Preliminary Estimating by Selective Unit Costs PETER JANDRISEVITS Merck & Co., Inc., Rahway, N. J.
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A summary sheet of all
A summary sheet indicating these major components should be prepared for each estimate. Under each major component a further outline of important cost items is shown. By using this mmmary sheet (Schedule I ) the estimate can readily be checked to ascertain that some consideration has been given to all items that may apply on the project. The items under each of the major cost components include:
major cost items will provide a check to ensure that all large items o f cost have been given some consideration. Errors in quantities or unit costs are less serious than the omission o f a large cost item. Supplementary informa-
I1 are for standard design equipment of the type frequently used
order to develop reasonably accurate preliminary construction cost estimates, the scope of a project should be deflned as clearly as possible
A series of unit costs can
and broken down into major cost categories.
be developed for each of these categories from past performances; current cost trends should be taken into consideration in establishing the contingency. Contingency factors should be flexible, depending on the degree of information available in the outline of the scope.
tion on items not considered a part of the basic project cost should be included in the estlmate used by management in reviewing the project.
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HE use of selected unit costs to develop pidiminary estiTreasonable mates is a simplified method of obtaining an estimate of accuracy with the expenditure of a minimum amounl, of time. This type of estimate is generally satisfactory for budget purposes, for production cost estimating and market surveys, or for determining the necessity for further detailed engineering work. This method has as a basic consideration the breaking down of the scope of a project into major components of cost and making allowances for all phases of work. An omission of a major component is more serious than an incorrect allowance. Usually the high and low allowances will offset each other, thus minimizing the degree of error. The procedure of breaking down the estimate into major cost factors rather than using- over-all “square foot” or “per of - pound . product” costs corrects the elements of cost which do not vary directly with the size of a project, such as outside service connections and certain fixed facilities and equipment. I t is essential, as in any other method of estimating, that some preliminary engineering be done to establish a fair definition of scope. This need not be in any detail but should include all major cost factors. Included in this scope definition should be letter-size sketch flow sheets, layouts, building plans, and plot plans as may be required for the particular project. These should provide proper space and allowances for necessary laboratories, offices, locker rooms, machine rooms, and storage space and should indicate utility requirements and other unusual conditions. A good definition of scope results in a good estimate. The degree of information available in the scope definition must be weighed in establishing the percentage for contingencies.
Process Equipment. Standard units: Costs listed in Schedule and include installation costs, process pipe, and service connections. The cost units between sizes shown can be extrapolated. Special units (items not included in list of standard equipment): Costs for these items, if similar to standard units, can be approximated from Schedule 11. If this group represents a large portion of the total cost, a few spot checks with equipment manufacturers should be made. The installed costs of these units will be approximately 200% of equipment costs. This percentage may vary between 180 to 220% depending on pize of units and type of operation. Some machinery items may not require such high percentage allowances for installation costs. Tankage and solvent recovery: Schedule I1 lists cost of tanks installed below or above ground with pumps, piping, and electrical connections and over-all costs of solvent recovery equip ment.
Schedule 1.
Summary of Estimate Project No. Date
Description A.
Process equipment (sketch flow sheets and layouts) Standard units
z$$g:t$
solvent recovery Special services: ventilation, refrigeration, air Yard facilities: storage areas Auxiliaries: specialties, instruments Other (sketch plans, areas) B.Base cost Added facilities t o base Other C. Outside facilities and service connections Sewers: process, storm, sanitary process returns, lowpotable, pressuresprinklers Water: high
pressure
Elec. feeds and substktions R.R.: roads, fences Refrigeration Site preparation Other
Components of an Estimate
$
...,, ...
Process equipment Buildings Outside facilities and service connections Plant utilities Contingency Supplementary information or requirements
Water: treatment, towers, we& fire service Electric Waste disposal, incinerators Refrigeration Other E . Contingencies, %; engineering, % ’ Total F. Supplementary information or requirements Contingent costs: spare parts Standby equipment eneral facilities
By developing a series of unit costs for each of these phases for the general type of work done and applying a proper judgment factor, which can be attained after some experience in the technique, a reasonably accurate estimate can be obtained.
~ ~ ~ ~ n ~ ~ ~ P t r f P a r k i n g Office’warehohse locker rooms Personnel, distkbution Other
2299
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There are six major components of an estimate, including:
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INDUSTRIAL AND ENGINEERING CHEMISTRY
2300 Schedule li.
Process Equipment-Standard
Reactors Glass lined Stainless steel Carbon steel Condensere Iiarbate Stainless steel Carbon steel (stainleaa steel tl.ibes) Recri vers G'ass lined Stainless steel Carbon steel Centrifugal pumpa IIastelloy Stainless steel Carbon steel Vacuum pumps Porcelain jet Stainless steel jet Iron jet (bronze nozzle C diffuser)
1,600 1,400 800
2 stage 1,900 1,400 800
Vacuum pumps (reciprocating), 180 c i i f t jmin. 1 stage Cast iron with micarta rings 2,500 Centrifuges 24-inch basket Stainless steel (Jierwte-coated) 7,500 6,000 Stainless steel 4,000 Carbon steel Filter (horizontal plate) sparklei 14-inch diameter, D-4 Hastelloy 7,000 3,300 Stainless steel 1,500 Carbon Steel Tray dryers, including trays 30 sq. f t Stainless steel 3,200 Carbon steel 2,100 Vacuum dryers with heating and trays -Lo_sq. ft Stainless steel 1,000 Carbon steel 3,000 Solvent recovery 18-inch 200 50-ft., 50-tray bubble-cap column sq. i t . condense! (column made in 5-ft seotions)
.
Stainless steel Carbon steel
3160,000 80,000
16,000
10,000 150 sq. it. 7,000
4,500 3,000 1000 gal. 6,600
7,000 2,100 40 gal./min. 1,600 1,500 900 3 stage (noncondensing) 3,300 2,600 1,700 2 stage 3,600 48-inch basket 12,000 10,500 7 ,,500 18-inch diameter, D-8 13,000 5,000 2,600 250 sq. ft 8,000 4,000
200 sq. i t 15 000 7 : 000 48-inch, 1200 ft. condcnncr
-iq
$250,000 150,000
These costs cover, in general, nece>*ary stills, calandrias exchangers, decanters, pumps, and tankage (before entering tank farm), structural steel supports, and column trays of light gage Expanded metal-packed columns cofit approximately the same; however capacities are about 100% more. Tank (buried and anchored storage with submerged pumps) Stainless steel Glass lined (not spark-tested) Carbon steel (Heresite-coated) Carbon steel Deduct above ground tanks on COILcrete saddles Pipelines yards above ground (not insulated) 2 inch = $2.00 t o $2.5O/ft. 4 inch = 3 . 0 0 t o 4.00/ft. Piue sumorts-$5.00 t o S6,OO/ft of pipe runs
Buildings-Unit Costs
1000 gal. $16,000
53,700 3,200 2,000 25 sq. ft. 2,200 1,500 700 50 gal
1,000 1,100 300 10 gal./min.
Schedule 111.
Units
50 gal.
5000 gal
$14,000 11,000 9,, 000 i ,000
20,000 gal $26,000 16,000 13,000 10.000
500
1,000
Sprcial services: These include items such as special process ventilation (standard general ventilation is covered in building costs), scrubbing and dust collecting systems, controlled airconditioned rooms, special unite for refrigeration (not standard refrigeration for 0" F. brine system), and air system for general service or process Yard facilities. Allowance should be made for process and solvent pipe linee in yard based 0x1 unite listed in Schedule 11. pavement and covers for storage areas, control panel enclosures, and other yard facilities. Auxiliaries, specialties, and special instruments. Regular saiety valves, pressure and temperature recorders are included in installed equipment costs. A percentage allowance of 5 to t5%, depcnding on type of process and detailed information available, should be included for items such as separators, jacketed lines, traps, small holding tanks, and other minor sprcialties. Other items: Ttrms not covered in the gencral list and having a major value such CLE laboratory instruments and apparatus and m:itciial handling equipment are included here.
Vol. 43, No. 10
Square Feet
Cost/
Sq. Trt.
~\'AREIlO UJL
Base: 1-story, truck platform height. 16 feet clear height. concrete floors, brick and cinder block walls; precast cdnorete roof on steel; heat, sprinklers, light8
5,000 20,000
Add: Washroom and office space (area included in 60,000 loading docks and base cost) $5.00 to SS.OO/sq. ft ramps, 55.bO t o $B.OO/sq. ft.; o t l k specialties ~pallets, racks, shelves, furniture, equipment)
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SHOPS, STORES, AKD LOCKER ROOM Base: 1-or %story, concrete floors, brick and cinder block walls; precast concrete roof on steel; partitions, heat, sprinklers, plumbing, lights, power
$ 7.60
6.50 5.50
5,000 20.000
13.00 11.00
5,000 30,000 60,000
18.00 17.00 16.00
Base: 2- and 3-story, 16 feet clear between floors; upper floors about l / a open wells; concrete, steel frame, brick and cement block walls; precast concrete roof: partitions for laboratories, lockeru, and office; elevator, 5,000 heat, ventilation (general), sprinklers, plumbing, electric lights (vapor and explosion proof) ; electric power panels, 15,000 30 000 main service piping headers (steam, water, brine, air)
21 00 19 00
Add: Lockers, bins, benches, furniture, 82.00 to $4.00/sq. ft.: other specialties, shop equipment OrPFICEs
Base: Single or multistory, concrete floors, brick, cinder block and plaster walls; steel frame; precast concrete roof; hung ceilings; asphalt tile floor covering; partitions (1j4 area private offices with removable partitions): beat, sprinklers, fluorescent lights, electric and telephone outlets, plumbing Add: Furniture (general) $2.00 t o 84.oO/sci. ft.; aircpnditioning, 84.00 to SS.OO/sq. ft.; other specialties, special partitions, furnishings MASUB'ACTURINQ
BUILDING
24 00
.4dd: Acid brick floors, gutterx, curbs and drain?, $2.50 to S3.00/sq. ft.; laboratory furniture, $20.00 t o 825.OOj sq. f,t.;, air-conditioning, S5,OO t o $7.00/sq. ft.; othn! specialties, enclosures, platfornis, docks
SPECIALPROCESS UNITB
Small special reaction units: 700 t o 1500 sy. it. at S30.00 t o $50.00 base cost; sterile processing units (add t o manufacturing bldg. units for special finishes and treatment), $5.00 t o SS.OO/sq. i t . LAROR.4TORIEe
Base: Sinale or niultistorv: concrete floors. brick. uin. der block a n J plaster walls: 'steel frame, precast concretc roof. asphalt tile floor corering. movable partitions, heat: sprinklers, plumbing and drdnage, lighting, general ventilation, service piping and power connections
5,000
50,000 40,000
2 3 00 2 1 00 20 00
Buildings. Basic cost: Building costs 011 a syuaie-foot basis are listed in Schedule I11 for warehouse, shop, locker room, office, manufacturing, and special process units. Unit costs for each type vary with size of the building. The basic cost includes only the minimum requirements for the particular building type. Added facilities: To the base cost additional allowances must be made for work beyond general outline of basic unit. rldditional unit costs are indicated in Schedule 111 for items such as offices and locker rooms in warehouse building; outside platforms o n wxrehouse; air-conditioning in oficcs, laboratories, 01 manufacturing buildings; acid brick floors; laboratory furniture and other special interior treatment of buildingfi. Other items: These include items not specially covered such as equipment enclosures in yard, special equipment supports or foundations forming part of building, and allowances for costs incurred because a building is an extension of an existing unit or has provisions for future extensions. Outside Facilities Service Connections. Approximate lengths and sizes of various service lines and areas or lengths of yard facilities are determined from a sketch plot plan. Schedule IV lids over-all unit costs for these various items. Included are process waste, storm drainage, and sanitary sexers; procese and returns, potable, and sprinkler water; high and low prv-
INDUSTRIAL AND ENGINEERING CHEMISTRY
October 1951
Schedule IV.
Outside Facilities and Service Connections
Sewers and drains: terra cotta pipe, concrete cradles, 4 to 8 ft. deep, 6 to 15 inches a t $8.00 to $16.00/ft.; manholes, $500.00 Water lines and returns: sprinkler lines, 6 t o 12 inches a t $6.00 t o $lO.OO/ foot; connections, $500.00 each Steamlines including insulation: 6 t o 12 inches a t $9.00 to $18.00/foot; pipe supports/ft. of pipe rune a t $10.00 to $15.00 Eleotric substations and fseders Substation and switch gear/100 kv.-a $3 500 t o $4 000. feeders (overhead) $3.00 t o $5.00/ft.; undergr&d, $8.00 t o ’ $lO:OO/ft.; connections bo mains, $2000 t o $4000; manholes, $1500 Railroad sidings, switch, $2500; sidings/ft., $7.00 Roads/sq. yd., $2.50 to $3.50 Fences, 7 feet high/ft., $3.50 to $4.50 Refrigeration (pipe line, ammonia or brine, including insulation) : 3 to 6 ’ inches, $6.00 to $10.00. pipe supports/ft. of pipe runs, $6.00 to $7.00; brine system (25-ton), (pumps and coolers, $10,000; 10,000-gal. storage, $6000
Schedule V.
Plant Utilities
Steam plant: Boiler (400-lb. design), feed water s y s t ~ mcoalhandling, , building, 80,000 lb./hr., $500,000 t o $600,000 (varies with auxiliaries requued) Water treatment: primary, settling, rinse water, 1,000,000 gal./day $30,000 t o $50 000; secondary filtering, 100,000 000 gal./day, $80,000 t o $100 000. river intake and t r e a h e n t , lOO,OOO,OOb gal./day $200 000 t o $250:000! wells, 1,000,000 gal./day, $8,000 t o $12,000; d o l i n g Lowers, 1,000,OOd gal./day, $12,000 t o $15,000 Electric transformers and main switchgear: 1000 kv.- a,, $30,000 t o $40,000 Waste disposal Process (1,000,000 gal./day) : equalization, simple setting, skimming, $80,000 t o $110,000. flocculation, sludge removal, filtration and incineration $150 000 io $200,000 Douulation, $100,000; 3000 DopulaSanitarv (orimarv’treatment) : 1200 . . . . tion, $16o,ooo Inoinerators: trash, &ton, 100 ton/day, $25,000 t o $150,000; sludge, 5ton, 50 ton/day, $25,000 t o $100,000 Refrigeration (0”F.): 50 t o 300 tons, $700 to $500/ton Sprinklers: tanks, gravity (100,000 gal.), $30,000; ground (200,000 gal., 1000 gal./min. pump), $30,000
.sure steam; sub-station and feeder electrical installations; brine or ammonia refrigeration lines and brine tanks with pumps; railroad sidings, fences, and roads; site preparation including general grading, relocation or removal of structures or facilities, and temporary work required to accommodate new construction; and other conditions peculiar to pioject or working conditions. Plant Utilities. Where a project requires extensive utilities or if certain existing utilities are overtaxed, allowances should be made for these in the estimate. Certain conditions can exist where even a modest over-all increase in a particular utility use may require considerable expenditure for new main lines or an addition to the basic plant. This cxpense may represent a major portion of the tots1 project cost and should not be overlooked. Schedule V includes approximate over-all costs for these utilities; however, if this item represents a large portion of the cost a more detailed study should be made. Included in this group are steam supply; water treatment, general and potable use,
2301
cooling towers, wells, fire service; electricity; process and sanitary waste disposal ; incinerators; and refrigeration system. If specially treated water, air, and vacuum are not furnished as a generd plant servicc. they should be included as part of thc process vquipment item. The cost for furnishing any temporary services should be included. The schedules referred to represent unit costa of the general type of equipment and facilities as constructed for Morck & Co., Inc. The actual values and the types of units should be devcloped to meet a particular plant’s requirement. Contingency and Engineering. An allowance of 5% for engineering (for buildings and facilities) and process “break-in” should be made on all estimatou. An additional allowance for process engineering should be made if this phase is done by a consulting engineering firm. The contingency factor may range from 10 to 25% depending on the completeness of the scope definition and type of project. A new development with no previous similx process experience and rather limited information in the scope definition should carry a 25% contingency factor. On a simpler type project, similar to others already constructed, usually a 10% cont,ingenc.y is satisfactory. The general price trend should also be taken into consideration in this factor. If an unusually rapid rising cost trend exi& an allowance should be added for this factor. Supplementary Information or Requirements. There fwquently are other contingent costs involved in a project that are not usually a part of a project cost. On larger projects an indication of the magnitude or general scope of these factors should be made to inform management of the probable additional costa that may he incurred. Included in this category would be standby equipment and spare part,s; general plant facilities as cafeteria, plant health, locker rooms, parking areas; control laboratory, research, general offices and warehouse, shops, and distribution problems. Thew are many other factors to consider in the over-all project analysis such as personnel requirements and raw materials; however, if theee do not directly affect the project cost they should be submitted in an accompanying report. Over-all personnc>l requirements on larger units may become BE important a problrm as cost in final decisions on a project. The outlined procedure may appear as a long detailed analysis of a project to obtain a preliminary estimate. With some expcrience, little additional time is required to go through the list on the summary of estimate sheet to make allowances for the major cost components of a project. Many items can be approximated without any detailed studies with the assumption that the high allowances will balance the low ones. With a schedule of unit costs maintained up to date to reflect price trends and developed for general types of projects encountered, this type estimate can be prepared in a reasonable time with a fair degree of accuracy. RECEIVED April 16, 1951.
* * * * * The second Resources symposium, which brings up to date the basic information available AhD ENGINEERING CHEMon the chemical industry in the Far West, will be published by INDUSTRIAL ISTRY in December 1951. Resources for the industry in the Southwest, the first of this series organized for the seven Federal Census Districts, was presented in August 1951. In the Far West continued expansion of the petroleum industry seems to be the dominant factor in its economy and development. Petrochemicals now in production include synthetic ruhber, ketones, alcohols, synthetic detergents, ammonia, chlorinated hydrocarbons, phthalic an hydride, and by-product sulfur. The area is well supplied with raw materials for major expansions during coming years; problems which will require attention, however, are those of distances, transportation, and markets. Scarcity of water is also a major problem in many parts of tbe area. Programs for the development, re-use, and salvage of additional water supplies are already in effect, but exchanges of water among numerous basins and adjustments of legal rights are necessary to the full utilization of present water supplies.
