ML16244A060
| ML16244A060 | |
| Person / Time | |
|---|---|
| Site: | McGuire  |
| Issue date: | 08/18/2016 |
| From: | Duke Energy Carolinas |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| 16-MN-003, MNS-16-070, N-786-2 | |
| Download: ML16244A060 (11) | |
Text
ATTACHMENT 1 RR 16-MN-003 CODE CASE N-786-2
CASE ASME BPVC.CC.NC.SZ -2 015 N-786-2 Approval Date: August 3, 2015 Code Cases will remain available for use until annulled by th e applicable Standards Committee.
Case N-786-2 (f) 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 Steel Piping flanged joints, socket welded or threaded joints, or branch Section XI, Division l connection welds.
Inquiry: As an alternative to replacement or weld repair in accordance with IWA-4400, what requirements may be 2 INITIAL EVALUATION app li ed for wa ll 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- forc ing 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-4400, 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 lea s t 275 psig (1.9 MPa) maximum operating conditions] car- J 0.75 Rtn om 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 surround ing 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-4311.
(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 the 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 be 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 XI in this Case refer to the 2015 Edition. For use of this Case with other Editions and Addenda, refer to t he Guide-line for Cross-Referencing Section XI Cases, Table 1.
The Committee's fu nction is to establish rules of safety, relating only to pressure integrity, governing the construction of boilers, pressure vessels, trans port tanks and nuclear compo nents, 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 th e constru ction of boilers, pressure vesse ls, trans port tanks and nuclear components, and th e inservice inspection of nuclear components and transport tanks. The user of the Code s hould refer to other pertinent codes, standards, laws, regulations or oth er relevant documents.
1 (N-786-2) NC - SUPP. 2
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CASE (continued)
N-786-2 ASME BPVC.CC.NC.52-2015 requirements of t he Const ruction 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 re inforcing sleeves as shown in Figure 2 (g) Longitudinal seam joint efficiency of 0.8 shall be may be 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 longitud inal seam is volumetrically examined.
pected to penetrate the wall and cause leakage. {h) Fatigue evaluation shall be performed if required
{1) 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 flex ibility 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 lWA-4000 no later than the end of the be reconciled with the original analysis.
design life of the repair.
(jJ Final configuration of t he attachment welds shall (2) Partial -structural reinforcement is designed to permit the examinations and evaluations required herein, accommodate design loadings at the segment being re in-including any required preservice or inservice examina-forced, taking partial cred it for the degraded segment tions of attachment or adjacent welds.
after factoring in predicted degradation over the life of the repair. Partial credit is considered taken if the design (k) The predicted maximum degradation of the carrier relies on any portion of the segment of piping beneath the base metal and reinforcing sleeve over the design life of sleeve, other than the base metal beneath the attachment the re inforcement shall be based on in-situ inspection 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 sim ilar 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 Ill 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 be ferritic, be applied.
with welds of compatible weld filler metal.
(/) 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 requ ired thickness for the predicted life of the repair. (m) 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 wi th hard enable 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 (f) Longitudinal seam welds shall be full penetration. sleeves only for the purpose of filling or venting during in-
- Backing may be app lied to prevent burn-through of the stallation, or for leak testing of the sl eeve, 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 refu eling outage, the maximum permitted service life is one fu el cycle, until the end of th e next refu eling outage.
NC - SUPP. 2 2 (N-786-2)
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CASE (continued)
ASME BPVC.CC.NC.52-2015 N-786-2 Figure l Type A Reinforcing Sleeve Type A Sleeve ~
Full-penetration longitudinal seam Piping 3.3 Specific Requirements - Type A Sleeves. 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-but 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 ("a" in Figure 5) of 45 deg.
(fJ If flexibility analysis was required by the original 3.4 Specific Requirements - Type B Sleeves.
Construction Code, and unless a lower stress intensifica-(a] If permitted by the design, suitable gasket material tion factor (SlF or i) is established, an SlF (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 sta ndard 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 l ess than (d) Partial-structural sleeves may be attached by fillet welds in accordance with the requirements of 3.2(a) . 2 .5 ~ Rtnom from any branch reinforcement. (See Figure (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 distan ce of at leasts 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 where (a) Manual welding of reinforcing sleeves on water-backed piping shall use the SMAW process and low-s ~ 0.75 J Rtnom ands ~ I 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-whe re 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 tn o m nominal wall thickness of the piping heating prior to welding.
3 Design thi ckness as prescribed by the Construction Code.
4 Testi ng has s hown that piping with areas of wa ll thickness less than the diameter of the electrode may burn through during welding on wate r-backed piping.
3 (N-786-2) NC - SUPP. 2 Copyright ASME International (BPVC)
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CASE (continued)
N-786-2 ASME BPVC.CC.NC.52-2015 Figure 2 Type B Reinforcing Sleeves 5- part ial penetrat ion ~ ,
attachment w eld. See 3.4 (e) ~
Full penetration longitud inal seam Full penetration longitudina l seam Tapered edge
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' _' I Partial-structural Full-structural (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 us ing the liquid pene-cleaned to bare metal. The entire area shall be cleaned, trant or magnetic particle method and shall satisfy th e if required for application of hardenable fill. surface exa minatio n accepta nce criteria for welds of th e (b) The sleeve shall be fitted tightly around the pipe. Construction Code or Section Ill (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 d e- tachment welds, including the piping base metal upon vices may be used to ensure fit. which th ey are applied, shall be measured ultrasonically (c) If hardenable fill is used, it may be applied prior to to verify and record baseline wall thickness.
sleeve installation or pumped into the annulus betwee n (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 pumped into the annulus, provisions shall be made to pre- with the Construction Code or Section Ill if longitudinal 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 rei nforcing 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- figu ration 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 le ngth shall be increas ed by the each 1/i in. thickness of weld depo sit, and final surface amount of fit-up gap. Care shall be exercised to avoid shall be examined in accordance with (a), in li eu of volu-s harp 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 penetra tion attachment welds. volume of the attachment weld, exclud ing 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 m ade if necessary. for the service life of the reinforcing sleeve, shall be NC- SUPP. 2 4 (N-786-2)
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CASE (continued)
ASME B PVC.CC.NC.SZ -2015 N-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 Hard ena ble fi ll 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 J Rtnom* 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 Ill are not violated in the sleeve or at the attachment welds, includ-ing the underlying base metal.
No Backing Backing Strip Backing Strip (1) More frequent thickness monitoring inspections 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 examined in accordance with the Construction Code or th icknesses will be maintained at least until the subse-Section Ill 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 Jll (NC-5300 or ND -5300). 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.
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CASE (continued)
N-786-2 ASME BPVC.CC.NC.52-2015 Figure 4 Bulge to Accommodate Girth Weld Constant root g ap NC - SUPP. 2 6 (N-786-2)
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CASE (continued)
ASM E BPVC.CC.NC.52-2015 N-786-2 Figure 5 Design Details - Type B Full-Structural Sleeves r - -
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D 'l LJ I Minimum pl ate length =
predi cted maxi mum degradati on Required t thickness req t - - - - x - - -- 1 Limit of branch re inforcement X 2: 2.5~ Rtnom
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ATTACHMENT 2 RR 16-MN-003 SLEEVE DESIGN
Attachment 2 Temporary Sleeve Repair at lRN-883 and lRN-884 Typ Existing 8" RN (service w a ter) header Note 1 SA-106 Gra de B Carbon steel schedule 40 1/ 4 Design pressure - 135 psig Desig n temperature - 150 F( l RN-884) 102 F (l RN-883)
Existing 3" p ipe stub SA- 106 Grade B Carbon steel sc hedule 40 3.5" 0D Typ Note l 1/8 3000# l /4" threaded carbon steel half coupling Typ . 2 places (Note 4)
Field to locate Typ Typ No te 1 1/4 Far Side DETAIL A Note l. 5 SCALE l: l Notes:
3- 1/ 2" NPS sleeve SA-106 grade B carbon steel 1) We ld size may be revised if required by Schedule 40x 2.5" long Weld Technica l Support with Engineering
(-3.5" ID after machining). approva l.
Split a long a xis Field to locate for w e ld ing . 2) Minor d imensional changes for sleeve are Note 2,3.4 acceptable to a llow proper fitup and w elding wi th Engineering approva l.
Existing 1RN-883/ l RN-884 Ball Drain Valve s, 300# C lass 3) Appropriate gasket materia l or sealant may be used between sleeve and b a se p ip ing to elim inate w eld ing/water interface concerns if necessary.
0
- 4) Insta ll l / 4" threaded carbon steel 3000#
half coup ling on both halves of sleeve for Existing 150# flanges to remain . testing and venting. Field to locate. Install Omitted for clarity. threaded carbon steel p lug and seal w eld after testing .
SECTION B-B 5) Backing strips may be utilized for longitudina l w e lds If field conditions require .
Sleev e may be machined as required for fitment of backing strips with Engineering approv a l.
Pagel of 1