BRITISH STANDARD BS A 305 1994 ISO 7961 1994 Bolts — Test methods Reproduced by IHS under l icense with BSI Uncontrol led Copy BS A 305 1994 This British Standard, having been prepared under the direc[.]
BRITISH STANDARD Bolts — Test methods Reprodu ced by I H S u n d er l i cen se wi th BSI - U n trol l ed Copy BS A 305:1994 ISO 7961:1994 BS A 305:1994 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Aerospace Standards Policy Committee (ACE/- ) to Technical Committee ACE/1 2, upon which the following bodies were represented: The Association of Electronics, Telecommunications and Business Equipment Industries British Industrial Fasteners Federation Ministry of Defence Society of British Aerospace Companies Ltd This British Standard, having been prepared under the direction of the Aerospace Standards Policy Committee, was published under the authority of the Standards Board and comes into effect on August 994 © BSI 2- 999 The following BSI references relate to the work on this standard: Committee reference ACE/1 Draft for comment 91 /82709 DC ISBN 580 23219 Reprodu ced by I H S u n d er l i cen se wi th BSI - U n trol l ed Copy Amendments issued since publication Amd No Date Comments BS A 305:1994 Contents Page Committees responsible National foreword Inside front cover ii Scope Normative references Tests Test validity 10 Test reports 10 Annex A (normative) Calibration of apparatus 11 Annex B (normative) Test reports 11 Annex C (informative) Formulae 12 Figure — Tensile test — Test device Figure — Tensile test — Position of the nut in relation to the complete threads (shank side) Figure — Tensile test — Upper and lower cup details Figure — Double shear test — Test device Figure — Double shear test — Upper and lower blocks Figure — Stress corrosion test — Test cylinder (principle) Table — Rates of load application — Tensile test Table — Rates of load application — Double shear test Table B — Information to appear in test report List of references © BSI 2- 999 Reprodu ced by I H S u n d er l i cen se wi th BSI - U n trol l ed Copy 10 11 Inside back cover i BS A 305 :1 994 National foreword This British Standard has been prepared under the direction of the Aerospace Standards Policy Committee It is identical with ISO 7961 : 994 Bolts — Test m etho ds, Aeros p ace — published by the International Organization for Standardization (ISO) Cross-reference The Technical Committee has reviewed the provisions of ISO 7500- : 986, to which normative reference is made in the text, and has decided that they are acceptable for use in conj unction with this standard A British Standard does not purport to include all the necessary provisions of a contract Users of British Standards are responsible for their correct application Compliance with a British Standard does not of itself confer immunity from legal obligations Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages to 2, an inside back cover and a back cover This standard has been updated (see copyright date) and may have had amendments incorporated This will be indicated in the amendment table on the inside front cover ii Reprodu ced by I H S u n d er l i cen se wi th BSI - U n trol l ed Copy © BSI 2- 999 BS A : 994 placed under the head during the test, when required by the procurement This International Standard specifies test methods specification or definition document to evaluate the for bolts for aerospace constructions effect of angularity The minimum clearance It is applicable whenever quoted in reference between the hole and the bolt shank shall be 0,13 mm At least 90 % of the bolt bearing area shall be supported by the spacer which shall have a The following standard contains provisions which, diameter sufficient to support the width across the on the hole through reference in this text, constitute provisions corners of the bolt The tolerance+0,08 diameter in the spacer shall be of this International Standard At the time of mm publication, the edition indicated was valid All used under bolt heads or nuts only standards are subject to revision, and parties to in the case outlined in agreements based on this International Standard are encouraged to investigate the possibility of depending on the fixture, capable of applying the applying the most recent edition of the standard test loads indicated below Members of IEC and ISO maintain Procedure registers of currently valid International Standards Assemble the bolt in the test device ( ) ISO 7500-1:1986, as shown in Figure Install the nut ( ) as shown in Figure Place the complete assembly between the loading platens of the machine Apply the load specified in the procurement specification or definition document at the rate specified in Table 1) , in a controlled way Tap ered sp acer, S cop e Normative re fe re nce Washers, 3.1 Tensile or co m p res siv e test m achine, 3.1.2 Metallic m aterials — Verificatio n 3.1 2.1 3.1 1 3.1 1 of static uniaxial testing m achines — Part : Tensile testing m achines Te sts 3.1 2.2 Te nsile te st at amb ie nt te mp e rature 3.1 Apparatus (see Figure 1) The test device shall be centred such that the stress at four equi-spaced points around the test sample is uniform within %, or such that the coaxiality between the bolt and the clearance holes is less than or equal to 0,025 mm to ensure the application of the tensile load along the axis of the bolt1) Other types of device may be used provided they respect the requirements of Figure fixed or removable, in conformity with Figure 3, which specifies only functional requirements (free-running or self-locking) or (assuming the role of a nut), of sufficient strength to guarantee bolt failure D oub le she ar te st Test dev ice Cup s, Tes t nut threaded p art 3.2.1 Apparatus See Figure and Figure 5, the latter only defining functional requirements NOTE Totally enclosed top and bottom blades may be used as an alternative 3.2.2 Procedure Assemble the bolt into the lower part of the guillotine The blend radius under the head and the threaded portion shall not be in contact with the lower part of the guillotine (see Figure 4) Apply the load required in the procurement specification or definition document at the rate specified in Table 2, in a controlled way If this load is attained without breakage of the bolt, the test may be terminated1) 3.2.2.1 3.2.2.2 1) Calibration requirements: see ISO 7500-1:1986 and Annex A of this International Standard © BSI 12-1999 Reprodu ced by I H S u n d er l i cen se wi th BSI - U n trol l ed Copy BS A 305:1 994 Figure — Tensile test — Test device Figure — Tensile test — Position of the nut in relation to the complete threads (shank side) Reprodu ced by I H S u n d er l i cen se wi th BSI - U n trol l ed Copy © BSI - 999 BS A 305:1994 Figure — Tensile test — Upper and lower cup details © BSI - 999 Reprodu ced by I H S u n d er l i cen se wi th BSI - U n trol l ed Copy BS A 305:1994 Table — Rates of load application — Tensile test Nominal shank diameter a 10 Rate 14 20 27 35 55 kN/min Nominal shank diameter a 12 14 16 18 20 22 24 Rate 80 110 140 180 220 270 320 kN/min Nominal shank diameter a 27 30 33 36 39 Rate 400 500 600 700 850 kN/min a For other shank diameters, bolts shall be tested at a loading rate, accurate to ± 10 %, of 750 N per minute per mm of nominal shank cross-section Figure — Double shear test — Test device Reprodu ced by I H S u n d er l i cen se wi th BSI - U n trol l ed Copy © BSI 12-1999 BS A 305:1994 Figure — Double shear test — Upper and lower blocks © BSI - 999 Reprodu ced by I H S u n d er l i cen se wi th BSI - U n trol l ed Copy BS A : 994 Tab le — R ate s of lo ad ap p lication — D o ub le she ar te st a No mi nal shank d i ame te r 10 Rate 10 18 27 40 54 70 110 kN/min a No mi nal shank d iame te r Rate 160 215 280 350 440 530 630 12 14 16 18 20 22 24 kN/min a No minal shank d i ame te r Rate kN/min 800 990 200 400 700 27 30 33 36 39 a For other shank diameters, bolts shall be tested at a loading rate, accurate to ± 10 %, of 750 N per minute per mm of double the nominal shank cross-section Te nsio n fatigue te st 3.3.1 Apparatus (see Figure 1) Universal joints and spherical seats shall not be used in the test column The test device shall be centred such that the stress at four equi-spaced points around the test sample shall 2)be uniform within % of the mean stress value Other types of device may be used provided they respect the requirements of Figure Test bolts shall not be re-used fixed or removeable, in conformity with Figure 3, which specifies only functional requirements or (assuming the role of a nut), with a height greater than or equal to 0,8 and of sufficient strength to ensure bolt breakage Tes t dev ice Cup s , Test nut threaded p art D NOTE Test nuts or threaded parts may be re-used provided that it meets the dimensional requirements and has not been damaged by a previous test For referee purposes, only unused nuts or threaded parts shall be used of an accuracy within ± % of the applied maximum load2) Load m easuring system , Autom atic lo ad m aintaining s ystem designed to incorporate the features indicated in Figure 3 Fixtures , 3.3.2 Procedure In the case of flush head bolts, the bearing between the bolt head and the loading cup in which it is to be tested shall be uniform There shall be no contact in the head-shank junction area Tes t conditions Torq ue There shall be no tensile stress due to torque or any other installation procedure Load lev el The fatigue test loads shall comply with the values specified in the procurement specification or definition document Freq uency The frequency of the test shall conform with the requirements of the procurement specification or definition document The maximum temperature of the bolt during test shall not exceed 50 °C S tre ss durab ility te st o f amb ie nt te mp e rature 3.4.1 Apparatus For to rq ue or elo ngation loading or heat treated to obtain a minimum Rockwell hardness of 45 HRC with sufficient strength to withstand the full tensile strength of the bolt being tested Steel b locks sp acers , Threaded p art, For external loading Installatio n as specified in Test bolts shall be assembled so that a minimum of 2) two and a maximum of three complete threads are exposed between the nut or threaded part ( ) Procedure bearing face and incomplete threads on the shank side Assemble the bolt in the test device ( ) and apply the load specified in the procurement specification or definition document Tes t dev ice, 3.1 1 Adap ted fixture 3.3.1 3.4.2 3.4.1 2.1 2) Calibration requirements: see ISO 7500-1:1986 and Annex A of this International Standard Reprodu ced by I H S u n d er l i cen se wi th BSI - U n trol l ed Copy © BSI 12-1999 BS A : 994 For the torque loading method, the load is achieved by torque tightening to a pre-determined torque; this torque may be determined by formula or by calibrating torque against a load cell assimilating the test assembly3) For the elongation loading method, the load is achieved by measuring bolt extension; this extension may be determined by formula or by calibrating extension against a load cell assimilating the test assembly3) During the test, the loaded portion of the bolt shank shall have two full threads exposed between the incomplete threads on the shank side and the bearing face of the threaded part Keep the bolt at ambient temperature in the loaded condition for the period of time specified in the procurement specification or definition document At the end of this time, disassemble and examine the bolt for the presence of cracks Bolts suspected of having cracks shall be sectioned and microscopically examined using × 100 magnification Cracked or fractured test bolts constitute failure of the bolt Insp e ctio n for grind ing b urns 3.5.1 Procedure Clean Remove all foreign matter from the bolts such as grease, dirt or oxide film Wetting test Rinse the bolts in cold water If water breaks occur, reclean the bolts “Nital” etch Immerse the bolts for to 2,5 in a % ( / ) solution of nitric acid (relative density 1,38) in ethanol, at ambient temperature Agitate the bath V V Neutralization Neutralization may be performed with either of the following baths: Am m onia solution Immerse the bolts for 30 s to 60 s in a solution of 50 g/l of ammonia (relative density 0,90), at ambient temperature Soda solution Immerse the bolts for 30 s to 60 s in a solution of 50 g/l of soda at ambient temperature Rinse Rinse the bolts for 10 s to 30 s in running water at a temperature below 25 °C Dry Dry the bolts with filtered compressed air at ambient temperature Exam ine for grinding b urns These burns appear as either white streaks (untempered martensite) or dark grey (zone of overtempering) on an even light grey background on the surface of the bolts 1 De- em b rittle Carry out a maximum of 12 h of “Nital” etch ( ) de-embrittlement treatment on the bolts at a temperature of 130 °C ± 10 °C or 190 °C ± 10 °C for at least h, depending on whether the tempering temperature of the parts is less than or equal to 200 °C or greater than 200 °C 3.5.1.3 NOTE After bleaching ( ) and up to drying ( ), operations should be carried out quickly to avoid oxidation This oxidation builds up a chamois colour reducing contrast at a defect Rinsing in running water at a temperature below 25 °C produces a uniform light grey colour on bolts without grinding defects, instead of a chamois colour for higher temperatures 3.5 3.5.1 Te nsile te st at e le vate d te mp e rature Apparatus as specified in Materials and dimensional tolerances shall be consistent with Rinse the bolts for at least in running water the temperature in which regulation and at a temperature below 25 °C thermocouples used shall determine, indicate and control the temperature of the bolt over its entire Immerse the bolts for to 2,5 in length within ± °C to 260 °C 4) a % ( / ) solution of hydrochloric acid Thermocouples shall (relative density 1,18) in ethanol, at ambient — have the following accuracy: temperature Agitate the bath ± ° C from 18 ° C to 276 ° C, ± 0,4 % from 277 ° C to 260 ° C; Rinse the bolts for 10 s to 30 s in running water at a temperature below 25 °C Tes t device, 3.1 1 Rinse Furnace, Bleaching V V Rinse 3) Formulae: see Annex C 4) Calibration requirements: see ISO 7500-1:1986 and Annex A of this International Standard © BSI 12-1999 Reprodu ced by I H S u n d er l i cen se wi th BSI - U n trol l ed Copy BS A : 994 — be fitted with ceramic insulators from 10 mm from the junction to 300 mm outside the furnace, and after, with an insulating material; — have their hot spot clamped against the bolt so as not to be affected by the ambient conditions; — be attached to each end of the bolt and, if possible, in the middle Tensile or com p ressive tes t m achine, depending on the fixture, capable of applying the test loads Procedure Mount the bolt to be tested, fitted with its thermocouples, in the test device ( ), and place this, with the furnace between the platens of the machine Heat the furnace to the temperature specified in the procurement specification or definition document The minimum time to reach this temperature shall be 60 per 25 mm of bolt diameter Maintain this temperature for 30 before applying the load, then throughout the test Apply the load specified in the procurement specification or definition document at the rate specified in Table 1, in a controlled way Record the bolt temperature for the full duration of the test 3 S tre ss re laxation te st at e le vate d te mp e rature Apparatus Tensile test m achine, Furnace, Procedure Mount the bolt to be tested, fitted with its thermocouples, in the test device ( ), and place this, with the furnace ( ), between the platens of the machine Heat the furnace to the temperature specified in the procurement specification or definition document The minimum time to reach this temperature shall be 60 per 25 mm of bolt diameter Maintain this temperature for 30 before applying the load, then throughout the test Apply the load specified in the procurement specification or definition document Maintain the test temperature and bolt length, and record load against time for the specified test duration Plot the stress relaxation curve Use the tensile stress area values specified in the bolt procurement specification or definition document to calculate the stress from the recorder load values Record the bolt temperature for the full duration of the test 3.7.1 3 3 S tre ss corrosion te st as specified in Materials and dimensional tolerances shall be consistent with the temperature capable of ensuring that the initial length of the bolt is maintained under load and to the nearest 0,005 mm This shall be accomplished by means of an extensometer connected to a mechanism to apply or remove the load whenever5) the initial length changes by 0,005 mm The load applied to the bolt shall be measured within ± % and recorded in which regulation and thermocouples used shall determine, indicate and control the temperature of the bolt over its entire length within ± °C to 260 °C 5) The thermocouples shall — have the following accuracy: ± ° C from 18 ° C to 276 ° C, ± 0,4 % from 277 ° C to 260 ° C; Test dev ice, — be fitted with ceramic insulators from 10 mm of the junction to 300 mm outside the furnace, and after, with an insulating material; — have their hot spot clamped against the bolt so as not to be affected by the ambient conditions; — be attached to each end of the bolt, and if possible in the middle 3.1 1 C AUTIO N — It is re co mme nd e d to take safe ty p re cautio ns to p rote ct from e xp losive fracture o f the te st b olt Apparatus in conformity with Figure which only specifies functional requirements, unless otherwise specified in the procurement specification or definition document They may only be re-used if they are undamaged and completely free from corrosive products The materials of the companion test nut and cylinders shall be those specified in the procurement specification or definition document or of galvanic compatibility with the bolt tested capable of showing variations in bolt length of 10 4m with an accuracy of 2,5 4m Tes t cylinders, Measuring ins trum ent, 5) Calibration requirements: see ISO 7500-1:1986 and Annex A of this International Standard Reprodu ced by I H S u n d er l i cen se wi th BSI - U n trol l ed Copy © BSI 12-1999 BS A : 994 Alternate im m ersion- em ersion dev ice, permitting 10 ± of immersion in the salt solution, of the bolt fitted in the test cylinder ( ), and emersion, for drying in circulating air during the remainder of the 60 cycle The racks supporting the test bolt assembly shall not contact the salt solution The materials of the test chamber and accessories shall not affect the test conditions The vented atmosphere of the test chamber shall be — free from oil and dust; — maintained at 24 °C ± °C; — sufficient to dry test samples completely in 50 Reclean the bolt nut, cylinder assembly then suspend it from the immersion-emersion arm using a non-metallic cord or hook to avoid — all contact with metallic materials; — any transfer of corrosion products and condensation between test cylinders; and to ensure drying of the exposed parts of the bolt during emersion Start and repeat the immersion-emersion cycle (see ) until the failure of the bolt, or for the specified time, examining the bolts with the naked eye every 24 h and at the end of the test to ascertain any indications of cracks or fracture 3 S tre ss rup ture te st at e le vate d te mp e rature Salt solution, — having a controlled and maintained content of 3,5 % ( / ) ± 0,5 % ( / ) of sodium chloride with not more than 0,01 % sodium iodide and not more than 0,3 % total impurities; — prepared from distilled or deionized water with not more than 200 ppm of total chlorides; — having a pH maintained between 6,5 and 7,5, controlled every 24 h and adjusted with chemically pure dilute hydrochloric acid or sodium hydroxide; — to be used for only for one type of bolt alloy; — to be changed at least every days 9.1 Apparatus as specified in Materials and dimensional tolerances shall be consistent with the temperature capable of loading and maintaining the constant load and within the limits specified in the procurement specification or definition document to an6)accuracy of % for the entire range of test loads in which regulation and thermocouples used shall determine, indicate and control the temperature of the bolt over its entire 6) length within ± ° C to 260 ° C Procedure The thermocouples shall Prepare the ends of the test bolt so that its — have the following accuracy: length can be measured accurately on a repeated ± ° C from 18 ° C to 276 ° C, basis ± 0,4 % from 277 ° C to 260 ° C; Clean the bolts to be tested with non-chlorinated solvents until the surface is free of — be fitted with ceramic insulators from 10 mm water break from the junction to 300 mm outside the furnace, and after, with an insulating material; After cleaning there shall be minimum handling with clean lintless gloves — have their hot spot clamped against the bolt so as not to be affected by the ambient conditions; Insert the bolt to be tested into the test cylinder ( ), fit the companion nut and tighten — be attached to each end of the bolt and, if manually A minimum of two full threads shall possible, in the middle extend beyond the nut with an accuracy of ± % Measure the overall length of the bolt Procedure Torque tighten the nut producing 75 % of the Fit the bolt to be tested, previously cleaned minimum specified strength of the bolt, using in a nonchloride solvent, in the test device ( ) torque, load and elongation comparison curves then place the assembly between the platens of the Seal the ends of the test bolt to avoid corrosion machine Attach the thermocouples to the bolt to be tested in accordance with m m m m Test dev ice, 3.1 1 Tens ile test m achine, Furnace, 3 Tim e recorder, 9 2 9.1 6) Calibration requirements: see ISO 7500-1:1986 and Annex A of this International Standard © BSI 12-1999 Reprodu ced by I H S u n d er l i cen se wi th BSI - U n trol l ed Copy BS A : 994 9.2 Attain and maintain, at the test temperature specified in the procurement specification or definition document, for at least 30 to ensure thermic balance and a uniform temperature of the bolt to be tested 9.2 Apply the test load specified in the procurement specification or definition document, in min, without either shock or overload 9.2 Maintain the load and the temperature for the remainder of the specified test duration, or if it occurs beforehand, until the fracture of the bolt under test Test validity All tests leading to a result which does not conform with the requirements of the procurement specification or definition document, but not attributable to the bolt being tested, shall not be considered as valid or useful The test shall be repeated Test rep orts Test reports shall contain the relevant information specified in Annex B D = Nominal diameter of the bolt A = (R + 0, 8) ± 0, 25 limited to , R = Radius under bolt head Material and thermic treatment: see Figure — S tre ss co rro sion te st — Te st cylinde r 10 Reprodu ced by I H S u n d er l i cen se wi th BSI - U n trol l ed Copy (principle) © BSI 2- 999 BS A 305:1 994 Annex A (normative) Calibration of apparatus A.1 C alib ration with the excep tion of the fatigue machine s hall b e carried out p eriodically and at least every months A.2 Fatigue machines s hall b e calib rated dynamically at ins tallation and als o when load cells and/or amp lifiers are changed They shall b e calib rated s tatically every 000 functional hours, or every months A.3 C alib ration s hall b e conducted b y a National official b ody or an organis ation controlled b y s uch a b ody Annex B (normative) Test reports For each tes t, the rep ort shall contain the information s p ecified in Tab le B Table B.1 — Information to appear in test report Stress durability Tensile test Double Tension Parameters at ambient shear fatigue temperature test test test at ambient Inspection for grinding burns temperature Part numb er Batch identity Manufacturer Material Stress Tensile test relaxation Stress at elevated test at corrosion elevated test temperature temperature Stress rupture test at elevated temperature × × × × × × × × × × × × × × × × × × × × × × × × × × × × × × × × × × × × × × × × × × × × × × × Procurement sp ecification or definition document reference × Tes t load Breaking load Pos ition of failure × × × × × × to failure × × Tes t duration Time/cycles × × Tes t tem p erature × × × × × v × I nitial b olt length × Bolt elongation D ecis ion ì â BS I - 99 Reprodu ced by I H S u n d er l i cen se wi th BSI - U n trol l ed Copy × × × × × × × × 11 BS A 305:1 994 Annex C (informative) Formulae C.1 Estimated torque to induce specified load T = 0, 001 KDF where T K D F is the torque, in newton metres; = 0, (friction factor); is the nominal diameter of test bolt, in millimetres; is the induced load, in newtons C.2 Estimated elongation to induce specified load e = 0, 001 F -L- + L t × -E A A t where e F E L A L A is the total bolt elongation, in millimetres; is the induced load, in newtons; is the modulus of elasticity for the material of the test bolt, in gigapascals; is the length of grip, in millimetres; is the cross- sectional area of bolt shank, in square millimetres; t is the thread length between bearing faces, in millimetres; t is the tensile stress area of thread (specified in the bolt procurement specification or definition document), in square millimetres 12 Reprodu ced by I H S u n d er l i cen se wi th BSI - U n trol l ed Copy © BSI 2- 999 BS A 305:1994 List of references See national foreword © BSI - 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