API SC6 Winter Meeting New Business: API Standard 6A718 – Inclusion of Additional Alloy 718...

API SC6 Winter Meeting

New Business:

API Standard 6A718 – Inclusion of Additional Alloy 718 Strength Classes - Inclusion of Additional Alloys

Tim Haeberle8 February 2011

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Contents

1. Inclusion Of Additional Alloy 718 Strength Classes

2. Inclusion Of Additional Alloys



Inclusion Of Additional Alloy 718 Strength Classes



Inclusion of Additional Alloy 718 Strength ClassesBackground

•API Standard 6A718, 1st and 2nd Editions, have included only one strength class: 120K

•A 120 KSI min yield strength is what has been historically required for Alloy 718 tubing hangers

•The 120 KSI min yield strength exceeds the 75 KSI design criteria applicable to valve gates, seats & stems

•API Standard 6A718 was developed “to supplement the existing requirements of API 6A and ISO 10423”, and it is still meeting that objective.

•However……..



Inclusion of Additional Alloy 718 Strength ClassesBackground - Continued

•Although intended for API 6A equipment, API 6A718 has now been specified for other types of oil and gas production equipment, such as down-hole safety valves

•The manufacturers of down-hole safety valves specify Alloy 718 with minimum yield strengths of:• 120 KSI• 130 KSI• 135 KSI• 140 KSI

•While the 130, 135, and 140 KSI grades exceed the mechanical property requirements of API 6A718 and therefore comply with the mechanical property requirements of API 6A718, there can be other spec compliance problems.



Inclusion of Additional Alloy 718 Strength Classes

Background – Continued

• The 135 and 140 KSI grades typically need to be precipitation hardened at a lower temperature than permitted by API 6A718, thereby rendering material heat treated in this manner out of compliance.

• Material in the 135 and 140 KSI grades is frequently “hand picked” from vendor inventory since it is difficult to achieve these strength levels while still meeting the NACE MR0175 / ISO 15156 hardness limit of HRC 40.



Inclusion of Additional Alloy 718 Strength Classes•There have been requests to include the 130, 135, and 140 KSI strength classes in API 6A718.

•The 130 KSI strength class could simply be added as another strength class without having to make any other changes.

•The 135 KSI and 140 KSI strength classes cannot simply be added in this manner.

•The 135 KSI and 140 KSI strength classes would require testing and evaluation of the environmental cracking resistance of each grade, if heat treated using a precipitation hardening temperature or time outside of the ranges specified in API 6A718.

•Additionally, there needs to be a review to determine if the 135 KSI and 140 KSI strength classes are actually commercial grades, or if the requirement for “hand picking” material from inventory makes them too special inclusion in an API standard.



Proposal:• Establish a small Work Group for “Inclusion of

Additional Alloy 718 Strength Classes” Alloy 718 manufacturers and suppliers Equipment manufacturers using the alternate

classes End users

• Work Group Objectives: Define the differences in processing required for

each of the alternate Alloy 718 strength classes Propose detailed qualification requirements for

evaluating the alternate Alloy 718 strength classes that must be heat treated at temperatures or times that do not comply with the existing API Standard 6A718

Inclusion of Additional Alloy 718 Strength Classes



Inclusion Of Additional Alloys



Inclusion of Additional Alloys

Background

•API Standard 6A718, 1st and 2nd Editions, have included only one alloy: Alloy 718

•Other high strength nickel base alloys are used for API Spec 6A equipment as well as down hole safety valves and other equipment

•There is a concern that the other high strength nickel base alloys do not have industry standard requirements for processing, microstructure, macrostructure, and mechanical properties

•There is a concern these alloys may be subject to precipitation of detrimental secondary phases and field cracking problems as had been experienced with Alloy 718 prior to the issuance of API Standard 6A718



Inclusion Of Additional Alloys

Background – Continued

• Some of the alternate alloys being used are:• Alloy 925• Alloy 935• Alloy 945• Alloy 625 Plus• Alloy 625M• Alloy 725

• Contributing to the concern is the fact that the patents on these alloys have started to expire, and this means that mills around the world, regardless of nickel alloy processing experience, may decide to start melting and selling these alloys




This is a more complex task than the inclusion of additional strength

classes!



Proposal:•Establish a small Work Group for “Inclusion of Additional Alloys”

Chairman - Paul Maxwell, Carpenter Technology Alloy manufacturers & suppliers (Special Metals, Foroni, etc.) Equipment manufacturers using the alternate alloys End users

•Work Group Objectives: First, work with API staff to determine if patented alloys should

be included in an API standard Second, work with API staff to determine if API Standard 6A718

should be expanded, or if a new standard should be developed for each alloy

Define the processing & testing required for each of the alternate alloys

Propose detailed qualification requirements for evaluating the alternates

Solicit test data for qualification of the alternate alloys




End Of Presentation

API SC6 Winter Meeting New Business: API Standard 6A718 – Inclusion of Additional Alloy 718...

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