Minutes of EFC WP 15. Corrosion in the Refinery Industry

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1 Minutes of EFC WP 15 Corrosion in the Refinery Industry Shell Pernis, Netherlands 10 April Welcome by Shell Pernis Wim Verstijnen welcomed the meeting and provided a short overview of the Shell Pernis refinery. The refinery was first commissioned during 1902 and has now been processing crude oil for more than 100 years. The refinery currently processes 20 million tons per annum (400,000 bbl/day), making it one of the largest refineries in Europe. 2 Presentation of the meeting - WP 15 Activities 2.1 Presentation of the meeting 23 persons attended the meeting and shortly introduced themselves. Apologies have been received from 35 persons. 2.2 WP15 Activities Francois Ropital provided a short overview of the activities of the working party. It has previously been decided to hold a meeting twice annually. One meeting in the spring, and one meeting coinciding with the annual Eurocorr conference. This year the Eurocorr conference will be held in Budapest, Hungary from 28 September to 2 October. The conference will include a symposium titled Maintenance and Reliability in Refining, sponsored by EFC WP 15. Cooperation with other EFC Working Parties was discussed. The format of such cooperation will still be discussed further but is likely to be joint meetings and Eurocorr sessions where topics of mutual interest will be presented and discussed. The meeting voted on their areas of (other WP s), and selected the following three Working Parties (in order of preference) for to be contacted for future joint meetings: WP 3: High-Temperature Corrosion WP1: Corrosion Inhibition WP 13: Corrosion in Oil and Gas Production

2 3 WP 15 Publications 3.1 Selected papers for EFC Refinery Corrosion publication John Harston continues to collection papers for a planned EFC WP15 publication. 3.2 EFC Guideline No. 40 Prevention of Corrosion by Cooling Waters This document is now finalised and will be available at the Eurocorr Conference. 3.3 Proposals for New EFC WP15 Documents Proposals for new publications were briefly discussed during the meeting. These are: A compendium of corrosion problems per refinery unit. Guidelines on where to inspect for naphthenic acid corrosion damage. Guidelines for the quantification of corrosion damage detected by visual inspection (this subject will be a discussion topic during the next meeting). A reference list of good literature. 4 Monitoring of Corrosion 4.1 Pulsed Eddy Current Measurements Shell Global Solutions gave a presentation on the use of the pulsed eddy current (PEC) technique for both thickness measurements, and corrosion monitoring.. The presentation dealt with the following topics: What is PEC (how does it work, etc.) Examples PEC Corrosion Monitoring Key points PEC functions by setting up a magnetic field in ferro-magnetic materials, and then measures the eddy current decay when the field is switched off. The probe does not need to have direct contact with the steel surface under measurement. This means that measurements can be made through almost any non-metal, up to a temperature of 500ºC. The technique has excellent same spot repeatability (0,2% of wall thickness). As an inspection tool, PEC has been applied in the following tasks: CUI (grid with a large number of measurements). LPG sphere leg inspections (through fire proofing). Riser inspection in the splash zone of offshore platforms. Minutes of EFC WP15 Corrosion in the Refinery Industry 10 April

3 Under-water inspections using remotely operated vehicles (ROV). It was mentioned during the presentation that Shell Global Solutions has filed a patent application for the use of pulsed eddy current (PEC) as a corrosion monitoring tool. In such applications it is important to note that the following: Measurements need to be made in exactly the same spot each time in order to achieve the desired repeatability (< 0,2% of wall thickness) The technique measures an average thickness over an area dependent on the stand-off distance and size of probe used. Can be used at high temperature (The highest temperature monitored so far is 500ºC). It is best to cut a hole in the insulation in order to move the probe as close as possible to the pipe wall. Multi-element fixed probes are now available. Corrosion monitoring of the outlet piping of an air cooler was presented as an example. Unusually high corrosion rates were detected in this application. The PEC monitoring tool provided flexibility, easy of use, and parallel measurements with ordinary UT. In this application it was important to take parallel temperature measurements, as the magnetic properties of a material is also dependent on the temperature. The presentation was closed by capturing the key points of using PEC: Simplicity Mobility Versatility During the discussion that followed, additional information was provided: The current PEC technique that Shell Global Solutions is marketing (licenses are now available) is limited to a minimum pipe size of 3,5. Wall thickness measurements in the range 3 mm to 35mm can be made. Although for monitoring, where signal quality is most critical, an upper thickness limit of approximately 25mm applies. The tool is not optimum for measuring pitting and other localised corrosion damage, as an average wall thickness is measured. This in turn is dependent on the probe size and stand-off distance (30 mm diameter at a 10 mm stand-off distance). Wall thickness measurements can be made through lagging material if this is constructed in aluminium or stainless steel. Lagging constructed in galvanised steel interferes with the measurements. 4.2 FSM-IT Field Experiences An overview of experiences with the use of FSM-IT in refineries was presented by CorrOcean. The presentation provided an overview of the development of this technique for corrosion monitoring. The first FSM installation was made in 1991, Minutes of EFC WP15 Corrosion in the Refinery Industry 10 April

4 while the first sub-sea installation was commissioned in An explanation of the FSM principles then followed. During the development of FSM-IT it was focussed on the following client requirements: Flexibility and ease of use. An upper temperature limitation of 500ºC. Fast response in order to monitor corrosion effects associated with crude changes. These requirements as well as field experience have resulted in improvements of the following: 1. Reference Plates a. Fixing method. b. Plasma spraying. 2. Current Feed a. Junctions. b. Current feed ferrule. c. Wire cores in pure Ni. 3. Cables. a. Insulation. b. Ceramic braiding. c. Pure Ni for high temperatures. 4. Insulation procedures. a. Free from air gaps. b. Free from steel wires. 5. Pipe support interference. 6. Service accessibility. The presentation concluded with a statement that the upgrade version of FSM-IT can now be considered reliable with a measurement accuracy of 0,5%. Fast corrosion information can be obtained with a high level of repeatability. 5 Corrosion under Insulation (CUI) 5.1 Inspection of Insulated Piping Scanraff Refinery in Sweden presented an overview of their inspection and maintenance program for insulated piping. This refinery, commissioned in 1975, is Minutes of EFC WP15 Corrosion in the Refinery Industry 10 April

5 located 100 km north of Göteborg, and currently processes 10 million tons per annum. A corrosion control program that includes the renovation of pipe ways was started in This program is now 70% complete and involves the following: Scaffolding of all pipe ways. Removal of all insulation. Visual and UT inspection (every 6 m) of all piping. New painting of all piping systems that operates at temperatures less than 200ºC. This program has revealed that 90% of the detected damage to piping systems is external, and does not require a plant shutdown to mitigate. Experience with inspection techniques has indicated RT provides good documentation, but is slow and has high cost. Eddy current techniques have low reliability, and also needs removal of the insulation. UT combined with a total surface visual inspection have proved to yield the best results. 5.2 CUI Best Practices An open discussion on CUI best practices followed. Regarding NACE RP0198 it was stated that most refineries considers this standard to be limited to new plants, and that only a few ideas have been adopted for existing refineries. Almost all refineries have a back-log regarding inspection and maintenance of piping systems. It seems that this is due to money/budget limitations and not due to technology limitations. CUI is more of a management problem, than a technical problem. Exxon-Mobil has been working in long-term solutions for this problem. This is based on seriously considering the use of thermally sprayed aluminium instead of painting systems, replacement of some piping systems in stainless steel (austenitic and duplex), and wrapping of austenitic stainless steel. Al-spray is seen by the meeting a good solution which can be applied, at marginal extra cost, for new constructions. The technique can be either flame sprayed or plasma sprayed. The discussion centred around in situ application Al-spraying, for existing equipment and piping. Potential problems with fire permits, accessibility and workmanship seem to arise. Exxon-Mobil will provide more details and feedback in a next meeting about the possibilities for in situ application. The meeting agreed that new lateral thinking, such as the use of plastic materials (including fibreglass, reinforced plastics) and/or stainless steel, is needed in this area. The perception in refineries is still that the non metallic materials are weak, easy to fail in fire conditions and that their quality is poor and difficult to control It was concluded that a state-of-the-art report on such alternative materials and an update of CUI inspection methods should be prepared during Minutes of EFC WP15 Corrosion in the Refinery Industry 10 April

6 6 Corrosion Survey on Hydrotreatment 6.1 Review of the discussion during the November 2002 meeting. Only few comments were done on last meeting discussions. Suggestions were proposed to exchange experiences on neutralisation procedures for ammonium chloride salts. Another point of discussion was the ageing of steels for old hydrocrackers. 6.2 Hydrogen Bake-outs Ion Science gave a presentation on using the hydrogen flux measurements to control/investigate H-outgassing for hydroprocesing reactors. Other areas of employment are corrosion monitoring. The tool is currently being used in high temperature NA-corrosion monitoring programme besides other CM tools. The quick response time and easy application of the tool has advantages over other tools which might be a reason to use it besides other tools or as stand alone. 7 Sour water service - SOHIC SOHIC joint survey EFC/EPERC initiative will be discussed during next WP15 during Eurocorr 2003 with the EPERC group. NACE Standard MR , "Materials Resistant to Sulfide Stress Cracking in Corrosive Petroleum Refining Environments," by Task Group 231, was ratified by the NACE Board at CORROSION/2003. The new NACE MR-0103 provides guidelines to address sour service requirements for refinery service, as opposed to the commonly used MR-0175, which has been designed originally for oil & gas exploration services. Question was raised if the new will MR Publication will effect the currently used procurement standards, which are now commonly based on MR Next meeting The "autumn meeting" will be hold on September 30 th Conference in Budapest. during the Eurocorr During the Eurocorr 2003 a refinery corrosion session will also take place titled Maintenance and Reliability in Refining. Acknowledgement The EFC WP 15 Refinery Corrosion Group would like to express thanks to Shell Netherlands for hosting this meeting with special thanks to Wim Verstijnen for the organisation of the meeting. Minutes of EFC WP15 Corrosion in the Refinery Industry 10 April

7 Minutes of EFC WP15 Corrosion in the Refinery Industry 10 April