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Safety Relief Valve FAQs

Safety Relief Valve FAQs

Companies that repair, test, maintain or...

An Update on U.S. Valve-Related Standards

An Update on U.S. Valve-Related Standards

It takes much time and effort by many pe...

Diagnostics for Commissioning and Startup

Diagnostics for Commissioning and Startup

Many facilities have found value in perf...

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Safety Relief Valve FAQs

Safety Relief Valve FAQs

Monday, 14 August 2017  |  Lyndon Garrick

Companies that repair, test, maintain or supply valves routinely receive inquiries from end users about safety-relief valves. Here are a few questions...

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Industry Headlines

Forum Energy Technologies Acquires Multilift

1 DAY AGO

Forum Energy Technologies, Inc. has acquired the stock of Multilift from Pelican Energy Partners, a Houston-based oilfield services focused private equity fund, and management. Based in Houston, Multilift manufactures the patented SandGuard and the Cyclone completion tools; products that extend the ...

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ValvTechnologies Names Teele Director of Global Quality Management

3 DAYS AGO

ValvTechnologies, Inc. has appointed Michael Teele director of global quality management. Based in Houston, Teele will be responsible for setting and maintaining global quality standards, systems and processes, as well as serving as a leadership champion of continuous improvement. With a deep technic...

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Executive Order to Speed Up Infrastructure Project Approval

1 DAY AGO

President Trump signed an executive order intended to roll back “rules regarding environmental reviews and restrictions on government-funded building projects in flood-prone areas as part of his proposal to spend $1 trillion to fix aging U.S. infrastructure,” Reuters reports .

“Trump's...

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DuPont and Dow Chemical Set Closing Date for Merger

2 DAYS AGO

DuPont and The Dow Chemical Company announced that all required regulatory approvals and clearances have been received, that all conditions to closing of their merger of equals have been satisfied, and that their merger of equals will close after the market closes on August 31, 2017.

“The compa...

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U.S. Factory Output Declined in July

7 HOURS AGO

Manufacturing output edged down 0.1% in July. The index for durables decreased 0.5%. Among durable manufacturing industries, with the indexes for primary metals and for furniture and related products each dropped more than 1%. The index for other manufacturing (publishing and logging) moved down 0.4%....

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Empire State Manufacturing Index Highest in Nearly Three Years

2 DAYS AGO

Business activity grew strongly in New York State, according to firms responding to the August 2017 Empire State Manufacturing Survey. The headline general business conditions index climbed fifteen points to 25.2, its highest level since September 2014. The new orders index rose seven points to 20.6 a...

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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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