Text

Submittal of 10 Cer 50.55a Request to Use ASME Code Case N-786-2 for the Fourth Inservice Inspection Program Interval
	ML16069A026
Person / Time
Site:	Wolf Creek
Issue date:	03/02/2016
From:	Mccoy J; Wolf Creek
To:	; Document Control Desk, Office of Nuclear Reactor Regulation
References
	ET 16-0007
	Download: ML16069A026 (15)
	v • d • e

WMLF CREEK 'NUCLEAR OPERATING CORPORATION Jaime H. McCoy Vice President Engineering March 2, 2016 ET 16-0007 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555

Subject:

Docket No. 50-482: 10 CER 50.55a Request to Use ASME Code Case N-786-2 for the Fourth Inservice Inspection Program Interval Gentlemen:

Pursuant to 10 CFR 50.55a(z)(1), Wolf Creek Nuclear Operating Corporation (WCNOC) hereby requests Nuclear Regulatory Commission (NRC) approval of the attached 10 CER 50.55a Request for the fourth 10-year inspection interval of WCNOC's Inservice Inspection (ISI)

Program. This 10 CFR 50.55a Request seeks approval to use American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code Case N-786-2, "Alternative Requirements for Sleeve Reinforcement of Class 2 and 3 Moderate-Energy Carbon Steel Piping, Section Xl, Division 1," as an alternative to ASME Code Section XI, Paragraph IWA-4000. The attachment provides the details of this 10 CFR 50.55a request.

WCNOC requests approval of the proposed alternative by February 28, 2017. A copy of ASME Code Case N-786-2 is provided as the enclosure for information.

This letter contains no commitments. If you have any questions concerning this matter, please contact me at (620) 364-4156, or Cynthia R. Hafenstine (620) 364-4204.

Sincerely, Jaime H. McCoy JHM/rlt

Attachment:

10 CFR 50.55a Request for Approval to Use ASME Code Case N-786-2

Enclosure:

ASME Code Case N-786-2 cc: M. L. Dapas (NRC), wia, w/e C. F. Lyon (NRC), w/a, w/e N. H. Taylor (NRC), w/a, w/e Senior Resident Inspector (NRC), wla, wie p il'

/ )-!

P.O. Box 411 / Burlington, KS 66839 / Phone: (620) 364-8831 l L*

An Equal Opportunity Employer M/F/HCNVET

Attachment to ET 16-0007 Page 1 of 6 Wolf Creek Nuclear Operating Corporation 10 CFR 5O.55a Request for Approval to Use ASME Code Case N-786-2

Attachment to ET 16-0007 Page 2 of 6 10 CFR 50.55a Request for Approval to Use ASME Code Case N-786-2 Proposed Alternative in Accordance with 10 CFR 50.55a(z)(1)

Alternative Provides Acceptable Level of Quality and Safety

1. ASME Code Component(s) Affected American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel (B&PV) Code,Section III, Class 2 and 3, moderate energy carbon steel piping systems.

2. Applicable Code Edition and Addenda

ASME B&PV Code Section Xl, 2007 Edition through 2008 Addenda.

3. Applicable Code Requirement

ASME B&PV Code, Section Xl, IWA-4400 provides the requirements for welding, brazing, metal removal, and installation of Repair/Replacement activities.

4. Reason for Request

In accordance with 10 CFR 50.55a(z)(1), Wolf Creek Nuclear Operating Station (WCNOC) is requesting the proposed alternatives to replacement or weld repair of pipe wall degradation (wall thinning conditions) in Class 2 and 3 moderate energy carbon steel piping systems, in accordance with IWA-4000. The degradation may be the result of erosion, corrosion, cavitation, and pitting mechanisms; but excluded is degradation resulting in any form of cracking.

One reason for this request is to permit installation of technically sound alternative repairs, in the form of Type A or partial-structure Type B reinforcing sleeves, in accordance with N-786-2.

This will allow adequate time for evaluation, design, material procurement, planning and scheduling for an appropriate repair or replacement of the item in accordance with the Owner's Requirements and the original or later Construction Code, considering the impact on system availability, maintenance rule applicability, and availability of replacement materials.

The other reason for this request is to permit installation of long-term alternative repairs, in the form of full-structural Type B reinforcing sleeves, in accordance with N-786-2, for locally degraded portions of piping systems. The design, construction, and inservice monitoring of the repair provide a technically sound equivalent replacement for the segment of degraded piping that is encompassed.

5. Proposed Alternative and Basis for Use Proposed Alternative In accordance with 10 CFR 50.55a(z)(1), WCNOC proposes to implement the requirements of ASME Code Case N-786-2, "Alternative Requirements for Sleeve Reinforcement of Class 2 and 3 Moderate-Energy Carbon Steel Piping, Section Xl, Division 1" for repair of degradation in

Attachment to ET 16-0007 Page 3 of 6 Class 2 and 3 moderate energy carbon steel piping systems resulting from localized erosion, corrosion, cavitation, or pitting mechanisms, but excluding degradation resulting in any form of cracking. ASME Code Case N-786-2 is provided as the enclosure to this letter.

ASME Code Case N-786-2 was approved on August 3, 2015, by the ASME Board on Nuclear Codes and Standards; however, this Code Case has not been incorporated into Nuclear Regulatory Commission (NRC) Regulatory Guide 1.147, "lnservice Inspection Code Case Acceptability, ASME Code Section Xl Division 1." As such, ASME Code Case N-786-2 is not available for application at nuclear power plants without specific NRC approval. Therefore, WCNOC requests NRC approval of the proposed alternative to implement these repair techniques.

Basis for Use ASME Code Case N-786-2 applies to Class 2 and 3 moderate energy (that is, systems less than or equal to 200 degrees Fahrenheit and less than or equal to 275 pounds per square inch gauge pressure maximum operating conditions) carbon steel piping.

ASME Code Case N-786-2 requires the design and examinations to comply with the Construction Code or ASME Code Section II1. Reconciliation and use of Editions/Addenda of ASME Code Section III will be in accordance with ASME Code Section Xl, Paragraph IWA-4220. If an Edition of ASME Code Section III other than the Construction Code is applied, it will have been accepted by the NRC in accordance with 10 CFR 50.55a. The Edition of ASME Code Section XI applicable to the WCNOC current 10-year inservice inspection interval, as defined in Section 2, applies to the repair.

The alternative repair described in ASME Code Case N-786-2 involves the application of Type A or Type B full encirclement sleeve halves welded together with full penetration longitudinal seam welds to reinforce structural integrity in the degraded area. In the case of Type B reinforcing sleeves, the ends are also welded to the piping in order to restore structural integrity of the piping. This alternative repair will be utilized when it is determined that it is suitable for the particular defect or degradation being resolved without removal. Use of this alternative repair method will be applied only to the items allowed by the Code Case; reinforcing sleeves will not be applied to pumps, valves, expansion joints, vessels, heat exchangers, tubing, flanges, flanged joints, socket welded or threaded joints, or branch connection welds.

ASME Code Case N-786-2 requires that the cause of the degradation be determined and that the extent and rate of degradation in the piping be evaluated to ensure that there are no other unacceptable locations within the surrounding area that could affect the integrity of the repaired piping. Surrounding areas showing signs of degradation shall be identified and included in the Owner's plan for thickness monitoring inspections of full-structural reinforcing sleeves. The area of evaluation will be dependent on the degradation mechanism present, but shall extend at least 0.754/Rtnom (R and tnom are the radius and nominal thickness of the pipe, respectively) beyond the toe of any sleeve attachment weld. If the cause of the degradation is not determined, the maximum permitted service life of any reinforcing sleeve shall be limited to the time until the next refueling outage. The initial degradation rate selected for design of all sleeves shall be at least two (2) times the maximum rate observed at the location of the repair. If the degradation rate for that location is unknown, four (4) times the estimated maximum degradation rate for that system or a similar system at the same plant site for the same degradation mechanism shall be applied, If both the degradation rate for that location and the cause of the degradation are not conclusively determined, four (4) times the maximum degradation rate observed for all degradation mechanisms for that system or a similar system at the same plant site shall be

Attachment to ET 16-0007 Page 4 of 6 applied. Where sleeves are applied on the outside of piping to mitigate externally corroded areas with potential for bulging, the corrosion cavity shall be restored to the original contour of the pipe with hardenable fill to minimize the gap beneath the sleeve.

Branch connections may be installed on reinforcing sleeves only for the purpose of filling or venting during installation or for leakage testing of the sleeve, and shall be limited to Nominal Pipe Size (N PS) 1 or smaller.

"Full-structural Type B" means that the sleeve and attachment welds alone maintain full capability to withstand structural (mechanical) and pressure loadings for which the piping is presently designed without need for additional support or reinforcement and without reliance on any piping that is encased by the sleeve. Type A and partial-structural Type B sleeves rely on the encased underlying piping to provide some structural (mechanical) and/or pressure retaining integrity.

When a reinforcing sleeve is installed over a leaking area, precautions, such as installation of a gasket or sealant beneath the sleeve, shall be taken to prevent welding on wet surfaces. Any residual moisture is then removed by heating prior to welding. If welding of any type of sleeve occurs on a wet surface, the maximum permitted life of the sleeve shall be the time until the next refueling outage.

Type B reinforcing sleeves attached to piping that has not been breached shall be equipped with pressure taps for performance of pressure testing.

ASME Code Case N-786-2 requires that the Owner shall perform a base-line inspection of Type B full-structural reinforcing sleeves, their attachment welds, adjacent base metal for a length of at least 0.75*f/-*nom, and the surrounding areas showing signs of degradation, using ultrasonic or direct thickness measurement. The Owner shall also prepare and implement a plan to repeat the thickness monitoring inspections at least every refueling outage, to verify that minimum of design thicknesses as required by the Construction Code or Section III are not violated in the sleeve or at the attachment welds, including the underlying base metal. More frequent thickness monitoring examinations will be scheduled based on the maximum degradation rates calculated using reductions in thicknesses observed during these inspections, such that the required design thicknesses will be maintained at least until the subsequently scheduled thickness monitoring examination. Provisions shall be made for access to full-structural reinforcing sleeves on buried piping in order to accomplish the required examinations.

Type A reinforcing sleeves and partial-structural Type B reinforcing sleeves completely encompass the degraded areas. These sleeves are designed to accommodate predicted maximum degradation and must be removed at the next refueling outage. Type A reinforcing sleeves and partial-structural Type B reinforcing sleeves shall be visually monitored for evidence of leakage at least monthly. If the areas containing these sleeves are not accessible for direct observation, monitoring shall be accomplished by visual assessment of surrounding areas or ground surface areas above such sleeves on buried piping, or monitoring of leakage collection systems, if available.

Type A reinforcing sleeves and partial-structural Type B reinforcing sleeves shall have a maximum permitted service life of the time until the next refueling outage, when a permanent repair or replacement must be performed. Neither the Type A nor the partial-structural Type B reinforcing sleeve may remain in service beyond the end of the next refueling outage after they are installed, unless specific regulatory relief is obtained. This means that if such a repair is performed in mid-cycle (e.g., one month before the scheduled refueling outage) the reinforcing

Attachment to ET 16-0007 Page 5 of 6 sleeve would be removed no later than the upcoming refueling outage (e.g., in one month) unless specific regulatory relief is obtained. Even if removal during the next scheduled refueling outage becomes challenging (e.g., it is installed on a system required to be functional during the refueling outage), it would still need to be removed when the system is not required to be functional and prior to the conclusion of the next scheduled refueling outage after it was installed. If a Type A or partial-structural Type B reinforcing sleeve is installed during a refueling outage, the maximum permitted service life is one fuel cycle, until the next refueling outage.

Full-structural Type B reinforcing sleeves will be removed and an IWA-4000 repair or replacement will be performed prior to the time that inservice monitoring indicates that pressure integrity (leak tightness) or structural integrity could be impaired based on measured degradation between monitoring activities. Additional requirements for design, installation, examination (including volumetric examination in accordance with NC-5200 and NC-5300, or ND-5200 and ND-5300), pressure testing, and inservice examination of reinforcing sleeves are provided in ASME Code Case N-786-2.

Implementing this proposed alternative during refueling outages will enable a greater number of scheduled corrosion inspections during the outages. The ability to install non-intrusive repair sleeves rather than scheduling contingency plans for piping replacement will enable longer corrosion inspection windows, increased scope of inspection, and improved overall plant safety.

Based on the above, the use of ASME Code Case N-786-2 for temporary repairs is justified, since utilizing ASME Code Case N-786-2 would result in an acceptable level of quality and safety. All other ASME Code Section Xl requirements for which relief was not specifically requested and authorized by the NRC staff will remain applicable, including third party review by the Authorized Nuclear Inservice Inspector.

6. Duration of Proposed Alternative The duration of the proposed request extends to the end of the first refueling outage following the end of WCNOC's Fourth 10-Year ISI Interval, which began on September 3, 2015 and ends September 2, 2025.

Any Type A and/or partial-structural Type B reinforcing sleeves installed before the end of the 10-year inservice inspection interval will be removed before the end of the refueling outage following their installation, even if that refueling outage occurs after the end of the 10-year interval.

7. Precedents NRC Safety Evaluation for Exelon Generation Co. LLC,

Subject:

[Associated plant names listed below] - Proposed Alternative to Utilize Code Case N-786, "Alternative Requirements for Sleeve Reinforcement of Class 2 and 3 Moderate-Energy Carbon Steel Piping, Section Xl, Division 1" [Associated TAC Numbers listed below], dated July 31, 2014 (ADAMS Accession No. ML14175B593). Exelon submitted this 10 CFR 50.55a request to use N-786 (the original revision of this ASME Code Case). WCNOC is submitting to use N-786-2.

Attachment to ET 16-0007 Page 6 of 6 Plant Names: Braidwood Station, Units 1 and 2; Byron Station, Units 1 and 2; Calvert Cliffs Nuclear Power Plant, Units 1 and 2; Clinton Power Station, Unit 1; Dresden Nuclear Power Station, Units 2 and 3; R.E. Ginna Nuclear Power Plant; LaSalle County Station, Units 1 and 2; Limerick Generating Station, Units 1 and 2; Nine Mile Point Nuclear Station, Units I and 2; Oyster Creek Nuclear Generating Station; Peach Bottom Atomic Power Station, Units 2 and 3; Quad Cities Nuclear Power Station, Units 1 and 2; and Three Mile Island Nuclear Station, Unit 1 TAC Nos.: MF0804, MF0805, MF0806, MF0807, MF0808, MF0809, MF0810, MF0811, MF0812, MF0813, MF0814, MF0815, MF0816, MF0817, MF0818, MF0819, MF0820, MF4030, MF4031, MF4032, MF4033, and MF4034.

ENCLOSURE ASME Code Case N-786-2, "Alternative Requirements for Sleeve Reinforcement of Class 2 and 3 Moderate-Energy Carbon Steel Piping,Section XI, Division 1" (7 pages)

CASE ASME BPVC.CC.NC.S2-2015 N-786-2 ApprovaL Date: August 3, 2015 Code Cases will remain availablefor use until annulled by the applicable Standards Committee.

Case N-786-2 (If)This Case may not be applied to pumps, valves, ex-Alternative Requirements for Sleeve Reinforcement of pansion joints, vessels, heat exchangers, tubing, flanges, Class 2 and 3 Moderate-Energy Carbon Steer Piping flanged joints, socket welded or threaded joints, or branch Section XI, Division 1 connection welds.

Inquiry:As an alternative to replacement or weld repair in accordance with IWA-4400, what requirements may be 2 INITIAL EVALUATION applied for wall reinforcement of Class 2 and 3 moderate-energy carbon steel piping systems that have (a) The material beneath the surface to which the rein-experienced wall thinning from localized erosion, corro- forcing sleeve is to be applied shall be ultrasonically mea-sion, and cavitation or pitting? sured to establish the existing wall thickness and the extent and configuration of degradation to be reinforced.

Reply: It is the opinion of the Committee that, in lieu of The adjacent area shall be examined to verify that the re-IWA-440 0,1 Class 2 and 3 moderate-energy [i.e., less than pair will encompass the entire unacceptable area, and or equal to 200°F (93°C) and less than or equal to that the adjacent base material, including at least 275 psig (1.9 MPa) maximum operating conditions] car- 0.75 Rno of base metal beyond the toe of the attach-bon steel piping experiencing wall thinning from localized ment welds, is of sufficient thickness to accommodate erosion, corrosion, and cavitation or pitting (collectively the attachment welds at the edges of the sleeve.

referred to herein as corrosion) may have the wall thick- (b) The cause and rate of degradation shall be deter-ness reinforced by applying full-circumferential reinfor- mined. The extent and rate of degradation in the piping cing sleeves to the outside surface of the piping in shall be evaluated to ensure that there will be no other accordance with the following requirements. Excluded unacceptable locations within the surrounding area that from these provisions are conditions involving any form could affect the integrity of the reinforced areas for the of cracking. life of the repair. Surrounding areas showing signs of de-gradation shall be identified and included in the Owner's 1 GENERAL REQUIREMENTS plan for thickness-monitoring inspections of full-structural reinforcing sleeves [see 8(c)]. The dimensions (a) Installation of the reinforcing sleeve shall be in ac- of the surrounding area to be evaluated shall be deter-cordance with a Repair/Replacement Plan satisfying the mined by the Owner, based on the type and rate of degra-requirements of IWA-4150. dation present.

(b) The design, materials, and installation shall meet (c) The effects of the reinforcing sleeve and attachment the requirements of the Construction Code and welds on the piping and any remaining degradation shall IWA-4000, except as stated in this Case. be evaluated in accordance with IWA-43 11.

(c) If the minimum required thickness of reinforcing sleeve necessary to satisfy the requirements of 3 is great-er than 1.4 times the nominal thickness for the size and 3 DESIGN schedule of tbe piping, this Case may not be used.

(d) Additional reinforcement or repair is not permitted 3.1 Types of Reinforcing Sleeves.

on top of an existing reinforcing sleeve. (a) Type A reinforcing sleeves as shown in Figure 1 (e) This Case may be applied only to piping not re- may he used for structural reinforcement of thinned areas quired to be ultrasonically examined for inservice which are not expected to penetrate the wall and cause inspection. leakage. The piping longitudinal stresses shall meet the 1 The references to Section Xl in this Case refer to the 2015 Edition. For use of this Case with other Editions and Addenda, refer to the Guide-line for Cross-Referencing Section Xl Cases, Table 1.

The Committee's function is to establish rules of safety, relating only to pressure integrity, governing the construction of boilers, pressure vessels, transport tanks and nuclear components, and inservice inspection for pressure integrity of nuclear components and transport tanks, and to interpret these rules when questions arise regarding their intent. This Code does not address other safety issues relating to the construction of boilers, pressure vessels, transport tanks and nuclear components, and the inservice inspection of nuclear components and transport tanks. The user of the Code should refer to other pertinent codes, standards, laws, regulations or other relevant documents.

Nr eproduction may be made of this material wcithoutwritten consent ofASM E.'if

CASE (continued)

N-786-2ASME BPVC.CC.NC.S2-2015 requirements of the Construction Code. Type A reinfor- any backing shall be recessed into the underside of the cing sleeves shall have a maximum service life of the time sleeve, or hardenable fill shall be used to fill the void, as until the end of the next refueling outage. 2 indicated in Figure 3.

(b) Type B reinforcing sleeves as shown in Figure 2 (g) Longitudinal seam joint efficiency of 0.8 shall be may he used for pressure plus full- or partial-structural used, except that 100% joint efficiency is permitted if reinforcement of thinned areas that penetrate, or are ex- the longitudinal seam is volumetrically examined.

pected to penetrate the wall and cause leakage. (h) Fatigue evaluation shall be performed if required (I) Full-structural reinforcement is designed to ac- for the original pipe, or if thermal gradients exceed commodate pressure plus axial and circumferential de- 100°F (56°C), or if lesser thermal gradients will occur sign loadings at the location for the design life of the during more than 200 heatup and cool-down cycles over repair without taking credit for any portion of the de- the life of the repair.

graded segment. Full-structural reinforcement sleeves (i) If flexibility analysis was required by the original shall be removed and the piping repaired or replaced in Construction Code, the effect of the reinforcement shall accordance with IWA-4000 no later than the end of the be reconciled with the original analysis.

design life of the repair.

(2) Partial-structural reinforcement is designed to U) Final configuration of the attachment welds shall permit the examinations and evaluations required herein, accommodate design loadings at the segment being rein-including any required preservice or inservice examina-forced, taking partial credit for the degraded segment tions of attachment or adjacent welds.

after factoring in predicted degradation over the life of (k) The predicted maximum degradation of the carrier the repair. Partial credit is considered taken if the design base metal and reinforcing sleeve over the design life of relies on any portion of the segment of piping beneath the the reinforcement shall be based on in-situ inspection sleeve, other than the base metal beneath the attachment welds, to provide structural or pressure integrity. Partial- and established data for similar base metals.

structural reinforcing sleeves shall have a maximum ser- The initial degradation rate selected for design of the vice life of the time until the end of the next refueling sleeve shall be at least 2 times the maximum rate ob-outage. served at that location; or if unknown, 4 times the esti-mated maximum degradation rate for that system or a 3.2 General Design Requirements -- Type A and B similar system at the same plant site for the same degra-Sleeves. dation mechanism. If the degradation rate for that loca-(a) The design of reinforcing sleeves shall be in accor-tion and the cause of the degradation are not dance with the requirements of NC-3100 and NC-3600 conclusively determined, 4 times the maximum degrada-or ND-3100 and ND-3600, and Section III Appendices, tion rate observed for all degradation mechanisms for Mandatory Appendix II.

that system or a similar system at the same plant site shall (b) Material for reinforcing sleeves shall he ferritic, be applied.

with welds of compatible weld filler metal.

(7) Weld seams encompassed by the sleeve shall be (c) The minimum width of reinforcing sleeves shall be ground flush. Alternatively, bulges may be rolled or 4 in. (100 mm).

formed in the sleeves to accommodate such obstructions.

(d) The thickness of the reinforcing sleeve shall be suf-Refer to Figure 4.

ficient to maintain required thickness for the predicted life of the repair. (mn) Sleeves shall closely match the outside surface of (e) The following factors shall be considered, as applic- the carrier piping. If required by design, gaps shall be able, in the design and application of the sleeves: filled with hardenable fill.

(1) all loading the sleeve is expected to encounter (n) Where sleeves are applied on the outside of piping (2) shrinkage effects, if any, on the piping to mitigate externally corroded areas with potential for (3) stress concentrations caused by installation of bulging, the corrosion cavity shall be restored to the ori-the reinforcing sleeve or resulting from existing and pre- ginal contour of the pipe with hardenable fill to minimize dicted piping surface configuration the gap beneath the sleeve.

(4) effects of welding on any interior coating (o) Hardenable fill shall be suitable for the system oper-(5) differential thermal expansion between reinfor- ating conditions, and shall be compatible with the sleeve, cing sleeve, the attachment welds, and the pipe weld metal, piping, and any exterior coating that is not re-(6) potential for loose debris in the system from con- moved from the piping.

tinued degradation of the reinforced area of the piping (p) Branch connections may be installed on reinforcing (9/ Longitudinal seam welds shall be full penetration. sleeves only for the purpose of filling or venting during in-Backing may be applied to prevent burn-through of the stallation, or for leak testing of the sleeve, and shall be pipe. If full contact between sleeve and pipe is required, limited to NPS 1 (DN 25) or smaller.

2 If a Type A or partial-structural Type B reinforcing sleeve is installed during a refueling outage, the maximum permitted service life is one fuel cycle, until the end of the next refueling outage.

NC - SUPP. 2 2 (N-786-2)

Copyright @)2015by the American Society of Mechanical Engineers. "I No repmoduction may be made ofthis material without written consent of ASME.'(a)ix

CASE (continued)

ASME BPVC.CC.NC.S2-2015 N-786-2 Figure 1 Type A Reinforcing Sleeve Sealant if required 3.3 Specific Requirements - Type A Steeves. Type A The thickness of the partial-penetration attachment sleeves in moist environments shall have edges sealed, welds shall equal the thickness of the sleeve, and the out-hut not seal welded, to prevent moisture intrusion and er edges of the welds shall be tapered to the piping sur-corrosion. face at a maximum angle ("ct" in Figure 5) of 45 deg.

3.4 Specific Requirements - Type B Sleeves. 6f0 If flexibility analysis was required by the original Construction Code, and unless a lower stress intensifica-(a) If permitted by the design, suitable gasket material tion factor (SIF or i) is established, an SIF (i) of 2.1 shall may be applied inside the sleeve to prevent moisture dur- be applied for attachment fillet welds and tapered edges ing welding (see Figure 2). of partial-penetration attachment welds on straight pipe (b) Hardenable fill and gasket material shall be compa- and at adjacent welds. Also, a stress multiplier of 1.7 shall tible with the system fluid. be applied to the SIF (i) for sleeves enclosing standard el-(c) Partial-structural sleeves shall be designed to with- bows, and an SIF (i) of 2.1 shall be applied for sleeve at-stand the design pressure. tachments on tees and branch connections provided the toe of the fillet or tapered edge is not less than (d) Partial-structural sleeves may be attached by fillet 2.5 Rno from any branch reinforcement. (See Figure welds in accordance with the requirements of 3.2(a).

(e) Full-structural sleeves shall be attached by partial- 5.)

penetration welds (see Figure 5) that, unless otherwise established by analysis in accordance with the require-ments of 3.2(a), extend for a distance of at least s in each axial direction beyond the area predicted, over the design 4 WATER-BACKED APPLICATIONS life of the repair, to infringe upon the required thickness, 3 (a) Manual welding of reinforcing sleeves on water-where backed piping shall use the SMAW process and low-s _>0.75 Rno and s _>1 in. (25 mm) hydrogen electrodes. 4 (b) When welding a reinforcing sleeve to a leaking area, precautions, such as installation of a gasket or sealant be-where neath the sleeve, shall be taken to prevent welding on wet R = D/2 = outer radius of the piping surfaces. Any residual moisture shall then be removed by tnom = nominal wall thickness of the piping heating prior to welding.

3Design thickness as prescribed by the Construction Code.

4 Testing has shown that piping with areas of wall thickness less than the diameter of the electrode may burn through during welding on water-backed piping.

3 (N-786-2) NC - SUPP. 2

CASE (continued) 2PCC.C.ZZ N-786-2 ASMFigue Figure 2 Type B Reinforcing Sleeves (c) For piping materials other than P-No. 1 Group 1, the (h) The surfaces of all welds shall be prepared, if neces-surface examination of welds required in 6 shall be per- sary, by machining or grinding, to permit performance of formed no sooner than 48 hr after completion of welding. surface and volumetric examinations required by 6. For ultrasonic examination, a surface finish of 250 RMS or better is required.

5 INSTALLATION 6 EXAMINATION (a) The circumference of the base material in the area to be welded or to provide backing for welding shall be (a) All welds shall be examined using the liquid pene-cleaned to bare metal. The entire area shall be cleaned, trant or magnetic particle method and shall satisfy the if required for application of hardenable fill. surface examination acceptance criteria for welds of the (b) The sleeve shall be fitted tightly around the pipe. Construction Code or Section III (NC-5300 or ND-5300).

Preheating the sleeve to achieve a shrink fit, or use of me- (b) Except for the tapered edges, partial-penetration at-chanical or hydraulic clamping, draw bolts, or other de- tachment welds, including the piping base metal upon vices may be used to ensure fit. which they are applied, shall be measured ultrasonically to verify' and record baseline wall thickness.

(c) If hardenable fill is used, it may be applied prior to sleeve installation or pumped into the annulus between (c) Longitudinal seam welds in the sleeve shall be ultra-the sleeve and base metal after the sleeve is in place. If sonically or radiographically examined in accordance with the Construction Code or Section IIl if longitudinal pumped into the annulus, provisions shall be made to pre-vent over-pressurization and intrusion of the hardenable seam welds in the piping require volumetric examination.

fill into the system. If the design does not permit a joint efficiency of 0.8, Class 3 longitudinal seam welds may be examined in accor-(d) Means shall be provided to isolate or divert leakage dance with (d), in lieu of volumetric examination.

to eliminate moisture during welding. If welding is per-(d) Partial-penetration attachment welds (Figure 2) formed on a wet surface, the maximum permitted life of shall be volumetrically examined when full-penetration the reinforcing sleeve shall be the time until the next re-girth welds in the carrier piping are required by the Con-fueling outage.

struction Code to be volumetrically examined. Where con-(e) Weld metal shall be deposited using a groove- figuration does not permit meaningful volumetric welding procedure qualified in accordance with Section examination, and for Class 3 longitudinal seam welds re-IX and the Construction Code. quiring volumetric examination [see (c)], the first layer, (f) Fillet weld leg length shall be increased by the each 1/2 in. thickness of weld deposit, and final surface amount of fit-up gap. Care shall be exercised to avoid shall be examined in accordance with (a), in lieu of volu-sharp discontinuities that could cause stress risers at metric examination.

the toes of fillet welds or tapered edges of partial- (e) When volumetric examination is required, the full penetration attachment welds. volume of the attachment weld, excluding the tapered (g) Provision for venting during the final closure weld edges but including the volume of base metal required or pressure testing shall be made if necessary. for the service life of the reinforcing sleeve, shall be NC -SUPP. 2 4 (N-786-2) by So An,~rka,, So&ty of M~di~,nic4I E,,ginee,~.

No ,eprodocfion maybe madeof fhis material withoat written ronseot of ASME.~

CASE (continued)

ASME BPVC.CC.

NCS-SN -786-2 Figure 3 8 INSERVICE EXAMINATION Type A and Type B Sleeve LongitudinaL Seams (a) Preservice and inservice examination of Type B full-structural reinforcing sleeve welds shall be performed in Hardenable fill accordance with IWC-2000 or IWD-2000, if required. [See 1(e).]

(b) The Owner shall perform a base-line inspection of full-structural reinforcing sleeves, their attachment welds, adjacent base metal for a length of at least 0.75 Rno, and the surrounding areas showing signs of degradation [see 2(b)], using ultrasonic or direct thick-ness measurement.

(c) The Owner shall prepare a plan to repeat the thick-ness monitoring inspections at least every refueling out-age, to verify that minimum design thicknesses as required by the Construction Code or Section III are not violated in the sleeve or at the attachment welds, includ-ing the underlying base metal.

(1) More frequent thickness monitoring inspections No Backing Backing Strip Backing Strip Strip With Recess Without Recess shall be scheduled when warranted by the degradation rates calculated using reductions in thicknesses observed during these inspections, such that the required design thicknesses will be maintained at least until the subse-examined in accordance with the Construction Code or Section 11I using either the ultrasonic or radiographic quently scheduled thickness monitoring inspection.

method, and shall, to the depth at the surface of the pip- (2) Provisions shall be made for access to full-ing, satisfy the acceptance criteria for weldments of the structural reinforcing sleeves on buried piping in order Construction Code or Section III (NC-5300 or ND-S300). to accomplish these inspections.

Any volume of the piping beneath the reinforcing sleeve (d) Type A and partial-structural Type B reinforcing that is credited in the design shall satisfy the volumetric sleeves shall be visually monitored for evidence of leak-acceptance criteria of NC-5320 and ND-5330, or age at least monthly. If the areas containing these sleeves NC-5320 and ND-5330, as applicable. are not accessible for direct observation, monitoring shall be accomplished by visual assessment of surrounding areas or ground surface areas above reinforcing sleeves 7 PRESSURE TESTING on buried piping, or by monitoring of leakage collection In lieu of IWA-4540, a system leakage test of the repair/ systems, if available.

replacement activity shall be performed in accordance (e) For Type A and partial-structural Type B reinfor-with IWA-5000 prior to, or as part of, returning to service. cing sleeves, regardless of when during a cycle or inspec-Type B reinforcing sleeves attached to piping that has not tion interval they are installed, the repair shall be been breached shall be equipped with pressure taps for considered to have a maximum service life of the time un-performance of pressure testing. til the end of the next refueling outage.

(f) If the cause of the degradation is not determined, the maximum permitted service life of any reinforcing sleeve shall be the time until the end of the next refueling outage.

5 (N-786-2) NC -SUPP. 2 Cprgt*205by the American Society of Mechanical Engineers.

No reproduction may be made of this material withoat written consent of ASME.~

CASE (continued)

N-786-2 4O1 igureC.C.

ASM Figure 4 Bulge to Accommodate Girth Weld NC -SUPP. 2 6 (N-786-2)

~' Copyright @ 2015 by the American Society of Mechanical Engine....

CASE (continued) 01 N-786-2 5

FigureCCC.C.

Figure 5 Design Details - Type B FuLL-StructuraL Sleeves ul~uI aulU ii utl ,--

°a Required thickness

-i/s r req I

X Ž 2.5J~Ym 7 (N-786-2) NC- SUPP. 2 Coyih 05b h mrcnScit fMcaia nier. *j No repr~lucfioSmay.b