Thursday 30 May 2013

Middle East Coronavirus Called 'Threat To The Entire World'

A nurse walks towards the Roger Salengro Hospital in Lille, France, where two patients were diagnosed with a coronavirus related to SARS.
A nurse walks towards the Roger Salengro Hospital in Lille, France, where two patients were diagnosed with a coronavirus related to SARS.
Michel Spingler/AP
If you've been following the news out of China about the latest bird flu and its threats to humans, may we direct your attention toward the Middle East for a minute?
A virus that many people had been calling a SARS-like virus because of the severe respiratory condition it has triggered in quite a few people has an : Middle East Respiratory Syndrome Coronavirus, or MERS-CoV. The World Health Organization has now , despite the group's preference not to put a place in the name of a virus.
Why's that? Well, the place name could lead to "unnecessary geographical discrimination that could be based on coincidental detection rather than on the true area of emergence of a virus," WHO says.
That said, we know that WHO wasn't fond of the provisional "SARS-like" designation for virus either.
All the cases reported so far have a link to the Middle East — the people either lived there, had traveled there, or were in close contact with an infected person who'd been there.
Now, there's in The Lancet that two people in France fell ill with the virus, too. A 64-year-old man who had visited Dubai in April was hospitalized in northern France later that month. A second man, who hadn't traveled abroad recently, shared a hospital room with the first patient for a few days in late April. At the time, the doctors didn't suspect the first man was infected with MERS-CoV.
The second man, a 51-year-old with a blood clot deep in his arm, was discharged at the end of April. But eight days later he showed symptoms of MERC-CoV infection. By then, the first man had been diagnosed with the virus, so the second man was quickly referred to specialists.
His condition deteriorated rapidly. Within days he experienced respiratory and kidney failure. The doctors report that he remains in intensive care. The first man died May 28.
The doctors write in The Lancet that these cases suggest the incubation period for the virus may be 9 to 12 days, longer than previously thought.
All told, the fatality rate for confirmed infections with the virus has been , according to WHO, based on so far. But the true fatality rate won't be clear until the fuller extent of cases, some probably much milder, becomes known.
But WHO is worried about MERS-CoV, even more than the H7N9 bird flu. "Looking at the overall global situation, my greatest concern right now is the novel coronavirus," said , director-general at WHO, in . "We understand too little about this virus when viewed against the magnitude of its potential threat. Any new disease that is emerging faster than our understanding is never under control. These are alarm bells and we must respond. The novel coronavirus is not a problem that any single affected country can keep to itself or manage all by itself. The novel coronavirus is a threat to the entire world."

Thursday 16 May 2013

FULL WELDED ENCIRCLEMENT SLEEVES

 MINIMUM THICKNESS FOR REPAIR GIRTH WELDS IN CORRODED
The minimum weldable thickness is numerically assessed in this work, as a function of pressure during the welding operations of a corroded gas pipeline, according to the approach by Battelle. The minimum weldable thickness is found to increase when the flow rate of the transported gas in the section being repaired increases. Integrtity of the reapairs is assessed, and alternative measures to momentarily increase the flow in the area of the repair are evaluated. .

1.- INTRODUCTION
Companies transporting natural gas have thousands of miles of buried pipes, which date back to the 40’s and 50’s. At that time, protection techniques against corrosion (e.g. protective coatings and cathodic protection) were not well developed, and the companies commonly face defects due to corrosion degradation. Worlwide the most common way to repair gas leakage is to change the defective portion of the pipe. To do this, however, it is necessary to stop pumping gas and vent the affected portion of the line. Where there are no loops to deviate the gas flow, doing this means stopping provision of gas to some areas, with the consequent losses to the users and the transporting company. One of the alternatives available to minimize service losses and restore serviceability of corroded lines is the use of full encirclement sleeve repairs.
Full encirclement welded sleeves are used to repair defects in underground gas pipelines, see Figure 1. The reinforcements consist of two half sleeves welded lengthwise, which are also welded circumferentially to the pipe if there is a gas leakage or other severe defects. Standard designs are found in API RP 1107 [1] . These reinforcements habitually are carried out in areas where local loss of thickness or gas leakage are detected, generally due to corrosion. When a through-the-thickness defect is detected, reinforcements with O'ring and venting valve are used to prevent gas form reaching the welding operations. This kind of repair requires a circumferential (girth) fillet weld to the pipe, to prevent gas leakage during subsequent service. The possibility of repairing gas leaks is probably the most important advantage of welded sleeve repairs over competeing techniques, such as clock springs [2].
In-field welding of these sleeves is normally a difficult task. Usually, short times and poor soil or weather conditions make cutting, handling and welding the sleeves to the buried pipes require especially trained personnel and equipment. It is no surpris e, therefore, that several weld repairs fail in different ways. These failures have in many cases been the driving force for changes and improvements in the fabrication of the sleeves, field welding procedures and non destructive testing of the repairs.
If not properly trained, due to the fear to burn through the pipe, welders tend to minimise the welding time and use high depostion rates, which are obtained with cellulosic electrodes. The use of cellulosic-coated  electrodes is a common practice in the construction of pipelines but for welds made onto in-service pipelines there is a serious risk of reduction in ductilility and toughness by Hydrogen Cracking [3] the specification of low-hygroscopic basic electrodes is now recommended, along with specified preheats and heat imputs to avoid high cooling rates and burn through [4] .
The occurrence of burn through during the circumferencial reinforcement-to-pipe weld is governed by the thickness of the pipe being welded and the penetration of the molten pool during welding. Weld penetration depends on weld heat input, heat dissipation along the pipe and the reinforcement, and the dissipation through the gases inside (natual gas) and around (air) the pipe. This last dissipation depends upon temperature and flow parameters, pressure and flow tate. The controlling parameter is the gas flow rate.