DETAILED ACTION
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 .
Status of Claims
Amended: none
Canceled: claims 1-16
Pending and under examination: claims 17-25
Response to Arguments
Applicant's arguments filed 09/09/2025 have been fully considered but they are not persuasive.
The examiner notes that the arguments are largely a restatement of the prior arguments, and as such, the response to arguments will largely be a restatement of prior responses to arguments.
With regard to the applicant’s arguments characterized by “Scotto, either alone or in combination with or evidenced by Yamadera, fails to teach or suggest all the elements of the claims as amended herein and so cannot render them obvious” (see page 3 of arguments; see also pages 4-5 of arguments), such as the P content, the Mo+W range, the arguments are not found persuasive:
Regarding the phosphorous (P) content, aside from the fact that the lower bound of the claimed P content is 0 wt.% meaning that it is not required to be present, more importantly, it is known in the metallurgical arts that P is understood to be an impurity unless otherwise stated. It is well-known within the chemical arts that 100% pure chemical substances of any kind are exceedingly rare, if not impossible, even if there is an infinitesimally small amount of an impurity; in this case, amongst the elements preventing absolute purity is P. Thus, even if a list of impurities with their respective quantities is not explicitly recited, it is known in the metallurgical arts that impurities are inevitable. To support this assertion, the 05/08/2024 Non-Final Rejection cited Yamadera as an alternative to the Office relying on “Official Notice” without documentary evidence (per MPEP 2144.03), wherein Yamadera discloses a duplex stainless steel for use in urea manufacturing plants (Abstract), and who explicitly teaches that “P is an impurity which exerts a bad influence on hot workability and mechanical properties of the steel”. Notably, Yamadera’s application of the stainless steel is the same application as the applicant’s own invention. Further, Yamadera states that in a stainless steel, it causes deterioration of the corrosion resistance by grain boundary segregation; 0.04% is an allowable upper limit as an impurity; the content of P should be as low as possible within the upper limit.” [0045-0046]. Moreover, the applicant’s own specification explicitly states that phosphorus is an impurity element (see first paragraph on page 12 of the instant specification The P content of Yamadera notably overlaps with the claimed range.
Regarding the claimed Mo+W range, Scotto teaches both a Mo range and a W range; thus, even if the Scotto reference does not itself add up Mo with W to express a range, this does not change the fact that there is inherently a sum of both Mo+W due to the fact of the ranges of each of Mo and W being recited. Thus, unless the applicant demonstrates that the claimed relationship of Mo+W being greater than 3.0% but less than 5.0% is critical per MPEP 716.02, the claimed sum is obvious in view of the claimed sum overlapping with the sum of the ranges of Scotto’s Mo and W. In the case where the claimed ranges "overlap or lie inside ranges disclosed by the prior art" a prima facie case of obviousness exists (MPEP 2144.05 I.). "It is well established that, while a change in the proportions of a combination shown to be old, such as is here involved, may be inventive, such changes must be critical as compared with the proportions used in the prior processes, producing a difference in kind rather than degree.") (MPEP 2144.05 III. A.). Generally, differences in concentration or temperature will not support the patentability of subject matter encompassed by the prior art unless there is evidence indicating such concentration or temperature is critical (MPEP 2144.05).
Regarding the “…and Ti, Nb, Hf, Ca, Al, Ba, V, Ce and B in an amount of max 0.5 wt% in total” limitation, Scotto teaches that the Ce content is 0-0.2% [0030], which is within the claimed range of “max 0.5 wt% in total”; the remainder of the elements listed in the instant claim are not present in the alloy of Scotto. Thus, it is understood that the remainder of the elements are not present, which meets the claimed “max 0.5 wt% in total”. In the case where the claimed ranges "overlap or lie inside ranges disclosed by the prior art" a prima facie case of obviousness exists (MPEP 2144.05 I.)
With regard to the applicant’s arguments characterized by “One of ordinary skill would simply not have known or been motivated to choose the amount of P based on Yamadera and Scotto when looking at and considering Scotto and Yamadera as a whole, as previously discussed” (see page 3-5 of the arguments), as discussed in the § 103 rejections and in the response to arguments above, Regarding the P content, aside from the fact that the lower bound of the claimed P content is 0 wt.% meaning that it is not required to be present, more importantly, it is known in the metallurgical arts that P is understood to be an impurity unless otherwise stated. To support this assertion, the 05/08/2024 Non-Final Rejection cited Yamadera as an alternative to the Office relying on “Official Notice” without documentary evidence (per MPEP 2144.03), wherein Yamadera discloses a duplex stainless steel for use in urea manufacturing plants (Abstract), and who explicitly teaches that “P is an impurity which exerts a bad influence on hot workability and mechanical properties of the steel”. Notably, Yamadera’s application of the stainless steel is the same application as the applicant’s own invention. Further, Yamadera states that in a stainless steel, it causes deterioration of the corrosion resistance by grain boundary segregation; 0.04% is an allowable upper limit as an impurity; the content of P should be as low as possible within the upper limit.” [0045-0046]. Moreover, the applicant’s own specification explicitly states that phosphorus is an impurity element (see third paragraph on page 11 of the instant specification. The P content of Yamadera notably overlaps with the claimed range.
Regarding the applicant’s arguments attempting to disparage the evidentiary reference Yamadera by stating that it teaches a slightly different Cr range, the rejection cited Yamadera for its disclosure of how the element P is an impurity, particularly when in a duplex stainless steel for use in urea manufacturing plants (Abstract); specifically, Yamadera explicitly teaches that “P is an impurity which exerts a bad influence on hot workability and mechanical properties of the steel”. Notably, Yamadera’s application of the stainless steel is the same application as the applicant’s own invention. A difference of only 1% of Cr despite the remainder of the reference being applicable for its teachings is not sufficient to constitute a lack of relevance for an evidentiary teaching regarding the applicability of the impurity P as known in the metallurgical arts. Moreover, the applicant’s own specification explicitly states that phosphorus is an impurity element (see third paragraph on page 11 of the instant specification. Thus, Yamadera is maintained as pertinent prior art, in view of it meeting not only one, but both prongs of analogous art as outlined in MPEP 2141.01(a) I.
The applicant’s arguments based on the previous Office Action(s) evidencing Yamadera cannot render the claimed elements obvious (see page 3 of the arguments) are not found persuasive, because as discussed above, the citing of Yamadera was for clearly showing that P is well-known as common knowledge in the metallurgical arts to be an impurity, and was an attempt to clarify the record without relying on “Official Notice”. It is known in the metallurgical arts that P is understood to be an impurity unless otherwise stated. To support this assertion, the Final Rejection cited Yamadera, who discloses a duplex stainless steel for use in urea manufacturing plants (Abstract), and who explicitly teaches that “P is an impurity which exerts a bad influence on hot workability and mechanical properties of the steel”. Notably, Yamadera’s application of the stainless steel is the same application as the applicant’s own invention.
The applicant’s arguments concerning Scotto allegedly failing to disclose a range for Mo+W and adding separate ranges for Mo and W not being predictable because Mo+W can have sums that are outside of the claimed ranges (see page 4 of the arguments) are not found persuasive, as Cr, Mo, and W have predictable effects within the disclosed ranges, for stainless steels used in urea plants. However, to be clear, the Office’s position is not based on varying ranges; the prima facie case of obviousness is based on overlapping ranges (MPEP 2144.05).
The declaration under 37 CFR 1.132 filed 03/09/2023 in parent application 15/746,384 was insufficient to overcome the rejection of claims 1-2 and 4-9 based upon § 103 as set forth in the last Office action (of application 15/746,384) because: the data made of record (which is pertinent to the present divisional application (18/481,659) is insufficient to demonstrate unexpected results or criticality of the claimed ranges:
The declarant states that the Safurex® Infinity (corresponding to prior art composition) had a corrosion rate of 0.054 mm/year while the Safurex® (corresponding to claimed composition) had a corrosion resistance of 0.044 mm/year, which is a reduction of 18%.
The declarant further states that the weight loss for the inventive sample was 2.9% while the weight loss for the prior art example was 3.7% (lower is better). However, the tested prior art examples have slightly higher Cr, Mo, and W contents, and as such, the small difference/improvement in the inventive example is expected to be due to the higher levels of Cr, Mo, and W. This is evidenced by Yamadera (US 20030155046 A1; of record) who states that “Ferrite stabilizing elements such as Cr and Mo accelerate the formation of a sigma phase. Since these are basic elements needed to maintain the corrosion resistance of a duplex stainless steel, it is impossible to decrease their content excessively. Taking this into account, the present inventors have discovered an alternative by substituting Mo with W (which is similar to Mo in function and effect) and have examined in detail the influence of Mo and W on the formation of a sigma phase.” [0028]. Thus, Cr, Mo, and W are clearly elements that are known to be used in stainless steels for improving the corrosion resistance. The applicant has not provided a sufficient amount of data or evidence to show that the alleged improvement is unexpected or critical.
With regard to the tested samples in the 03/09/2023 declaration, which appears to be a different corrosion resistance test than corrosion resistance tests in Tables 1-3 of the instant specification (because the inventive examples in the specification had a higher corrosion rate than the comparative example in the declaration; higher corrosion rate is worse), the only basis of comparison for the two examples in the declaration is comparing the two examples with one another. As such, the declaration effectively only has two data points, which is an insufficient number of data points to demonstrate criticality of the claimed ranges. To establish unexpected results over a claimed range, applicants should compare a sufficient number of tests both inside and outside the claimed range to show the criticality of the claimed range (MPEP 716.02(d) II.).
As discussed in the rejection mailed 02/18/2022 in the parent application 15/746,384, the Mo+W content is very clearly correlated with the corrosion rate/resistance, based on the data in Tables 1-3 of the instant specification:
PNG
media_image1.png
653
998
media_image1.png
Greyscale
PNG
media_image2.png
653
998
media_image2.png
Greyscale
As can be seen from the charts above, the corrosion rate has an extremely close correlation with the Mo+W content (R2 = 0.923 for a linear model, and R2 = 0.9473 for an exponential model, wherein an R2 value of 1 is a perfect correlation) (and presumably a close correlation with the Cr content as well, based on Yamadera as discussed above), which means that the improvements discussed in the declaration are not a difference in kind, but rather, merely a difference in degree. "It is well established that, while a change in the proportions of a combination shown to be old, such as is here involved, may be inventive, such changes must be critical as compared with the proportions used in the prior processes, producing a difference in kind rather than degree."); In re Wells, 56 F.2d 674, 675 (CCPA 1932) (MPEP 2144.05 III. A.). Any differences between the claimed invention and the prior art may be expected to result in some differences in properties. The issue is whether the properties differ to such an extent that the difference is really unexpected (MPEP 716.02).
Claim Rejections - 35 USC § 103
In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status.
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.
The factual inquiries for establishing a background for determining obviousness under 35 U.S.C. 103 are summarized as follows:
1. Determining the scope and contents of the prior art.
2. Ascertaining the differences between the prior art and the claims at issue.
3. Resolving the level of ordinary skill in the pertinent art.
4. Considering objective evidence present in the application indicating obviousness or nonobviousness.
Claims 17-25 are rejected under 35 U.S.C. 103 as being unpatentable over Scotto et al. (US 20160082408 A1) as evidenced by Yamadera et al. (US 20030155046 A1).
Regarding claims 17-25, with regard to the claimed “A stripper tube”, Scotto teaches that a shell-and-tube stripper (Abstract) which has a bundle of tubes made from the following duplex stainless steel composition [0019]-[0032], which overlaps with the claimed ranges:
Element
Claims 17 and 25
(wt. %)
Claim 18
(wt. %)
(bolded differ from claim 17)
Claim 19
(wt. %)
(bolded differ from claim 17)
Scotto [0019]-[0032]
C
0-0.030
0-0.020
0-0.030
0-0.05
Si
0-0.8
0-0.8
0-0.8
0-0.8
Mn
0-2.0
0-2.0
0-2.0
0.3-4.0
Cr
29.0-31.0
29.0-31.0
29.0-31.0
28-35
Ni
5.0-9.0
5.0-9.0
5.0-9.0
3-10
Mo
<5.0
<5.0
<4.0
1.0-4.0
W
<5.0
<5.0
<4.0
0-2.0
N
0.25-0.45
0.25-0.45
0.25-0.45
0.2-0.6
Cu
0-2.0
0-2.0
0-2.0
0-1.0
S
0-0.02
0-0.01
0-0.02
0-0.01
P
0-0.03
0-0.02
0-0.03
-
Mo+W
3.0<Mo+W<5.0
3.0<Mo+W<5.0
3.0<Mo+W<4.0
1.0-6.0 (calculated)
Fe
Balance
Balance
Balance
Balance
With regard to the Mo and W contents and sum or Mo and W, Scotto teaches overlapping Mo and W contents of 1.0-4.0% and 0-2.0% respectively, which corresponds to a Mo+W sum of 1.0-6.0%, and which overlaps with the range of between 3.0 and 5.0 as required by claim 17, and overlaps with the claimed range of between 3.0 and 4.0 as required by claim 18. In the case where the claimed ranges "overlap or lie inside ranges disclosed by the prior art" a prima facie case of obviousness exists (MPEP 2144.05 I.). Similarly, a prima facie case of obviousness exists where the claimed ranges or amounts do not overlap with the prior art but are merely close (MPEP 2144.05 I.).
With regard to the claimed “and wherein the corrosion resistance of the duplex stainless steel is less than 0.223 mm/year as evaluated in an oxygen-free carbamate solution at a temperature of 210°C, wherein the corrosion rate is calculated after an exposure of 14 days in the oxygen-free carbamate solution” in claim 17 and “and wherein the corrosion resistance of the duplex stainless steel is less than the corrosion resistance of a comparable duplex stainless steel having a content of Mo+ W less than 3.0, as evaluated in an oxygen-free carbamate solution at a temperature of 210°C, wherein the corrosion rate is calculated after an exposure of 14 days in the oxygen-free carbamate solution” in claim 25, Yamadera evidences that Mo, Cr, and W are basic elements needed to maintain the corrosion resistance of a duplex stainless steel. As such, in view of Scotto teaching overlapping ranges of Mo, Cr, and W, it is prima facie expected to have corrosion resistance values that overlap with the claimed range. In the case where the claimed ranges "overlap or lie inside ranges disclosed by the prior art" a prima facie case of obviousness exists (MPEP 2144.05 I.). Similarly, a prima facie case of obviousness exists where the claimed ranges or amounts do not overlap with the prior art but are merely close (MPEP 2144.05 I.). Generally, differences in concentration or temperature will not support the patentability of subject matter encompassed by the prior art unless there is evidence indicating such concentration or temperature is critical. "[W]here the general conditions of a claim are disclosed in the prior art, it is not inventive to discover the optimum or workable ranges by routine experimentation." (MPEP 2144.05).
The ranges disclosed by Scotto additionally overlap with the narrower Mn, Si, Ni, and N contents claimed in claims 20-24.
Although Scotto does not explicitly disclose the P content, it is known in the steel arts that P is an impurity in steel, and is preferably excluded or minimized as much as possible. Notably, Scotto discloses a similar steel with a disclosed P content of 0-0.04 [0033-0044]. The understanding that P is a known impurity is evidenced by Yamadera, who discloses a duplex stainless steel for use in urea manufacturing plants [Abstract], and who explicitly teaches that “P is an impurity which exerts a bad influence on hot workability and mechanical properties of the steel. Further, in a stainless steel, it causes deterioration of the corrosion resistance by grain boundary segregation. 0.04% is an allowable upper limit as an impurity. The content of P should be as low as possible within the upper limit.” [0045-0046]. The P content of Yamadera overlaps with the claimed range. In the case where the claimed ranges "overlap or lie inside ranges disclosed by the prior art" a prima facie case of obviousness exists (MPEP 2144.05 I.). Similarly, a prima facie case of obviousness exists where the claimed ranges or amounts do not overlap with the prior art but are merely close (MPEP 2144.05 I.).
Scotto further teaches that a stripper comprising a shell and a bundle of tubes made of a duplex stainless steel is fed a carbamate solution [0049] (wherein the duplex stainless steel is defined in [0019]-[0044] as discussed above), which meets the claimed step of “for the production of urea or a liquid distributor for a stripper for a plant for production of urea”.
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 Adil Siddiqui whose telephone number is (571)272-8047. The examiner can normally be reached M-F 10AM-6PM CST.
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, Keith Walker can be reached at 571-272-3458. 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.
/ADIL A. SIDDIQUI/Primary Examiner, Art Unit 1735