US Treasury Secretary Janet Yellen says the failure to lift the federal debt limit by Congress would cause an "economic catastrophe" that would raise the costs of borrowing "into perpetuity." She speaks Tuesday at a conference in Washington. Follow Bloomberg for business news & analysis, up-to-the-minute market data, features, profiles and more: http://www.bloomberg.com Connect with us on... Twitter: https://twitter.com/business Facebook: https://www.facebook.com/bloombergbusiness/ Instagram: https://www.instagram.com/quicktake/?hl=en