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Last updateFri, 26 May 2017 2pm

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The Future of Coal: Efficiency Over Politics?

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Valve World Americas Event Set for June 20-21

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Emerson Acquires MYNAH Technologies

2 DAYS AGO

Emerson has completed the purchase of MYNAH Technologies, a long-time Emerson alliance partner. The addition of MYNAH will help support Emerson Automation Solutions and its Operational Certainty program. Terms of  the acquisition were not disclosed.

MYNAH software is currently in use at more than ...

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Roger Fix Named Chairman of Flowserve

3 DAYS AGO

In its most recent annual meeting, Flowserve announced that Bill Rusnack and Lynn Elsenhans have retired as members of the board of directors. Flowserve also announced that board member Roger Fix has been elected to replace Rusnack as chairman.

"Bill and Lynn provided years of distinguished service to ...

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Oil-Fired Plants Provide Small Amount of U.S. Electric Capacity, Generation

1 DAY AGO

According to the U.S. Energy Information Administration , roughly 70% of petroleum-fired electric generating capacity that still exists today was constructed prior to 1980. Utility-scale generators that reported petroleum as their primary fuel comprised only 3% of total electric generating capacity at...

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ExxonMobil, SABIC Agree on Proposed Petrochemical Project

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Affiliates of Exxon Mobil and SABIC (Saudi Basic Industries Corporation) signed an agreement to conduct a detailed study of the proposed Gulf Coast Growth Ventures project in Texas and begin planning for front-end engineering and design work. The agreement was signed during the Saudi-US CEO Forum in R...

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Kansas City Fed Manufacturing Survey Shows Expansion in May

10 HOURS AGO

Tenth District manufacturing activity continued to expand at a moderate pace in May, and expectations for future activity increased strongly. Price indexes were mixed, but recorded little change overall. The month-over-month composite index was 8 in May, up from 7 in April but down from 20 in March.

Ac...

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Business Borrowing for Capital Investment Up 8% in April

1 DAY AGO

The Equipment Leasing and Finance Association’s (ELFA) Monthly Leasing and Finance Index, which reports economic activity from 25 companies representing a cross section of the $1 trillion equipment finance sector, showed their overall new business volume for April was $7.9 billion, up 8% year-ov...

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Nickel-Copper Alloys

materials_q_and_a_graphicQ: Are the nickel-copper alloys (such as UNS N04400) acceptable for use in accordance with the NACE sour service standards?

 

A: This question has been asked frequently, usually in relation to a valve for an upstream hydrocarbon application involving sour water that also contains chlorides. Nickel-copper alloys can be an economical option for such applications. However, changes in the NACE standards within the last decade have complicated the issue.

The original version of NACE MR0175 released in 1975 allowed N04400 material with a 35 HRC maximum hardness requirement. In 1982, N04405, the higher-sulfur, free-machining version of N04400, was balloted, approved and added by addendum. M35-1 and M35-2, two cast “equivalents” of N04400, were balloted and added to a 1991 revision.

In addition to weak grades, the ­precipitation-hardenable N05500 was also included in the original 1975 ­version, with a maximum hardness of 35 HRC provided the material was hot-worked and age-hardened, solution-annealed, or solution-annealed and age-hardened.

When the MR0175 rewrite was under production as a precursor to ISO 15156, the weak grades (N04400, N04405, M35-1 and M35-2) were omitted for general usage and relegated to specific oil and gas field applications (i.e., they were no longer allowed for valve components). Many end users felt this alloy family was not needed for general sour upstream petroleum applications.

In addition, because of some field failures in N05500 fasteners, an effort was made to eliminate this material as well. In the end, N05500 was retained in the new standard, but was relegated to use in:

  • Wellhead and Christmas tree components other than bodies or bonnets, with specific pH and hydrogen sulfide partial pressure restrictions
  • Non-pressure-containing internal components in valves, pressure regulators or level controllers, and
  • The same specific oil and gas field applications as soft alloys.

Because NACE defines valve shafts and stems as pressure-containing components, this material could no longer be used for shafts and stems when compliance with MR0175 was required.

Shortly after NACE MR0175-2003 was released, it was converted to ISO 15156, which NACE then adopted back as NACE MR0175/ISO 15156. No changes were made regarding the ­nickel-copper materials.

In the meantime, NACE MR0103, the downstream (oil refining) sour service standard, was released (in 2003), and included N04400, N04405, M35-1, M35-2 and M30C (another N04400 cast equivalent), as well as N05500 with the same metallurgical requirements that were specified in the pre-2003 versions of NACE MR0175. No restrictions regarding the types of components that could be made from the N05500 grade were made.

In 2005, ISO 15156-3:2003 Technical Corrigendum 2 (essentially an addendum to NACE MR0175/ISO 15156) was released, allowing use of N04400 and N04405 for general purposes. However, the cast grades were not included in this change.

When NACE MR0175/ISO 15156 Second Edition was published in 2009, N04400 and N04405 were inserted into the main document along with the other solid solution nickel alloys.

A summary of the acceptability of these various nickel-copper materials is shown in Table 1.

vmfall12_repair_table1

The ramification of this situation is that it is not possible to produce many valve designs using an all nickel-copper construction in accordance with the current version of NACE MR0175. If the body style requires a casting (such as a globe valve), the cast alloys are not permitted. In addition, N04400 and N04405 are rarely strong enough to use for shafts or stems, and N05500 is not allowed for those components.

Therefore, unless the valve body can be produced from a wrought material form such as a plate or forging, and the shaft can be made from the lower-strength N04400 or N04405, some other, non-nickel-copper material will need to be used for the body and the stem or shaft.


Don Bush is a principal materials engineer at Emerson Process Management–Fisher Valve ­Division (www.emersonprocess.com). Reach him at This email address is being protected from spambots. You need JavaScript enabled to view it..

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