceptional quality, from the moment raw steel is selected to the final inspection before shipment.
This article takes you on the step-by-step journey of an API 20E bolt, covering how it’s made, what tests it undergoes, and why each stage of production is essential for performance in high-stress environments.
Bolts may seem simple, but in oil and gas applications, they must:
Because of this, API 20E outlines strict manufacturing and testing protocols to prevent defects, ensure traceability, and verify mechanical properties. The goal is to guarantee bolts perform reliably in critical safety and containment applications.
Here’s how an API 20E bolt makes its way from raw steel to field-ready fastener:
The journey begins with selecting steel from approved mills. The steel must meet the chemical and metallurgical specifications required by API 20E and the application’s needs.
Each batch of steel is assigned a unique heat number, which provides full traceability to:
This heat number will follow the bolt throughout its lifecycle.
Once the steel arrives at the bolt manufacturer’s facility, it undergoes initial inspection to verify:
Only materials that meet the standard proceed to the next step. The steel bars are then stored in a designated traceable inventory system, sorted by heat lot.
The long steel bars are cut into individual blanks, sized based on the bolt’s intended dimensions. Preparation may also include:
At this stage, quality teams ensure the material still matches the heat lot records and is suitable for forging.
The bolt head is formed using either:
In hot forging, the cut blank is heated in a furnace and placed into a die to be shaped under pressure. This strengthens the grain structure and prepares it for threading.
Formed bolts are immediately marked (if required) and sorted by production lot.
Heat treatment is a critical stage that gives the bolt its desired mechanical properties. Most API 20E bolts undergo:
This process modifies the microstructure of the steel, improving:
The exact heat treatment cycle must be controlled, recorded, and validated with test coupons—sample materials heat-treated with the production lot.
After heat treatment, bolts are machined to their final dimensions, including:
Thread rolling may be performed before or after heat treatment, depending on bolt grade and customer requirements. Rolled threads are often preferred because they:
This step is precisely controlled to avoid introducing stress risers or defects.
API 20E requires non-destructive examination depending on the Bolting Specification Level (BSL). For BSL-2 and BSL-3, bolts undergo:
Each test must be:
To verify that heat treatment was successful and that the bolts meet strength requirements, manufacturers perform:
Test results must fall within the limits defined by API 20E or the applicable material standard (e.g., ASTM A193, A320).
Once bolts pass all testing, they undergo a final visual inspection to confirm:
Each bolt is marked (typically on the head) with:
At BSL-3, third-party inspectors may witness this process or review final records.
One of the core principles of API 20E is traceability. Every bolt must be accompanied by a documentation package that includes:
For high-criticality applications (BSL-3), this may also include:
Bolts are packed according to their application:
Special packaging (e.g., offshore-rated crates) may be used for export or subsea deployment.
A defining feature of API 20E-compliant bolting is that every step is traceable—from steel mill to end user.
Here’s a simplified flow of traceability:
| Stage | Identifier | Purpose |
|---|---|---|
| Steel melting | Heat Number | Links to chemical composition |
| Bar rolling | Heat Lot | Groups material processed together |
| Bolt manufacturing | Production Lot | Ensures uniform processing and QC |
| Testing & NDE | Lot Number + Reports | Validates quality and performance |
| Final product | Head Marking | Physical ID for field traceability |
This traceability allows manufacturers and customers to:
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As a leading manufacturer and exporter, NP Energy Products is committed to delivering premium API 20E Bolting solutions with a focus on quality, reliability, and customer satisfaction.
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