Tubes in several heat exchangers within a critical waste heat boiler (high temperature, high pressure) developed stress corrosion cracking and needed to be plugged. The customer ﬁrst tried Welding plugs in place which required preheating of the tubesheet followed by post weld stress relieving after welding. This resulted in additional delays and costs with getting the waste heat boiler back in operation. Based on information provided by the customer, EST Group engineered, manufactured and tested Pop-A-Plug P2 plugs constructed with ASTM A-182 F22 CL3 material for inside diameters upto 2.76 (70.1 mm). Although these Pop-A-Plugs required a few days to be manufactured, they only required a very short time for actual installation. Since there were no more issues with heat affected zones (like with a welded plug) no further tube and weld damage has occurred. This allowed the waste heat boiler to be returned into service and the entire plant returned to operation.