SSPC TU 9-2001 Estimating Costs for Protective Coatings Projects《保护涂料工程的预估成本 编辑修订 2004年11月1日》.pdf

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1、SSPC-TU 9March 1, 2001 Editorial Revisions November 1, 200410-1171. ScopeThis technology update provides information on ap-proaches and models for estimating the initial and lifetime cost of protective coatings projects.2. Description2.1 IMPORTANCE AND USE: Cost is a major factor in determining if p

2、rotective coatings or another corrosion control alternative should be used for corrosion control. If protective coatings are used, cost is a major consideration in selecting the coating system to be used.The cost of coating systems can be interpreted in sev-eral manners. Of major interest is the cos

3、t of the applied or installed coating system (often called turnkey costs). Owners must also be concerned with operational and maintenance costs that occur over the life of the structure. The installation and maintenance costs are often collectively described under the designation life-cycle cost (or

4、 long term cost). Additional cost factors include costs for inspection and indirect costs, such as loss of product, downtime, and inconvenience to the community.The cost of an applied coating system is often an insig-nifi cant portion of the overall cost of a facility or structure, but is an importa

5、nt consideration before selection. Coating cost can range from less than 1% to as high as 10% of the overall cost of the project. Acquiring accurate and reliable cost data is a major challenge for the protective coating industry. This technology update will review some of the major concepts, conside

6、rations, and approaches to this critical subject.2.2 OUTLINE OF CONTENTS: The technology update includes the following sections:SectionTypes of costs 3Methods for estimating initial cost 4Methods for estimating lifetime cost 5Models and data sources 63. Types of Costs3.1 INITIAL VS LIFETIME COSTS: W

7、hen discussing costs, it is useful to distinguish between the initial costs for a coating project and the costs incurred in protecting that structure over its lifetime. The initial cost is the most visible cost, since it is the money spent in the short term at the commencement of the period; the fi

8、nancial impact is both immediate and quantifi able. Lifetime costs include the initial cost and all other potential costs involved in the upkeep and maintenance of the coated structure. In the long term, lifetime cost has the greater impact on the fi nancial viability of the company or its project.

9、Short-term budget considerations, however, are often infl uential in making choices of coating types, working method, contract style, and other alternatives, often ensuring that managers focus on the initial costs. This section and Section 4 will discuss initial costs. Lifetime costs will be covered

10、 in Section 5.3.2 INDIRECT VERSUS DIRECT COSTS: Initial costs can be classifi ed as direct costs or indirect costs. Direct costs are those which are readily attributed to the coating activity, for example, the cost of a coating contract or an engineering service. Direct costs are relatively easy to

11、measure. Indirect costs are those which arise because of the need for coating work, but are not readily identifi able or measurable. Examples are given in Table 1.Indirect costs are often unpredictable, and are therefore extremely diffi cult to estimate and often not considered ex-plicitly in cost a

12、nalysis.Over the lifetime of a structure (e.g., 40 years), there are likely to be many costs associated with corrosion protection, including both direct and indirect costs.4. Methods for Estimating Initial Costs4.1 UNIT COSTS: The most common and straightforward means of estimating costs is by using

13、 unit costs. The work is broken into measurable units, e.g., an area of surface to be prepared and coated. In some cases, the estimate is based on the number of hours of labor required. Depending on the complexity of the job, various additional cost items will be added to the base cost. These includ

14、e costs for special equipment and costs for subcontracted items, several of which were described in the previous section.In this section, we will describe two approaches to the unit cost method, Cost per unit area Labor and materials4.2 ACTIVITIES BREAKDOWN (COST PER UNIT AREA): One of the simplest

15、approaches is to estimate the SSPC: The Society for Protective CoatingsTECHNOLOGY UPDATE NO. 9Estimating Costs for Protective Coatings ProjectsSSPC-TU 9March 1, 2001Editorial Revisions November 1, 200410-118cost per unit surface area (cost per square meter $/m2 or cost per square foot $/ft2). These

16、estimates may be based on historical records of similar projects or may be obtained by breaking the unit costs into specifi c sub-elements (see below). It is assumed that the amount of labor and material is roughly proportional to the amount of surface to be coated. This assumption is certainly vali

17、d for coating materials and thinners. For labor, the cost per square meter may vary, but the method allows one to modify labor rates based on differ-ent conditions.The costs of a coating system can be broken into the following components: surface preparation; application of coating; coating material

18、s; number of coats required; and required curing conditions. Numerous analyses have been done to show which proportion of the total cost is attributed to each of these items. These data are general. As each job is unique, it is important to be aware of the assumptions made in deriving these numbers.

19、 Modifi cations are often made based on the following factors: Height of surfaces to be coated Condition of the structure (e.g., pitted and rusting, previously painted) Type and shape of structure (e.g., for accessibility) Location (e.g., shop or fi eld) Geographic location Weather Additional modifi

20、 cations may be made for hazardous paint removal or other special considerations.4.3 LABOR AND MATERIALS METHOD: This ap-proach is based on deriving estimates for the following components: Surface area to be painted Number of worker hours required to perform each stage of the work Labor costs, inclu

21、ding benefi ts Material costs Equipment costs Overhead costsThese components are described below. Appendix 1 provides a sample calculation in US units and Appendix 1M is the metric version.4.3.1 Surface Area To Be Painted: The surface area of each item to be painted (e.g., tank bottom, walls, piping

22、) is measured or estimated, and the cost of painting per unit area (e.g., a square meter) is then applied to achieve the total paint-ing cost. Books and tables are available to assist estimators in making unit area (square meter) calculations (Ref 2).4.3.2 Estimate of Required Worker Hours: After th

23、e surface area (square meters) has been calculated, the time required for surface preparation and/or paint application must also be calculated for each item of work. The total area of each item (Area) divided by the number of square meters that can be completed per worker hour (Production Rate) yiel

24、ds the total worker hours required to complete the work.Production rates and worker hour estimates can also be obtained from estimating guides. Most painting contractors and experienced estimators, however, know from past experi-ence the average production rate to be used for a given work item. The

25、estimator must decide on the number and size of crews to be mobilized.4.3.3 Labor Costs: Wage rates for union blasters and painters can be obtained from the local offi ce of the union having jurisdiction in the project area. Prevailing wage rates are also available from trade publications and govern

26、ment sources. Estimating guides can be useful references as well.The wage rate should include all labor payments, including the hourly wage, fringe benefi ts, and insurance. This is often referred to as the “charge-out rate.”4.3.4 Material Costs: The number of liters (gallons) of paint, thinner, cle

27、anup solvents, etc. must be estimated based on the areas being coated and the dry fi lm thickness DFT in micrometers (or mils) of coating to be applied.Loss factors must also be estimated. Material loss factors, such as overspray, range generally from 10 to 50 percent of the total paint purchased, d

28、epending on weather conditions, job location, and the type of surface to be coated. The practical Direct CostsCost of coating materialInitial application costRepair of damaged coatingsReplacement of corroded partsComplete or partial repainting for maintenance (of exterior coatings or internal lining

29、s)Indirect CostsDown time for maintenance or repair workLoss of product from leaks or vessel contaminationEnvironmental or worker health damage from defi cient corrosion protection or hazardous productsAdministrative and overhead costs of engineering staffTable 1Direct Versus Indirect CostsSSPC-TU 9

30、March 1, 2001 Editorial Revisions November 1, 200410-119spreading rates are normally more useful than the theoretical spreading rate fi gures quoted in the coating manufacturers product data sheets.The estimate should also include the cost of consumable supplies. Abrasives, cleaning rags, respirator

31、s and respirator cartridges, overalls and other protective clothing, masking tape, and small tools such as scrapers and wire brushes are all considered consumable items that are expended during the course of work.4.3.5 Equipment Costs: The cost of the equipment used on a job must also be estimated;

32、such costs might include charges for the use of compressors, dust collectors, vacuum or recycling equipment, containment, spray guns, airless or conventional spray pots or guns, and air and paint hoses. Fuel costs for diesel compressors and electrical generators should also be estimated. Most painti

33、ng contractors have standard costs for these items, and charge clients on either a daily, weekly, or monthly basis.4.3.6 Overhead Costs: Indirect costs of overhead, insurance, licenses, taxes, etc., must be added to the direct cost to arrive at a total cost.5. Methods for Estimating Lifetime Cost5.1

34、 LIFE CYCLE COST CONCEPT: Life cycle costs are those costs incurred protecting steel from corrosion over the life of the structure. This includes the initial cost of applying the protective coating system, the various inspections and touch-ups, and maintenance painting activities. It is important to

35、 recognize that, in many instances, a strategy that may result in a lower initial cost may cost more in the long run because of higher maintenance or even replacement costs.Applying life cycle cost in practice is complicated by a number of factors. The cost of purchasing materials or ser-vices is no

36、t constant over time. The numbers tend to increase because of infl ation. Even more signifi cant is the cost of tying up money that could otherwise be invested and generate interest. Also, tax treatments differ for capital costs (incurred as part of the construction and initial coating) compared to

37、maintenance costs. The total costs of future maintenance or repair can be estimated, but with diffi culty, because they are highly variable. This can be attributed to the subjective defi nitions of “lifetime,” the unpredictability of coating system performance, the lack of standard methods for asses

38、sing lifetime, and variables associated with protection and maintenance philosophy, time value of money, and others.It is important to recognize that the data on a coatings lifetime will always be uncertain to some degree. Even with the most thorough testing, there are variables affecting the lifeti

39、me that cannot be controlled or precisely defi ned. For example, the defi nition of coating failure may vary from one situation to another. There is also variability in the substrate, the particular coating material, and the exposure environment. It is sometimes useful to defi ne a range for the lif

40、etime of a coating system. For example, for alkyds on bridges in moder-ate exposure environments, the lifetime is often estimated at 7 to 12 years before fi ve percent of the surface is degraded by rusting.5.1.1 Limitations of Data on Lifetime: As discussed in Section 4, methods are generally availa

41、ble to estimate the initial cost of a coating system. Maintenance costs can also be esti-mated in a similar manner. Depending on the circumstances, it is normally necessary to assess the condition of the coating and the accessibility of the structure, as well as the presence of lead and other hazard

42、ous components of the paint. For life-cycle costing, however, the most diffi cult factor to determine is the lifetime of the coating, the time until a full repaint, partial repaint, or touch-up is required. Industry has developed numerous laboratory and fi eld procedures for predicting lifetimes. In

43、 addition, data have been compiled on performances of coatings on structures in service. A thorough discussion of these models and methods is beyond the scope of this technology update. Examples of some models are provided in Section 6.Two life-cycle methods will be discussed in this section: cost p

44、er unit area per year, and present value method.5.2 COST PER UNIT AREA PER YEAR: Lifetime costs of coating systems and other corrosion control options can be calculated using methods of varying levels of sophistica-tion. The simplest approach is to compare alternatives on the basis of cost per unit

45、area per year ($/m2/yr) over the lifetime being considered. This normally entails determining initial application costs, estimating the service life of the coating system, and calculating the subsequent repainting or regular maintenance costs.In the following examples, two painting systems are compa

46、red for an industrial exposure environment.1The data needed for each system are initial cost, maintenance costs, and the lifetime until maintenance.System A: Two-coat alkyd applied over commercial blast cleaned steel (SSPC-SP 6/NACE No. 3) Initial painting: $6.24/m2; 7-year lifetime Maintenance pain

47、ting: $5.27/m2; 4-year lifetimeSystem B: Three-coat inorganic zinc-rich over near-white blast cleaned steel (SSPC-SP 10/NACE No. 2) Initial painting: $12.38 /m2; 15-year lifetime Maintenance painting: $11.63 /m2: 9-year lifetimeFirst, looking at a 15-year time period: Alkyd: $6.24 for years 17, SSPC

48、-TU 9March 1, 2001Editorial Revisions November 1, 200410-120$5.27 for years 811, $5.27 for years 1215, Total of $16.78 /m2for 15 years of protection, or $1.12 /m2per year Inorganic zinc-rich system:$12.38 for 15 years of protection, or $0.83/m2per year.The alkyd had a lower initial cost ($6.24/m2vs

49、$12.38/m2). However, the inorganic zinc had a lower cost per m2per year when averaged over 15 years.The example is also extended to show costs for a 50-year period.1The result of this further analysis shows that total cost was $64.15/m2for the alkyd ($1.283/m2/yr.) system, and $58.88/m2for the zinc system ($1.178/m2/yr.).5.3 PRESENT VALUE METHOD AND COATING LIFE-TIME COST5.3.1 Time Value of Money Discounted Flow Method: The cost per unit area per year procedure neglects an important factor in determining the economics of corrosion protection systems the time v