NACE and Inconel

[davidmoul]

Hi guys,

just a quick question to poweruser of the NACE MR0175 norm, as I would like to be sure of that:

In case of using an Inconel 625 in annealed condition, there is no hardness requirement for the base material and for the welds?

For the base material, paragraph 6.2.2 says that the limit is given in the table (annex A). However, in this annex and for the solid-solution Nickel based alloy, there is absolutely no prescription.

Moreover, in paragraph A.4.3 called "Welding solid-solution Nickel-based alloys of this material group", it is written that "there are no hardness requirements for welding solid-solution nickel based alloys with solid solution nickel-based alloy weld metal".

Am I misunderstanding something? The fact is that we traditionnaly ask for an hardness limit of 33HRC, however I don't know why this rule. It is claimed in our internal documentation that it is required by the NACE MR0175 norm, but according to me it is not... Right?

 

[SJones]

There is no hardness requirement for annealed N06625 in the latest version of ISO 15156-3. There are some hardness restrictions for cold worked alloys in specific applications, such as downhole items, which is what the text is alluding to.

The 33 HRC may have come from pre-2003.

Steve Jones
Materials & Corrosion Engineer

http://www.linkedin.com/pub/8/83b/b04