Lesson 9

24/09/2013 Lesson 9 - Estimating & Comparing Weld Metal Costs

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BASIC

WELDING FILLER METAL

TECHNOLOGY

A Correspondence Course

LESSON IX

ESTIMATINGAND COMPARING

WELD METAL COSTS

ESAB ESAB Welding &

Cutting Products

©COPYRIGHT 2000 THE ESAB GROUP, INC.

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Chapter Table of

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Lesson 1The Basics of Arc

Welding

Lesson 2Common Electric

Arc Welding

Processes

Lesson 3

Covered Electrodes

for WeldingMild Steels

Go To Test

Lesson 4

Covered Electrodes

for Welding Low AlloySteels

Print

Lesson 5

Welding Filler Metalsfor Stainless Steels

Glossary

Lesson 6

Carbon & Low AlloySteel Filler Metals -GMAW,GTAW,SAW

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Flux Cored ArcElectrodes CarbonLow Alloy Steels

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Estimating &Comparing Weld

Metal Costs

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Reliability of Welding

Filler Metals

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TABLE OF CONTENTSLESSON IX

ESTIMATING AND COMPARING WELDMETAL COSTS

Section Nr. Section Title Page

9.1 Introduction .................................................................................................. 1

9.2 Factors For Cost Formulas ...................................................................... 2

9.2.1 Labor & Overhead ......................................................................................... 2

9.2.2 Deposition Rate ............................................................................................. 2

9.2.3 Operating Factor ............................................................................................ 3

9.2.4 Deposition Eff iciency .................................................................................... 4

9.2.5 Deposition Eff iciency of Coated Electrodes .............................................. 4

9.2.6 Efficiency of Flux Cored Wires ..................................................................... 6

9.2.7 Efficiency of Solid Wires for GMAW ............................................................ 6

9.2.8 Efficiency of Solid Wires for SAW ............................................................... 7

9.2.9 Cost of Electrodes, Wires, Gases and Flux ................................................ 7

9.2.10 Cost of Pow er ................................................................................................ 7

9.3 Deposition Data Tables ............................................................................. 8

9.4 Cost Calculations ....................................................................................... 12

9.4.1 Calculating the Cost Per Pound of Deposited Weld Metal ....................... 12

9.4.2 Calculating the Cost Per Foot Of Deposited Weld Metal ......................... 14

9.5 Cost Calculations - Example 2 ................................................................ 15

9.6 Comparing Weld Metal Costs .................................................................. 17

9.6.1 Example 3 ....................................................................................................... 19

9.7 Other Useful Formulas .............................................................................. 20

9.8 Amortization of Equipment Costs .......................................................... 21

Appendix A Lesson IX Test Questions ......................................................................... 22

Appendix B Problem 1 Worksheet ................................................................................ 26

Appendix C Problem 2 Worksheet ................................................................................ 27


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© COPYRIGHT 2000 THE ESAB GROUP, INC.

LESSON IX

ESTIMATING AND COMPARING WELD METAL COSTS

9.1 INTRODUCTION

Estimating the costs of depositing w eld metal can be a diff icult task because of the many

variables involved. Design engineers must specify the type and size of w eld joint to w ithstand

the loads that the w eldment must bear. The w elding engineer must select the w elding process,

and type of f iller metal that w ill provide the required w elds at the least possible cost. With

w ages and the cost of operations rising, selection of the process that deposits w eld metal

most expediently must be carefully considered. Labor and overhead account for approxi-

mately 85% of the total w elding cost.

9.1.0.1 Welding costs may be divided into tw o categories; the “f ixed” costs involved regard-

less of the f iller metal or w elding process selected, and those related to a specif ic w elding

process. Fixed costs entail material handling, joint preparation, f ixturing, tacking, preheating,

w eld clean-up and inspection. Although some of these items w ill be affected by the process

and f iller metal chosen, they are a necessary part of practically all w elding operations. Calcu-

lating these costs is best left to the manufacturer since they w ill depend upon his capabilities

and equipment. The cost of actually depositing the w eld metal how ever, w ill vary considerably

w ith the f iller metal and w elding process selected. This cost element is inf luenced by the

user’s labor and overhead rates, deposition rate and eff iciency of the f iller metal, operating

factor, and cost of materials and pow er.

9.1.0.2 This lesson w ill cover cost estimating for steel w eldments produced by the four most

common arc w elding processes in use today: shielded metal-arc w elding, gas metal-arc

w elding, f lux cored arc w elding and submerged arc w elding. Gas tungsten arc w elding w ill not

be considered here because the variables, such as deposition rate and eff iciency, are depen-

dent on operator technique, stub use, etc. The GTAW process is a relatively costly method of

depositing w eld metal, and is usually chosen for w eld quality or material thickness and compo-

sition limitations, rather than economy.

9.1.0.3 Large f irms w ill frequently conduct their ow n deposition tests and time studies to

determine w elding costs, but many smaller shops do not know the actual cost of depositing

w eld metal.

9.1.0.4 In estimating w elding costs, all attempts should be made to w ork w ith accurate data,

w hich in some cases is diff icult to secure. For this reason, this lesson contains charts, graphs


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LESSON IX

and tables that provide average values that you may use. Electrode manufacturers w ill usually

supply the deposition data you need through their Technical Services Department, if it is not

already published in their literature.

9.2 FACTORS FOR COST FORMULAS

9.2.1 Labor and Overhead - Labor and overhead may be considered jointly in your

calculations. Labor is the w elder’s hourly rate of pay including w ages and benefits. Overhead

includes allocated portions of plant operating and maintenance costs. Weld shops in manu-

facturing plants normally have established labor and overhead rates for each department.

Labor and overhead rates can vary greatly from plant to plant, and also w ith location. Figure 1

show s how labor and overhead may vary and suggests an average value to use in your calcu-

lations w hen the actual value is unknow n.

9.2.2 Deposition Rate - The deposition rate is the rate that w eld metal can be deposited

by a given electrode or w elding w ire, expressed in pounds per hour. It is based on continuous

operation, not allow ing time for stops and starts caused by inserting a new electrode, cleaning

slag, termination of the w eld or other reasons. The deposition rate w ill increase as the w elding

current is increased.

9.2.2.1 When using solid or f lux cored w ires, deposition rate w ill increase as the electrical

stick-out is increased, and the same amperage is maintained. True deposition rates for each

w elding f iller metal, w hether it is a coated electrode or a solid or f lux cored w ire, can only be

established by an actual test in w hich the w eldment is w eighed before w elding and then again

after w elding, at the end of a measured period of time. The tables in Figures 8-11 contain

average values for the deposition rate of various types of w elding f iller metals. These are

based on w elding laboratory tests and published data.

FIGURE 1

HOURLY WELDING LABOR & OVERHEAD RATES

Small Shops $10.00 to $25.00/hr.

Large Shops $25.00 to $50.00/hr

Av erage $30.00/hr.

APPROXIMATE LABOR AND OVERHEAD RATES


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LESSON IX

9.2.3 Operating Factor - Operating factor is the percentage of a w elder’s w orking day

that is actually spent w elding. It is the arc time in hours divided by the total hours w orked. A

45% (.45) operating factor means that only 45% of the w elder’s day is actually spent w elding.

The balance of time is spent installing a new electrode or w ire, cleaning slag, positioning the

w eldment, cleaning spatter from the w elding gun, etc.

9.2.3.1 When using coated electrodes, (SMAW) the operating factor can range from

15%-40% depending upon material handling, f ixturing and operator dexterity. If the actual

operating factor is not know n, an average of 30% may be used for cost estimates w hen w eld-

ing w ith the shielded metal arc w elding process.

9.2.3.2 When w elding w ith solid w ires (GMAW) or metal cored w elding (MCAW) using the

semi-automatic method, operating factors ranging from 45%-55% are easily attainable. Use

50% for cost estimating purposes.

9.2.3.3 For w elds produced by f lux cored arc w elding (FCAW) semi-automatically, the

operating factor usually lies betw een 40%-50%. For cost estimating purposes, use a 45%

operating factor. The estimated operating factor for FCAW is about 5% low er than that of

GMAW to allow for slag removal time.

9.2.3.4 In semi-automatic submerged arc w elding, slag removal and loose f lux handling

must be considered. A 40% operating factor is typical for this process.

9.2.3.5 Automatic w elding using the GMAW, FCAW, and SAW processes, requires that

each application be studied individually. Operating factors ranging from 50% to values ap-

proaching 100% may be obtained depending on the degree of automation.

9.2.3.6 The chart in Figure 2 show s average operating factor values for the various w elding

processes that may be used for cost estimating w hen the actual operating factor is not know n.

FIGURE 2

WELDING PROCESS

SMAW * GMAW *FCAW *SAW

30% 50% 45% 40%

*Semi-Automatic Only

+ Metal Cored Wires are Included

APPROXIMATE OPERATING FACTOR

+


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LESSON IX

9.2.4 Deposition Efficiency - Deposition efficiency is the relationship of the weight of

the w eld metal deposited to the w eight of the electrode (or w ire) consumed in making a w eld.

It can be accurately determined only by making a timed test w eld, and carefully w eighing the

w eldment and the electrode or w ire, before and after w elding. The eff iciency can then be

calculated by the formula:

Deposition eff iciency = Weight of Weld Metal ÷ Weight of Electrode Used

(or)

Deposition Rate (lbs/hr) ÷ Burn-off Rate (lbs/hr)

9.2.4.1 The deposition eff iciency tells us how many pounds of w eld metal can be expected

from a given w eight of the electrode or w elding w ire purchased. As an example, 100 pounds

of a f lux cored electrode w ith an eff iciency of 85%, w ill produce approximately 85 pounds of

w eld metal, w hile 100 pounds of coated electrode w ith an eff iciency of 65%, w ill produce

approximately 65 pounds of w eld metal, less the w eight of the stubs discarded, as described

below .

9.2.5 Coated Electrodes - The deposition efficiency of coated electrodes by AWS

definition, and in published data, does not consider the loss of the unused electrode stub that

is discarded. This is understandable since the stub length can vary w ith the operator and the

application. Long continuous w elds are usually conducive to short stubs w hile on short inter-

mittent w elds, stub length tends to be longer. Figure 3 illustrates how the stub loss influences

the electrode eff iciency w hen using coated electrodes.

9.2.5.1 In Figure 3, a 14” long by 5/32” diameter E7018 electrode at 140 amperes is con-

sidered. It is 75% eff icient, and a tw o inch stub loss is assumed. The 75% eff iciency applies

FIGURE 3

DEPOSITION EFFICIENCY = 75%actual efficiency, including stub loss = 9 ÷ 14 = 64.3%

12" LENGTH OF ELECTRODE CONSUMED

AMOUNT THAT BECOMES WELD METAL

(LENGTH CONSUMED X EFFICIENCY)

14"

LOST TO

SLAG,SPATTER

& FUMES

2"

STUB

LENGTH

9"


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LESSON IX

only to the 12” of the electrode consumed in making the w eld, and not to the tw o inch stub.

When the tw o inch stub loss and the 25% that is lost to slag, spatter and fumes are consid-

ered, the eff iciency minus stub loss is low ered to 64.3%. This means that for each 100 pounds

of electrodes purchased, you can expect an actual deposit of approximately 64.3 pounds of

w eld metal if all electrodes are used to a tw o inch stub length.

9.2.5.2 The formula for the eff iciency including stub loss is important, and must alw ays be

used w hen estimating the cost of depositing w eld metal by the SMAW method. Figure 4

show s the formula used to establish the eff iciency of coated electrodes including stub loss. It

is based on the electrode length, and is slightly inaccurate, i.e. it does not take into consider-

ation that the electrode w eight is not evenly distributed, due to the f lux being removed from the

electrode holder end. (Indicated by the dotted lines in Figure 3.) Use of the formula w ill result

in a 1.5-2.3% error that w ill vary w ith electrode size, coating thickness and stub length. The

formula how ever, is acceptable for estimating purposes.

9.2.5.3 For the values given in Figure 3 the formula is:

Eff iciency - Stub Loss = (14-2) x .75

14

= 12 x .75

14

= 9

14

= .6429 or 64.3%

In the above example, the electrode length is know n, the stub loss must be estimated, and the

eff iciency taken from the tables in Figures 8 and 9. Use an average stub loss of three inches

for coated electrodes if the actual shop practices concerning stub loss are not know n.

9.2.5.4 The follow ing stub loss correction table w ill assist in your determination of coated

electrode eff iciencies. Figure 5 lists various eff iciencies at a given stub loss.

EFFICIENCY (ELECTRODE LENGTH — STUB LENGTH) X DEPOSITION EFFICIENCY

ELECTRODE LENGTH

=

EFFICIENCY MINUS STUB LOSS

FIGURE 4

MINUS STUB LOSS


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LESSON IX

9.2.6 Efficiency of Flux Cored Wires - Flux cored w ires have a low er f lux-to-metal ratio

than coated electrodes, and thereby, a higher deposition eff iciency. Stub loss need not be

considered since the w ire is continuous. The gas shielded w ires of the E70T-1 and E70T-2

types have eff iciencies of 83%-88%. The gas shielded basic slag type (E70T-5) is 85%-90%

efficient w ith CO2 as the shielding gas, and the eff iciency can reach 92% w hen a 75% argon,

25% CO2 gas mixture is used. Use the eff iciency f igures in Figure 9 for your calculations if the

actual values are not know n.

9.2.6.1 The eff iciency of the self-shielded types of f lux cored w ires has more variation

because of the large variety of available types that have been designed for specif ic applica-

tions. The high deposition general purpose type, such as E70T-4, is 81%-86%, depending on

w ire size and electrical stick-out. The chart in Figure 9 show s the optimum conditions for each

w ire size and may be used in your calculations.

9.2.7 Efficiency of Solid Wires for GMAW - The eff iciency of solid w ires in GMAW is

very high and w ill vary w ith the shielding gas or gas mixture used. Using CO2 w ill produce the

most spatter and the average eff iciency w ill be about 93%. Using a 75% argon-25% CO2 gas

mixture w ill result in somew hat less spatter, and an eff iciency of approximately 96% can be

expected. A 98% argon-2% oxygen mixture w ill produce even less spatter, and the average

eff iciency w ill be about 98%. Stub loss need not be considered since the w ire is continuous.

Figure 6 show s the average eff iciencies you may use in your calculations if the actual eff i-

ciency is not know n.

FIGURE 5

ELEC. DEPOSITION 2" 3" 4" 5"

LENGTH EFFICIENCY STUB STUB STUB STUB

60% 50.0% 45.0% 40.0% 35.0%

65% 54.2% 48.7% 43.3% 37.9%

12" 70% 58.3% 52.5% 46.6% 40.8%

75% 62.5% 56.2% 50.0% 43.7%

80% 66.6% 60.0% 53.3% 46.6%

60% 51.4% 47.1% 42.8% 38.5%

65% 55.7% 51.1% 46.4% 41.8%

14" 70% 60.0% 55.0% 50.0% 45.0%

75% 64.3% 58.9% 53.6% 48.2%

80% 68.5% 62.8% 57.1% 51.4%

60% 53.3% 50.0% 46.6% 43.3%

65% 57.7% 54.2% 50.5% 46.9%

18" 70% 62.2% 58.3% 54.4% 50.5%

75% 66.6% 62.5% 58.3% 54.2%

80% 71.1% 66.6% 62.2% 57.7%

STUB LOSS CORRECTION

TABLE FOR COATED

ELECTRODES

EFFICIENCY INCLUDING

STUB LOSS


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.045" - 1/16"

GMAW


LESSON IX

9.2.8 Efficiency of Solid Wires for SAW - In submerged arc w elding there is no spatter

loss and an eff iciency of 99% may be assumed. The only loss during w elding is the short

piece the operator must clip off the end of the w ire to remove the fused f lux that forms at the

termination of each w eld. This is done to assure a good start on the succeeding w eld.

9.2.9 Cost of Electrodes, Wires, Gases and Flux - You must secure the current cost

per pound of the electrode or w elding w ire, plus the cost of the shielding gas or f lux if appli-

cable, from the supplier. The shielding gas f low rate varies slightly w ith the type of gas used.

The f low rates in Figure 7 are average values w hether the shielding gas is an argon mixture or

pure CO2. Use these in your calculations if the actual f low rate is not available.

In the submerged arc process (SAW) the ratio of f lux to w ire consumed in the w eld is approxi-

mately 1 to 1 by w eight. When the losses due to f lux handling and f lux recovery systems are

considered, the average ratio of f lux to w ire is approximately 1.4 pounds of f lux for each pound

of w ire consumed. If the actual f lux-to-w ire ratio is unknow n, use the 1.4 for cost estimating.

9.2.10 Cost of Power - Cost of electrical pow er is a very small part of the cost of deposit-

ing w eld metal and in most cases is less than 1% of the total. It w ill be necessary for you to

know the pow er cost expressed in dollars per kilow att- hour ($/kWh) if required for a total cost

estimate.

FIGURE 6

Shielding

Gas

Ef f iciency

Range

Av erage

Ef f iciency

Pure CO2 88 - 95% 93%

94 - 98% 96%

98% Ar - 2% O2 97 - 98.5% 98%

DEPOSITION EFFICIENCIES - GAS METAL ARC WELDINGCARBON AND LOW ALLOY STEELS

Wire Diameter .035" .045" 1/16" 5/64" - 1/8"

CFH 30 35 35 40 45

FCAW/MCAW

APPROXIMATE SHIELDING GAS FLOW RATE - CUBIC FEET PER HOUR

FIGURE 7


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LESSON IX

9.3 DEPOSITION DATA CHARTS

9.3.1 SHIELDED METAL ARC WELDING - Coated Electrodes.

DEPOSITION DATA - SMAW - COATED ELECTRODES

FIGURE 8

NOTE: EFFICIENCY RATES DO NOT INCLUDE STUB LOSS

E6011

ELECTRODE DEPOSITION EFFICIENCY

DIAMETER AMPS RATE lbs/hr %

3/32 75 1.3 61.0%

1/8 120 2.3 70.7%

5/32 150 3.7 77.0%

3/16 180 4.1 73.4%

7/32 210 5 74.2%

1/4 250 5.6 71.9%

E6012



1/8 130 2.9 81.8%

5/32 165 3.2 78.8%

200 3.4 69.0%

3/16 220 4 77.0%

250 4.2 74.5%

7/32 320 5.6 69.8%

6013



3/32 85 1.6 73.0%

1/8 125 2.1 73.0%

5/32 140 2.6 75.6%

160 3 74.1%

180 3.5 71.2%

3/16 180 3.2 73.9%

200 3.8 71.1%

220 4.1 72.9%

7/32 250 5.3 71.3%

270 5.7 73.0%

290 6.1 72.7%

E7014



1/8 120 2.4 63.9%

150 3.1 61.1%

5/32 160 3 71.9%

200 3.7 67.0%

3/16 230 4.5 70.9%

270 5.5 73.2%

7/32 290 5.8 67.2%

330 7.1 70.3%

1/4 350 7.1 68.7%

400 8.7 69.9%

E6010



3/32 75 1.5 72.0%

1/8 100 2.1 76.3%

130 2.3 68.8%

5/32 140 2.8 73.6%

170 2.9 64.1%

3/16 160 3.3 74.9%

190 3.5 69.7%

7/32 190 4.5 76.9%

230 5.1 73.1%


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LESSON IX

DEPOSITION DATA - SMAW - COATED ELECTRODES (Con't.)

FIGURE 9

NOTE: EFFICIENCY RATES DO NOT INCLUDE STUB LOSS

E7016



1/8 100 1.7 63.9%

130 2.3 65.8%

5/32 140 3.0 70.5%

160 3.2 69.1%

190 3.6 66.0%

3/16 175 3.8 71.0%

200 4.2 71.0%

225 4.4 70.0%

250 4.8 65.8%

1/4 250 5.9 74.5%

275 6.4 74.1%

300 6.8 73.2%

350 7.6 71.5%

E7024



1/8 140 4.2 71.8%

180 5.1 70.7%

5/32 180 5.3 71.3%

210 6.3 72.5%

240 7.2 69.4%

3/16 245 7.5 69.2%

270 8.3 70.5%

290 9.1 68.0%

7/32 320 9.4 72.4%

360 11.6 69.1%

1/4 400 12.6 71.7%

LOW ALLOY, IRON POWDER ELECTRODES

TYPES E7018, E8018, E9018, E10018, E11018,

AND E12018



3/32 70 1.37 70.5%

90 1.65 66.3%

110 1.73 64.4%

1/8 120 2.58 71.6%

140 2.74 70.9%

160 2.99 68.1%

5/32 140 3.11 75.0%

170 3.78 73.5%

200 4.31 73.0%

3/16 200 4.85 76.4%

250 5.36 74.6%

300 5.61 70.3%

7/32 250 6.50 75.0%

300 7.20 74.0%

350 7.40 73.0%

1/4 300 7.72 78.0%

350 8.67 77.0%

400 9.04 74.0%


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0.045


LESSON IX

FLUX CORED ARC WELDING (FCAW)

GAS SHIELDED TYPES E70T-1, E71T-1, E70T-2,

E70T-5, & ALL LOW ALLOY TYPES



.035 130 3.2 82%

140 3.6 82%

160 4.2 83%

180 5.6 83%

200 6.5 84%

220 7.5 85%

.045 160 4.0 83%

180 4.9 87%

200 6.5 90%

220 6.8 84%

240 7.3 84%

280 10.5 89%

.052 170 3.9 84%

190 5.3 87%

210 5.5 86%

240 6.7 85%

270 8.1 85%

300 10.3 87%

1/16 180 4.2 87%

200 4.7 85%

220 5.6 87%

250 7.7 86%

275 8.5 86%

300 9.3 86%

350 11.7 86%

5/64 250 6.4 85%

350 10.5 85%

450 14.8 85%

3/32 400 12.7 85%

450 15.0 86%

500 18.5 86%

DEPOSITION DATA - FCAW/MCAW

FIGURE 10

METAL CORED ARC WELDING (MCAW)

E70T-1, E71T-1, AND ALL ALLOY TYPES



0.035 150 4.4 93%

200 6.5 92%250 9.4 92%

250 8 91%275 11.4 93%

300 11.6 95%

0.052 275 8 90%

300 9.6 93%

325 10.1 93%1/16 300 8.6 89%

350 11.9 94%400 14.6 93%

450 16.2 96%

5/64 350 11.6 94%

400 13.2 95%450 15.8 97%

500 20.4 97%3/32 400 11.5 95%

450 14.5 97%

500 16.5 97%

550 21 98%

NOTE: DATA REFLECTS USE OF 75% ARGON

25% CO2 GAS SHIELDING. DEPOSITION RATES

AND EFFICIENCIES WILL INCREASE WITH THE USE

OF HIGHER ARGON MIXTURES.

9.3.2 FLUX CORED ARC WELDING/METAL CORED ARC WELDING - Deposition

data for gas shielded FCAW on all low alloy w ire types and MCAW on all alloy types.


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LESSON IX

SUBMERGED ARC W IRES

(1" STICKOUT)

ELECTRODE MELT-OFF EFFICIENCY


5/64 300 7.0

400 10.2

500 15.0

3/32 400 9.4

500 13.0

600 17.2

1/8 400 8.5

500 11.5

600 15.0

700 19.0

5/32 500 11.3

600 14.6

700 18.4

800 22.0

900 26.1

3/16 600 13.9

700 17.5

800 21.0

900 25.0

1000 29.2

1100 34.0

NOTE: Values f or 1" Stickout

DEPOSITION DATA

FIGURE 11

FLUX CORED ARC WELDING (FCAW)

SELF-SHIELDED

ELECTRODE DEPOSITIONEFFICIENCY


E70T-3 3/32 450 14 88%

E70T-4 3/32 400 15 85%

0.12 450 20 81%

E70T-6 5/64 350 11.9 86%

3/32 480 14.7 81%

E70T-6 3/32 325 11.4 80%

7/64 450 18 86%

E71T-7 .068 200 4.2 76%

5/64 300 8 84%

E71T-8 5/64 220 4.4 77%

3/32 300 6.7 77%

E61T8-K6 5/64 235 4.3 76%

E70T-10 .045 150 2.6 88%

1/16 220 3.3 78%

5/64 250 4 94%

E71T-11 .045 150 2.4 82%

1/16 200 3.6 83%

5/64 240 4.5 87%

3/32 250 5 91%

E70T4-K2 3/32 300 14 83%

E71T-GS .030 100 1.6 75%

.035 120 2.1 84%

.045 150 2.4 82%

1/16 200 3.6 83%

5/64 250 3.9 81%

GAS METAL ARC W ELDING

SOLID W IRES

DEPOSITION RATE lbs/hrELECTRODE 98%A/2%O275%A/25%CO2Straight CO2

DIAMETER AMPS *98% *96% *93%

.030 75 2.0 1.9 1.8

100 2.6 2.6 2.5

150 4.1 4.0 3.9

200 6.8 6.7 6.5

.035 80 2.2 2.1 2.0

100 2.7 2.7 2.6

150 4.2 4.1 4.0

200 6.2 6.0 5.9

250 9.0 8.8 8.6

.045 100 2.1 2.0 1.9

125 2.8 2.8 2.7

150 3.6 3.5 3.4

200 5.6 5.5 5.3

250 7.8 7.6 7.4

300 10.2 10.0 9.7

350 13.2 12.9 12.5

1/16 250 6.5 6.4 6.2

275 7.7 7.6 7.3

300 9.0 8.8 8.5

350 11.3 11.0 10.7

400 14.0 13.7 13.3

450 17.4 17.1 16.5

* USE THIS FIGURE AS THE DEPOSITION EFFICIENCY IN THE

COST CALCULATIONS ON SHEET ONE.

9.3.3 FLUX CORED ARC WELDING,

GAS METAL ARC WELDING, AND SUB-

for self-shielded FCAW, and solid w ires using

GMAW and SubArc.


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MERGED ARC WELDING - Deposition data

Assume

99%

Efficiency

















LESSON IX

9.4 COST CALCULATIONS - EXAMPLE 1

9.4.1 Calculating the Cost Per Pound of Deposited Weld Metal

9.4.1.1 Example 1 - Calculate the cost of w elding 1,280 ft. of a single bevel butt joint as

show n in Figure 14 using the follow ing data.

a. Electrode - 3/16” diameter, 14” long, E7018, operated at 25 volts, 250 amps.

b. Stub Loss - 2 inches

c. Labor and Overhead - $30.00/hr

d. Electrode Cost - $.57/lb

e. Pow er Cost - $.045/kWh

9.4.1.2 The formulas for the calculations are show n on the Weld Metal Cost Worksheet in

Figure 12. The follow ing explains each step in the calculations.

Line 1- Labor and Overhead - $30.00/hr (given)

Deposition Rate - From shielded metal arc w elding deposition data chart in

Figure 9 = 5.36 lbs/hr.

Operating Factor - Since it is not stated above, use an average value of 30% (.30)

show n in Figure 2.

The cost of labor and overhead per pound of deposited w eld metal can now be

calculated as $18.66/lb.

Line 2 - Electrode Cost Per Pound - $.57 (given)

Deposition Eff iciency - From the shielded metal arc w elding deposition table in

Figure 9 = 74.6%. Since this is a coated electrode, the eff iciency must be adjusted

for stub loss by the formula follow ing Figure 3. We know that the electrode length is

14" and the stub loss is 2" (given). The formula becomes:

Eff iciency - Stub Loss = (14-2) x .746 ÷ 14 = .639 or 63.9%

63.9% is the adjusted eff iciency to be used in Line 2.

The cost of the electrode per pound of deposited w eld metal can now be calculated

as $.89/lb.

Line 3 - Not applicable for coated electrodes.

Line 4 - Not applicable for coated electrodes.


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LESSON IX

FIGURE 12

EXAMPLE 1

WELD METAL COST WORKSHEET

COST PER POUND OF DEPOSITED WELD METAL

LABOR &OVERHEAD

LABOR & OVERHEAD COST/HRDEPOSITION OPERATINGRATE (LBS/HR) x FACTOR

=

ELECTRODE

GAS

FLUX

POWER

ELECTRODE COST/LB

GAS FLOW RATE(CU FT/HR) x GAS COST/CU FT

DEPOSITION RATE (LBS/HR)

FLUX COST/LB x 1.4

DEPOSITION EFFICIENCY

COST/kWh x VOLTS x AMPS1000 x DEPOSITION RATE

TOTAL COST PER LB. OFDEPOSITED WELD METAL

SUM OF 1 THROUGH 5 ABOVE

DEPOSITION EFFICIENCY=

=

=

=

1.

2.

3.

4.

5.

6.

7.

8.

30.00

5.36 x .30

30.00

1.60818.66= =

.57

.639= .89

= =N A

X 1.4 = =N A

= =.045 x 25 x 250

1000 x 5.36

281.25

5,360

.052

COST PER FOOT OF DEPOSITED WELD METAL

COST PER POUNDOF DEPOSITEDWELD METAL

XPOUNDS PER

FOOT OFWELD JOINT

$ 19.60

= 19.60x .814 = $15.95

TOTAL FEETOF WELD

=COST PER

FOOTX

1,280x 15.95 = $20,422

COST OF WELD METAL - TOTAL JOB


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LESSON IX

Line 5 - Cost of Pow er - $ .045/kWh (given).

Volts & Amperes - 25V and 250A (given).

Constant - The 1,000 already entered, is a constant necessary to convert to

w att-hours.

Deposition Rate - 5.36 lbs/hr as used in Line 1.

The cost of electrical pow er to deposit one pound of w eld metal can now be

calculated as $.052.

Line 6 - Total Lines 1, 2, and 5 to f ind the total cost of depositing one pound w eld

metal. The total of $19.60.

9.4.2 Calculating The Cost Per Foot of Deposited Weld Metal

Calculating the w eight of w eld metal requires that w e consider the follow ing items.

a. Area of the cross-section of the w eld.

b. Length of the w eld.

c. Volume of the w eld in cubic inches.

d. Weight of the w eld metal per cubic inch.

9.4.2.1 In the f illet w eld show in Figure 13, w e know that the area of the cross-section (the

triangle) is equal to one-half the base times the height, the volume of the w eld is equal to the

area times the length, and the w eight of the w eld then, is the volume times the w eight of the

material (steel) per cubic inch.

9.4.2.2 We can then w rite the formula:

Weight of Weld Metal = ½ x Base x Height x Length x Weight of Material

Substituting the values from Figure 13, w e have:

Wt/Ft = .5 x .5 x .5 x 12 x .283 = .4245 lbs

9.4.2.3 Weights may vary depending on the density of the particular material you are at-

tempting to calculate. The chart in Figure 14 w ill eliminate the need for these calculations for

steel f illet and butt joints, since it lists the w eight per foot directly.

9.4.2.4 Estimating the w eight per foot of a w eld using the chart, requires that you make a

draw ing of the w eld joint to exact scale, and dimension the leg lengths, root gap, thickness,

angles and other pertinent measurements as show n in Figure 15. Divide the cross-section of

the w eld into right triangles and rectangles as show n. Sketch in the reinforcement, i.e., the


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LESSON IX

domed portion above or below the surface of the plate, w here required. The reinforcement

should extend slightly beyond the edges of the joint. Measure the length and height of the

reinforcement and note them on your draw ing. The reinforcement is only an approximation

because the contour cannot be exactly controlled in w elding. Refer to the w eight tables in

Figure 14 for the w eights per foot of each of the component parts of the w eld, as sketched.

The sum of the w eights of all the components is the total w eight of the w eld, per foot as show n

in Figure 15A.

Line 7 - The total cost per pound as determined in Line 6 is entered, and multi-

plied by the w eight per foot as determined in Figure 14.

9.4.3 Calculating the Cost of Weld Metal - Total Job

Line 8 - The cost of the w eld for the total job is determined by multiplying the total

feet of w eld (given) by the cost per foot as determined in Line 7.

9.5 COST CALCULATIONS - EXAMPLE 2

Calculate the total cost of depositing 1,280 ft of w eld metal using the CO2 shielded, f lux cored

w elding process in the double V-groove joint show n in Figure 14 using the follow ing data.

1. Electrode - 3/32”, E70T-1 @ 31 volts, 450 amps.

2. Labor and Overhead - $30.00/hr.

3. Deposition Rate - 15 lbs/hr. From Table in Figure 10.

4. Operating Factor - 45% (.45). Average from Figure 2.

1/2"

1/2"

(A)HEIGHT

(B) BASE

Weight of Steel = .283 lb per cu. in.Weight of Weld = 1/2 (1/2) x 1/2 x 12 x .283

= .424 lbs.

CALCULATING THE WEIGHT PER FOOT OF A FILLET WELD

FIGURE 13


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V-GROOVE


LESSON IX

FIGURE 14

WEIGHT PER FOOT OF WELD METAL FOR FILLET WELDS AND

ELEMENTS OF COMMON BUTT JOINTS (lbs/ft)

STEEL

B TT T T T

TT T

T TT

H

G GS SS

S SSSS

C C

C C

B B B

AA

C

B B

A

B B

C

CB

A

B

C

C

B B

lbs./f t. of Rectangle A lbs./f t. of Triangle B lbs./f t. Reinf orcement C

T G S H

Inches 1/16" 1/8" 3/16" 1/4" 3/8" 1/2" 5° 10° 15° 22 1/2° 30° 45° 1/16" 1/8" 3/16" 1/4"

1/8 .027 .053 .080 .106 .159 .212 .002 .005 .007 .011 .015 .0273/16 .040 .080 .119 .159 .239 .318 .005 .011 .016 .025 .035 .060 .0271/4 .053 .106 .159 .212 .318 .425 .009 .019 .028 .044 .061 .106 .035

5/16 .066 .133 .199 .265 .390 .531 .015 .029 .044 .069 .096 .166 .044 .8843/8 .080 .159 .239 .318 .478 .637 .021 .042 .064 .099 .138 .239 .053 .1067/16 .091 .186 .279 .371 .557 .743 .028 .057 .087 .129 .188 .325 .062 .124

.106 .212 .318 .425 .637 .849 .037 .075 .114 .176 .245 .425 .071 .141 .2129/16 .119 .239 .358 .478 .716 .955 .047 .095 .144 .223 .311 .451 .080 .159 .2395/8 .133 .265 .398 .531 .796 1.061 .058 .117 .178 .275 .383 .664 .088 .177 .265 .35411/16 .146 .292 .438 .584 .876 1.167 .070 .142 .215 .332 .464 .804 .097 .195 .292 .3893/4 .159 .318 .478 .637 .995 1.274 .084 .169 .256 .396 .552 .956 .106 .212 .318 .424

13/16 .172 .345 .517 .690 1.035 1.380 .098 .198 .301 .464 .648 1.121 .115 .230 .345 .4607/8 .186 .371 .557 .743 1.114 1.486 .114 .230 .349 .538 .751 1.300 .124 .248 .371 .49515/16 .199 .398 .597 .796 1.194 1.592 .131 .263 .400 .618 .863 1.493 .133 .266 .398 .5301 .212 .425 .637 .849 1.274 1.698 .149 .300 .456 .703 .981 1.698 .141 .283 .424 .566

.239 .478 .716 .955 1.433 1.910 .188 .379 .577 .890 1.241 2.149 .159 .318 .477 .6371 1/4 .265 .531 .796 1.061 1.592 2.123 .232 .468 .712 1.099 1.532 2.653 .177 .354 .531 .7071 3/8 .292 .584 .876 1.167 1.751 2.335 .281 .567 .861 1.330 1.853 3.210 .195 .389 .584 .7771 1/2 .318 .637 .955 1.274 1.910 2.547 .334 .674 1.023 1.582 2.206 3.821 .212 .424 .637 .849

1 5/8 .345 .690 1.035 1.380 2.069 2.759 .393 .792 1.201 1.857 2.589 4.484 .230 .460 .690 .9201 3/4 .371 .743 1.114 1.486 2.229 2.972 .455 .918 1.393 2.154 3.002 5.200 .248 .495 .743 .990

.390 .796 1.194 1.592 2.388 3.184 .523 1.053 1.599 2.473 3.447 5.970 .266 .531 .796 1.0612 .425 .649 1.274 1.698 2.547 3.396 .594 1.197 1.820 2.813 3.921 6.792 .283 .566 .849 1.132

2 1/4 .478 .955 1.433 1.910 2.865 3.821 .752 1.516 2.303 3.561 4.963 8.596 .318 .637 .955 1.273.530 1.061 1.592 2.123 3.184 4.245 .928 1.871 2.844 4.396 6.127 10.613.354 .707 1.061 1.415

2 3/4 .584 1.167 1.751 2.335 3.502 4.669 1.123 2.264 3.441 5.319 7.414 12.841.389 .778 1.167 1.5563 .636 1.274 1.910 2.547 3.821 5.094 1.337 2.695 4.095 6.330 8.823 15.282.424 .849 1.273 1.698

EQUAL LEG

FILLETS

(USE 45°COLUMN)

SINGLE

BEVEL

SINGLE

V-GROOVE

DOUBLE DOUBLE

BEVEL

SINGLE V

NO GAPREINFORCEMENT

GG


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LESSON IX

5. Electrode Cost - $.80/lb (from supplier).

6. Deposition Eff iciency - 86% (.86) From Table in Figure 10.

7. Gas Flow Rate - 45 cubic feet per hour. From Figure 7.

8. Gas Cost - $.03/cubic foot (from supplier).

9. Cost of Pow er - $.045/kWh.

10. Wt/Ft of Weld - From Figure 15B = .846 lbs/ft.

These values are show n inserted into the formulas on the Weld Metal Cost Worksheet in

Figure 16.

9.6 COMPARING WELD METAL COSTS

It is interesting to note that the amount of w eld metal deposited in Example 1 and Example 2 is

almost the same, w hile the total cost of depositing the w eld metal is three times higher in

Example 1 as show n below . This is because the f lux cored process has a higher deposition

rate, eff iciency and operating factor and also allow s a tighter joint due to the deep penetrating

characteristics of the process.

Example 1 - 1,280 ft x .814 lbs/ft = 1,041.9 lbs at $13,939

Example 2 - 1,280 ft x .846 lbs/ft = 1,082.9 lbs at $ 4,352

9.6.0.1 When comparing w elding processes, all efforts should be made to assure that you

use the proper w elding current for the electrode or w ire in the position in w hich the w eld must

be made. As an example, consider depositing a given size f illet w eld in the vertical-up posi-

45°

22.5° 22.5°

1/16"

7/8"

5/8" 1/2"

1/8"

A B

C

B

B

C

C

1"

1/2"

1/2"

1/16"lbs./f t.

A = .265B = .425C = .124

TOTAL WEIGHT/FT. .814 lbs

lbs./f t.

B = .176 x 4 = .704C = .071 x 2 = .142

TOTAL WEIGHT/FT. .846 lbs

ESTIMATING WELD METAL WEIGHT

FIGURE 15

A B

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LESSON IX

FIGURE 16

EXAMPLE 2

WELD METAL COST WORKSHEET

COST PER POUND OF DEPOSITED WELD METAL

LABOR &OVERHEAD

LABOR & OVERHEAD COST/HR

DEPOSITION OPERATINGRATE (LBS/HR) x FACTOR

=

ELECTRODE

GAS

FLUX

POWER

ELECTRODE COST/LB

GAS FLOW RATE(CU FT/HR) x GAS COST/CU FT

DEPOSITION RATE (LBS/HR)

FLUX COST/LB x 1.4

DEPOSITION EFFICIENCY

COST/kWh x VOLTS x AMPS

1000 x DEPOSITION RATE

TOTAL COST PER LB. OFDEPOSITED WELD METAL

SUM OF 1 THROUGH 5 ABOVE

DEPOSITION EFFICIENCY=

=

=

=

1.

2.

3.

4.

5.

6.

7.

8.

30.00

15 x .45

30.00

6.754.44= =

.80

.86= .93

= =

x 1.4= =

N A

= =.045 x 31 x 450

1000 x 15

627.75

15,000

.042

COST PER FOOT OF DEPOSITED WELD METAL

COST PER POUNDOF DEPOSITEDWELD METAL

XPOUNDS PER

FOOT OFWELD JOINT

$ 5.51

= 5.51 x .846 = $4.66

TOTAL FEETOF WELD

=COST PERFOOT

X1,280x 4.66 = $5,965

COST OF WELD METAL - TOTAL JOB

45 x .03

1 5

1.35

1 5.09


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LESSON IX

tion by the GMAW process and FCAW process semi-automatically. In both processes the

w elding current and voltage must be low ered to w eld out-of-position, and in GMAW, the short

circuiting arc transfer must be used. Example 3 compares the w eld metal cost per pound

deposited by these processes, using the proper current and voltage for depositing a ¼” f illet

w eld on ¼” plate, vertically up.

Note: The cost of electrical power is comparable in all processes and therefore, can be eliminated as a factor.

9.6.1 Example 3

FCAW GMAW

Electrode Type - .045” dia. E71T-1 .045” dia. ER70S-3

Labor & Overhead - $30.00/hr $30.00/hr

Welding Current - 180 amperes 125 amperes

Deposition Rate - 4.9 lbs/hr (Fig. 9) 2.8 lbs/hr (Fig. 10)

Operating Factor - 45% (Fig. 2) 50% (Fig. 2)

Electrode Cost - $1.44/lb $.66/lb

Deposition Eff iciency - 85% (Fig. 9) 96% (Fig. 6)

Gas Flow Rate - 35 cfh (Fig. 7) 35 cfh (Fig. 7)

Gas Cost Per Cu. Ft. - $.03 CO2 $.11 75% Ar/25% CO2

This data is tabulated in the chart in Figure 17.

9.6.1.1 As you can see, the cost of depositing the w eld metal is about 33% less using the

Flux Cored Arc Welding process. Since there is no slag to help hold the vertical w eld puddle

in the GMAW process, the w elding current w ith solid w ire must be low ered considerably. This,

of course, low ers the deposition rate, and since labor and overhead is the largest factor in-

volved, it substantially raises deposition costs. In the f lat or horizontal position, w here the

w elding current on the solid w ire w ould be much higher, the cost difference w ould be consider-

ably less pronounced.


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LESSON IX

9.7 OTHER USEFUL FORMULAS

The information discussed below will assist you in making other useful calculations:

TOTAL POUNDS OF ELECTRODES REQUIRED (REF. EXAMPLE 1)

The f ollowing inf ormation/v ariables must be determined prior to completing calculations:

(1) Proposed Method Cost Calculation (2) Present Method Cost CalculationFlux Cored Arc Welding Gas Metal Arc Welding

E71T-1 .045 Dia. at 180 Amps (3)ER70S-3 .045 Dia. at 125 Amps (4)

Actual Labor & O/H Rate f or y our Customer30.00$ Actual Labor & O/H Rate f or y our Customer 30.00$

Deposition Rate in Pounds per Hour4.9 Deposition Rate in Pounds per Hour 2.8

Operating Factor45% Operating Factor 50%

Electrode Cost per Pound1.44$ Electrode Cost per Pound 0.66$

Deposition Ef f iciency85% Deposition Ef f iciency 96%

Gas Ty peCO2 Gas Ty pe 75% Ar/25% CO2

Gas Flow Rate35 Gas Flow Rate 30

Gas Cost per Cubic Foot0.03$ Gas Cost per Cubic Foot 0.11$

Equipment Cost-$

Prepared For: NAME INFO Customer Name: NAME INFO Date:

(1) Proposed Method Cost Calculation (2) Present Method Cost Calculation

Result

Formulas f or Calculating Flux Cored Arc Welding Gas Metal Arc Welding

(Cost

Reduction )

Cost per Pound Deposited Weld Metal E71T-1 .045 Dia. at 180 Amps ER70S-3 .045 Dia. at 125 AmpsCost

Increase

Labor& = Labor & Ov erhead Cost /Hr = $30.00 = $30.00 = $13.605 $30.00 = $30.00 = $21.429 ($7.823 )

Ov erhead Deposition

Rate (lbs / hr) X

Operating

Factor 4.9 X 0.45 = 2.205 2.8 X 0.5 = 1.4

Electrode Electrode Cost/lb = 1.44 = 1.694 0.66 = 0.688 $1.007

Deposition Ef f iciency 0.85 0.96

Gas Type = CO2 Gas Type = 75% Ar/25% CO2

GasGas Flow Rate (Cuf t/hr)

X Gas Cost/Cu f t. = 35 X 0.03 = 1.05 = 0.214 30 X 0.11= 3.3 = 1.179 ($0.964 )

Deposition Rate (lbs&/hr) 4.9 2.8

Sum of the Abov eTotal Variable Cost/lb

Deposited Weld Metal = $15.514Total Variable Cost/lb

Deposited Weld Metal = $23.295 ( $7.781)

T otal

Total Pounds =

Deposition Efficiency

Wt/Ft of Weld x No. of Ft of Weld

Substituting the values from Example 1:.814 x 1,280

.630= 1,631 lbs

WELDING TIME REQUIRED (REF. EXAMPLE 1)

Welding Time =Wt/Ft of Weld x Ft of Weld

Deposition Rate x Operating Factor

Substituting the values in Example 1: .814 x 1,280

5.36 x .30=

1,042

1.608= 648 Hrs.


Welding

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Arc Welding

Processes

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Covered Electrodes


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LESSON IX

9.8 AMORTIZATION OF EQUIPMENT COSTS

Calculations show that you can save $7.00 per pound of deposited w eld metal by sw itching

from E7018 electrodes and the SMAW process to an ER70S0-3 solid w ire using the GMAW

process. How ever, the cost of the necessary equipment (pow er source, w ire feeder and gun)

is $2,800. How long w ill it take to amortize or regain the cost of the equipment know ing that

the deposition rate of the ER70S-3 is 7.4 lbs/hr and the operating factor of the GMAW process

is 50%? The formula is:

Equipment Cost

$ Savings/Lb(Deposition Rate x Operating Factor) = Man Hrs÷

400 ÷ 3.7 = Man Hrs

Substituting the values in the formula:2,8007.00 ÷ (7.4 x .50) = Man Hrs

If w e divide 108 into eight hour days (108 ÷ 8 = 13.5) the deposited w eld metal savings of one

man w orking an eight hour day for 13-1/2 days w ill pay for the cost of the equipment.


Welding

Current

Chapter Table of

Contents


Arc Welding

Processes

Lesson 3

Covered Electrodes


Lesson 4

Covered Electrodes


Go To Test

Lesson 5


Print

Lesson 6


Glossary

Lesson 7


SearchChapter

(FasterDownload)


Electrodes

Turn Pages

Lesson 9


Metal Costs

SearchDocument

(SlowerDownload)

Lesson 10


Filler Metals














Lesson 9

Documents

cost of electrodes

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pound of deposited weld

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