10423:2009 / API 6A 20th ed.

Table 9 – Steel composition limits

API 6A 15th -19th editions included a maximum composition limit on Nickel:

API 6A 20th edition deleted limit on Nickel.• Reasons for change:– Nickel limit is not required for non-NACE

equipment (Matls Class AA, BB, CC). – Deleting limit on Ni allows use of additional

material grades such as 4340 for AA-CC.– Deleting limit on Ni allows use of full ASTM

chemistry range of currently-used materials such as F6NM.

API 6A 20th edition deleted limit on Nickel.• Concerns about this change:– Users of undocumented equipment cannot base

acceptance for sour service on hardness alone. – Practice of using hardness testing as basis of

conformance to NACE MR0175 is prevalent.– Limits interchangeability of equipment.– Limits flexibility of repaired and remanufactured

equipment. (Not addressed in Annex J)

API 6A 20th edition deleted limit on Nickel.• Questions about this change:– Is the benefit of using 4340 or unrestricted F6NM

significant relative to the increased risk? – Are there other alloys/material grades that would

also be used as a result of this change?– Should the change be addressed in Annex J?– Does this affect other product specifications that

reference 6A/10423?

Proposed new work item:• Convene a new task group or ask Materials

Task Group to consider the effects of this change from 6A 15th – 19th editions, and make a recommendation to keep or reverse it.