Page 9 - Industrial Process Plant Construction Estimating and Man Hour Analysis

xxiv Introduction

Labor productivity and analysis
Labor—Man-hour unit rates

Labor productivity is concerned with direct craft labor. Direct craft labor means
the craft is working in the field erection of process piping and equipment. The
man-hour is defined as the amount of work performed by the average worker in
one hour.
Formula: Man-Hour¼Time Quantity (Refer to the Unit Quantity Method)
Once time values are known for a construction task, they are multiplied by
the quantity. Time may be for individuals or for crew work, and it is based on the
construction task. Time is expressed relative to a unit of measure, such as LF,
EA, SF, and Ton. The unit of time may be a minute, hour, day, month, or year.
Examples of man-hour units are as follows:
(1) HRSG—seal weld side, roof, and floor casing field seams; number of
welder man-hours per lineal foot of field welding, 0.35MH/LF
00
(2) Welding butt weld, carbon steel, arc-uphill, WT<¼0.375 ; number of
welder man-hours per diameter inch of welding, 0.50MH/DI
The union/nonunion craft, experience factor, and PF&D allowances have
been included in the craft unit man-hours. Standard unit rates can be used to
estimate work anywhere in the United States. The estimator must determine
all factors that will affect labor productivity and overtime impacts. The man-
hour units and quantities are based on historical data that have been verified
by statistical analysis, and the man-hour rates are competitive.

Productivity measurement

Historical records provided the direct craft man-hour data for field installation of
piping and equipment. Two methods for the measurement of construction time
were used to collect, analyze, and compile the actual man-hour data in this book.
(1) Foreman report—job cost by cost code and type
(2) Nonrepetitive one-cycle time study
(3) There are several ways in which actual time data are compiled and ana-
lyzed from the foreman’s report. One method is to compile data for
man-hour analysis obtained from the foreman’s report for mathematical
analysis. Then, the engineer will determine the productivity rates. The
productivity rates are then entered into the estimating system to be used
to estimate future work that is similar.

The following example will enable the reader to set up cost codes and ana-
lyze historical data, from field erection cost reports, using graphic analysis to
verify direct craft man-hours.