Aws Module 10.ppt

MODULE 10 – VISUAL INSPECTION AND OTHER NDE METHODS & SYMBOLS

WELDING INSPECTION TECHNOLOGY

BEFORE, DURING AND AFTER WELDING INSPECTION  BEFORE WELDING

 REVIEW APPLICABLE DOCUMENTATION  CHECK WELDING PROCEDURE  CHECK INDIVIDUAL WELDER QUALIFICATION  ESTABLISH HOLD POINTS  DEVELOP INSPECTION PLAN  DEVELOP PLAN FOR RECORDING INSPECTION RESULTS AND MAINTAINING THOSE RECORDS

 DEVELOP SYSTEM FOR IDENTIFICATION OF REJECTS

 BEFORE WELDING  CHECK CONDITION

OF WELDING EQUIPMENT

 CHECK QUALITY AND CONDITION OF BASE AND FILLERMATERIALS TO TO BE USED

 CHECK WELD PREPARATIONS  CHECK JOINT FIT-UP  CHECK ADEQUACY OF ALIGNMENT DEVICES  CHECK WELD JOINT CLEANLINESS

 CHECK PREHEAT, WHEN REQUIRED

 DURING WELDING  CHECK WELDING VARIABLES FOR COMPLIANCE WITH WELDING PROCEDURE

 CHECK QUALITY OF INDIVIDUAL WELD PASSES  CHECK INTERPASS CLEANING

 CHECK INTERPASS TEMPERATURE  CHECK PLACEMENT AND SEQUENCING OF INDIVIDUAL WELD PASSES

 CHECK BACKGOUGED SURFACES  MONITOR IN-PROCESS NDT, IF REQUIRED

 AFTER WELDING  CHECK FINISHED WELD APPEARANCE  CHECK WELD SIZE  CHECK WELD LENGTH  CHECK DIMENSIONAL ACCURACY OF WELDMENT  MONITOR ADDITIONAL NDT, IF REQUIRED  MONITOR POST WELD HEAT TREATMENT  PREPARE INSPECTION REPORTS

NONDESTRUCTIVE TESTING (NDT)  TESTS DEVELOPED TO PROVIDE AN INDICATION OF THE ACCEPTABILITY OF THE TEST OBJECT WITHOUT RENDERING IT UNUSABLE FOR SERVICE.

 NDT METHODS  PENETRANT

TEST (PT)

 MAGNETIC PARTICLE TEST (MT)  RADIOGRAPHIC TEST (RT)  ULTRASONIC TEST (UT)  EDDY CURRENT TEST (ET)

 PENETRANT TEST

- PENETRANT TESTING REVEALS SURFACE DISCONTINUITIES BY THE BLEEDOUT OF A PENETRATING MEDIUM AGAINST A CONTRASTING COLORED

BACKGROUND.

 TWO PENETRANT INDICATIONS  VISIBLE  FLUORESCENT  METHOD OF EXCESS PENTRANT REMOVAL  WATER WASHABLE – CONTAIN AN EMULSIFIER WHICH ALLOWS THE OILY PENETRANT TO BE RINSED OFF FROM THE SURFACE W/ A LOW PRESSURE WATER WASH.

 METHOD OF EXCESS PENTRANT REMOVAL  SOLVENT REMOVABLE – REQUIRE SOLVENT TO REMOVE THE SURFACE PENETRANT FROM THE TEST OBJECT.

 POST-EMULSIFIABLE – ARE REMOVED BY ADDING AN EMULSIFIER AFTER THE DWELL TIME. - APPLICATION OF EMULSIFIER PERMITS THE PENETRANT TO BE REMOVED BY WATER.

 SIX DIFFERENT TYPES OF PENETRANTS  VISIBLE/WATER WASHABLE

 VISIBLE/SOLVENT REMOVABLE  VISIBLE/POST-EMULSIFIABLE

 SIX DIFFERENT TYPES OF PENETRANTS (CONTINUED)  FLUORESCENT/WATER WASHABLE  FLUORESCENT/SOLVENT REMOVABLE  FLUORESCENT/POST-EMULSIFIABLE  THE PENETRANT IS ALLOWED TO REMAIN ON THE TEST SURFACE FOR A PERIOD OF 5 AND 30 MINUTES, WHICH IS CALLED “DWELL TIME”.

 ADVANTAGES  THE USE OF PENTRANT IS NOT LIMITED TO METALLIC MATERIALS  WELL SUITED FOR EVALUATING WELD OR BRAZED JOINTS BETWEEN DISSIMILAR METALS

 PROCESS IS QUITE PORTABLE

 DISADVANTAGES  IT WILL NOT DETECT SUBSURFACE DISCONTINUITIES

 RELATIVELY TIME-CONSUMING TEST WHEN COMPARED TO MPT  CLEANING REQUIRED FOR CERTAIN APPLICATION  THE PRESENCE OF SURFACE NONRELEVANT INDICATIONS MAY MAKE INTERPRETATION DIFFICULT.

 MAGNETIC PARTICLE TEST (MPT)

- USED PRIMARILY TO DISCOVER DISCONTINUITIES IN FERROMAGNETIC MATERIALS.

PERMANENT MAGNET YOKE

LINES OF FORCE

N S

DISCONTINUITY

 TWO METHODS OF MPT  DRY METHOD – CALLED THE DRY MAGNETIC PARTICLE METHOD  WET METHOD – ALSO CALLED THE OIL OR WATER SUSPENSION PARTICLE METHOD - HAS HIGHER SENSITIVITY

 ADVANTAGES  APPLICATION OF MAGNETIC PARTICLE INSPECTION INCLUDE THE EVALUATION OF MATERIALS WHICH ARE CONSIDERED TO BE MAGNETIC AT THE TEST TEMPERATURE.

 EQUIPMENT IS PORTABLE

 RAPID TESTING SPEED AND LOW COST  VERY GOOD FOR SURFACE DISCONTINUITY DETECTION  TEST CAN BE DONE THROUGH THIN PAINT COATINGS

 DISADVANTAGES  CAN ONLY BE USED ON MATERIALS THAT CAN BE MAGNETIZED  MOST PARTS REQUIRE DEMAGNETIZATION AFTER TESTING AND THAT VERY THICK COATINGS MAY MASK DETRIMENTAL INDICATIONS

 ROUGH SURFACES SUCH AS THOSE SEEN ON WELDS OR CASTINGS CAN MAKE EVALUATION MORE DIFFICULT

 RADIOGRAPHIC TESTING (RT) – THIS METHOD IS BASED ON THE PRINCIPLE OF PREFERENTIAL RADIATION TRANSMISSION, OR ABSORPTION. SOURCE X-RAYS

STEEL STEP WEDGE FILM

DARKEST LIGHTEST EFFECT OF PART THICKNESS ON RADIATION TRANSMISSION (ABSORPTION)

EFFECT OF MATERIAL DENSITY ON RADIATION TRANSMISSION (ABSORPTION) SOURCE X-RAYS Pb

Cu

Fe

Al FILM

LIGHTEST

DARKEST

SOURCE

X-RAYS

FILM

ORIENTATION OF RADIATION SOURCE, TEST PLATE AND RADIOGRAPHIC FILM

 ADVANTAGES  IT CAN DETECT SUBSURFACE DISCONTINUITIES IN ALL COMMON ENGINEERING MATERIALS

 THE DEVELOPED FILM SERVES AS AN EXCELLENT PERMANENT RECORD OF THE TEST IF THE FILM IS STRORED PROPERLY AWAY FROM EXCESSIVE HEAT AND LIGHT

 DISADVANTAGES  HAZARDOUS TO HUMANS BECAUSE OF THE EXCESSIVE RADIATION EXPOSURE

 VERY EXPENSIVE EQUIPMENT  OPERATORS AND INTERPRETERS REQUIRE LENGTHY TRAINING PERIODS

 TEST METHOD REQUIRES ACCESS BOTH SIDES OF THE MATERIAL

 ULTRASONIC TEST (UT) – IS AN INSPECTION METHOD WHICH USES HIGH FREQUENCY SOUND WAVES, TO MEASURE GEOMETRIC AND PHYSICAL PROPERTIES IN

MATERIALS. - UT USES ELECTRICAL ENERGY IN THE FORM OF AN APPLIED VOLTAGE, AND THIS VOLTAGE IS CONVERTED BY A TRANSDUCER TO MECHANICAL ENERGY IN THE FORM OF SOUND WAVES. - THE TRANSDUCER ACCOMPLISHES THIS ENERGY CONVERSION DUE TO A PHENOMENON REFERRED TO AS “PIEZOELECTRIC” EFFECT.

 TWO TYPES OF TRANSDUCERS  LONGITUDINAL OR STRAIGHT BEAM – USE TO DETERMINE MATERIAL THICKNESSES OR THE DEPTH OF A DISCONTINUITY BELOW THE MATERIAL THICKNESS.

 SHEAR WAVES OR ANGLE BEAM – ARE USED EXTENSIVELY FOR WELD EVALUATION BEACAUSE THEY SEND THE SOUND INTO THE PART AT AN ANGLE.

 TWO GENERAL TYPES OF UT

 CONTACT TESTING – THE TRANSDUCER IS ACTUALLY PLACED AGAINST THE SURFACE OF THE PART

 IMMERSION – THE PART TO BE EVALUATED IS PLACED UNDERWATER AND THE SOUND IS TRANSMITTED FROM THE TRANSDUCER AND INTO THE PART THROUGH THE WATER.

 ADVANTAGES  CONSIDERED TO BE A VOLUMETRIC TEST  IT IS CAPABLE OF DETERMINING NOT ONLY THE LENGTH AND AND LATERAL LOCATION OF A DISCONTINUITY, BUT IT WILL ALSO PROVIDE THE OPERATOR WITH A DETERMINATION OF A DEPTH OF THAT FLAW BENEATH THE SURFACE.

 IT WILL BEST DETECT THOSE MORE CRITICAL PLANAR DISCONTINUITIES SUCH AS CRACKING AND INCOMPLETE FUSION.

 HAS DEEP PENETRATION ABILITY UP TO 200 in. IN STEEL AND CAN BE VERY ACCURATE

 DISADVANTAGES  IT REQUIRES A HIGHLY SKILLED AND EXPERIENCED OPERATOR BECAUSE INTERPRETATION CAN BE DIFFICULT.

 THE TEST OBJECT MUST BE FAIRLY SMOOTH, AND COUPLANT IS REQUIRED FOR CONTACT TESTING.

 REFERENCED STANDARDS ARE REQUIRED, AND THIS TEST METHOD FOR WELD INSPECTION IS GENERALLY LIMITED TO GROOVE WELDS THAT ARE THICKER THAN ¼ in.

 EDDY CURRENT TEST (ET) – WHEN A COIL CARRYING AC IS BROUGHT NEAR A METAL SPECIMEN, EDDY CURRENT ARE INDUCED IN THE METAL BY ELECTRO-

MAGNETIC INDUCTION.

 ADVANTAGES  CAN BE USED TO MEASURE THE THICKNESS OF THIN SECTIONS, ELECTRICAL CONDUCTIVITY, MAGNETIC PERMEABILITY, HARDNESS, AND THE HEAT TREATMENT CONDITION OF TEST OBJECT.

 THIS METHOD CAN ALSO BE USED TO SORT DISSIMILAR METALS AND TO MEASURE THE THICKNESS OF NONCONDUCTIVE COATINGS ON ELECTRICALLY CONDUCTIVE TEST ONJECTS.

 ADVANTAGES  IT CAN BE READILY AUTOMATED  THE PROBE NEED NOT TOUCH THE TEST OBJECT, NO COUPLANT IS REQUIRED, AND THE METHOD IS EXPEDIENT, ALL OF WHICH MAKES “ASSEMBLY LINE” INSPECTION RELATIVELY EASY.

 CAN BE USED FOR THE INSPECTION OF ANY ELECTRICALLY CONDUCTIVE MATERIAL, WHETHER MAGNETIC OR NONMAGNETIC.