Used 47 Square Feet Pfaudler Glass Lined Thimble Heat Exchanger. 55"OAH x 30" Dia. tubes rated 35psi @350F. Shell rated 125 psi @ 350F. Internal vacuum rated 125psi. Inner chamber rated @ 20 psi. FV External @350F. (4) Lug mounted. Serial # E179-0927. National board # 39451. CRN# F2942.5. Built 1980.