1. Material issues
Many companies use irregular materials, usually referring to nickel content. The price of raw materials varies greatly, and this is one of counterfeiting. In particular, fake 321 high nickel and 316 high nickel are very serious.
2. Size issues
Many customers basically have no technical support for inspection. For example, for a 90-degree elbow, the conventional one is R=1.5D, and some production molds are mostly 1.25D. Don’t underestimate the 0.25D, the product weight varies greatly. The so-called factory standard is much shorter than the standard.
3. Thickness issues
Of course, current customers are very smart and use calipers to measure the thickness. Although sometimes customers feel that they barely meet the standard after inspection, they ignore one point, that is, the thickness of the backarc is not enough! Because the wall is reduced during the elbow push process, so The caliber barely meets the standard, but the back is basically unqualified.
4.Solid solution treatment and non-destructive testing, sand rolling treatment and sandblasting treatment
Many companies do not do solid solution treatment and 100% penetrant non-destructive testing, and many of them use sandblasting instead of sand rolling. After these steps are omitted, costs are greatly reduced.
5. Seamless welding
Welding seamlessly means making welded elbows, which are sandblasted after being polished and pickled. There is no sign of welding on the surface, and even advanced flaw detection equipment cannot tell that it is a welded elbow.
6. Spot welding, repair welding
There will be thin in the elbow pushing process, so in general, manufacturers will use thicker pipes. If thin raw materials are used, the product will definitely be unqualified.
Post time: May-27-2021