Notes on purchasing seamless steel pipe

When purchasing seamless steel pipes (SMLS), it's essential to be aware of several critical issues that can affect the quality and performance of the pipes. Here are some key points to consider.

Material Issues:

Nickel Content: Some manufacturers may claim higher nickel content to distinguish their products. However, the difference in nickel content above 7% is minimal and not easily discernible. The significant price difference between materials can lead to deceptive practices, such as falsely labeling 321 high nickel and 316 high nickel pipes.

Size Issues:

Elbow Dimensions: Many customers lack technical support for testing dimensions. For example, a 90-degree elbow should have a radius (R) of 1.5 times the diameter (D). However, in some markets, elbows are produced with a radius of only 1.25D. This small difference in material weight can significantly impact the pipe's performance and is often referred to as a "factory standard," which is much shorter than the industry standard.

Thickness Issues:

Measuring Thickness: Customers often use calipers to measure pipe thickness, but they may overlook the back arc thickness, which can be insufficient due to the elbow push process. The thickness may appear compliant, but the actual performance could be compromised.

Solution Treatment and Non-Destructive Testing:

Skipping Treatments: Some manufacturers skip solution treatment and 100% penetration non-destructive testing. Instead, they use sandblasting to cut costs. This omission can significantly reduce the pipe's quality and performance.

Seamless Welding:

Disguising Welds: Some manufacturers produce welding elbows and then grind, pickle, and sandblast them to hide any signs of welding. Advanced detection equipment may not reveal these welds, presenting the product as seamless when it is not.

Spot Welding and Repair Welding:

Thinning Issues: During the elbow push process, thinning can occur. Manufacturers typically use thicker pipes to compensate. If thinner raw materials are used, the final product will be unqualified. Thinning of about 40 microns is common, but poor technology or the use of drawn pipes can result in significantly lower thickness than the standard.

Conclusion

When purchasing seamless steel pipes, it's crucial to be vigilant about material quality, accurate sizing, proper thickness, thorough treatment, and testing. Choose reputable manufacturers who adhere to industry standards and provide transparent information about their products. This will ensure that you receive high-quality seamless steel pipes that meet your specifications and perform reliably in their intended applications.