USED: Graham Spiral Heliflow Heat Exchan... USED: Graham Spiral Heliflow Heat Exchanger, 169.8 sq ft, model306060-28L, 316L stainless steel. Shell rated 150 psig @ 130 deg F.Tubes rated 250 psig @ 350 deg F. NB #18438. Year 1991. and the product is still available, |