TORONTO — The Toronto stock market closed little changed Monday amid weak Chinese data and dealmaking in the Canadian financial sector.Here are the closing numbersTSX — 12,382.67 +9.37 0.08%S&P 500 — 1,642.81 -0.57 -0.03%Dow — 15,238.59 -9.53 -0.06%Nasdaq — 3,473.77 +4.55 0.13%The S&P/TSX composite index was up 9.37 points to 12,382.67 following six losing sessions with pressure coming in particular from base metals stocks.The tepid performance followed a slide of more than 2% last week, leaving the TSX in negative territory for the year.“I don’t think there is going to be anything too much to keep it in positive territory”, said John Stephenson, portfolio manager at First Asset Funds Inc.“You have too much of a resource focus, a market that’s really twinned between two dominant sectors, financials being one and materials/energy being two.”Lululemon Athletica Inc. (TSX:LLL) (Nasdaq:LULU) was also in focus and its shares fell almost 9% in aftermarket trading in New York after CEO Christine Day said she is stepping down. Day will remain in the job until a successor is named. The yoga wear retailer also handed in earnings of 32 cents a share, which met expectations and announced plans to delist from the TSX.The Canadian dollar advanced, up 0.08 of a cent to 98.14 cents US amid a solid report on the housing sector.Canada Mortgage and Housing Corp. said Monday that housing starts were trending at 182,756 units in May compared with 182,971 in April. The trend is a six-month moving average of the monthly seasonally adjusted annual rates of housing starts.But the seasonally adjusted stand-alone annual rate was 200,178 units in May, an increase from 175,922 in April.U.S. indexes were generally listless after registering sharp gains at the end of last week because of a strong jobs report.The Dow Jones industrials was down 9.53 points to 15,238.59, the Nasdaq added 4.55 points to 3,473.77 and the S&P 500 index slipped 0.57 of a point to 1,642.81.Traders also took in an upgrade on the U.S. credit rating from Standard & Poor’s. S&P revised its long-term outlook to stable from negative, citing economic strength and the dollar’s status as a reserve currency. The agency had downgraded the U.S. sovereign rating to AA-plus from its top rating of AAA in 2011.Prices for oil and copper declined as data released on the weekend showed China’s trade, retail sales and other activity in May were weaker than expected, fuelling concerns about the country’s shaky economic recovery.China’s trade surplus rose to $20.4 billion in May from $18.2 billion the prior month. However, export growth slowed dramatically to just one% from a year ago, which was the slowest increase since July 2012. Imports slipped 0.3% from year-earlier levels.“Of those three figures, I’d say that the weak import result is the most worrying as it suggests domestic demand has weakened considerably,” said BMO Capital Markets senior economist Jennifer Lee.Meanwhile in Japan, the first-quarter growth rate was revised up from an annualized rate of 3.5% to 4.1%.Elsewhere on the TSX, shares of E-L Financial Corp. (TSX:ELF) jumped after it announced the pending $1.125-billion sale of Dominion of Canada General Insurance Co. to Travelers Companies Inc. (NYSE:TRV), a major U.S. insurance company. E-L Financial gained $56 or 9.46% to $648 on a thin volume of 3,135 shares.Consumer staples stocks led advances with Shoppers Drug Mart (TSX:SC) ahead 38 cents to $45.75.The gold sector was also supportive, up about 0.35% with August bullion up $3 to US$1,386 an ounce. Barrick gold Corp. (TSX:ABX) climbed 21 cents to C$20.81.The energy sector climbed 0.2% even as July crude on the New York Mercantile Exchange shed 26 cents to US$95.77 a barrel. Suncor Energy (TSX:SU) improved by 14 cents to C$31.80.The base metals sector was the biggest TSX drag, down 0.85% as July copper fell three cents to US$3.24 a pound on top a 10-cent slide over the previous two sessions. Copper is widely viewed as an economic barometer as it is used in so many applications. Sector heavyweight Teck Resources (TSX:TCK.B) lost 61 cents to C$25.04.Railway stocks fell alongside miners as Canadian Pacific Railway (TSX:CP) declined $2.30 to $126.86.The tepid performance on the TSX continued the generally negative showing on the TSX, which gained momentum after Fed chairman Ben Bernanke said May 22 that the U.S. central bank might pull back on its $85-billion-a-month bond-buying program if economic data, especially hiring, improved significantly. Other Fed officials have spoken about a winding down of bond purchases sooner.The quantitative easing program has kept interest rates low and also helped fuel a strong rally on U.S. stock markets.The TSX has been dragged lower by mining stocks in particular, a reflection of a slow global recovery.But speculation about cutting back on the QE program has had the effect of pushing U.S. Treasury yields sharply higher, which in turn has had a negative effect on TSX defensive sectors as well.“We have seen REITs pull back in the last couple of weeks by eight% or thereabouts, same for utilities and pipelines — so it’s a pretty big pullback,” added Stephenson.“And . . . financials in Canada are interest sensitive to a degree and you have weakening data in terms of housing. And people are saying this is not a very good story.” What investors were watching today: Condo building surge signals economy gaining momentumOMERS, AIMCo to buy Europe’s cinema giant for $1.5-billionTravelers to buy Dominion of Canada General Insurance for $1.1-billionToronto ranked in top 10 most competitive cities in worldON DECK TUESDAY ECONOMIC NEWSCANADAManpower Survey (Q3) UNITED STATES10 a.m.Wholesale trade (April): Economists expect a 0.2% rise in inventories, 0.1% decline in sales Job openings and labor turnover survey (April)
Protecting the integrity of centrifugal process pumps used in critical applications in mining is one key to minimising downtime and ensuring the safety of workers. Jacques Visser of Morgan Advanced Materials examines the various technologies available for ensuring pump safety and how the use of modern materials and designs are bringing new dimensions of performance to these applications. In particular he focuses on the efficacy of bursting discs or rupture discs.Centrifugal pumps are widely used in most types of mining, primarily for the removal of slurry, but also for other tasks such as water removal. Their effective and continued operation is essential, as any interruption can result in the undesired build-up of liquids in working areas, with the potential to compromise both process efficiency and the safety of operators.However, the uniquely demanding conditions under which these pumps operate mean they can be subject to the build-up of pressure when, for example, suction or delivery valves become closed or operate incorrectly, or lines become blocked due to the presence of solids such as sand, grit or small pieces of rock.In these instances, the rapid increase in pressure can lead to the failure of a pump and, even worse, a pump explosion with the potential for severe injury or even death to operatives working nearby.And while the cost of a specialist replacement pump may be significant, to say nothing of the cost of downtime while this critical component is sourced and installed, even these costs pale into insignificance when compared with the financial and reputational damage resulting from a workplace fatality.The risk is illustrated by several well-documented cases, such as an incident in Virginia, USA, in 2002, when a fine coal transfer pump which had been left standing for two days was started without gland service water and quickly overheated. The pump was stopped by an operator, but the gland service water then entered the red hot all-metal casing, rapidly creating a build-up of steam which caused the pump to explode and the operative to lose his life.To combat this risk and to help maximise pump life, a variety of technologies have been developed over the years designed to shut off operation before pressure within the pump reaches a level where it is prone to fail.Among them is the use of current detection equipment, whose success is based on the premise that current drops when pump valves are closed. However, research on motors between 2 and 110 kW in duty has shown that there is frequently no relationship between the current change and the size of the pump, or the speed or duty of the motor, making this type of safety monitor of questionable value in many applications. Another alternative is the use of pressure sensing equipment, although once again a question arises as to the relationship between pressure at immediate delivery before and after valve closures or the occurrence of blockages. Furthermore, any rise in pressure is only likely to be detectable at the point when the fluid starts to boil, which is by definition too close to the point at which the pump may explode. Meanwhile, any probes used with this equipment are likely to have their effectiveness hampered by the presence of chemicals and slurries, while these systems are in the main considered an expensive option. The same issue also has the potential to cause problems with temperature monitoring equipment. While generally a more reliable option than pressure sensing as the temperature increases immediately when valves are closed, this option is again expensive as probes or thermocouples not only have to be hard-wired to the breaker but are also subject to the effects of slurry build-up, again impacting on their performance and ability to provide the rapid, reliable data needed to trigger a shutdown.Strain gauges are a further option for specifiers and system designers, but again are not always found to be reliable, while fusible plugs are reliant on the same technology as temperature and pressure sensing and so do not overcome the issues associated with these technologies. Meanwhile, pressure relief valves again add to cost while their presence may compromise the leak-tightness of the whole system and they may not react quickly enough to relieve a rapid pressure build-up. And while most pumps are fitted as a matter of course with safety valves, these components require regular testing and maintenance to ensure they will come into action at the desired pressure. Indeed, the issue of maintenance is a key one given that many mines operate a continuous shift pattern, meaning that downtime for routine maintenance to pumps and associated components has to be minimised. Concerns over the effectiveness and cost of these technologies, as well as the need for a truly maintenance-free solution, led to the development of the first bursting discs or rupture discs. A rupture disc is a sacrificial part containing a domed membrane which fails instantly – within milliseconds – at a pre-determined pressure and cannot reseal itself. This is ideal in scenarios where pressure may be subject to rapid build-up and other forms of pressure relief may either be unable to respond quickly enough. Many of the early discs were made from foil, in many ways an ideal material but one which is relatively delicate and can therefore be susceptible to damage such as bending and scratching, which is most likely to occur when the disc is inserted into its holder. In these instances, the performance of the disc may be compromised, with the most likely scenario being that it will ‘burst’ at too low a pressure, resulting in unnecessary downtime and the cost of a replacement. This cost is by no means insignificant – around £400 per unit is not untypical, depending on the application – while ancillary items such as the specialist holder raise purchase costs further, meaning that foil discs represent an expensive option given their relative fragility.The issues with foil discs drove leading materials companies to seek a more cost-effective and practical solution using a more robust material which did not require a specialist holder, and which was less prone to damage during the installation process and so to premature failure resulting from accidental alterations to the disc’s shape or surface profile. The solution came in the late 1980s in the form of the first graphite discs. These were (and still are) designed to fit between the bolts within the standard ANSI flanges found on most pumps, eliminating the need for a separate holder and easing installation. Furthermore, with graphite being a harder and tougher material, the discs can withstand a certain amount of scratching with no compromise to their burst pressure, and can operate at a broad range of temperatures between -50 and 250ºC. The use of a PTFE material bonded to the disc optimises resistance to any alkalis present and ensures their presence does not impact on the disc’s service life or performance.The flexibility and versatility of graphite enables the production of discs to very precise customer parameters – indeed, there are very few, if any, ‘standard’ products on the market. Rather than relying on calculations using pump casing pressures, burst pressure is typically calculated by taking the working pressure and adding 75%, meaning a pump with a working pressure of 1 bar will require a disc with a burst pressure of 1.75 bar. Physical destructive testing of sample discs from individual batches before they leave the facility guarantees that the discs will operate to the agreed customer parameters, with test certificates provided to ensure that local and international safety regulations are satisfied.The sophistication of modern manufacturing techniques even allows the production of discs which can cope with negative or vacuum pressure. For these applications, for example where the system is subject to hydraulic back pressure, discs can be manufactured with a vacuum bar inside the orifice, meaning they will still operate effectively in the presence of any vacuum ‘pull’. Discs can be manufactured in diameters of between 12 and 406 mm in a variety of thicknesses to suit virtually any application. If fitted correctly, graphite rupture discs have an almost unlimited service life, require no interim maintenance, and can typically be changed within a matter of minutes. While they are frequently used in conjunction with a safety valve, a rupture disc on its own is more than capable of ensuring that pre-determined pressure within a pump cannot be exceeded. The latest development has seen the introduction of ‘centreline’ discs to completely negate the issue of scratch damage. The versatility and cost-effectiveness of graphite discs has seen them tested against other methods specified by many of the leading international mining companies as the preferred system for protecting pumps from excess pressure build-up.