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Changes to H2S testing...

24/11/2010

Improved H2S risk analysis with IP 570 (ISO 8217) & ASTM D7621

IP 570 for the ‘Determination of Hydrogen Sulfide in Fuel Oil – Rapid Liquid Phase Extraction Method’ is now accompanied by an equivalent new ASTM method D7621. IP 570 is the only H2S method to be included within ISO 8217 Marine Fuel specification and represents a significant development in testing.

Challenges facing the Marine Industry
Hydrogen Sulfide (H2S) has long been acknowledged as a potential safety issue in the marine industry and regulations call for all marine fuels to be screened for H2S prior to loading. However traditional tests may not detect low levels of H2S or fully evaluate whether entrained H2S might be released from the fuel during onboard storage and handling.

The industry previously used a number of lengthy analytical techniques such as test method IP 399 for the determination of H2S in marine fuel and refinery feedstock for marine blends. However this traditional 2 to 3 hour wet chemistry test is complex and requires a trained chemist to obtain a result. This duration, or availability of trained chemists, means results may only be available after a vessel has put to sea; consequently high demurrage costs may be incurred whilst ships are quarantined on the terminal berth waiting for test reports. IP 399 is currently under review and the marine fuels industry has decided to adopt new improved analytical technology (IP 570), which is suitable for field analysis, in the latest fuel specification ISO 8217.

Why measure H2S?
H2S gas is highly toxic to humans, animals and aquatic life; it also has potential to corrode pipelines, storage tanks and other ship components which may cause operability problems, including engine breakdown. Some marine residual fuel cargoes may be innocuous when initially loaded but can evolve and produce dangerous levels of H2S in the vapour space during transit. The key issue is to measure the potential that a fuel could have to release H2S over a period of time under suitable conditions when that fuel is transferred, heated or agitated by the rolling action of the ship. Significant concentrations of H2S are known to accumulate in the headspaces of storage tanks and marine fuel bunker cargoes and pose a serious and potentially lethal hazard.

H2S Analyser meets the challenges of latest marine fuel safety specifications ISO 8217
A new unique, advanced technology, H2S Analyser has been developed by SetaAnalytics to determine the potential amount of entrained Hydrogen Sulfide (H2S) that could be released by a fuel. The H2S Analyser fully complies with the IP 570 method and has also been designed for use with fuels and associated feedstocks. It will also analyse Heating Oil, Gas Oil, Diesel, Distillate Marine Fuels and Kerosene, including aviation fuels.

This new Analyser is unique in that it measures the H2S in the fuel and hence is a much better indicator of the potential release of H2S in a specific fuel. Alternative vapour space measurements do not quantify the risk.

The H2S Analyser uses advanced integrated analytical sensor technology which removes operator subjectivity and gives reliable, rapid and precise measurements. The instrument offers a cost effective solution for H2S measurement involving no expensive chemicals or the need for analytical test preparations by a trained laboratory technician. Its fast repeat measurement capability offers a much improved means of assessing required remediation treatment of feedstock components and off-spec fuel products.

In operation, a weighed 5 ml sample of fuel is mixed with a proprietary diluent whilst being heated at 60°C to maximise solubility and optimise release of the entrained H2S. The sample is purged with air at a fixed flow rate and the liberated H2S passes over a proprietary H2S selective sensor. The sensor output is integrated and the amount of H2S in the fuel calculated in mg/kg. The instrument can measure over the range 0 to 250 mg/kg (ppm) and total test duration from sample introduction to result is 15 minutes.

Case study - A leading Global Oil Company Refiner reports on using the H2S Analyser:

“We are now able to run H2S determination tests in our laboratory and no longer need to outsource IP 399 tests and wait for results. This means improved/shorted tank turnover time and product release. In addition we now have better control of production operations, for example being more easily able to identify bad actors in our blending streams. Also better control of our H2S ‘scavenging’ by being able to test multiple samples in a short test time which allows us to fine tune the use of additives in our products. This ability represents significant potential cost savings for us and a more stable product for our customers“.

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