ASTM B366 UNS N06625 Inconel 625 Butt Welding Elbow

1. Why is an Inconel 625 butt welding elbow so expensive?

Recently, we've supplied a batch of Inconel 625 90° L/R(long radius) seamless elbows(6" SCH80) to an US client. The elbows are manufactured to ASME B16.9. According to ASTM B 366, these UNS N06625(Alloy 625) elbows shall be marked as "WPNCMCS" where "S" indicates the seamless construction of the elbow. An interesting thing is the Inconel 625 elbow is much more expensive than the Inconel 625 seamless pipe. To be specific, in the view of USD per kg, a relative Inconel 625 seamless pipe is approximate USD72.00 per kg while the Inconel 625 elbow is around USD265.00 per kg which is more than 3 times of the pipe. Why is there such a price gap? How is that possible?

2. The complexity of making an Inconel 625 seamless elbow

Usually, a butt welding seamless elbow manufactured to ASME B16.9 shall be made from a seamless pipe length in the same material. In this case, the UNS N06625(Inconel 625) elbow 6" SCH80 requires the raw material of 140mm(O.D) Inconel 625 seamless pipes with wall thickness of 13.75mm(during the hot-extruding process, the outside diameter of the pipe length will be expanded while the wall thickness will be reduced). The fact is it is very difficult to source this 140mm raw material commercially in the market. You have to make it from scratch: First, an Alloy 625 ingot shall be cast by using electroslag furnace. The ingot is taken to the pipe mill to get a custom-designed Inconel 625 seamless pipe through piercing process. The pipe will be cut into several calculated pipe lengths which then shall be preheated by mid-frequency heater and be pushed through a mandrel to form the elbow. Each of these steps shall be conducted and tested strictly in accordance with relative nickel alloy standards. To summarize, the complex production process makes the Inconel 625 elbows especially expensive.

Views: Author：hbmetals Date:15/11/04