A spiral steel pipe is typically sold from a single piece in the following situations:

High production difficulty: The production of spiral steel pipes requires specialized equipment and processes, which may be beyond the capabilities of small-scale manufacturers. As a result, these manufacturers may sell spiral steel pipes in quantities starting from one to reduce production costs. Custom services: Some spiral steel pipe manufacturers offer customization services, producing according to customer specifications. In such cases, the manufacturers might provide a "one-off" purchase option to cater to individual customer needs. Low market demand: In certain markets, such as rural or remote areas, demand is low, and spiral steel pipe manufacturers may offer a "one-off" purchase service to meet these needs. Note that "one-off" spiral steel pipes often come at a higher price due to higher production costs. Additionally, for bulk purchases, it's recommended to choose manufacturers with scale and strength to ensure product quality and reasonable pricing.

Foshan Shunde Langyao Iron and Steel Co., Ltd. was established on May 11, 2015. The legal representative is Huang Songming, and the company is engaged in the sale of steel products and domestic commercial activities.

The national standard for spiral steel pipes refers to "Spiral Steel Pipe for Fluid Transportation" GB/T 9711-2011, which was jointly issued by the General Administration of Quality Supervision, Inspection and Quarantine and the Standardization Administration of the People's Republic of China. It applies to the production, inspection, and use of spiral steel pipes for fluid transportation, and clearly stipulates the quality and safety requirements for spiral steel pipes.

During the development process, relevant experts and corporate representatives actively participated, collectively discussing and revising the standard's content to ensure its scientificity and practicality. Additionally, the standard is divided into two parts: GB/T9711.1 and GB/T9711.2, with the quality and testing requirements of GB/T9711.2 being generally higher than those of GB/T9711.1.

In addition, common national standard spiral steel pipes materials include Q235B, L245, L290, and 3L60, among which Q235B material is mainly used in municipal engineering, heating pipelines, drainage pipelines, and gas pipelines, while materials like L245, L290, and L360 are more commonly used for oil and natural gas pipelines. These steel pipes are also known as pipeline steel pipes and are typically used for long-distance transportation.

In summary, the national standard for spiral steel pipes was developed through multiple stages and processes, ensuring its scientificity and practicality. At the same time, the common materials for national standard spiral steel pipes are widely used.