1、 Standard Test Method Standard Test Method for Measuring Deposit Mass Loading (“Deposit-Weight-Density”) Values for Boiler Tubes by the Glass-Bead-Blasting Technique This NACE International standard represents a consensus of those individual members who have reviewed this document, its scope, and pr
2、ovisions. Its acceptance does not in any respect preclude anyone, whether he or she has adopted the standard or not, from manufacturing, marketing, purchasing, or using products, processes, or procedures not in conformance with this standard. Nothing contained in this NACE International standard is
3、to be construed as granting any right, by implication or otherwise, to manufacture, sell, or use in connection with any method, apparatus, or product covered by Letters Patent, or as indemnifying or protecting anyone against liability for infringement of Letters Patent. This standard represents mini
4、mum requirements and should in no way be interpreted as a restriction on the use of better procedures or materials. Neither is this standard intended to apply in all cases relating to the subject. Unpredictable circumstances may negate the usefulness of this standard in specific instances. NACE Inte
5、rnational assumes no responsibility for the interpretation or use of this standard by other parties and accepts responsibility for only those official NACE International interpretations issued by NACE International in accordance with its governing procedures and policies which preclude the issuance
6、of interpretations by individual volunteers. Users of this NACE International standard are responsible for reviewing appropriate health, safety, environmental, and regulatory documents and for determining their applicability in relation to this standard prior to its use. This NACE International stan
7、dard may not necessarily address all potential health and safety problems or environmental hazards associated with the use of materials, equipment, and/or operations detailed or referred to within this standard. Users of this NACE International standard are also responsible for establishing appropri
8、ate health, safety, and environmental protection practices, in consultation with appropriate regulatory authorities if necessary, to achieve compliance with any existing applicable regulatory requirements prior to the use of this standard. CAUTIONARY NOTICE: NACE International standards are subject
9、to periodic review, and may be revised or withdrawn at any time in accordance with NACE technical committee procedures. NACE International requires that action be taken to reaffirm, revise, or withdraw this standard no later than five years from the date of initial publication. The user is cautioned
10、 to obtain the latest edition. Purchasers of NACE International standards may receive current information on all standards and other NACE International publications by contacting the NACE International FirstService Department, 1440 South Creek Drive, Houston, Texas 77084-4906 (telephone +1 281-228-6
11、200). Reaffirmed 2013-05-08 Reaffirmed 2006-03-15 Approved 1999-04-24 NACE International 1440 South Creek Dr. Houston, Texas 77084-4906 +1 281-228-6200 ISBN 1-57590-082-3 2013, NACE International NACE TM0199-2013 Item No. 21236 TM0199-2013 NACE International i _ Foreword This standard test method wa
12、s developed to document the procedures used in determining the amount of deposit accumulation on a boiler tube surface, commonly expressed as the deposit-weight-density (DWD) value, via the glass-bead-blasting (GBB) technique. The GBB technique for determining DWD values is suitable for removing a w
13、ide variety of boiler deposit types, but it is especially useful when deposition is tightly adherent and would be difficult to dislodge completely via other mechanical or chemical cleaning processes (as specified in Method A and Method B of ASTM(1) D 34831). Typically, the GBB technique allows for c
14、omplete deposit removal in a very short time frame, without the risk of error induced by incomplete removal of tightly adherent scale or excessive loss of the metal substrate during the cleaning process.2 This standard is for use specifically by those involved in providing technical assessments conc
15、erning boiler cleanliness, such as university/corporate research laboratories, independent research/engineering consulting firms, or those in the chemical cleaning industry. This standard is intended to be used to obtain accurate deposit-loading data, which may be pertinent to establishing the neces
16、sity of chemically cleaning boiler systems to avoid boiler tube failure incidents (such as those related to under-deposit corrosion and tube metal overheating) and to track the rate of deposit growth over time. This standard was originally prepared in 1999 by NACE Work Group T-7H-6f, as assigned by
17、the T-7H-6 Task Group on “Failure AnalysisBoiler Waterside,” which was a component of Unit Committee T-7H, “Corrosion and Its Control in Steam-Generating Systems.” It was reaffirmed in 2006 and 2012 by Specific Technology Group (STG) 11, “Water Treatment,” and is published by NACE International unde
18、r the auspices of STG 11. In NACE standards, the terms shall, must, should, and may are used in accordance with the definitions of these terms in the NACE Publications Style Manual. The terms shall and must are used to state a requirement, and are considered mandatory. The term should is used to sta
19、te something good and is recommended, but is not considered mandatory. The term may is used to state something considered optional. _ (1) ASTM International, 100 Barr Harbor Dr., West Conshohocken, PA 19428-2959. TM0199-2013 ii NACE International _ NACE International Standard Test Method Standard Te
20、st Method for Measuring Deposit Mass Loading (“Deposit-Weight-Density”) Values for Boiler Tubes by the Glass-Bead-Blasting Technique Contents 1. General 1 2. Test Equipment and Apparatus . 1 3. Test Specimen Preparation . 2 4. Test Procedure 2 5 Test Specimen Handling After Cleaning . 3 6. Potential
21、 Interferences . 4 References 4 Appendix A: Sample DWD Report Calculation Sheet (Nonmandatory) . 5 _ TM0199-2013 NACE International 1 _ Section 1: General 1.1 This standard describes a simple test method that employs GBB equipment to remove boiler waterside deposits on a piece of tubing removed from
22、 a representative area of a boiler. The test specimens are cut from a sample tube, weighed before and after the cleaning process, and the amount of deposit per surface area is estimated by measuring the weight loss of the tube sample test piece after deposit removal via GBB and dividing by the surfa
23、ce area of the test piece. The DWD value that is obtained by this method is typically expressed in mg/cm2 or g/ft2 units, and is defined as the weight of the deposit per boiler tube surface area.(2) Currently, DWD values are commonly expressed in g/ft2 units. Procedures for test specimen processing,
24、 dimensional analysis techniques, sources of potential interferences, and a sample DWD report calculation sheet are included. 1.2 Measurement of deposit accumulation obtained by this test method should not be the sole source of information used to decide on the necessity of chemically cleaning a boi
25、ler. Although producing an accurate DWD value may be an important factor to aid in evaluating boiler cleanliness (and there are references in the literature3,4,5 that utilize DWD data to assist in establishing chemical cleaning guidelines as a function of boiler pressure), other details should be co
26、nsidered. For example, the chemical composition and relative thickness of the specific waterside scale formed on the heat transfer surface are key parameters that must be taken into account in the process of making a decision to clean a boiler system to avoid tube failure. In addition, specific boil
27、er design, heat flux patterns, and operating conditions have significant influence on the amount of deposit loading that can be sustained prior to the occurrence of overheating and other deposit-related failure processes. 1.3 Caution should be used in the interpretation of high-DWD values obtained f
28、rom tubes subject to extreme temperature conditions (beyond the oxidation limit of the steel). This is because the DWD value produced may be unusually high as a result of the presence of excessive magnetite scale via in situ oxidation. As such, deposit-loading estimates of superheater tubes, reheate
29、r tubes, or water-bearing tubes subject to excessive heat flux may actually reflect the presence of heavy in situ oxides rather than transported and deposited water-formed scale constituents. No attempt to differentiate between water-formed scale and in situ oxidation products is made; the overall d
30、eposit weight per surface area is estimated with this test method. Other techniques (such as X-ray diffraction, microchemical analysis of deposit layers, metallography, etc.) may be needed to ascertain the relative distribution of deposit constituents and the influence of severe oxidation (excessive
31、 magnetite) on the DWD value. (2) 1 g/ft2 is equivalent to 1.075 mg/cm2. _ Section 2: Test Equipment and Apparatus 2.1 A commercial GBB cabinet shall be used to perform this test. Various commercial units that have a glass viewing window incorporated within an enclosed blast cabinet are available. T
32、ypical operating requirements are compressed air at 690 kPag (100 psig) with a minimum 0.34 m3/min (12 ft3/min) flow rate. 2.2 Medium-size glass beads, 150 to 250 m diameter range (60 to 100 mesh size) shall be used in the blast cabinet. 2.3 A dry-cutting band saw machine, portable band saw, or othe
33、r appropriate dry-cutting device shall be used to cut the test specimens from boiler tube sample segments. 2.4 An analytical laboratory balance accurate within a minimum of 0.01 g in the range of 200 to 600 g capacity (or larger capacity) shall be used. 2.5 A small flexible ruler or measuring tape w
34、ith gradations of 1.0 mm or 1/16 in shall be used. 2.6 A point micrometer with a 0 to 25 mm (0 to 1.0 in) range, 0.025 mm (0.0010 in) increments, contact points with 15 included angle, or similar, may be used to estimate deposit thickness (via before/after-cleaning measurements) and on the cleaned s
35、pecimens to estimate general corrosion loss and to assess pit depths. 2.7 An instant-film copy camera, 35 mm or digital image camera, or other photographic system may be used to record deposit appearance and other features. 2.8 Engineering graph paper may be utilized to estimate surface area of the
36、test specimen. TM0199-2013 2 NACE International _ Section 3: Test Specimen Preparation 3.1 Test Specimen 3.1.1 The optimal length of tubing cut from the boiler for evaluation is 0.6 to 0.9 m (2 to 3 ft). However, it is not uncommon to receive tube sections/samples that are very short in length or cu
37、t out in rectangular or circular shapes. Modification to the following steps may be required to determine the DWD value for unusually shaped or undersized test pieces. Comments should be added to the report (see Appendix A Nonmandatory) when unusual conditions are observed. 3.1.2 With this method, s
38、traight-bored cylindrical tube samples from a boiler should be cut lengthwise in half, and the deposit accumulation on each half should be measured individually on test specimens that are cut to approximately 76 mm (3.0 in) in length. This produces a standard test specimen with a surface area of abo
39、ut 6,000 to 6,500 mm2 (9 to 10 in2). Longer test specimens may be processed, but this may be limited by the capacity of the analytical balance being used. Test specimens less than 76 mm (3.0 in) long may be processed if necessary, but the deposit-loading result may not be as representative if deposi
40、ts are not homogeneous (see Paragraph 6.1). 3.2 Test Specimen Preparation: The following procedure shall be used in test specimen preparation. 3.2.1 Visually inspect the length of tubing cut from the boiler to assess the nature of the internal deposit. For tubes exposed to a differential heat flux (
41、waterwall, screen, etc.), identify the hot and cold sides of the tube for test specimen removal from both sides, and locate areas of the heaviest deposit accumulation. In the case of tubes exposed to a more uniform heat flux pattern around the tube circumference (economizer, superheater, etc.), remo
42、val of a test specimen from one side of the tube may be adequate. If one side appears more heavily deposited, it should be used for the test specimen. 3.2.2 Inspect the internal surface to ensure that no cutting debris or weld spatter (from torch cutting) is present in the region to be tested. By vi
43、sual inspection, select a region containing a representative sample of the internal surface deposits (typically a 76 mm 3.0 in length in the center of the tube sample). Avoid sampling at previously torch-cut ends where contamination or deposit loss could have occurred. 3.2.3 If necessary, clean the
44、external surface of the test specimen(s) by using the glass-bead blaster. This step must be taken if loosely adherent external scale is present on the tube sample and could possibly spall off in subsequent processing. During external scale cleaning, care must be taken to avoid any inadvertent remova
45、l of internal deposit. This external cleaning step may be considered optional if the external surfaces oxide layer is very thin and tightly adherent (i.e., no risk of inadvertent deposit spalling of the external surface during handling of the test specimen see Paragraph 6.3). To avoid sample mix-up,
46、 write the test specimen identification information on the external surface (or on the cut tube edges) immediately after removing any external scale. 3.2.4 With a dry-cutting saw, complete transverse cuts to produce a test specimen that is preferably 76 mm (3.0 in) long in a representative region, t
47、hen split the test specimen lengthwise to create two half-pieces (hot-side/cold-side). After cutting, re-inspect the surface for artifacts from the cutting process and carefully remove any debris and/or metal fines. Deburr rough-cut edges as necessary with a metal file. Using a felt-tip marker, pain
48、t pen, or vibratory engraver, identify the test specimens (i.e., specimen number, hot, cold, etc.) by marking on the external surface or the saw-cut end of the section. _ Section 4: Test Procedure 4.1 Photography of an area of the internal surface exhibiting deposits representative of the test specimen may be
