The Drawbacks of Using Thick-Walled Tubing in Industry

Inefficiency in Manufacturing and Increased Costs

The production of thick-walled tubing is a complex process that involves additional steps such as secondary heat treatment. This not only slows down manufacturing but also leads to higher production costs. According to industry leaders like Tiangang and Baosteel, the combination of roughing, heat treatment, and potential rework due to thread processing errors can significantly inflate expenses. The cost of producing thick-walled tubing remains elevated as a result of these inefficiencies.

Susceptibility to Slip Failures Under Tension

When subjected to axial tensile loads, the joints of thick-walled tubing can experience slip failures. The forces acting on the load-bearing and guiding surfaces of the thread change under tension, potentially leading to a decrease in friction and subsequent slippage. This mechanical shortcoming can compromise the integrity of the tubing in demanding applications.

Inadequate Gas Seal Performance at High Pressures

Thick-walled tubing may struggle to maintain a gas-tight seal under higher pressures due to structural gaps. This limitation becomes particularly problematic in complex well conditions such as deep wells, high-pressure gas wells, and environments with heavy corrosion. The risk of leaks and related accidents increases in these scenarios, raising concerns about the tubing's reliability.

Poor Anti-Galling Properties

The uneven stress distribution in thick-walled tubing can lead to thread galling, where the threads become stuck or damaged due to excessive contact stress. This issue is most prevalent at the first effective thread, where the local maximum stress can be significantly higher than the rest of the thread surface, leading to difficulties during loading and unloading.

Limited Thread Repair Options

The standard repairable length for thick-walled tubing threads is relatively short, allowing for only 2-3 uses before the risk of slippage increases. This limitation not only poses safety risks but also results in economic losses, as the majority of the tubing remains intact after a few uses. In times of low oil prices, maximizing the lifespan of oil pipes is crucial for cost savings and efficiency in the oil industry.

Challenges in Accessory Production

Producing accessories such as short sections for thick-walled tubing is difficult due to the limitations of the upsetting process. Small-scale production is often outsourced to smaller factories, which may lack the capability to produce materials resistant to hydrogen sulfide, leading to potential safety hazards. Consequently, these accessories are expensive, difficult to source, and have long production cycles.

Long Lead Times and Persistent High Prices

The intricate process of manufacturing thick-walled tubing results in longer lead times and sustained high prices, particularly for anti-sulfur tubing. The thickening process alone can add approximately 800-1000 yuan per ton to production costs, according to factory statistics.

In conclusion, while thick-walled tubing offers certain mechanical advantages, its drawbacks in terms of efficiency, safety, and cost must be carefully weighed against the requirements of specific industrial applications. The selection of tubing materials should be guided by a thorough understanding of these factors to ensure optimal performance and value.