Lang / Hand factors are based on purch. or delivered equipement cost?
Lang / Hand factors are based on purch. or delivered equipement cost?
(OP)
Dear all,
Can you please provide confirmation whether the Lang, the Hand and the Wroth factors for preparing cost estimates are based on purchased or on delivered equipment?
Various sources suggest differently:
+James R. Couper suggests in Perry's Chemical Engineers' Handbook ed. 8 that Lang and Hand start with purchased equipment cost while Wroth starts with delivered equipment cost. Note: in the same book, on the same page authors states Lang is based on delivered equipment cost
+ same author James R. Couper suggests in Process Engineering Economics that Lang is based on delivered equipment; Hand is based on purchased equipment costs; later the author summarizes that Lang and Hand methods start with delivered equipment costs, but the Wroth method begins with purchased costs
+ Max S. Peters and Klaus D. Timmerhaus suggest in Plant Design and Economics for Chemical Engineers ed. 5 that Lang is based on delivered equipment cost
+ Gavin Towler / Ray Sinnott suggest in Chemical Engineering Design Principles, Practice and Economics of Plant and Process Design suggests that Lang is based on purchased equipment cost
+ Harry Silla in Chemical Process Engineering Design and Economics suggests that Lang is based on delivered while Hand factor is based on purchased equipment cost
Can you please provide additional information?
If anyone has access to the original publications by Lang, Hand or Wroth, please let me know.
Thank you in advance.
Best regards,
Stan
Can you please provide confirmation whether the Lang, the Hand and the Wroth factors for preparing cost estimates are based on purchased or on delivered equipment?
Various sources suggest differently:
+James R. Couper suggests in Perry's Chemical Engineers' Handbook ed. 8 that Lang and Hand start with purchased equipment cost while Wroth starts with delivered equipment cost. Note: in the same book, on the same page authors states Lang is based on delivered equipment cost
+ same author James R. Couper suggests in Process Engineering Economics that Lang is based on delivered equipment; Hand is based on purchased equipment costs; later the author summarizes that Lang and Hand methods start with delivered equipment costs, but the Wroth method begins with purchased costs
+ Max S. Peters and Klaus D. Timmerhaus suggest in Plant Design and Economics for Chemical Engineers ed. 5 that Lang is based on delivered equipment cost
+ Gavin Towler / Ray Sinnott suggest in Chemical Engineering Design Principles, Practice and Economics of Plant and Process Design suggests that Lang is based on purchased equipment cost
+ Harry Silla in Chemical Process Engineering Design and Economics suggests that Lang is based on delivered while Hand factor is based on purchased equipment cost
Can you please provide additional information?
If anyone has access to the original publications by Lang, Hand or Wroth, please let me know.
Thank you in advance.
Best regards,
Stan





RE: Lang / Hand factors are based on purch. or delivered equipement cost?
you are talking about estimates in the +/-30% range. Don't try to be too accurate on items with small effects on the final number.
The article "Making Sense of your Project Cost Estimate" by J.C. Lagace, CHEMICAL ENGINEERING Magazine of August 2006 might be helpful.
Kind Regards,
hahor
RE: Lang / Hand factors are based on purch. or delivered equipement cost?
Regards
StoneCold