Materials & Welding: 2007

Wednesday, December 19, 2007

Stainless steel specialist course

Stainless steel specialist course
ISSF has delivered another e-learning module for the Stainless steel specialist course. The Stainless steel specialist course Read more...

YU445 stainless grade

YU445 stainless grade
Yieh United Steel Corp. (Yusco) has added a new stainless steel grade YU445 to its catalogue. With high Cr, extremely low C, Read more...

Wednesday, December 12, 2007

The combination of stress corrosion resistance, low density, low modulus and non-magnetic properties possessed by titanium alloys makes many of them suitable for service in sour conditions. Titanium has been successfully used in a variety of sour service applications in the drilling, logging and production phases of the oilfield industry. Sour service environments are defined by NACE International specification MR0175 as "fluids containing water and hydrogen sulphide (H2S) that is at a total pressure of 0.4MPa (65psia) or greater, and if the partial pressure of hydrogen sulphide in the gas is greater than 0.0003MPa (0.05psia)". The acidity of the environment is below pH 3.5, and carbon dioxide, and chlorides are also normally present. Titanium alloys are available in a range of strength levels, and this permits selection for a wide variety of oilfield and geothermal applications including pipework, manifolds, valves and pumps, chokes, kill and booster lines, instrument casings and drill strings. The lower strength alloys such as Grades 2 and 12 are currently used in sour water piping systems, for low pressure lines and for wellhead seal rings. Medium strength alloys (Grades 25, 28 and 29) are used for offshore sour service taper stress joints providing maximum flexibility in highly stressed dynamic production riser systems. Current applications for the highest strength grades (Beta-C, Ti-6-2-4-6), most corrosion resistant because of their high molybdenum content, include packers, safety valves, springs and formation test components. The current revision (2001) of MR0175, lists the above seven titanium alloys, (see table), have been tested and found acceptable for direct exposure to sour environments. Conditions for supply, including heat treatments, are detailed in the specification as well as the maximum hardness allowed for each alloy. Name/ASTM Ref Composition UNS Ref Commercially Pure Gr.2 Ti - 99% R50400 Grade 12 Ti-0.8Ni-0.3Mo R53400 6-2-4-6 Ti-6Al-2Sn-4Zr-6Mo R56260 Grade 28 Ti-3Al-2.5V-0.1Ru R56323 Grade 25 Ti-6Al-4V-0.5Ni -0.05Pd R56403 Grade 29 Ti-6Al-4V-0.1Ru R56404 Beta-C, Grade 19 Ti-3Al-8V-6Cr-4Zr-4Mo R58640 The widely available 'workhorse' titanium alloy, Ti-6Al-4V, (ASTM Grade 5) is not currently listed, but is nonetheless used as a standard material for drilling and non magnetic instrument housing applications in sour down hole environments. The relatively short exposure times of measuring and logging while drilling operations, (MWD and LWD), are a factor in the success of such applications. Other titanium alloys, including ASTM Grades 7,9,18,21,23,24 and Ti-4Al-4Mo-2Sn (Ti-550) similarly not listed in the MR0175 list may also be expected to perform satisfactorily to specific levels of exposure in sour conditions. Any alloy may be release tested as satisfactory for operation under the proposed service conditions, pH, H2S, CO2, chlorides etc., at an appropriate temperature, for example in accordance with the guidelines for the selection and testing of corrosion resistant alloys for sour service, in the European Federation of Corrosion Handbook EFC 17. CAUTION: Special attention is required when certain down hole treatments are applied where titanium equipment is in use. ACIDISING: Hydrofluoric acid (HF) and Hydrochloric acid (HCl) are commonly used for sour service production. All titanium alloys are rapidly attacked by HF, even in very dilute concentrations and in fluoride containing solutions below pH7. Titanium should not be specified or used if regular HF acidising is anticipated. If in exceptional circumstances titanium equipment is accidentally subjected to exposure for very short periods to hydrofluoric acid or active fluorides, limited general corrosion may be expected. Once the HF is removed or has been reduced to insignificant levels, (less than 20ppm), corrosion will not continue. The protective titanium oxide film will reform spontaneously, restoring the original level of corrosion resistance. Similar considerations apply to titanium when uninhibited hydrochloric acid, (HCl), or HCl/HF mixtures are used. Inhibited hydrochloric acid, may be used with titanium in accordance with supplier instructions. Alternative acidising solutions, including a selection of organic acids, to which titanium alloys are resistant should also be considered. METHANOL : Methanol is one of the few specialised environments which may cause stress corrosion cracking (SCC) in titanium alloys. SCC failures have occurred in dry methanol, methanol/acid and methanol/halide mixtures. Water is an effective inhibitor and will maintain the passivity of titanium alloys in oilfield environments if present in the weight % concentrations identified in the following table: Titanium Alloy Grade %water- Intermittent exposure % water - Sustained exposure 1,2,7,11,16,17 1.5 2.0 9, 12 2.0 2.0 28 2.5 3.0 5,23 3.0 3.0 19, 29, 6-2-4-6 5.0 10.0 Intermittent exposure = short term non continuous Sustained exposure = long term continuous MERCURY: Susceptibility of some titanium alloys to SCC in mercury has been demonstrated under clean conditions in the laboratory. In the field there are no reported cases of liquid metal embrittlement of titanium by mercury. Titanium alloys are highly resistant to solutions of mercury salts over the pH range 3 - 11,at metal temperatures well in excess of the boiling point of the solution.

254 SMOR for oil platforms

254 SMO® for oil platforms
Outokumpu has made the first supply of its high-performance super-austenitic grade 254 SMO® for an offshore project in Qatar, Read more...

Wednesday, November 28, 2007

Minimize Hydrogen in Steel

Hydrogen in steel is bad news for mechanical properties and the metal's chemical characteristics. A recent Key to Steel article details the chemistry of hydrogen problems. The feature also discusses the sources of hydrogen pick up in steel production from the addition of materials and components, such as lime and coke.

Thursday, November 22, 2007

Can Elliptical Holes in Bridge Beams Stem Cracking?

Albany Times Union
State transportation engineers are watching closely to see whether four experimental holes cut in the steel of the Patroon Island Bridge will lead to a solution for a persistent problem with cracking on the bridge's floor beams. Workers suspended beneath the westbound lanes cut elliptical holes in two floor beams in an effort to help increase bridge flexibility.

New database on the properties of solid materials

The National Institute of Standards and Technology has published a new database on the properties of solid materials at temperatures ranging from cryogenic to room temperature. Officially known as NIST Standard Reference Data Database #152, the Cryogenic Materials Properties Database is available online, free of charge.
Learn more.

Australian Company to Use Waste Plastic to Make Steel

Asia Pulse Pte Ltd.
Australian steelmaker OneSteel has signed an agreement with the University of NSW in which waste plastic will replace up to 30% of the coke and coal used in their steelmaking process. The technology has been tested for the past two years at OneSteel's Sydney plant in Rooty Hill.

Wednesday, November 21, 2007

Overlay welding strip

Sandvik has introduced a new welding strip titled Sandvik 24.29.5.Lcu, for overlay welding. Suitable for oil and gas applications, Read more...

Monday, October 22, 2007

Websites: Quick Reference

An exhaustive list of links related pressure vessels, engineering & Construction related for your ready reference. (Most of them related to UK, but useful)

Request to members: when browsing these sites, and if you any good info which is interesting you may share in the forum for the benefit of members, else a link to the topic if the file is big

Thanking you for your cooperation!

Organizations and associations

Organization URL

AEA Technology plc www.aeat.co.uk

American Bureau of Shipping www.eagle.org

American Consulting Engineers Council www.acec.org

American Institute of Engineers www.members-aie.org

American Institute of Steel www.aisc.org

Construction Inc.

American Iron and Steel Institute www.steel.org

American National Standards Institute www.ansi.org

American Nuclear Society www.ans.org