Manufacturing and Testing of Welded Stainless Steel Tubing: You Have a Choice Part 2—Feedwater Heater Tubing

The stainless steel feedwater heater specifications, ASTM A688/ASME SA 688 and ASTM A803/SA 803, were developed over 30 years ago. At that time, no one envisioned the temperatures and pressures that today’s super and ultra-critical units would operate. The increased pressures, temperatures, and expectations for reliability require special manufacturing techniques and testing for long tube life. The current ASTM/ASME specifications should be considered minimum requirements, and for long term reliability a number of additional special manufacturing processes and tests are essential. This paper summarizes many of the manufacturing and testing choices that should be specified to ensure high reliability. It identifies the advantages and disadvantages of each option and provides suggestions on what should be specified to ensure a reliable cost-effective feedwater heater tube for today’s applications.