FAQ's

What are the sour service limits for UNS N08029?

UNS N08029 Seamless Tube: Specifications and Material Type

The UNS N08029 seamless tube is specified in ASTM B668-14 and belongs to materials type 4c according to ISO 15156-3 Table A.12. However, the material is not included in ISO 15156-3 2015 Annex D, Table D.3 – Chemical compositions of some solid-solution nickel-based alloys.

Questions on Including UNS N08029 in ISO 15156-3 and Extending Acceptable Limits

There are several questions regarding the inclusion of UNS N08029 in ISO 15156-3 and extending acceptable limits. Here are the answers:

Question 1: Including UNS N08029 in ISO 15156-3 Annex D, Table D.3

Table D.3 is an informative table, and adding a material that complies with type 4c is not a technical change. This means that the material can be added to the document at the next opportunity or Technical Circular requested for editorial changes.

Question 2: Extending Acceptable Limits through NACE Ballot

Consulting ISO 15156-3 Annex B, particularly B.2.4, test data from a minimum of three separately processed heats will be required to extend the limits. The available data points “”A”” and “”B”” may not be sufficient to extend the acceptable limit to the yellow area in the attached figure. Therefore, a NACE Ballot is recommended to propose new limits.

Question 3: Testing Methods for Proposing New Limits

According to B.3.3, both constant load and SSR (at least duplicate specimens) testing methods can be used to propose the new limit.

Question 4: Using 1 G/l Sulfur to Represent Elemental Sulfur Environment

The appropriateness of using 1 g/l sulfur to represent an environment with elemental sulfur depends on the specific application and the level of accuracy required. It is recommended to consult with experts in the field to determine the best approach.

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