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Last updateFri, 26 May 2017 2pm

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The Future of Coal: Efficiency Over Politics?

The Future of Coal: Efficiency Over Politics?

Many changes in the power industry have ...

Valve World Americas Event Set for June 20-21

Valve World Americas Event Set for June 20-21

End users, distributors, EPC/AEC personn...

Water Hammer

Water Hammer

Water hammer is a shock wave transmitted...

Turning the Tables on Valve Corrosion

Turning the Tables on Valve Corrosion

Multiple valve manufacturers and users w...

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Industry Headlines

Emerson Acquires MYNAH Technologies

3 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

4 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

2 DAYS 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

4 DAYS AGO

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

1 DAY 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

2 DAYS 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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NACE MR0175/ISO 15156

materials_q_and_a_graphicQ: I see that there is a new version of NACE MR0175 called NACE MR0175/ISO 15156. Why did MR0175 become an ISO standard, and how do the requirements in the ISO version differ from those in the previous version?

A: This topic is too broad to cover completely in a column of this size. However, we would like to offer a brief history and a summary of one major change that will affect valve companies and their suppliers.

You may recall that MR0175-2003 invoked some major changes compared with the 2002 revision. Many of these changes were encouraged by the European Federation of Corrosion (EFC). The EFC had already issued two reports closely related to MR0175: Publication 16, "Guidelines on Materials Requirements for Carbon and Low Alloy Steels for H2S-Containing Environments in Oil and Gas Production," and Publication 17, "Corrosion Resistant Alloys for Oil and Gas Production: Guidance on General Requirements and Test Methods for H2S Service" ISO requested that NACE work to merge MR0175 and these documents into a single ISO standard. The "rewrite" of MR0175, which was eventually published as MR0175-2003, was the first step in that merger.

The biggest change in the 2003 version was the introduction of environmental application limits (such as maximum H2S partial pressures, maximum temperature limits, pH restrictions) for almost all of the CRAs (corrosion-resistant alloys-the various classes of stainless steels, nickel alloys, titanium alloys, etc). Some materials were actually deleted from the document (N06600 and N04400, to name two). However, for the materials that remained, there were few changes in actual metallurgical requirements. MR0175-2003 was then converted into ISO 15156, which was published in December 2003. In North America, it is sold by NACE as NACE MR0175/ISO 15156.

NACE MR0175/ISO 15156 is actually published in three parts:

  • Part 1: General principles for selection of cracking-resistant materials
  • Part 2: Cracking-resistant carbon and low-alloy steels, and the use of cast irons
  • Part 3: Cracking-resistant CRAs (corrosion-resistant alloys) and other alloys

The format of the document changed dramatically from that of the MR0175-2003 standard. The PDF version of MR0175-2003 was 44 pages. The three-part ISO version totals 147 pages. Although much of this expansion is due to the different format of the ISO standard, some new information was added (such as information about H2S-related cracking mechanisms other than sulfide stress cracking), and some new metallurgical requirements were imposed.

The environmental restrictions that originated in MR0175-2003 were passed along to the ISO 15156 document with essentially no changes, which means that selection of materials will not be affected vs. MR0175-2003.

Obviously, there are many new requirements that need to be evaluated by each manufacturer. However, the change that will most affect equipment suppliers and their foundries relates to new requirements for the qualification of welding procedures. NACE MR0175/ISO 15156 provides much more specific requirements for qualification of welding procedures than previous versions of MR0175. All procedure qualifications are required to include hardness surveys, whether or not post-weld heat treatment is performed. The hardness surveys must be performed using either 10 kg or 5 kg Vickers (HV 10 or HV 5) or Rockwell 15N (HR15N), and the indentations must be located according to specific survey layouts provided in the standard. Hardness surveys performed using Rockwell C (HRC) are allowed only if the design stress does not exceed two-thirds of specified minimum yield strength and if the welding procedure specification requires postweld heat treatment. Therefore, in most cases the use of HRC will not be acceptable.

The major implication of this new requirement is that it applies to all material categories, even those that are not hardenable by heat treatment. One normally associates the use of hardness surveys with the qualification of procedures for alloys that are hardenabled by heat treatment, such as the carbon steels, alloy steels, martensitic stainless steels, and duplex stainless steels. Materials that are not hardenable by heat treatment usually are exempt from these kinds of tests. Per ISO 15156, even procedure qualifications for austenitic stainless steels and solid-solution, nickel-based alloys must include hardness surveys. Most equipment suppliers, including valve manufacturers, likely did not perform hardness surveys for these types of materials, and even hardness surveys included in existing procedure qualifications for materials hardenable by heat treatment are very unlikely to have been performed per the layout specified in the new standard.

These new requirements mean that foundries and valve manufacturers will need to update existing procedure qualifications by either performing the hardness surveys on leftover procedure qualification coupons (if they happen to still be available), or by creating new weld coupons for the hardness surveys. When the range of alloys supplied into sour applications is considered, updating welding procedures to meet these new requirements will consume a great deal of time and expense.

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