NEW HEAT EXCHANGER INDEXES ADDED TO TABLE

Gerald L. Farrar Contributing Editor Changes are being made in the heat exchangers category of the Nelson-Farrar Itemized refining cost indexes table. On the basis of a refinery construction survey just completed, a new method for calculating the composite (overall) heat exchanger index has been adopted: New composite index (0.1)(CI) + (0.7)(CSI) + (0.2)(SSI) For comparison: Old composite index = (0.4077)(CI) + (0.5923)(CSI) where: CI = copper index = {cost of 1 copper admiralty shell}

July 1, 1991

2 min read

Gerald L. Farrar
Contributing Editor

Changes are being made in the heat exchangers category of the Nelson-Farrar Itemized refining cost indexes table.

COMPOSITE HEAT EXCHANGERS

On the basis of a refinery construction survey just completed, a new method for calculating the composite (overall) heat exchanger index has been adopted:

New composite index (0.1)(CI) + (0.7)(CSI) + (0.2)(SSI)

For comparison: Old composite index = (0.4077)(CI) + (0.5923)(CSI)

where: CI = copper index =

{cost of 1 copper admiralty shell}

---------------------------------- (100)

{ $5,685 }

CSI = carbon steel index =

{cost of 1 steel shell}

----------------------- (100)

{ $3,573 }

SSI = stainless steel index (see below)

Even though the calculation now includes 304 stainless steel, the old and new calculations yield essentially the same number for January 1991. Therefore, the new composite heat exchanger index effective January 1991, will reflect stainless steel cost trends, and can still be compared with past composite heat exchanger indexes.

STAINLESS STEEL HEAT EXCHANGERS

This index relates the current cost of a 304 stainless steel shell to a projected 1946 cost.

SSI =

{cost of 1 stainless steel shell}

------------------------------------ (100)

{proj. 1946 cost of 1 stainless shell}

It was defined to be numerically equal to the carbon steel heat exchanger index as of January 1991. This yields an extrapolated 1946 cost of a 304 stainless steel exchanger shell of $8,791 (1946 carbon steel shell $3,790).

Although based on a projected (not actual) 1946 cost, this index will accurately reflect the change in stainless steel heat exchanger costs after January 1991.