Prosecution Insights
Last updated: April 19, 2026
Application No. 17/909,986

METHOD FOR REDUCING CORROSION FATIGUE OF EVAPORATING TUBE IN BOILER

Non-Final OA §103
Filed
Sep 07, 2022
Examiner
KEYWORTH, PETER
Art Unit
1777
Tech Center
1700 — Chemical & Materials Engineering
Assignee
Kurita Water Industries Ltd.
OA Round
5 (Non-Final)
58%
Grant Probability
Moderate
5-6
OA Rounds
3y 5m
To Grant
82%
With Interview

Examiner Intelligence

Grants 58% of resolved cases
58%
Career Allow Rate
447 granted / 775 resolved
-7.3% vs TC avg
Strong +24% interview lift
Without
With
+23.9%
Interview Lift
resolved cases with interview
Typical timeline
3y 5m
Avg Prosecution
47 currently pending
Career history
822
Total Applications
across all art units

Statute-Specific Performance

§101
0.9%
-39.1% vs TC avg
§103
50.9%
+10.9% vs TC avg
§102
14.9%
-25.1% vs TC avg
§112
28.5%
-11.5% vs TC avg
Black line = Tech Center average estimate • Based on career data from 775 resolved cases

Office Action

§103
Notice of Pre-AIA or AIA Status The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA . Applicant’s Submission of a Response Applicant’s submission of a response was received on 10/20/2025. Claim Rejections - 35 USC § 103 The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action: A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made. Claim(s) 1 and 5-6 is/are rejected under 35 U.S.C. 103 as being unpatentable over Hayakawa et al. (JP 2017012991 in IDS but machine translation provided by Examiner) in view of Yoneda et al. (JP 5013064 in IDS but machine translation provided by Examiner), Zuback et al. (US 2008/0135478), and McCune et al. (US 11,447,412). Regarding claim 1 and 5, Hayakawa teaches that it is beneficial to include a polyacrylic acid scale dispersant with a MW weight of 1000-100000 in a concentration between 10-500 mg/L in order to prevent scale problems within the boiler along with reverse osmosis treatment of the feedwater ([0012]-[0014], [0016], and [0024] - [0030]). Hayakawa further teaches that chloride ions are removed via RO membranes and RO membranes have a rejection rate over 93%, thus the resulting value for the chloride ions is between 1.4-5.7 mg/L (Tables 1-2). Hayakawa fails to teach that chloride ions are controlled but fails to include sulfate ions as an ion that is controlled/monitored. Yoneda teaches a method for inhibiting corrosion fatigue in a boiler, the method comprising monitoring and controlling the chloride ion and sulfate ion concentration below a specific threshold ([0032], [0038[], [0047], [0058]-[0059], and [0067]-[0069]). Yoneda further teaches that various ion concentrations can be monitored and controlled to an unspecified value (the concentration “C”). One skilled in the art would have found it obvious to monitor and control the sulfate concentration along with the chloride concentration as it is known that sulfate concentrations also affect the scale and corrosion in a boiler system. Further, one skilled in the art would have found it obvious to have certain desirable thresholds for the concentration values of chloride and sulfate ions as doing so allows for monitoring and controlling the ions in desired ranges in order to reduce the risk of boiler tube fatigue due to the chloride and sulfate ions in an efficient manner as the less ions would result in less fatigue. It is noted that regardless whether the values used for the chloride concentration in Table 2 of Hayakawa or mathematical values argued by Applicant, Hayakawa in view of Yoneda fails to teach the chloride/sulfate ion concentration being 1 mg/L or less as claimed. However, a prima facie case of obviousness exists where the claimed ranges or amounts do not overlap with the prior art but are merely close (Titanium Metals Corp. of America v. Banner, 778 F.2d 775, 783, 227 USPQ 773, 779 (Fed. Cir. 1985) (Court held as proper a rejection of a claim directed to an alloy of "having 0.8% nickel, 0.3% molybdenum, up to 0.1% iron, balance titanium" as obvious over a reference disclosing alloys of 0.75% nickel, 0.25% molybdenum, balance titanium and 0.94% nickel, 0.31% molybdenum, balance titanium. "The proportions are so close that prima facie one skilled in the art would have expected them to have the same properties."). See also Warner-Jenkinson Co., Inc. v. Hilton Davis Chemical Co., 520 U.S. 17, 41 USPQ2d 1865 (1997) (under the doctrine of equivalents, a purification process using a pH of 5.0 could infringe a patented purification process requiring a pH of 6.0-9.0); In re Aller, 220 F.2d 454, 456, 105 USPQ 233, 235 (CCPA 1955) (Claimed process which was performed at a temperature between 40°C and 80°C and an acid concentration between 25% and 70% was held to be prima facie obvious over a reference process which differed from the claims only in that the reference process was performed at a temperature of 100°C and an acid concentration of 10%); In re Scherl, 156 F.2d 72, 74-75, 70 USPQ 204, 205-206 (CCPA 1946) (prior art showed an angle in a groove of up to 90° and an applicant claimed an angle of no less than 120°); In re Becket, 88 F.2d 684 (CCPA 1937) ("Where the component elements of alloys are the same, and where they approach so closely the same range of quantities as is here the case, it seems that there ought to be some noticeable difference in the qualities of the respective alloys."); In re Dreyfus, 73 F.2d 931, 934, 24 USPQ 52, 55 (CCPA 1934)(the prior art, which taught about 0.7:1 of alkali to water, renders unpatentable a claim that increased the proportion to at least 1:1 because there was no showing that the claimed proportions were critical); In re Lilienfeld, 67 F.2d 920, 924, 20 USPQ 53, 57 (CCPA 1933)(the prior art teaching an alkali cellulose containing minimal amounts of water, found by the Examiner to be in the 5-8% range, the claims sought to be patented were to an alkali cellulose with varying higher ranges of water (e.g., "not substantially less than 13%," "not substantially below 17%," and "between about 13[%] and 20%"); K-Swiss Inc. v. Glide N Lock GmbH, 567 Fed. App'x 906 (Fed. Cir. 2014)(reversing the Board's decision, in an appeal of an inter partes reexamination proceeding, that certain claims were not prima facie obvious due to non-overlapping ranges); In re Brandt, 886 F.3d 1171, 1177, 126 USPQ2d 1079, 1082 (Fed. Cir. 2018)(the court found a prima facie case of obviousness had been made in a predictable art wherein the claimed range of "less than 6 pounds per cubic feet" and the prior art range of "between 6 lbs./ft3 and 25 lbs./ft3" were so mathematically close that the difference between the claimed ranges was virtually negligible absent any showing of unexpected results or criticality.). In this case, the values recited in Table 2 of Hayakawa (1.4 mg/L) or the values calculated by Applicant (3.5 mg/L), the values would be considered close enough to have similar properties when applied to the Yoneda process. No support is found that the value of 1 mg/L would have any unexpected results over the values taught in the prior art. It is noted that it could be argued that while the specific concentration values would have been obvious, the processes in Yoneda and Hayakawa does not teach a means to reduce said values to the claimed concentrations. McCune teaches that providing multiple reverse osmosis membranes in series is commonly used in order to remove dissolved ions, such as chloride, to desired levels (claim 4 and C9/L52-C10/L5). As such, one skilled in the art would have found it obvious to provide reverse osmosis membranes in series in order to reduce the desired concentration of ions, such as chloride and sulfate, to desired levels of 1 mg/L or below. Hayakawa fails to teach controlling the silica concentration to be less than 1 mg/L. Zuback teaches that for processes that require high purity water, such as boiler water, reverse osmosis membranes can be used to control the silica concentration to be below 1 mg/L (Table 1, [0001], and [0034]). As such, one skilled in the art would have found that the reverse osmosis membranes in Hayakawa would inherently reduce the silica concentration to desired levels. Further, as discussed above, Yoneda teaches controlling various concentrations to be within certain ranges and McCune teaches providing multiple reverse osmosis membranes in series to achieve a desired concentration result. Regarding claim 6, it is noted that Examiner is using Applicant’s specification [0002] to define “a small-type once-through boiler.” Hayakawa discusses the process being applied to a generic boiler and not a small-type once through boiler as claimed. Yoneda teaches that the method is used to inhibit corrosion in once-through boilers ([0002], [0039], and [0070]). Yoneda does not explicitly state that the once-through boilers are small-type once-through boilers. However, one skilled in the art would understand that the broad recitation of once-through boilers would include all sized once-through boilers, including small-type once-through boilers. As such, one skilled in the art would have found it obvious to apply the modified Hayakawa process to any known boilers that would have issues with fatigue due to chloride/sulfate ions in order to prevent excessive corrosion and scale in the boiler, wherein said boilers would include small-type once through boilers as claimed. Response to Arguments Applicant's arguments filed 10/20/2025 have been fully considered but they are not persuasive. It is noted that the above rejection has been modified to address reverse osmosis membranes being used to reduce the silica concentration to be below 1 mg/L in boiler type operations. Applicant argues that Yoneda provides a teaching away of silica concentrations in the range claimed. In order for a reference to teach away from the claimed invention the disclosure must “criticize, discredit, or otherwise discourage the solution claimed….” In re Fulton, 391 F.3d 1195, 1201, 73 USPQ2d 1141, 1146 (Fed. Cir. 2004). In this case, no such criticizing disclosure is found. In fact, Yoneda teaches the argued teaching away is directed to filtration membranes, which include nanofiltration membranes. Yoneda also states that the embodiments taught are based on nanofiltration membranes and not reverse osmosis membranes. Hayakawa PNG media_image1.png 18 19 media_image1.png Greyscale teaches the use of reverse osmosis membranes and Zuback explicitly teaches that reverse osmosis membranes are capable of removing silica in the water being treated for boiler applications to be below 1 mg/L. Therefore, Applicant arguments directed to a potential teaching away in a secondary reference is not persuasive. Conclusion THIS ACTION IS MADE FINAL. Applicant is reminded of the extension of time policy as set forth in 37 CFR 1.136(a). A shortened statutory period for reply to this final action is set to expire THREE MONTHS from the mailing date of this action. In the event a first reply is filed within TWO MONTHS of the mailing date of this final action and the advisory action is not mailed until after the end of the THREE-MONTH shortened statutory period, then the shortened statutory period will expire on the date the advisory action is mailed, and any nonprovisional extension fee (37 CFR 1.17(a)) pursuant to 37 CFR 1.136(a) will be calculated from the mailing date of the advisory action. In no event, however, will the statutory period for reply expire later than SIX MONTHS from the mailing date of this final action. Any inquiry concerning this communication or earlier communications from the examiner should be directed to PETER KEYWORTH whose telephone number is (571)270-3479. The examiner can normally be reached 9-5 MT (11-7 ET). Examiner interviews are available via telephone, in-person, and video conferencing using a USPTO supplied web-based collaboration tool. To schedule an interview, applicant is encouraged to use the USPTO Automated Interview Request (AIR) at http://www.uspto.gov/interviewpractice. If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Jennifer Dieterle can be reached at (571) 270-7872. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300. Information regarding the status of published or unpublished applications may be obtained from Patent Center. Unpublished application information in Patent Center is available to registered users. To file and manage patent submissions in Patent Center, visit: https://patentcenter.uspto.gov. Visit https://www.uspto.gov/patents/apply/patent-center for more information about Patent Center and https://www.uspto.gov/patents/docx for information about filing in DOCX format. For additional questions, contact the Electronic Business Center (EBC) at 866-217-9197 (toll-free). If you would like assistance from a USPTO Customer Service Representative, call 800-786-9199 (IN USA OR CANADA) or 571-272-1000. /PETER KEYWORTH/Primary Examiner, Art Unit 1777
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Prosecution Timeline

Sep 07, 2022
Application Filed
Dec 12, 2024
Non-Final Rejection — §103
Feb 13, 2025
Response Filed
Mar 11, 2025
Final Rejection — §103
May 29, 2025
Request for Continued Examination
Jun 02, 2025
Response after Non-Final Action
Aug 14, 2025
Non-Final Rejection — §103
Oct 20, 2025
Response Filed
Jan 08, 2026
Final Rejection — §103
Mar 09, 2026
Request for Continued Examination
Mar 10, 2026
Response after Non-Final Action
Apr 10, 2026
Non-Final Rejection — §103 (current)

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Study what changed to get past this examiner. Based on 5 most recent grants.

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Prosecution Projections

5-6
Expected OA Rounds
58%
Grant Probability
82%
With Interview (+23.9%)
3y 5m
Median Time to Grant
High
PTA Risk
Based on 775 resolved cases by this examiner. Grant probability derived from career allow rate.

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