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What to Know About the 3rd Edition of API RP 578

By Don Mears, Oil & Gas Specialist at Thermo Fisher Scientific. Thermo Fisher Scientific, November 19, 2019
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Introduction

The American Petroleum Institute (API) released its third edition of Recommended Practice (RP) 578 in February 2018, entitled, “Guidelines for a Material Verification Program for New & Existing Assets.” Nearly two years later, the updated guidelines are still not widely known despite significant changes and updates that help ensure oil and petrochemical companies have a proper asset integrity program in place, relative to material verification. Considering most “assets” used in the oil and gas industries are constructed of metallic materials, these recommended practices apply to virtually the entire oil and gas industry, making API 578 a critical component of business operations.

Material Verification

Most notably, the latest edition of API RP 578 makes clear that all oil and petrochemical facilities owner/users are now required to implement an effective Material Verification Program (MVP). It also recommends Positive Material Identification (PMI) strategies for ferrous and nonferrous alloys during the construction, installation, maintenance, and inspection of new and existing process equipment, as appropriate. It applies to metallic materials purchased for use either directly by the owner/user or indirectly through distributors, fabricators or contractors, and includes the supply, fabrication, and installation of these materials. Ensuring the integrity of all oil and gas assets – not just alloy piping systems – minimizes corporate risk by further mitigating the release of hazardous substances that can result from nonconforming materials of construction. 

API RP 578 identifies seven areas of consideration and general concern in material verification, mainly focusing on the systems most susceptible to corrosion. Knowing which assets are at high-risk for degradation (corrosion, cracking, creep, etc.) and what elements should be tested are critical to establishing an effective MVP that leverages the latest and most appropriate PMI technology.

Technology

Alloy substitutions for carbon steel, carbon steel substitutions in low alloy steel systems, residual elements in carbon steels in hydrofluoric acid alkylation units, and process units susceptible to sulfidation are all at risk for increased corrosion rates. Safe and reliable operation of these systems, and others, are dependent upon what alloy is used, which can be difficult to determine because all of them look alike to the human eye. Today’s PMI technology can differentiate between alloys, identifying various elements including carbon content, and detect residual elements.

In order to conduct PMI, testing can be done with any of the three analytical technologies referenced in API RP 578: Laser Induced Breakdown Spectroscopy (LIBS), X-ray Fluorescence (XRF) or Optical Emission Spectroscopy (OES).

Laser Induced Breakdown Spectroscopy (LIBS)

Included in the third and latest edition of API RP 578, LIBS is a powerful analytical technique that uses a laser to ablate the surface of a sample, which causes it to emit characteristic wavelengths of light that the analyzer can use to identify specific elements that make up the alloy. While this may sound like a complex process, LIBS analyzers are easy to use and available in the form of a portable handheld device. It is considered a minimally destructive technique, requiring little sample preparation, and provides results in seconds. Most importantly, LIBS analyzers can detect carbon content, even in low and high-grade alloys.

X-Ray Fluorescence (XRF)

XRF analyzers use X-rays to excite the surface of a sample, which then emits fluorescent X-rays that are unique to each element. XRF analyzers are easy-to-use thanks to their point and shoot capability, non-destructive and deliver instant results. However, unlike LIBS, XRF analyzers can’t determine carbon content.

The latest XRF analyzers are equipped with silicon drift detectors (SDD) that enable detection of “light” elements, including magnesium, sulfur, phosphorus, aluminum and silicon. The third edition of API RP 578 specifies that these devices should be used, particularly for refractory installations (anchors) which were once not able to be tested at all.

Optical Emission Spectroscopy (OES)

The third technology included in API RP 578 is OES. OES uses electricity to excite the sample to emit a spark which generates light at specific wavelengths and densities which are particular to the elements of interest. This means a hot work permit is required and it can’t be used outside in bad weather. It is also a destructive technique that melts the surface of the sample a very small amount. OES, like LIBS, can detect carbon, but unlike LIBS and XRF, it isn’t available in a handheld instrument and requires more expertise to use. OES is typically housed in a large system that needs to be carried in a bulky backpack or maneuvered via pushcart, which can be difficult to maneuver and operate in the field.

Of all the available technologies, XRF analyzers are a user’s primary PMI tool, thanks to their portability and ease of use. However, LIBS can and should be implemented wherever carbon detection is required. It is very mobile and easy to use. These are complementary technologies in the tool kit of oil and petrochemical equipment owner/users that empower them to ensure the integrity of their assets.

Trust, but Verify

Verifying the materials of construction can have an impact on the integrity of all assets and is increasingly important in a globalized market as many businesses are purchasing material from overseas and from vendors they may have never worked with before. Inexperienced or unreliable suppliers and contractors sometimes try to cut costs by not performing PMI or by using an outside testing lab to verify the shipped materials. Sometimes, this means their accompanying Mill Test Reports are not always accurate and a “trust but verify” approach is necessary to confirm the alloy’s chemical makeup.

Using API RP 578 will help oil and gas asset owners and users implement and maintain a trustworthy MVP as part of their overall asset integrity management system. With new analytical technology, such as LIBS and XRF analyzers with SDD capability, adhering to these guidelines can be done effectively and efficiently, helping minimize corporate risk, keeping employees safe and business operations highly reliable.


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