Mar 1 (Reuters) - Thermadyne Holdings Corp on Thursday added $100 million of senior secured notes to an existing issue, said IFR, a Thomson Reuters service. The sale took place in the 144a private placement market. Jefferies and RBC were the joint bookrunning managers for the sale. BORROWER: THERMADYNE HOLDINGS CORP AMT $100 MLN COUPON 9 PCT MATURITY 12/15/2017 TYPE SR NTS ISS PRICE 100 FIRST PAY 6/15/2012 MOODY'S B2 YIELD 9 PCT SETTLEM