Bulgaria's gas transmission system operator Bulgartransgaz said that it has opened a 1.1 million levs ($638,600/562,400 euro) tender for repair of pigging station Stryama, on the transit gas pipeline to Greece and FYROM.Works must be completed within no more than 270 days, Bulgartransgaz said in a tender notice on Thursday.The deadline for submitting offers is November 26.Bids will be ranked based on price and time for completing works.