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WELDING INSPECTION - STEELS
COURSE REF: WIS.5
The Welding Institute Training Services Group Abington Hall, Abington
Cambridge CBI 6AL
CSWIP WELDING INSPECTOR
THEORY A - 30 QUESTION MULTICHOICE - 30 MINUTES
THEORY B - MANDATORY QUESTION DUTIES OF:A WELDING INSPECTOR TO YOUR CHOICE OF CQDE (NO MORE THAN 30 MINUTES ON THIS QUESTION) APPROX. 3OO.WORDS;
.b . . . 4 FROM 6 TECHNOLOGY QUESTIONS 1 HR 15 MINUTES
INSPECTION AND SENTENCING OF A PIPE TO YOUR CODE 1 HR 45 MINUTES
INSPECTION OF A PLATE TO CSWIP ACCEPTANCE LEVELS 1 HR 15 MINUTES
BEND & MACROS (3 OFF) 45 MINUTES
10 QUESTIONS ON YOUR CODE RE APPLICATION lo-20 MINUTES
. WELDING INSPECTION - STEELS -
COURSE REF: WIS5
TERMINOLOGY THE DUTIES OF A WELDING INSPECTOR CODES AND STANPARDS WELD PROCEDURES & PROCEDURE & WELDER APPROVAL MECHANICAL TEStlNG SYMBOLS MATERIALS CONSUMABLES THE FOUR FACTORS FOR ESTABLISHING A WELD MANUAL METAL ARC WELDING TUNGSTEN INERT GAS WELDING DEFECTS WHICH MAY BE DETECTED BY SURFACE INSPECTION METAL INERT GAS WELDING SUBMERGED ARC WELDING CALIBRATION OF EQUIPMENT RESIDUAL STRESS AND DISTORTION WELDABILITY HEAT TREATMENTS NON DESTRUCTIVE TESTING REPAIR BY WELDING GAS WELDING, CUl-l-ING & GOUGING ARC CU-l-l-ING OTHER WELDING SYSTEMS INTERNAL DEFECTS 8. THEIR INTERPRETATION
1 2 3 4 5 6 7 8 9
10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
WELDING INSPECTION - STEELS
ALL COURSE MEMBERS PLEASE READ CAREFULLY
1. The general working programme is attached.
2. Any alterations will be announced by the course tutor.
3. The lectures and tutorials etc are supported by the course text, please read as appropriate.
Question papers will be used to reinforce most sessions please the questiaas, these will be discussed or marked at the
discretion of the lecturer/tutor.
The end of course assessments are marked and the results recorded.
Standards reproduced with the permission of British Standards Institute.
KEY KNOWLEDGE FOR WELDING INSPECTION PERSONNEL
The information contained in this course text supplements the lectures given in the course WIS 5.
Terminology given in the test is that recommended in BS 499 Pt 1: 1983; Weld Symbols to BS 499 Pt 2 : 1980. To supplement this further, however, an indication of both International (ISO) and American standards is given.
The sections are written in general terms and do not include all of the conditions that may apply to a specific fabrication or product.
TWI 17L7L7/ THE WELDING INSTITUTE - *
Use of the correct terminology is important. This course uses BS 499.
WELDS and JOINTS
Frequently the terms weld and joint are used incorrectly. Exact definitions are given in BS 499 Welding terms and symbols.
TYPES OF WELD
Smil hdenh tlonr at each weld
Illustration depicts resistance weld. Spot welds can be made with MIG or TIG processes.
WELDING TECHNOLOGY issue 0191 1.1
TYPES OF JOINT
The four basic welds can be used to join various types of joints.
The following are some typical joints
TYPE OF JOINT EXAMPLES
1.2 WELDING TECHNOLOGY
PLATE EDGE PREPARATION FOR BUTT WELDS
The illustrations show standard terminology for the various features of plate edge preparations.
Single - V
Double - V
Single - U
FEATURES OF COMPLETED WELD
A butt weld in a plate, made by welding from both sides, has two weld faces, four toes. In a full penetration weld made from one side, the protruding weld on the underside is the penetration bead.
WELDING TECHNOLOGY issue 0191 1.3
If a weld is sectioned, polished and etched, the fusion boundary can be established. Metal lying between the two fusion boundaries is weld metal, a mixture of deposited metal and plate material that has been melted. Adjacent to the fusion boundary is the heat affected zone (HAZ), in which the plate material has a metallurgical structure modified by the heat of welding.
Fillet welds also have I
A weld face
A fusion boundary
A heat affected zone Hat affrctrd zonr
The shape of a fillet weld in cross-section is described by three terms
Mitre fillet .
Excess weld metal, as illustrated, is often referred to as weld reinforcement. This does not necessarily mean it strengthens a joint.-
m WELDING TECHNOLOGY Issue 0191
SIZE OF WELDS
For full penetration butt welds, the general rule is: design throat thickness, t = ,_......~ __.. JL thickness of the thinner part joined.
_...- - . --____ __ _ ,
Partial penetration butt welds
The term pti.al..penetr$on strictly implies butJ we!dst_hat_,ar~--de~~g~r?_ed.~o hg,ce Iess..than full penetration. Failure to achieve full penetration when it is wanted should be listed as the defect Il$@JL_ETE~ PEf$ZTfWTlON.
The throat thickness of a partial penetration weld made from both sides- &and the design throat thickneq-t,.+.t,. Note that the degree of penetration tYi&t be known.
Fillet weld sizes are calculated by reference to allowable -shear stress on the _---_-- ..----~-~ ---, throat-sea, i.e. throat area = design throat thickness x length of geld. -The _ _ .-.-.~._~~ size required is specifiedon_d_rawings in terms of leg leng$h-rsJ: , ~_ ---- _. .-. . ..___- --
n( ) ., 1,
For fillet welds with equal leg lengths:
where t, is as defined for mitre and convex fillets.
WELDING TECHNOLOGY Issue 0191
TWI m TIE WELDING INST!TUTE
If an asymmetrical fillet weld is required, both leg lengths are;-spe_cified and t, is taken as the minimum throat dimension.
Deep penetration fillet weld
With high current density processes, e.g. submerged arc and MIG (spray). penetration along the joint line can be produced.
This gives an increase in throat thickness with no change in leg length.
WELDING TECHNOLOGY 1.6 Issue 0191
wJX.IUNG PCFJT;IONS (BS 499: 1991/ISO 6947)
PD HorizonCal overhead
I Vertical up
PB Horizontal vertical
;,?TE : To avoid confusion with evlsting abbreviations, eg F for t^lar, in principle trre letter '?' (fcr position) has bee; placed i:. fronr of trle s\-mbcl to ind:cate 'zain positlor.'
SECTION 1X - PART QW, UELDISG 1986 Edition . -i * -i . QW-461 Positions .tContd)
. . .-
/ ;e5 t?eg : 5dq.
\ , I
* QW-4b1.4 GROOVE WELDS IN
, tb) 2F
PIPE - TEST POSITIONS
---I. (cl 3F td) 4F
QW-4615 FILLET WELDS IN PLATE - TEST P.OSlTlONS . . .
116 :, ..
Sketch a single vee butt joint and a single bevel butt joint
Sketch a tee joint and indicate for fillet welds:
a) leg length b) throat thickness c) root d) toes
Complete the of the sketch:
Q5. What is excess weld metal?
TWI THE WELDING INSTITUTE
THE DUTIES OF THE WELDING INSPECTOR
At any point in the course of welding, i.e. tacking, root pass, filler pass or capping pass, but particularly for the rootand cap, ,a detailed inspectiommay be required. British Standard.-.3289 :. @I&gives guidance- on -tools -an-d _---.. responsibilities together with sketch.es of typical defects. ._^, - _-.. ,-
q J f
I3 j 0 !q719q- d; ~i j I- t -1 0 /
4 9 t>i : 3 : in , The inspector at this point must - +q)., (Xi, . cj
4 observe, idenentj@~and perhaps record th.e features of the weld. _...-..-.-, -_.., __-. -.._..._ -_
b) decide whether the weld is acceptable in terms of the particular leve!s which are permitted; defect levels may be in-house or National Codes of Practice.
When the defect size is in excess of the permitted level then either a concession must be applied for (from a competent person) or the weld rejected.
CODE OF PRACTICE FOR VISUAL INSPECTION
A code of practice for an inspection department could take the form outlined below. It is appreciated that full implementation of the code would be extremely costly and therefore it may be necessary to reduce the amount of inspection to less than is- theoretically req.u&ed.
AIDS OF VISUAL INSPECTION
Illumination: Good lighting is essential J Inspection lenses: The magnification should not exceed 2-2X diameters.
If higher magnification is required use a binocular microscope.
Optical viewing devices area progressive development from the use of a hand torch and mirror, frequently with the add~~f.~a~m-ag?ifier and_(jght.s.our.ce. __.-.- -,
In order to achieve accessibility probe units are available down to a diameter, properties for which are:
1. Large field of vision. 2. Freedom from distortion of Image. 3. Accurate preservations of colour yalues. 4. Adequacy of illumination.
WELDING TECHNOLOGY Issue 0191 2.1
TWI m 1 THE WEmING INSTITUfE
VISUAL INSPECTION PRACTICE
The inspector should be familiar with the foll