API Pipe Comprehensive Analysis

Why is API Pipe the core standard in the oil and gas industry?

In the process of oil and gas transportation, pipeline safety is of vital importance. Once a leak or burst occurs, it will lead to catastrophic consequences, causing irreversible damage to the environment and even casualties. So how can we prevent this from happening? How to ensure the safe transportation of oil? The American Petroleum Institute standard pipeline solves this problem. Since then, the API standard has been widely used in various scenarios. This article will analyze the API standard in detail, so that you can have a more comprehensive understanding of API.

What is API Pipe?

API and API 5L Standards Detailed Explanation

API 5L standard developed by the American Petroleum Institute (API) is the authoritative standard for pipelines in China. This standard covers two materials: carbon steel and alloy steel.
Steel grade classification: The classification of steel in API 5L is very important. From ordinary Gr.B to high-strength X42-X120, different steel grades can be selected according to different needs and scenarios.
Example: X80 steel grade pipeline has a yield strength of 80,000 psi and is suitable for ultra-high pressure natural gas transmission.

Typical materials and production processes of API Pipe

Material

 Mainly L245 and L415 carbon steel, but in some specific high-corrosion environments, acid-resistant steel (such as X65 Sour Service) should be used.

Production process
Seamless pipe: A welded pipe without a weld seam manufactured by cold drawing or hot rolling. It has higher pressure resistance and toughness, suitable for small-diameter and high-pressure scenarios.
Welded pipe: It is mainly divided into two categories: ERW and SAW. ERW is used for low-pressure scenarios, and SAW is used for large-diameter long-distance pipelines to meet different scenario requirements.

API certification mark and compliance requirements

API certification is an important symbol to ensure that pipeline products meet industry standards and safety requirements.
Compliant API Pipe must contain the following logos (laser engraving or coding): API monogram, manufacturer license number, steel grade (such as X70), size (such as NPS 24 inches).

The difference between API Pipe and other industrial pipes

API Pipe vs ASTM Pipe

The difference between API 5L and API 5CT

API 5L: Line pipes used to transport oil and natural gas.
API 5CT: Casing and tubing used for the inner structure of oil wells (such as J55 and K55 steel grades).

API Pipe’s core application scenarios

1. Oil and gas pipelines
Land long-distance pipelines: API pipes are widely used for long-distance transportation on land. For example, the China-Russia East Line uses X80-grade API, with a pressure of up to 12MPa.
Submarine pipelines: They are also widely used on the seabed, but unlike on land, submarine pipelines use bimetallic composite pipes to cope with seawater erosion.
2. Process pipelines in refineries
High-temperature and high-pressure reactor connecting pipes: Pipes with steel grades above X60 and hic tests are usually used.
3. Unconventional energy scenarios
Shale gas horizontal wells: API 5CT P110 casings are usually used because they need to support the pipe wall. This type of pipeline is also very strong in pressure resistance, which can exceed 10,000PSI.
CO2 storage pipelines: In order to safely transport supercritical CO2, API pipes have the ability to resist phase change corrosion.

FAQs：

1: Can API Pipe be used for ordinary water pipes?
Although it is feasible, it is a bit of an overkill because API has strong capabilities in all aspects and the price is also high.

2: What is the difference between API 5L Gr.B and X42?
‌Gr.B‌: The lowest steel grade, with a yield strength of 35 ksi, suitable for low-pressure branch lines.
‌X42‌: Yield strength of 42 ksi, used for medium and low pressure sections of trunk lines, the cost is about 15% higher than Gr.B.