Brazetek 155K BTU 316L Stainless Steel Shell & Tube Heat Exchanger. SKU: BT-ST-155 / SP-155S-0. Operating Pressure: 190 psi Number of tubes: 30 Surface area (heat transfer area): 0.33 sq. Or 3.55 sq. For use as a pool heat exchanger (as well as for hot tubs & spas), see. Quick Sizing – Swimming Pool Heating Applications. AISI 316L stainless steel offers superior corrosion resistance Fully welded construction ensures long-lasting performance Helically wound tubes optimize heat transfer Large inlet/outlet ports allow for high flow rates with minimal restriction Mounting brackets included.