To avoid failures due to hydrogen embrittlement, it is important to know the amount of hydrogen absorbed by certain steel grades under service conditions. When a critical hydrogen content is reached, the material properties begin to deteriorate. The hydrogen uptake and embrittlement of three different carbon steels (API 5CT L80 Type 1, P110 and 42CrMo4) was investigated in autoclave tests with hydrogen gas (H2) at elevated pressure and in ambient pressure tests with hydrogen sulfide (H2S). H2 gas with a pressure of up to 100 bar resulted in an overall low but still detectable hydrogen absorption, which did not cause any substantial hydrogen embrittlement in specimens under a constant load of 90% of the specified minimum yield strength (SMYS). The amount of hydrogen absorbed under conditions with H2S was approximately one order of magnitude larger than under conditions with H2 gas. The high hydrogen content led to failures of the 42CrMo4 and P110 specimens.

TX 75083-3836 U.S.A., fax 01-972-952-9435. AbstractIn its most simple case the tapered round thread of casing or tubing is sealed by a thread compound i.e. a special kind of grease containing solids. To date, dopes that contain lead and other heavy metals, so called API-modified thread compounds, have found widespread use. This is surprising since metal free or even biodegradable thread compounds are available. OMV decided to initiate a project evaluating environmentally friendly thread compounds. To find out which of the non toxic products have a good sealing performance, laboratory tests were carried out. Due to the lack of a standardised sealing tightness test for thread compounds a new benchmark test method was developed.In the past, there have been two approaches for testing the "tightness" of the various thread compounds: the simplified grooved plate tests and the full scale tests on high pressurized and mechanically loaded pipes. Unfortunately, the plate tests do not provide reliable results, and the full scale tests are very expensive.For the test described in this paper threaded pipes in small standard dimensions were used; relatively low testing pressures and no mechanical load were applied. Two parameters were implemented in a new way: temperature load and test duration. Temperature load was applied for the whole duration of the tests. The usual test duration was approximately two weeks but during the development phase some tests were run for several months.This new combination of test equipment allowed inexpensive testing of many different thread compounds simultaneously. Not only performance differences between thread compounds could be examined, but also other relevant parameters such as varying temperature, pressure, torque etc. could be easily recorded.After this new method had been refined seven environmentally friendly thread compounds were selected for testing, two of them being universal compounds. For reference purposes API-modified thread compounds from two different manufacturers were tested. Enormous differences in the sealing abilities of the products were found.Life cycle costs can actually be reduced through the use of an inexpensive and effective thread sealing compound. Savings are possible due to a reduction in the number of workovers, of expensive down time and lost production.It was clearly shown that some of the environmentally friendly thread compounds perform better and are cheaper than the old fashioned toxic API-modified compounds.

Stainless steels have a great variety of potential applications in the petroleum industry, mainly as an alternative to carbon steel in corrosive environments. Within a number of media that can cause corrosion problems with these materials, only chloride solutions and hydrogen sulfide are of importance in oilfield service.A reliable tool that permits the proper selection of stainless steels has yet been missing. In order to provide engineering diagrams for this purpose, pitting and stress corrosion cracking (SCC) tests were performed. Specimens were exposed to NaCl solutions containing from 3 to 100,000 ppm Cl À at temperatures from 40 to 200 8C. This test configuration was chosen to give a better representation of actual service conditions than accelerated standard test procedures do.Tested materials were the austenitic stainless steel grades 321, 316Ti (API LC30-1812) and 254 SMO, and 22Cr duplex (austenitic-ferritic) steel (API LC65-2205). Based on an optical examination of the specimens, no-risk regions of chloride concentration vs. temperature have been identified. Subsequently, service temperature limits have been deduced for each tested material.Thus, material failures by pitting and SCC can be prevented without overdesigning. The results of the testing series are applicable to all chloride environments without presence of H 2 S, as they have to be handled by primary production equipment, as well as transportation and gas processing facilities.Nichtrostende Stähle haben ein großes Anwendungspotential in der Ö l-und Gasindustrie, da sie eine Alternative zu Kohlenstoffstahl in korrosiver Umgebung darstellen. Von den Medien, in denen Korrosionsprobleme mit nichtrostenden Stählen auftreten könnten, spielen in der Ö l-und Gasindustrie nur chloridhaltige Lösungen und Schwefelwasserstoff eine Rolle.Bisher gab es keine zuverlässige Möglichkeit zur richtigen Auswahl eines geeigneten nichtrostenden Stahls. Lochkorrosions-und Spannungsrisskorrosionstests (SCC) wurden durchgeführt, um Auswahldiagramme erstellen zu können. Probekörper wurden in NaCl-Lösungen mit Chloridgehalten zwischen 3 und 100 000 ppm und bei Temperaturen von 40 bis 200 8C ausgelagert. Diese Testanordnung wurde gewählt, weil sie die Betriebsbedingungen besser repräsentiert als beschleunigte Standardtestverfahren.Die getesteten Werkstoffe waren die Austeniten 321, 316Ti (API LC30-1812) und 254 SMO und ein 22Cr Duplexstahl (API LC65-2205). Basierend auf einer optischen Auswertung der Proben wurden Chloridkonzentrationen in Abhängigkeit von der Temperatur identifiziert, die kein Risiko hinsichtlich eines Lochfraßes bzw. einer Spannungsrisskorrosion darstellen. In Folge konnten Betriebstemperaturlimits für jedes getestete Material abgeleitet werden.Mit Hilfe dieser Kurven können Werkstoffprobleme auf Grund von Lochkorrosion oder Spannungsrisskorrosion vermieden werden, ohne ein Overdesign vorzunehmen. Die Ergebnisse der Testreihen sind für alle chloridhaltigen Medien in Abwesenheit von H 2 S anwendbar, vom Produktionsequipment über die Transportleitungen...

Microbiological methanation is investigated in an underground natural gas reservoir. Since H2 is involved in the process, hydrogen embrittlement of steel must inevitably be considered. Therefore, a routine for testing has been developed and a unique autoclave test bench was designed to simulate field conditions. The 2205 duplex stainless steel (UNS S31803) was investigated. Constant load tests (CLTs) and immersion tests with subsequent hydrogen analyses were performed. The specimens were exposed to different partial pressures of H2 under both dry and wet conditions (with brine). Additionally, the influence of CO2 under wet conditions was covered. Tests were performed at two different temperatures (25°C and 80°C) and lasted for 30 days. In general, the duplex stainless steel shows a good resistance to hydrogen embrittlement, but a significantly higher hydrogen uptake was obtained compared to other steel grades.

A new testing facility for a high-velocity, three-phase fl ow consisting of a gas fl ow loop and a jet impingement rig is described. Flow velocities between the nozzle and specimen have been determined through computational fl uid dynamics (CFD) simulations and by particle image velocimetry. Tests were conducted on typical carbon steels (J55 and C95) that are used in tubings for the gas and oil industry. Flow conditions of a sweet gas condensate well have been applied. Mass-loss rates have been determined after testing times of between 4 h and 168 h using optical profi lometry. Damaged surfaces were investigated using optical and scanning electron microscopy. The effects of material and fl ow velocity on the mass-loss rate have been investigated. Mass loss of specimens under given conditions is determined by siderite formation and increasing degradation of siderite layer by impacts of sand and fl uid droplets. Degradation happens by erosionenhanced corrosion. Normalized steel J55 behaves like a ductile material resulting in a maximumdegradation rate under small impact angles outside the focal spot. Compared to J55 the quenched and tempered material C95 shows a generally lower depth of attack with its maximum degradation under large impact angles, indicating a brittle behavior. Cementite of pearlite may act additionally as a cathode and accelerate corrosive attack. KEY WORDS: carbon dioxide corrosion, carbon steel, erosioncorrosion, erosion-enhanced corrosion, fl ow-induced localized corrosion, fl ow loop, jet impingement, multiphase fl ow 0010-9312/08/000035/$5.00+$0.50/0