When the owner shall establish a written material verification program for all types of positive material identification (PMI) as part of the American Petroleum Institute’s (API) standards for operational safety and environmental sustainability in the oil and gas industry, the question is what are your options?
With 100% PMI needed for high-risk systems and fully documented material verification that provides the extend the type of PMI testing needed for during construction of new and existing pipes including maintenance and repair, the question is, is your analyzer really up to its job?
Our job is to help you find a solution that helps you comply and hopefully provides other benefits as well to your operations.
The API 5L specification gives standards for grades of pipe suitable for use in carrying gas, water and oil in the natural gas and oil industries. The specification covers welded and seamless pipe and covers the following grades: A25, A, B and "X" Grades X42, X46, X52, X56, X60, X65, X70, and X80.
The standard gives two basic pipeline specifications: PSL 1, which is a standard quality for line pipe, and PSL 2 which includes additional testing requirements, including chemical composition.
The following table is an example of the specification for PSL-2 grade seamless pipe.
| Grade | C (max) | Mn (max) | P (max) | S (max) | Ti (max) |
| B | 0.24 | 1.2 | 0.025 | 0.015 | 0.04 |
| X42 | 0.24 | 1.3 | 0.025 | 0.015 | 0.04 |
| X46, X52, X56, X60 | 0.24 | 1.4 | 0.025 | 0.015 | 0.04 |
| X65, X70, X80 | 0.24 | 1.4 | 0.025 | 0.015 | 0.04 |
Table showing maximum element levels for PSL-2 seamless pipe.
However, the elements listed in the above table aren’t an exhaustive list of what needs to be tested within API 5L:
As a minimum, each required analysis shall include the following elements:
| Carbon (C) | Chromium (Cr) | Silicon (Si) |
| Manganese (Mn) | Niobium (Nb) | Titanium (Ti) |
| Phosphorus (P) | Copper (Cu) | Vanadium (V) |
| Sulfur (S) | Molybdenum (Mo) | Boron (B)* |
*Boron needs only you be checked if the heat analysis figure supplied is above 0.001%.
In addition to the elements stated above, you must check for any other alloying element that’s been added during steelmaking for a purpose other than deoxidation.
If API 5L tells you what need to test for, API RP 578 tells you how you must carry out the test. This not only applies to the in-plant refining process but also for suppliers who provide materials.
The API RP 578 Guidelines for Material Verification Programs for New and Existing Assets provides guidelines to create a quality assurance system to verify the composition of components including the fabrication and metals. This recommended practice (RP) was upgraded in February 2018 and now covers all assets within oil and gas industries whether offshore, onshore, midstream, upstream, or downstream.
This huge scope includes positive material identification (PMI) strategies for ferrous and non-ferrous components during construction, installation, maintenance and inspection of new and existing piping systems covered by ASME B31.3 and API 570. This applies to alloy materials including what is being provided by suppliers including fabricators.
API RP 578 guidelines include three testing technologies, XRF, OES and LIBS – with LIBS being a new addition to the specification. However, to get the most from your investment in analysis equipment, in practice you’ll need to choose an instrument that can analyze everything you need to in a single measurement.
Here’s what you need to consider as you make your choice between the different analyzers:
The variation with each measurement on key element results makes it easy to mis-interpret the grade. In this field, to be accurate but not precise is risky.
To have confidence in your results, you need to measure carbon equivalency. This means measuring many elements – not just carbon – to low detection limits. Handheld LIBS can’t measure elements such as boron, making it impossible to accurately calculate the standard PCM CE formula.
Many elements that you need to measure for compliance – such as phosphorus and sulfur – can still only be measured with OES.
Essentially, OES technology has been relied upon for years by engineers, quality managers and scientists to deliver the full chemistry of a sample with excellent precision and accuracy. Non-destructive XRF is used for hundreds of applications but it’s not able to analyze lighter elements on the period table well enough.
Whilst it’s great to see the advancements in handheld LIBS, it’s not a handheld OES and as such a direct replacement to portable OES instruments. You’ll still need to rely on OES technology if you need to measure carbon, phosphorus, sulfur, boron, arsenic and tin in low alloys and stainless steels, and nitrogen in duplex steels.
Our recommendation
Our PMI-MASTER Smart gives you the performance and ease of use of an OES instrument in a portable analyzer. Weighing just 15kg, the PMI-MASTER Smart is compact enough for small and hard to reach spaces and can be easily taken up a ladder or down a shaft. The long-life battery can deliver up to 300 analyses, enough to last all day when working in a remote area.
To find out more about measurement capability, download our extensive report: Ultimate Guide to LIBS vs OES. We’ve put the OES and LIBS analyzers head to head – you can see what we found in the report.
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