Sour service

For sour service, National Association of Corrosion Engineers (NACE) MR-01-75 requires that steel material have a Rockwell C hardness of less than 22 and contain less than 1% nickel to prevent sulfide stress cracking. 

Note There are also other grades of casing available from various manufacturers. For example, Lone Star offers steel grades SS-95 for sour service, S-80 and S-95 for nominal service. Mannesmann offers a C-90 for sour service and SOO-95, 124, 140 for high-strength service. There is also available a tentative API grade V-150 = 150,000 psi, = 180,000 psi), which has... 

Hardness, including surface hardness, especially for materials for sour service or environments in which stress corrosion cracking is expected. It is also important where erosion corrosion is likely ... 

Sour-service standards, which specifies alloying and processing, homogeneous microstructure, and segregation control... 

B. D. Craig, T. V. Bruno, W. M. Buehler. Complexities of Failure Analyses in Sour Systems. Canadian Welding Society/American Society for Metals conference Materials and Welding for Sour Service and Low Temperature Service . Calgary, Alberta, Canada, 1997-11-20/21. 

Another factor in the costing of an injection well is the choice to use an existing well versus drilling a new well. It may be cheaper to work over an existing well and recomplete in the target zone than to drill a new well. However, it is very important that the re-used well is suitable for high sour service. 

Most copper alloys are unsuitable with ammonia, sometimes in even trace amounts and for wet sour services. Most are corroded by caustics. Some brass alloys contain zinc in excess of 15%. Unless properly inhibited by arsenic, antimony, or phosphorus, such alloys can dezincify in brackish or saline waters. To evaluate copper alloys, contact an alloy specialist or the copper alloy trade organization ... 

For upset conditions, indicate autoretrigeration, liquid water, wet sour service, carry-over of crack-inducing agents or corrodents, etc. Consider start-ups, shut-downs, regeneration, presulfiding, loss of flow, etc. 

A rutile electrode normally gives high weld hydrogen contents. Sour service... 

Presence of CO2 remains the greatest threat to the integrity of oil and gas assets in a production enviromnent. However, due consideration must be given to other chemical constituents that may influence the corrosivity of CO2, for example, H2S, which is commonly present in hydrocarbon fluids. National Association of Corrosion Engineers (NACE) publication MR0175 defines sour service as the critical concentration of HjS in terms of its partial pressure equal to 0.05 psia. 

Nickel (Ni). Nickel is the most important austenite stabilizer. The type 304 austenitic stainless steel, for example, has 8% nickel for a chromium content of 18%. Thus, depending upon the chromium content, the nickel content has to be adjusted so that the required austenitic structure could be obtained. Austenitic steels have good weldability. They exhibit good toughness at lower temperatures. Nickel content beyond 8% adds to the corrosion resistance of steel. Higher nickel content is, however, not desirable for sour service. 

Modified Cr steels and duplex stainless steels are used in sour service at elevated temperatures. Cr steels showed no pitting even at high chloride concentrations. This is because of the absence, or extremely low level, of oxygen in the fluids. 

The application of duplex stainless steels in sour service is still a subject of discussion (Heselmans et al., 1997 Schofield and Felton, 1997 Smith and Fowler, 1997). Although duplex steels are highly resistant to localized chloride-induced pitting, in severe... 

Processes or conditions involving wet hydrogen sulfide, that is, sour services, and the high incidence of sulfide-induced HlC may result in sulfide stress cracking (SSC), which has been a continuing source of trouble in the exploration and exploitation of oil and gas fields, and the subject of many international standards [22]. However, similar problems are encountered wherever wet hydrogen sulfide is encountered (e.g., acid gas scrubbing systems, heavy water plants, and waste water treatment). 

An industrial example for which standards have been feverishly developed in recent past is the oil and gas production handling sour (HjS rich) fluids, an extremely corrosive environment for even the most noble alloys. Over the past 20 years a number of laboratory test methods to predict the behavior of steels in sour service have been developed, for example, in Fig. 11.28. 

A Test Method to Determine the Susceptibility of Cracking cf Linepipe Steels in Sour Service. OTI 95 635. Sudbury, U.K. Health and Safety Executive (HSE), 1996. 

GPa. Current hardness limitations for sour service restrict the use of these alloys to less than the maximum strength. 

Particularly common in the oil and gas industry, where the use of steel pressure vessels is widespread, the risks of HlC should be considered when hydrogen snlfide partial pressure becomes greater than 3.5 mbar. Carbon steel pressure vessels should not be affected by HlC damage where HjS levels are lower than this figme in a normal service life cycle. HlC is prevalent in wet HjS environments, which is often known as sour service such cracking over a prolonged period of time without inspection will reach a critical point and the steel component, i.e. pressure vessel, could easily fail. 

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