A NACE-compliant stainless steel pressure gauge is the perfect solution for refineries and other petrochemical applications that work with sour crude oil, whose higher sulfur content has greater potential for corroding instrumentation and causing costly problems. 

The sulfur found in crude oil is highly corrosive. This element can harm equipment and result in a host of serious issues, ranging from leaks and unplanned shutdowns to damaging the environment and human health. The aftermath of corrosion isn’t cheap. According to the National Association of Corrosion Engineers(NACE), the “total annual cost of corrosion in the oil and gas production industry is estimated at $1.372 billion.” One of the ways to manage corrosion effectively is to use stainless steel pressure gauges rather than ones made of copper alloys or other materials. 

The Problem With Sulfur

Sulfur is abundant in nature and, in fact, essential for life. Found in both plants and animals, this element appears on earth mostly as a variety of organosulfur compounds (OSC). Therefore, it’s little surprise that fossil fuels, which come from ancient organic matters, contain varying amounts of sulfur – from 0.1% to 5.0% by weight. 

The sulfur found in crude oil is mostly OSC, but there are also small amounts of elemental sulfur (S) and hydrogen sulfide (H2S). The latter, with its characteristic “rotten egg” smell, is particularly problematic. The combination of water and hydrogen sulfide can cause sulfide stress cracking (SSC), a form of hydrogen embrittlement, in welded areas and affect microstructures. H2S is also an extremely dangerous health hazard, causing breathing and nerve damage, and, in high enough concentrations, death.

Sweet vs. Sour Crude Oil

Crude oil with less than 0.5% sulfur content is considered “sweet.” The small amount of sulfur makes sweet oil extraction, transportation, and refining easier and safer. “Sour” crude, on the other hand, contains more than 0.5% sulfur. Due to this higher concentration, sour crude can corrode equipment and cause serious damage. 

As an interesting side note, early prospectors actually tasted crude oil to get an estimate of its sulfur content. When the sulfur content is low, the oil is mildly sweet on the tongue. When the sulfur content is high, its taste is less pleasant.

NACE Standards

NACE Internationalfocuses on finding ways to “protect people, assets, and the environment from the adverse effects of corrosion.” Recognized all over the world, this organization provides updated standards that cover all industries where corrosion is an issue.

NACE international standards MR0175 and MR0103 are specifically aimed at the oil, petrochemical, and natural gas industries. MR0175 covers materials recommended for use in processes containing H2S. MR0103 covers metallic materials resistant to sulfide stress cracking in corrosive oil refining environments.

WIKA’s Stainless Steel Pressure Gauges

To provide the oil and gas industry with the instrumentation it needs for safe and efficient operations, WIKA manufactures stainless steel gauges in compliance with NACE standards, and offers an optional material certification that documents the appropriateness or suitability of the material used in our gauge for sour gas environments. WIKA’s XSEL® process gauge Model 23x.34, for example, is a pressure gauge whose bourdon tube, pressure connection, and all wetted parts are made of 316L stainless steel. Through finite element analysis (FEA) and lab testing,WIKA engineers have validated their 316L stainless steel pressure gauge for the most critical operating conditions, in accordance withISO 15156-3/NACE MR0175.

Model 23x.34 works very well in corrosive environments of both gaseous and liquid media. It has excellent load-cycle stability, is shock resistant, and can measure positive pressures up to 30,000 psi (2,000 bar). Its case is made of fiberglass-reinforced thermoplastic and can be dry or filled with glycerin or silicone. All the materials used in this stainless steel pressure gauge meet the recommendations and guidelines established in NACE standards MR0175 and MR0103. 

For NACE-compliant sour gas service, discover WIKA USA’s range of stainless steel pressure gauges with material certificates, as well as our professionals’ expertise in pressure measurement and the oil and gas industry.

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