ML19221A842
| ML19221A842 | |
| Person / Time | |
|---|---|
| Issue date: | 01/02/1973 |
| From: | NRC OFFICE OF STANDARDS DEVELOPMENT |
| To: | |
| References | |
| REGGD-01.010, REGGD-1.010, NUDOCS 7907100075 | |
| Download: ML19221A842 (3) | |
Text
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DIRECTOAATE OF REGULATORY STANDARDS REGULATORY GUIDE 1.10 MECHANICAL (CADWELD) SPLICES IN REINFORCING BARS OF CATEGORY I CONCRETE STRUCTU RES' A. INTROOUCTION is not normally mntrolled to an extent that would pr rmit reliable welding, and (2) the lappng of these ban General Design Cntenon 1 of Appendix A to 10 is prdibited by applicable codes (American Concrete CFR Part 50, " General Design Cnteria for Nuclear Institute: Building Code Requirements for Reinforced Power Plants," requires that structures, systems and Concrete, ACI 318 71).
components important to safety be designed, fabncated, erected and tested to quahty standards mmmensurate Visual trupection of all the mechanical splice:is the with the importance of the safety functions to be fundamental inspection technique, and it can reveal performed. His guide desa1bes an acceptable method of certain defidencies. However, some splice: that pass the implemniting this critenon with regard to the testing visual ins pecticris may not meet teruile test and sampitng of mecharuca! rpices in reinforcing bars spec 1Deatkris. In order to provide a check on the visual used on Category I concrete structures.* The Advuory inspections, and to detect symptornatic deficenoes, Committee on Reactor Safeguards has been consulted destructive tuting of some sphce samples is considered conceming this guide and has concurred in the essential as a supplement to the visual inspections. A suitable destructive testing program would provide an regulatory pontion.
adequate basis for assuring that mechanical splices made
.. DISCUSSION on in. pace reinforctng bars achieve at least the load-8 Retnforang ban for concrete structures are joined together esther by lappose welding, er mechanical The testing program in this guide is generally based m.
spicing. The most common type of mechanical:plice is on present industry practice, and is directed at sampmg called a Cadweld splice. The minimum requirements for typical, highly redundant bar to-br. tensile medanical lapping and welding splice: are established by existing
- splices, codes. however, the strength and testing requirements for mechanical spices are not specifically defined in C. REGUI.A10RY POSITION such codes.
The following procedures should be used for the The mechuucal (Cadweld) splice is used most testing of reinforcing bar mechanical splices in Category frequently for #14 and #18 remforcing ban because(1)
I concrete strta:tures:
the weldmg of these bars can be performed reliably only if the bar chemistry is contrciled and the bar chemistry 1.
Crew Qualifkation: Each rnember of the spbctag (or each crew if the members work as a unrt) crew should prYpere two qualification splices for each of the
' This guide u a revision of former Safety Gukia 10. As such, splice positions (e.g., horizontal, vertical, diagonal) to be it to appucabis to water-cooled nuclear poww plants.
used, ne qualification splice should meet the
' Structures, systems and components of a nuclear power requirements E cified by the designer of the structure plant are desagnated as Category I tf they are dergned to and approved by the licenace, pass visualinspectf(*1 as withstand the sfracts of the Safe Shutdown Earthquake (SSE) provided by paragraph 2 below, and meet the tensile and remain functionat. See Safety Guids 29, " Seismic Design tests as provided by paragrapi 3 below.
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Each member of the sphemg crew (or each crew of appropnate for the grade of remforcing bar using loading ihe members work as a urut)is subject to requali:lcation rates set forth in ASTM A 370+8, " Standard Methoda if (1) the specific splice position (e g.,
honzontal, and Definitions for Mecharucal Testmg of Steel vertical, diafonal) has not been used for a pertod of Produc ts."'
ihree months or more. or if(2) completed spces faal to b.
The average tensile strength of each group of 15 pass Ibe snual mspectmo tesi m paragraph 2 below, or consecutive samples should equal or exce'ed the 1.nl to p.a, the tens:le tests m parag;.pn 3 below, or if guaranteed ultimate tensile strength specified for the t il there n another reamn to question their abbty. The remforcmg bar.
r eq ua h t isa n on pr oce d u re should be identical to the ormmal quahlication pro edure desen5cd abose c
if ony sample tested f a.h to nicer the provisions of paragraph 34. above, the procedure of paragraph Sa 2.
Visual Impectwn I ach sphce should be mspected below should be followed if the aserage tensile strength poor to f orming to assure that all preparations requ red of the 15 samples tested fails to meet the prosismns of by the deugner and the sphee manufacturer hase been parapaph 3b above, the procedure of paragraph $b.
properly carned out (e g, cleaning, drymg. abgnment).
below should be followed.
All completed mechanical spbces should be inspected at both ends of the sphce and at the tap hole in the center The locations of all remforemg bar spbces, mcludmg of the sphcc sleese m anordance w nh the requirements replacements for production test samples of mecharuca!
speufied by the designer of the structure and approsed sphces should be shown on the as but!t drawings which by the hcensee. All visual inspections on completed are kept for the plant hfetime. For one year after the sphces should be performed only after the sphees have commencement of commercial operation, additional cooled to ambent temperstures.
records should be kept of all sphce samples tested, showing the splice location and identification number, as Among the items w hidi should be included in the well as whether the tested splice was a production or specifications are lonptudmal centenng of sleeve on the sister sphce.
spheed ends, allowable voids in filler metal, extent of 4.
Tensile Test Frequency: Separate test cycles sbauld leakmg of filler metal. permissible gap between rebar be estabhshed for mechamcal sphces m hor iontal, ends. cartidge size, gas blow out, arNunt of packmg and s!ag at the tap hole Sphces that fail to pass vtsual vertical and diagonal bars, for each bar size, and for mspecten should be decarded and replaced and should each sphemg crew as follows-a.
Test Frequency for Production Sphcc Test not be used as tensi!e test <amples Samples. (Program to be used where no curved bars are 3.
Tensile Test
- Srme samples may be production Cadwelded). If only production spbces are tested, the direetly from m-place remforcmg) sam # frequency should k sphces (i e. thos:
.i those remosabk spbces made
$1 ster sphce>
or
.m m plate next to production sphees and under the same 1 of the first 10 sphces dhe% 9h tunditions) 2 of the next and subsequent units of 100 Since sened remfortmg ban will not tensile test a a urately, production sphce samples should not t>e b.
Test Frequency f.or C ombinations of removed from curved remforcing bars for tensile testing Productwn and Sister Sphces. If production and sister Straig.hr uster sphte sades shou!J oc made as testing substitutes f or ea<h of the required curved reinforcmg sphces are tested, the sample frequency should be:
nai production sphces. The samphng frequency specified I
productmn sphce of the first 10 m paragraph 4b should then be fallowed.
production sphces i
Production and 3 sister sphces, for the next Production sph;e samples should not he cut from the structure where the mecharucal splicmg 3:cese is 90 production sphces 3
sphces, either productmn or sister sphces, shop welded to an anchorage m a regwn of high stress le ak -ugh t barrer (e.g.,
for the next and subsequent umts of toncentranon. r.nd or 3r a embedded structural ueel sec uons or hner plate).
100 sphces. At least one fourth of the Represen t ause mter sphse samples should be used in total number of sphces tested should u is h t 3e s be production sphces 5.
Procedure for Substandard Tensile Test Results Sphie umpics should be subjected to tenule tests m wordance with the samphng frequency specified m paragraph 4b. be'ow. to determine a.
If any production or sister sphce tested fails to paragraph 4a or meet the tensile test specification of paragraph 3a.
m otm m m e w oh the fuh,w mg ac<eptance standards a
fl e tens.c a rength of each umple tested should equal or euced 12( per ent of the mmimum
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s ie ld u ren gth specified m the ASTM Standard Testns and Mateoals,19 6 H.< c street Philad, Ir ia. P,eg % v131 %
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U 1.10-2
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corrective action. The designer and the beenace should ar.d the obsened rate of sphces that fail the that time does not exceed 1 for each 15 specify the extent of repairs necessary and the actions above wmetutnc test s.amples, the ssmphng procedure thould required to prevent further failures from the identihed 9
tensile tesi at causes.
t,e st arted anew.
if two or more sphces from any of these m b
if any production or sister spl ce used for additional sphce samples faji to meet the tensde test the tensde test specification in specification of paragraph 3a. above, the balar.ce of the testmg fads to meet p.ir.ngraph 3a abine, and the obsened ra c of spilces 100 production splices under investigation should be r
t h.i t fail the tensile test exceeds i for each 15 rejected and replaced t
When mechanical sphctng is resumed, the consecutne test samples, mechanic <' 7 ici.tg should be terminateil in addition, Inc adjacent prouuction sphces samphng procedure should be started anew on each side of the last fa; led splice and four other b.
If the aserage tenstle strength of the 15 consecutive samples fails to meet the provisions cf sphces distributed uniformly throughout the balance of the 100 production sphces under investigation should be parapaph 3b above, the designer of the structure and the hcensee should evaluate and assess the acceptabihty tested and an independent laboratory analysis should be of the reduced average tenule strength with respect to made 'o identify the cause of all fadures The results of the required strength at the location from which t'e these tests should be evaluated by the designer of the structure and the licensee to determine the required samples were taken.
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1.10-3