1、Designation:D477805 Designation: D4778 10Standard Test Method forDetermination of Corrosion and Fouling Tendency ofCooling Water Under Heat Transfer Conditions1This standard is issued under the fixed designation D4778; the number immediately following the designation indicates the year oforiginal ad
2、option or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method provides directions for fabricating and operating a t
3、est apparatus to simultaneously monitor the corrosionand fouling tendency of real and pilot cooling water systems under heat transfer conditions.1.2 Interpretation of the results of this test method must be left to the investigator. Many variables are involved which may notbe easily controlled or fu
4、lly understood. Variations in design and operating conditions may produce results that are not comparablefrom unit to unit.1.3 The values stated in inch-pound units are to be regarded as the standard. The values given in parentheses are provided forinformation only.1.4 This standard does not purport
5、 to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D1129 Te
6、rminology Relating to WaterD2331 Practices for Preparation and Preliminary Testing of Water-Formed DepositsD2777 Practice for Determination of Precision and Bias of Applicable Test Methods of Committee D19 on WaterG1 Practice for Preparing, Cleaning, and Evaluating Corrosion Test SpecimensG16 Guide
7、for Applying Statistics to Analysis of Corrosion Data3. Terminology3.1 DefinitionsFor definitions of terms used in this test method, refer to Terminology D1129.3.2 Definitions of Terms Specific to This Standard:3.2.1 corrosioncorrosion, nthe deterioration of the metal by reaction with its environmen
8、t.3.2.2 foulingfouling, ndeposition of organic matter or inorganic matter, or both, on heat transfer surfaces that result in the lossof heat transfer efficiency.3.2.3 heat fluxheat flux, nheat transfer per unit area per unit time.4. Summary of Test Method4.1 Water from the system to be tested flows
9、across a heated tube of the desired metallurgy at a constant flow rate and heat flux.Corrosion rate is determined by weight loss while fouling tendency is determined by the deposit weight.5. Significance and Use5.1 Deposits on heat transfer surfaces reduce efficiency of the heat exchanger affected.
10、A method for easily determining thecorrosion and fouling tendency of a particular water under heat transfer conditions will allow the evaluation of changes in thevarious system variables such as heat flux, flow velocity, metallurgy, cycles-of-concentration, and treatment schemes on heatexchanger per
11、formance.1This test method is under the jurisdiction of ASTM Committee D19 on Water and is the direct responsibility of Subcommittee D19.03 on Sampling of Water andWater-Formed Deposits, Analysis of Water for Power Generation and Process Use, On-Line Water Analysis, and Surveillance of Water.Current
12、 edition approved Jan.Dec. 1, 2005.2010. Published January 2005.March 2011. Originally approved in 1988. Last previous edition approved in 19992005 asD477894(1999)D4778 051. DOI: 10.1520/D4778-05 DOI: 10.1520/D4778-10.2For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact A
13、STM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.1This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been m
14、ade to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Co
15、pyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.6. Apparatus ( Fig. 1)6.1 Test SpecimenA metal tube of38 or12 in. (9.5 or 12.5 mm) outside diameter with sufficient inside diameter to snugglyaccommodate the cartridge heater. The tube sho
16、uld be cut to a length sufficient to extend12 in. (12.5 mm) from each end of thetest assembly. If both corrosion and deposition are to be determined, metallurgy of the test specimen should match that of the heatexchanger being modeled.6.2 Cartridge HeaterA14 or38 in. (6.2 or 9.5 mm) diameter. Heated
17、 surface should be 4 to 8 in. (10 to 20 cm) long witha minimum power rating sufficient to provide 110 % of the heat load required (see Eq 7, 8.2.2). The heater should have an unheatedsection of sufficient length to allow the center of the heated section to be placed consistently in the center of the
18、 test specimen.6.3 Power ControllerA device to set and control the power to the heater, such as a variable transformer, is used to adjust theheat flux in order to maintain the surface temperature of the test specimen consistent with the heat exchanger being modeled. Thepower controller should be rat
19、ed to maintain at least 120 %, but not more than 400 % of the power required.6.4 Flow ControlA flow meter or a flow control device such as an orifice, or both, is recommended to maintain a consistentflow rate during the test period.6.5 Safety EquipmentA pressure or flow sensor/controller is necessar
20、y to cut power to the heater in the event of a flowinterruption. A high temperature cutoff is recommended for added protection.NOTE 1All pipe is threaded 1 in. (25 mm) PVC. Heater should befused and grounded in accordance with local electrical codes.FIG. 1 Test Apparatus and Parts ListParts List:(1)
21、 test specimen (6) acrylic tube, 10 in. (25 cm) long by 1 in. (25 mm)outside Diameter(2) tube fitting; nylon (no metal parts) (7) Cartridge type heater (not shown)(3) reduci ng bushing, PVC(4) tee, 1 in. (25 mm) PVC(5) tube fitting, 1 in. (25 mm) tube by 1 in.(25 mm) male pipe thread stainless steel
22、FIG. 2 Test Assembly and Parts ListD4778 1026.6 Test AssemblySee Fig. 2.7. Materials7.1 Vapor Phase Inhibitor Paperenvelopes constructed of vapor phase inhibitor paper.8. Procedure8.1 Installation of Test Device:8.1.1 Placement of the test device with respect to the cooling water system is an import
23、ant factor in monitoring fouling andcorrosion in interpreting the test results. Fouling and corrosion are both affected by temperature. In the case of corrosion, the higherthe water temperature, the greater will be the corrosivity of the water. Fouling, however, is a far more complex phenomenon,invo
24、lving one or more of several types of foulants, namely, particulate matter, precipitates, biomass, corrosion products, andcontamination. There are five phases involved in the fouling phenomenon: initiation, attachment, removal, transport, and aging.8.1.2 Several of the foulants are temperature sensi
25、tive. Precipitates, such as calcium carbonate, tend to precipitate more rapidlyas temperatures increase. Most biomasses, on the other hand, would agglomerate more rapidly at temperatures between 90 and105F (32.2 and 40C).8.1.3 The test device may be installed to take its inlet water from one of thre
26、e locations: cold water supply to a heat exchanger,a heat exchanger outlet, or warm water return to the cooling tower. The choice of location is a function of the type of foulingproblem(s) experienced with the particular system. No matter where it is placed, the fouling conditions in the test device
27、 shouldsimulate the plant equipment as closely as possible. Specifically, the surface or interface temperature and the shear stress of thewater film against the heated surface in the test device should be the same as in the plant equipment being monitored.8.2 Determination of Setup Conditions:8.2.1
28、Calculate plant heat exchange conditions as follows:Vp5 0.408 Fp!P/D2N!(1)where:V = water velocity, ft/s,p= process,F = water flow rate, gal/min,P = number of passes,D = number of tubes in process heat exchanger, in., andN = number of tubes in process heat exchanger.q/A!p5 1910 To2 Ti! Fp!/DLN!(2)wh
29、ere:q/A = heat flux on inner tube, Btu/h/ft2,p= process,T = temperature, F,o= outlet water,i= inlet water,F = water flow rate, gal/min,D = inside diameter of tube in process heat exchanger, in.,L = length of heater section, ft, andN = number of tubes in process heat exchanger.8.2.2 Calculate the tes
30、t device setup as follows:Vt5 Vp# D/d22 d1!#(3)where:V = water velocity, ft/s,t= test device,p= process,D = inside diameter of tube in process heat exchanger, in.,d2= inside diameter of outer tube in test device, in., andd1= outside diameter of inner (heated) tube in test device, in.Ft5 2.45 Vtd222
31、d12!(4)where:D4778 103F = water flow rate, gal/min,t= test device,V = water velocity, ft/s,d2= inside diameter of outer tube in test device, in., andd1= outside diameter of inner (heated) tube in test device, in.W 5 9.8 Ts2 Tb!V0.8L 1 1 0.096 Tb! for d15 0.50! (5)where:W = power supplied to heater,
32、W,T = temperature, F,s= surface or interface,b= bulk water, andV = water velocity, ft/s,L = length of heater section, ft, andd1= outside diameter of inner (heated) tube in test device, in.W 5 7.94 Ts2 Tb! V0.8L1 1 0.096 Tb! for d15 0.375! (6)where:W = power supplied to heater, W,T = temperature, F,s
33、= surface or interface,b= bulk water,V = water velocity, ft/s,L = length of heater section, ft, andd1= outside diameter of inner (heated) tube in test device, in.E 5 WR!0.5(7)where:E = voltage of heater, V,W = power supplied to heater, W, andR = resistance of heater, ohm.8.3 Preparation of Test Spec
34、imen:8.3.1 Remove all metal burrs from each end of the tube with a file or emery belt.8.3.2 Throughly degrease the tube inside and out in accordance with Practice G1, and brush to remove adherent grease or metalgrit.8.3.3 Dry with a clean cloth and store in a desiccator until dry.8.3.4 Weigh the cle
35、an dry specimen to the nearest milligram.8.3.5 Store the weighed specimen in a suitable manner (protective atmosphere) to prevent atmospheric corrosion during storageand in transit. Vapor phase inhibitor paper is suitable for this purpose.8.4 Assembly of Test Apparatus :8.4.1 Install earth ground to
36、 test apparatus and secure in accordance with local electrical codes.8.4.2 Remove test specimen from protective atmosphere.8.4.3 Insert cartridge heater into test specimen to prescribed depth.NOTE 1If the fit is not snug, hot spots may occur and the heater life may be significantly shortened.8.4.4 A
37、ssemble test specimen/cartridge heater into test apparatus using nylon fittings such as Swagelok. Connect heater leadsto voltage control device.8.4.5 Flush inlet water line for 10 min to remove any foreign matter.8.4.6 Connect inlet and outlet water lines.8.4.7 Turn water on and adjust flow to that
38、calculated in Eq 4, 8.2.2.8.4.8 Connect power controller to power source. Turn on power.8.5 Operation:8.5.1 A minimum test period of 14 days is recommended. A period of 30 to 60 days is preferable in order to more accuratelyevaluate corrosion and deposition.8.5.2 Maintain flow and power as constant
39、as possible during the test period, making frequent small adjustments rather thaninfrequent, but large adjustments when and if fluctuations do occur. Keep a log of all changes and adjustments.8.6 Analysis:8.6.1 At the end of the test period, turn off power and disconnect power controller from power
40、source. Then slowly shutdownwater flow.D4778 1048.6.2 Carefully drain water from test apparatus to prevent disruption of deposit film.8.6.3 Remove the test specimen from the apparatus without disturbing deposit film. Note the deposit characteristics such asvolume, thickness, color, and appearance. P
41、hotograph the deposit where possible.NOTE 2If there is any delay in transporting the test specimen to the laboratory where the analysis will be performed, then it should be placed in aprotective atmosphere in the interim period.8.6.4 Dry the specimen in a desiccator to constant weight. Weigh to the
42、nearest milligram.NOTE 3Deposit may flake off during drying. Place a long sheet of paper under the specimen to collect any fallen deposit and add the weight of thisdeposit to the test specimen weight.8.6.5 If the deposit is to be analyzed for composition, remove as much of it as possible with a plas
43、tic knife and add to it thedeposit collected in 8.6.4. Chemical analysis of the deposit may be performed in accordance with Practices D2331, but this stepis optional.8.6.6 Clean the test specimen as well as possible with a plastic knife. Remove oily deposits in accordance with Practice G1.Remove rem
44、aining loose deposits from the specimen by wiping with a soft cloth or bristle brush. If the test specimen is clean,proceed to 8.7. If adherent deposits remain, remove the deposits in accordance with Practice G1.8.6.6.1 Dry with paper towels followed by warm air drying.8.6.6.2 Subject a weighed blan
45、k coupon of the same metallurgy to the identical cleaning procedure used for the test specimenand reweigh to determine the blank correction factor to be applied to the weight losses.8.7 After drying, reweigh a clean tube to the nearest milligram.9. Calculation9.1 Calculate the deposit weight by subt
46、racting the weight of cleaned test specimen from the weight of specimen with depositas follows:Wd5 W22 W1(8)where:Wd= weight gain due to deposition, mg,W2= weight of test specimen with deposit, mg, andW1= initial weight of test specimen, mg.9.2 Calculate the metal weight loss by subtracting the weig
47、ht of the cleaned test specimen from the initial specimen weight andcorrecting for the change in weight of a blank after cleaning as follows:Wc5 W11 2 W42 W5!/W4# 2 W2(9)where:Wc= weight loss due to corrosion, mg,W1= initial weight of test specimen, mg,W4= initial weight of blank specimen, mg,W5= we
48、ight of cleaned blank specimen, mg, andW2= weight of test specimen with deposit, mg.9.3 Calculate the average corrosion rate for the test specimen as follows:Xc5 7.09 Wc!/d1LeZt!(10)where:Xc= average corrosion rate, mills/yr,Wc= weight loss due to corrosion, mg,d1= outside diameter of test specimen,
49、 in.,Le= total length of exposed test specimen, in.,t = exposure time, days, andZ = density of metal (see Table 1), g/cm3.9.4 Calculate the average rate of fouling for the test specimen as follows:Xd5 0.0493 Wd!/d1Lht!(11)D4778 105where:Xd= average rate of fouling, mg/cm2/day,Wd= weight gain due to deposition, mg,d1= outside diameter of test specimen, in.,Lh= length of heated section, in., andt = exposure time, days.10. Precision and Bias10.1 The precision and bias of this test method are as specified in Practice G1. The preci
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