WSS Study Guide WC2.1 Intermediate Quality Control and Inspection Methods PDF

WSS Study Guide WC2.1 —„ Intermediate Quality Control and Inspection Methods Square based diamond pyramid indentor (138° between opposite faces) Vickers hardness number ~^ HV= 1.854 P/d* D is the mean diagonal of the indentation in millimeters _~¬ trên < = s : CWB Group Indu: Vickers hg...

WSS Study Guide WC2.1 —„ Intermediate Quality Control and Inspection Methods Square based diamond pyramid indentor (138° between opposite faces) Vickers hardness number ~^ HV= 1.854 P/d* D is the mean diagonal of the indentation in millimeters _~¬ trên < = s : CWB Group Indu: Vickers hgørdness test The Brinell, Rockwell and Vickers testers may be used for hard and soft, Terrous and non-ferrous metals. The three methods are complementary †o each other and have different uses and advantages. The Brinell impression, being large, can only be used for obtaining hardness values OVver a relatively large area such as the face of a weld. The Vickers test, however, can be applied to survey the hardness of relatively smaill areas — sections of welds, heat-affected zones, etc. WSS Study; Guide WC2.1 Intermediate Quality Control and Inspection Methods A summary of the differences between hardness testing methods is shown in Table 1. NGOãENONHNE-NE 250HV10 238 HB HRC 22 Uses a diamond Uses a large steel ball Uses diamond or ball Applies small load Applies large load Applies large load Need to measure indent Need to measure indent No need to measure indent Thick and thin samples FRequires thick sample Requires thick sample Micro or macro hardness Used for macro hardness Micro and macro hardness Preferred for regionsinweld Not recommended for welds Limited use on welds mm Dịfferences between the hardness testing methods Information from several regions of the weld may be obtained by conducting a hardness traverse or a complete pattern of test indentations. Figure 15 shows typical linear hardness traverses, where several equallyspaced indentations are made. The distinct difference between the as-welded and stress relieved results can often be used to check whether stress relieving has been undertaken. The results of hardness traverses across a groove weld in the as-welded and stress relieved condition are shown in Figure 16. Page 21 | Copyright © 2015 CWB Group Industn Ị „ „— .WSS Study Guide WC2.1 A . Intermediate Quality Control and Inspection Methods s ® Inweld metel ® Infusionzone O In base metal (Size of weld determines number of check points) A typical pattern of hardness check points FiG.15: A typical pattern oƒ hardness check points gcross a weld 3001 ® Viekers 2501 ~= hardness number ~- ~- ¬ °.... ® 2003 1501 Lị Ml As welded ^ ® N ° ° Stress relieved Typical results from a linear hardness traverse across a weld showing both as-welded and stress relieved results ¬ re. Page 22 Copyright © 2015 CWB Group Industry Services 16: Typical results ƒrom ø linegr hardness traverse across qø weld showing both gs-welded and stress relieved results Anblomedfihe cwbgroup E..l WSS Study|Guide WC2.1 Intermediate Quality Control and Inspection Methods cwbgroup v 2.4 Impact Test Ít is possible in a welded structure that a material showing good ductility in a tensile test can fail in a brittle manner. There have been many examples of unexpected brittle fractures in structures such as ships, bridges and pressure vessels, and they have often occurred when the stresses were well below the yield stress. This is because many materials that may have shown good ductilitv in a plain tensile test behave in a completely different manner when notches Or Cracks are present. They may also behave differently due to differences in loading or due to a low service temperature. Steels, in particular, tend to exhibit brittle behaviour when sharp notches are present, when the temperature is low or when they are subject to impact loads. Toughness is a measure of the ability of a material to resist the growth of a crack. To measure the toughness of material and to reveal its behaviour in the presence of notches, several tests have been devisedk. The most common toughness test is the Charpy impact test, in which a notched specimen is broken by a swinging pendulum and the amount of energy absorbed by the specimen is recorded. The energy can be measured by allowing the pendulum to drop from a fixed height and measuring how high it swings up after fracturing the specimen. lf the specimen is brittle and absorbs little energy, the pendulum wlill swing up almost to its original height. lf the specimen is tough, the pendulum will only swing up a small distance. The value of energy absorbed is read directly from a dial on the machine and is measured in joules or foot-pounds (ft-lb). A typical Charpy impact testing machine is shown in Figure 17. 015 CWB Group Industry Services WSS Study Guide WC2.1 „— . Intermediate Quality Control and Inspection Methods ^ rie.17| m_ To carry out the test the specimen is loaded into the anvil with a pair of special tongs that facilitate location of the specimen in the machine. The specimen is supported at each end and the pendulum strikes the back 0f the specimen behind the notch. This puts the side with the notch into ~^ tension, causing the specimen to fracture from the notch. Charpy impoct testing machine The most commonly used specimen, the Charpy V-notch (CVN), is 10x 10 x55 mm and has a V-notch 2 mm deep with a 0.25 mm tip radius. Subsize specimens are sometimes used when testing thinner material. WSS Study Guide WC2.1 Intermediate Quality Control and Inspection Methods 8mmz0.025 1/2 length of ¬I specimen mm NỔ 10 mm + 0.025 mm 55 mm +0mm -2.5mm R= 0.25 mm z 0.025 mm mm Charpy impact specimen Steels usually become more brittle at low temperatures and this behaviour may be revealed by conducting tests at several temperatures. The energy absorbed at each temperature may then be plotted against the temperature. Figure 19 shows the results of testing at eight different temperatures. The graph shows low energy at low temperatures, then an increase in energy through a temperature interval known as the transition range. At high temperatures, the curve flattens out to give an upper shelf. The transition temperature at which a certain energy, for example 20.J, is reached is often used as a method of comparing the toughness of several materials. CWBï WSS Study Guide WC2.1 acorn An |nirlarive ñ øf the cwbgroup Intermediate Quality Control and Inspection Methods 14001~ U pper shel lf 80 CVN Energy 60 — (0oules) Transition temiperature 40-= 2U. for 20 Joules -¬===-—= Lower shelf e J J | l -60 -50 -40 -30 | | -20 J -iD l 0 J 10 J 20 J 30 J 40 J 50 | 60 Temperature °C rà A typical transition curve for steel showing the energies absorbed dt various temiperdtures When conducting impact tests on welds, it is most important that the specimens are machined from the right location, and that the notch is oriented correctly. A totally misleading result may be obtained ïf the notch is in the wrong position. For example, when impact tests are required as part of the classification of an electrode, they are machined from the same test weld as the tensile specimens. The test plate is 20 mm thick and the impact specimens are located mid-thickness as shown in Figure 20. The notch is placed perpendicular to the plate surface on the centreline of the weld. WB Group Industry Services WSS Study Guide WC2.1 Intermediate Quality Control and Inspection Methods Z Weld centreline rie.20| Orientation oƒ impact specimen for weld metal tests The testing of the heat-affected zone can be more troublesome because of its narrow width and the fact that it is usually sloping. In most cases, the notch samples only part of the heat-affected zone. To locate the position, the specimens should be machined as over-length blanks, then etched to reveal the weld and heat-affected zone. The desired position of the notch can then be marked and the specimens cut to final length (see Figure 21). Heat-affected zone Em Location oƒ heat-affected zone impact specimen WSS Study Guide WC2.1 Intermediate Quality Control and Inspection Methods 2.5 Nick-Break Test The nick-break test is used for revealing internal weld discontinuities. No special equipment is needed: a hacksaw, a hammer and a vise are the only tools required. The size of the specimen may vary, but ït usually consists of a strip approximately 25 mm wide The specimen is notched on VÏse Of across supports. lt is through the weld centerline - removed through the weld and parent metal. each side at the weld centre and placed in a then struck with a hammer until ït fractures as shown in Figure 22. Vise G2 Method oƒ muking a nick-break test with a hammer and vise The fractured surface is examined for discontinuities such as porosity, slag inclusions, incomplete penetration and incomplete fusion. This test is required in codes to evaluate the entire surface area within a region of the welded joint. The nick-break test wÏill clearly reveal discontinuities if they are present, but it is a spot check only and may not necessarily be indicative of the quality of the entire weld. It is difficult to determine the acceptability of fractured specimens and, where possible, published acceptability standards should be applied. ® Page 28 Copyright © 2015 CWB Group Industry Services WSS Study|Guide WC2.1 hs Intermediate Quality Control and Inspection Methods 2.6 Fillet Weld Break Test The ñllet weld break test ïs similar to the nick-break test and is used to evaluate the general quality of the weld. An example of a fillet weld break test is the test used for the qualification of tack welders in CSA Standard W47.1. A 6 mm maximum size single pass fillet weld is deposited for a length of 50 mm using the assembly as shown SMAW 4mmØmax. 50mm 13mm 100 mm ¡in Figure 23. Force riG.23| Fillet weld break test A force is applied to the back side of the welded T-joint until the fillet weld fractures and the fractured specimen is examined for porosity, penetration and other criteria. WE Group Indus WSS Study Guide WC2.1 Intermediate Quality Control and Inspection Methods 2.7 Macroscopic Examination c.3Ÿ$+}$. lt is sometimes useful to cụt through the finished weld to examine its cross-section. With proper polishing and etching of the surface as shown in Figure 24, the following details can be observed and measured: Extent and shape of penetration Presence of cracks, inclusions and incomplete fusion Number of passes Size of weld rm Lả Page 30 Copyright © 2015 CWB Group Industry Services Etched cross-section oƒ a weld WSS Study Guide WC2.1 Intermediate Quality Control and Inspection Methods Lesson 2 Objectives After completing this lesson you should be able to: $ Identify the items to check during the visual inspection of welds; before, during and after welding $ Describe the basic principles of liquid penetrant, magnetic particle, radiographic and ultrasonic inspection $ Describe the advantages, disadvantages and application of liquid penetrant, magnetic particle, radiographic and ultrasonic inspection 3. NonDestructive Test Methods 3.1 Visual Inspection The basis for all weld examination methods is inspection with the human eye. Special techniques or devices might be used to improve the visibility Of surface discontinuities or to look within the weld, but the final decision regarding acceptance almost always comes back to a visual inspection and associated measurements. A trained and experienced visual inspector requires few tools, and can make decisions on the spot thus making corrective action easy and immediate. Visual inspection is fast, inexpensive and is performed before, during and after welding. Visual Inspection Prior to Welding After preparation of the material, but before welding starts, there are many items to check. For example, the weld preparations must be verified to ensure they comply with the requirements. In verifving the weld preparation and fit-up dimensions ït is important to note the difference between the workmanship tolerances and the range of values for which the welding procedure is valid. For example, a prequalified joint from CSA W5 may be valid for all groove angles down to some minimum value. Page 31 | Copyright © 2015 Cwb Group Industry | WSS Study Guide WC2.1 n Intermediate Quality Control and Inspection Methods lf this minimum groove angle is specified in the procedure it is still subject to the minus 5° workmanship tolerance given in Table 5.5 of CSA W59. In addition to the dimensions of the joint, the condition of the edge preparation and cleanliness of the material must be checked. The requirements for these are normally given in the governing standard Or the contract specification. For example, the quality of a flame cut edge is specified in CSA W59. This same standard also requires that surfaces to be welded be Tree of scale, slag, loose rust, paint, grease, etc. Some of the items to check include: $ $ Ensuring approved welding procedures are available Checking that welders are qualified (see Figure 25) ® Welder Qudlificalion This card is valid only whle employed by a CWB certiied company: Transferal ible Wolder Name:.Joe Welder Exp. Date: May 06, 2013 Employer. ABC Company, Anytown, ON “Thickness Range: 3mm 8 above Materal: Carbon Steel Mode of Transfer. Spray/Globular/Pulsed Process: GIMAVV Mode: SEMI-AUTO Standard: CSA W47.1 Single Electrode Mechanized Single Electrode Automatic Class: FLAT Classificaion: 8 Seo roverso for conditons. TS xosoc.eo .Sv.gvt.s.. rie.25] ® Page 32 Copyright © 2015 CWB Group Industry Services Welder identificdtion card Ensuring that codes and standards are available Ensuring that drawings are available Checking the base metal type (MIill test report or certificate) Verifying the welding process being used Checking the types of electrodes Checking the positions of welding Checking the preheat requirements Inspecting the joint preparation and fit-up WSS Study Guide WC2.1 in Intermediate Quality Control and Inspection Methods $ Checking the joint preparation surfaces (see Figure 26) mm $ Plate edge defects may need correction Checking for the presence of moisture, scale, slag, oil, grease, paint etc. on the Joint surface $ Determining the weld locations $ Identifying the weld size requirements Visual Inspection During Welding Some ơf the items to check include: $ Ensuring the use of approved welding procedures (see Figure 27) WSS Study Guide WC2.1 mi An initlative. Intermediate Quality Control and Inspection Methods CWB Fom —— WELDING PROCEDURE WPDSNO.: DATA SHEET 160E/2018-1 SMAW-2E-4918 DATE: Rev.: 0 Company Name: ABC Welding Ref. Standards: CSA W47.1/ W59 Address: 2345 East Street, Toronto Ref. WPS: SMAWS-1 Welding Processes: _ Pulsed: 1 Shielding Gas Type: Positions: Process Mode: [ ]Yes No Pulsed: 2 [lYes No Joint Configuration & Pass/Layer Sequence Manual [L]Semi-Auto Joint Type: [Butt Penetration: [1] Complete IÌTee Backing: Material: Backgouging: LiYes No [L]Machine Corner UlPartial ELiAuto Lap L]Edge ETT= 4 Fillet Thickness: |Method: |Depth: ⁄ Electrode Extension: Nozzle Diameter(s): Flux Classification: Tungsten Electrode: GAP 0-1 mm |Type: | 5zg | NA 7 R ä Gleaning Procedures | se a chipping hammer and wire brush. Remove slag 1] 5 from all finished welds and before welding over. Dreviously deposited metal. CSA W186 Rebar Splice Type: L]Direct Splice LlIndirect Splice = 2 L]Lap Splice [IlRebar to Structural Member Only Identification of Ease Material (for CSA W186 indicate carbon equivalent, max. phosphorus & sulphur content) Part I I.: Specification & Crade Thickness or Dia. JSteelsin Groups 1.2and3of Table 11.1/12.1 |Steels in Groups 1, 2and 3 of Table 11.1/12.1 5.0 5.0 mmmm- Special Requirements 16.0mm 16.0mm Identification of Filler Material Process Trade Name SMAW. |Welding Parameters Thick-| Weld ness | Size/ Layer (. )|ET 5.0 Pass | Welding Number | Process | Dia. ( ) Classification Group Filler Treatment E4918 F4 CI. 5.2.2.4. CSA W59 Wire Feed 8peed | Currentl ( ) A Volt V Current | Welding Polarity Spesd (3) 1 | Burn-Off | Gas Flow Rate Rate ( ) li SMAW| 3.2 NA 120-140 AC/DC+ NA 1 1 SMAW| 32 NA 120-140 AG/DC+ NA 8.0 1-2 1-3 |SMAW| 3.2 NA 120-140 AG/DC+ NA 10.0 1-2 1-4 |SMAW| 4.0 NA 160-180 AC/DC+ NA 12.0 16.0 1-3 13 1-6 17 |SMAW| |SMAW| 40 4.0 NA NA 160-160 160-180 AC/DC+ AC/DG+ NA NA W59 CWB Acceptance Interpasstemp.max.: Company Authorization |150°C Interpasstemp.min.: | Table 5-3 Remarks: Date: riG.27i 2015 CWB Group Industry Services Welding procedure data sheets Heat Input ( ) ) 1 6.0 Heat treatment : l Preheatmin: |Table 5-3, CSA oÍ 1F cwbgroup hại WSS Study Guide WC2.1 An iniganve si cwbgroup Intermediate Quality Control and Inspection Methods Visual Inspection During Welding $ $ $ $ $ $ Reviewing welder, welding operator and tack welder qualifications to ensure they are current and applicable to the work being carried out Checking that welders only weld joints for which they are qualified Verifying that the materials are compatible Ensuring that welding parameters are in accordance with the approved welding procedure Ensuring that electrodes are stored and handled correctly Monitoring the preheat and interpass temperatures, ïf required Visual Inspection After Welding Some of the items to check include: $ $ Checking to ensure that all the required welds have been made Measuring the weld sizes to ensure they are correct (see Figure 28) Throat full size mm Page 35 Copyright © up Indus Measuring fillet weld sizes with gauges Shortleg Oversize leg