Pt

What kind of angle do we want for wetting?

3-5 degree angle or less

Fluorescent dye type 1

Greenish yellowish need black light and dark room to see

Visible dye type 2

Red

Disadvantages of solvent removable dye

• A disadvantage of solvent removable dye is it has a longer removal time then either water washable or PEs types.• very difficult to use on rough surfaces. • cannot be used to check threaded surfaces.

Discontinuities and defects

• A discontinuity is a break in the normal structure of the part. This may be intended such as a press fit or riveted joints or unintended such as slag, cracks or other flaws. • A defect is any discontinuity that is judged harmful to the products end use and is determined by the acceptance criteria given in the code, specification or procedure to be unacceptable.

Evaluation by level one technician

• A level one technician may be permitted to do evaluation if the specification and procedures allow for it. • The level one will need to be trained and qualified for each pacific part and written instructions for the parts or components for which evaluation is to be performed. • technical publication T9074-AS-GIB-010/271 for the military strictly forbids level one technicians from performing evaluation.

Linear vs rounded indications

• A linear indication will be any indication with the longest dimension equal to or greater than three times the shortest dimension. • A rounded indication will be any indication with the longest dimension less than three times the shortest dimension. • make sure you read your specification for the definition because it may vary from this definition.

Non-aqueous wet developers

• A non-aqueous wet developer has the developer powder suspended in a solvent or alcohol base. (form d for fluorescent and form e for visible) • this solvent or alcohol will evaporate very quickly and leave and even coat of developer on the surface. • is in the can • non-aqueous developers are the most sensitive of developers.

Refractometer

• A refractometer is used to verify the proper mix for the emulsifier. • The manufacture will have a recommended percentage of mixture required for their emulsifier.

ASTM wash temp and pressure

• ASTM E-1417 requirements: - water pressure shall be adequate to remove the penetrant but shall not exceed 40 psi. - water temperature shall be between 50° and 100°F. - when Hydro air nozzles are used the air pressure shall not exceed 25 psi - A course spray shall be used a minimum of 12 inches between the nozzle and the part. • ASME section v article 6 has slightly different requirements than ASTM standards. - The water temperature is controlled to a maximum temperature of 100 in degrees The water temperature is controlled to a maximum temperature of 110°F. - The pressure must be regulated to no more than 50 psi. - The part temperature is permitted to be as high as 125°F.

Aqueous wet developers

• Aqueous wet developers can be applied directly to the part immediately after the excess penetrant has been removed. • Application can be by spraying or dipping the part. (Form b wet soluble, form c wet suspendible) • The part is usually dried and then oven with the temperature no greater than 160°F. The part temperature may not exceed 125°F at any time. • aqueous wet developers will drive to a even thin coating across the part. Care must be taken to avoid any pooling of the developer fluid in cavities or concave areas of the part. • this type of developer is good on smooth and machined parts. • water soluble should never be used with a water washable penetrant.

Black light

• Black lights are required to view the results of the fluorescent examination. The wavelength (365 nm) of the black light causes the penetrant to Fluoresce. • The black light will usually need five minutes minimum to warm up and will need a filter on the front to allow only those wavelengths (365 nm) to pass that cause the penetrant to fluoresce. The operators eyes also need 1 to 2 minutes to adjust to the dark and area before performing interpretation. (ASTM E1417) ASME Section v requires five minutes for the eyes to adjust.

Black light intensity and integrity

• Black lights shall be checked for intensity each day. This check shall be done with the light centered on the meter at a minimum of 15 inches from the meter also verify you have that intensity at the part surface. The intensity shall be a minimum of 1000 micro-watts per square centimeter (µW/cm2). • Black light integrity shall be verified by inspecting the filter, bulb and wiring for cracks, dirt or other extraneous material that may impair the light function. • special black lights, if used, shall also be verified to these requirements.

Cleaning application

• Degreasers, solvents, vapor cleaning, ultrasonic and steam cleaning is used to remove dirt, grease and oily substances on the surface and in the openings. The solvents must be highly volatile and evaporate from the flaws openings. • acid and alkaline Etches are used to remove rust, scale and dirt embedded in the surface. If a surface is etched additional cleaning must be done to remove the acid or alkaline as it will have deleterious effects on the dye and especially fluorescent dye.

Developer application

• Developer will provide a contrasting background and provide a blotting or capillary action to draw the penetrant out of the discontinuities that hold penetrant. • even though some indications will be visible without developer it is still important to use the developer to make sure all discontinuities will be visible. • The actual bleed out of the dye will be larger than the actual flaw. Final interpretation will be based on the actual size of the bleed out and not the flaw size.unless a procedure or code calls for it.

LOX and chemistry control

• LOX stands for liquid oxygen. Anytime you are inspecting material that will come in contact with gaseous or liquid oxygen you must use special penetrant materials qualified for liquid oxygen systems. • some materials will require the control of sulfur and halogens in the penetrant materials. Most of these systems require a combined total of less than 1% by weight.

Non-relevant indications

• Nonrelevant indications are indications caused by features that are there by design or as defined as non-relevant by the specification. • typical non-relevant indications by design would be pressfit parts, drilled holes, keyed or spline parts and rivets. • Nonrelevant is also defined by some acceptance standards such as any indication less than 1/16" in any dimension.

Post emulsifiable

• Post emulsifiable penetrance are oily and can be of the visible or fluorescent type. They are not readily removed with just water washing. And emulsifier must be applied to the surface prior to water washing. Post emulsifiable penetrants are oily and can be of the visible or fluorescent type. They are not readily removed with just water washing. And emulsifier must be applied to the surface prior to water washing. ( Method b lipophilic and Method d hydrophilic) • this type is very sensitive and capable of picking up very tight small cracks or surface anomalies. • The penetrants are highly penetrating but the emulsifier is not penetrating by its nature but will penetrate the flaw if left on too long.

Selection of the proper technique

• Proper selection of the technique will depend on a combination of parameters. - type of material - sensitivity requirements - surface condition - part configuration - The number of parts to be examined - availability of electricity, water, compressed air and allowable area to work.

• Post emulsified

• Removed By a course water spray only after an application of an emulsifier to the penetrant coated surface. (Method B lipophylic and Method D hydrophilic)

Advantages of the post emulsifier system

• The Post emulsifier system is more sensitive to broad surface indications. • The wash cycle is less critical since the die cannot be washed out as easily with just water.

Preparation of the aluminum block

• The aluminum block should be approximately 3/8" thick x 2" wide x 3" long. • heat the block over a Bunsen burner to 950°F then quench it in cold water. The heating should be centered on the block as close as possible. • once the block is quenched you need to cut through the center of the block making two individual pieces. • preparation directions for this block are contained in ASME section v article 6 appendix III.

Black light filter

• The black light filter must be kept clean at all times. Prior to starting up each day the filter should be wiped down and allowed to dry before starting. • if the light and filter are hot do not try to clean it until it cools down. • do not lay a hot filter on a cool surface or it will shatter. • replace all damaged filters and inspect daily.

Emulsifier washability

• The emulsifier washability shall be verified by processing two panels both using unused penetrant and one using the used emulsifier with the other using the unused emulsifier. When completely processed and developed they are to be compared under the black light. • The used emulsifier panel shell exhibit no greater florescence than that of the unused emulsifier.

Interpretation

• The first step is to determine if the indications are false indications, relevant or non-relevant indications. What caused the indication. • interpretation must be performed under the correct lighting conditions. These requirements should be listed in the procedure or specification. • do not attempt to quantify the depth of the flaw under the surface by the amount of penetrant bleed out on the surface. The flaw could go deep or it could be shallow but spread out just under the surface.

Forging

• The forging process is performed by hammering or pressing metal at high temperatures to form certain shapes.

Capillarity ( Capillary action )

• The interaction between contacting surfaces of a liquid and a solid that distorts the liquid surface from a planar shape. Also called capillary action. • another definition is The action by which the surface of a liquid where it is in contact with a solid (as in a capillary tube) is elevated or depressed depending on the relative attraction of the molecules of the liquid for each other and for those of the solid.

• General steps

• The liquid must be either colored with a die visible under normal white light or with a fluorescent dye that will be visible under a "black light" (ultraviolet light) • clean the part. • allow the part to dry. • apply penetrant to the surface. • allow the penetrant to "dwell " on the surface. • clean the penetrant off. • apply developer. • interpret/evaluate the results. • post cleaning.

Manufactures tests

• The manufacturer performs a variety of test on their material including the meniscus test, a viscosity test, brightness test and many more. • The viscosity is measured by using a viscometer and the measurement is in centi-strokes. • The meniscus test is used to determine the dye concentration in the fluid. This test can also reveal any detrimental effects of ultraviolet light and contamination of acids or alkalise.

History of PT

• The original liquid penetrant testing was called the " oil and whiting" method. • this technique originated in the railroad and forging industry using kerosene as the penetrant and white talcum powder as a developer. • The materials are much better and more sensitive today than the " oil and whiting" materials.

Penetrant system performance

• The penetrant system performance check must be done daily. This can be done with a TAM panel or with a known defect standard. The TAM panel works best. • The results of processing the TAM panel must be compared with the processing results of unused penetrant. If the used penetrant shows equivalent sensitivity the penetrant shall be approved.

Dwell time

• The penetration time (the time the penetrant is left on the surface) is known as the penetrant dwell time. • The penetrant dwell time may be different for different material types and the type of discontinuity sought. • Cold temperatures for either the penetrant or material surface will require longer dwell time's to accomplish the same results as warm temperatures.

Post emulsifier removal process

• The post emulsifiable process requires the addition of an emulsifier to the dye after the full penetrant dwell time has been reached. The emulsifier will render the dye water washable at this time. • The emulsifier time must be closely regulated and should be arrived at by careful testing to determine the maximum time required to remove the dye from the surface but not from the shallow discontinuities.

Disadvantages of post emulsifier systems

• The post emulsifier technique requires an additional step to process the part. • The emulsifier application is a critical step and must be watched closely. If left on too long the whole examination must be repeated. • The amount of fluid requiring treatment as regulated waste increases. • more equipment required. • difficult to remove penetrant from hidden keyways and threads.

Advantages of solvent removable penetrant

• The solvent removable technique is very portable and can be performed almost anywhere. • The solvent removable has good sensitivity. • it has the least amount of liquid waste to control. • there is no need for electricity or water. Even with fluorescent penetrant, battery black lights can be used.

Water concentration of penetrant and emulsifiers

• The water content of penetrance and emulsifiers must be checked according to the schedule posted previously from E-1417. The time and the type of test required depends on the type of penetrant and emulsifier that are used. • The water levels permitted shall be in accordance with the specification you are required to use such as E-1417.

Water washability

• The water wash ability test can be performed along with the system performance test if using the TAM panel. One side of the panel will be blasted. • place an area of used penetrant on the blasted surface and an area of unused penetrant on the blasted surface. • after processing the area of used penetrant and unused penetrant shall be compared. The used portion shall not have more florescence than the unused portion.

Water wash disadvantages

• The water wash technique is a little less sensitive than the post emulsifiable or solvent removable techniques. • The waste water must be treated prior to releasing back in the typical drain for city waste water. • The technique may require a longer drying time and in the oven to accomplish the drying. • The penetrant is subject to water contamination. • easily over washed.

Performance of evaluation

• Who is permitted to perform interpretation and evaluation? • trainees are not permitted to perform any evaluation without strict oversight by a level two or three certified individual. • level two and level III individuals certified in the method may perform evaluation.

Application of the penetrant

• after the surface has been properly cleaned and dried the penetrant must be applied to the surface. • The penetrant must cover the area of interest as described by the procedure. Some procedures require the weld and 1 inch adjacent material to be examined others require the weld and 1/2 inch adjacent material.

Post cleaning

• all parts must be cleaned to completely remove all traces of penetrant materials including penetrant and developer. • developer, if left on the part will attract moisture causing rust and corrosion on the surface. • clean up all cans in rags or cloths and dispose properly in containers specified for that kind of waste.

Cleanliness, water pressure and temperature

• all stations must be checked each shift for cleanliness and maintained in a neat and clean fashion. • The water wash pressure shall be checked and be no greater than 40 psi when spraying. • The water temperature shall be controlled and maintain between 50° and 100°F. • these checks are not required to be recorded.

Portable technique equipment

• both visible and fluorescent penetrant can be used in portable situations. • A typical kit would include as a minimum spray cans of cleaner and developer, and either a bulk container or spray can of penetrant. Clean cloths and brushes if applying dye with a brush. • if fluorescent penetrant is used then a black light will be required along with equipment to maintain a darkened area to view the results of the examination. Black lights that are battery powered are readily available and meet the intensity requirements.

Dry developer condition

• check the dried developer daily for caked developer, penetrant contamination, dirt and that it is fluffy. (Form a) • to check for contamination of penetrant, use a 4 inch block and apply the developer as you would with a production piece. View the part under the black light and any florescence will require evaluation in according to your standard. The ASTM standard requires replacement if 10 or more specs fluoresce in a 4 inch diameter. Look at the developer bin with the black light for any fluorescent particles also.

Developers

• developers come in a variety of ways. • dried developers are like a dry talcum powder and must remain dry and free of contamination from penetrant. • aqueous wet developers have two types and are either wet soluble or wet suspendable in water. These developers are applied right after washing the penetrant from the surface. • non-aqueous developers are a developer suspended in a volatile mixture, such as alcohol, that will dry quickly when applied to the surface of the part.

Drying oven calibration

• drying ovens shall be calibrated quarterly. The temperatures must be maintained for a maximum of 160°F. • The controller must be capable of maintaining the temperature within +/- 15°F. • The temperature gage must be accurate to +/-10°F. • part must not exceed 125°F

Advantages of water wash

• each method has its advantages and disadvantages. • water wash is very effective on parts with rough surfaces or parts with threads and keyways. The dye is easily removed from the surfaces of these parts with the water wash. • larger parts and a larger number of parts can be processed quicker and more effectively with the water wash technique over the solvent removable technique.

Penetrant removal

• each type of penetrant selected will have its unique removal process. • no matter what type of removal you are performing you must be careful not to over clean and remove dye from broad shallow discontinuities on the surface. • removal should be complete enough to remove interfering "background" but not so much as to remove dye from discontinuities.

Emulsifiers

• emulsifiers are designed to apply to the penetrant coated surface after the designated penetrant dwell time. • The emulsifier will mix with the penetrant on the surface and render the resultant mixture water washable. • emulsifier times are very critical and should be tested for the time to be the minimum needed to remove the penetrant from the surface and not any broad shallow flaws. • lipophilic emulsifiers work by diffusion and hydrophilic emulsifiers work by a scrubbing action. • do not brush emulsifiers on.

False indications

• false indications are indications that are caused by reasons other than discontinuities or material imperfections. Typical false indications are caused by under washing the part, penetrant on the operators hands or penetrant on the work station. • developer contamination may also cause false indications. Usually associated with dry developer.

Forging burst

• forging bursts happen when the part is forged at an incorrect temperature. • burst can occur internally or externally.

Bar

• if a billet is used to manufacture bar stock, the nonmetallic inclusions are "stretched" out into long thin "stringers". • a seam could be caused by a folding of the metal during the rolling process or by a small crack stretched out lengthwise.

Lamination

• if lamination is present in the play it can cause a variety of problems depending on its size in the use of the plate. • If used to make rolled and welded pipe in the lamination is open to a welding surface the lamination may cause large discontinuities in the weld that the welder cannot avoid.

Temperature

• if the temperature of the part or material is too hot the penetrant materials may lose their ability to penetrate properly or bleed back due to some of the constituents being boiled off. • A hot part may cause drying of the penetrant materials. Additional application of the penetrant may help to keep the penetrant wet. • if the temperature is too cold it will not penetrate the surface openings as fast as when it is warm. (Due to the viscosity of the liquid)

Water wash removal of penetrant

• if using the water washable process, make sure the water temperature and pressure meets the requirements of the procedure. The warmer the temperature the easier the dye will remove. • use a course spray and not a fine forceful spray. • hold the water nozzle at about a 45° angle to the surface to be washed. • keep the spray back from the surface about 12 inches.

Comparison of test conditions

• if you need to qualify the penetrant for different test conditions such as temperatures outside the ranges listed in national specifications you would need to prove equal or better detection capability. • this comparison can be performed on an aluminum block of 2024-T-3 material that has been cracked from the center out.

Terminology

• indication-A signal or response from the examination performed • false indication-any signal or indication that occurs due to poor technique or processing and is usually not repeatable if the part is re-processed from the beginning. • non-relevant indication-A signal response due to a discontinuity or design. Examples would be a press fit, keyways, rivet joint or if it was defined by the specification or code. And example of this is a code that states "any indication 1/16" or less shall be considered non-relevant". Nonrelevant indications are not to be evaluated. • relevant indication-an indication that is due to a condition noted in the acceptance criteria and must be evaluated for acceptance or rejection.

Inherent discontinuities

• inherent discontinuities are those that are formed during the solidification of the molten metal used to produce the material. • casting discontinuities are considered an inherent cast discontinuity but fall under the primary process and category. Keep in mind for test purposes casting flaws should be categorized as inherent or inherent cast discontinuities.

Final interpretation and evaluation

• interpretation - The act of determining if the indication is relevant, or false. (determining what caused the indication) • evaluation - determining if the relevant indication is cause to reject or accept the part or component. • you must know and have access to the acceptance criteria to be able to perform the evaluation properly.

Adhesion

• is the property that will cause the fluid to want to adhere to the surface of the solid which it is contained in.

Ventilation

• keep the area, where the tanks are located and where penetrant testing is done, well ventilated. • prevent a build up of the fumes. Penetrant materials in general require flash point of 120° or higher. • developer areas should be well ventilated with good air circulation to prevent inhalation of the developer.

Leak through testing

• leak through testing is applying die on one side of the material and developer on the opposite side of the part. • this type of test will require much higher penetrant dwell times to show the leak. • sometimes could be as long as a hours or more. • Cold temperatures will greatly affect the dwell time.

Measurement meters

• light meters shall be calibrated every six months. • pressure gauges shall be calibrated every six months. • temperature gauges shall be calibrated every six months.

What is liquid penetrant testing?

• liquid penetrant is used to find surface discontinuities ( discontinuities open to the surface).

Applicable specifications or codes

• liquid penetrant testing is usually performed in accordance with guidelines from some specification or code. - ASTM E165 (general pt standard) - ASTM E1208 (lipophilic emulsified) - ASTM E 1209 (water washable) - ASTM E 1210 (hydrophilic emulsified) - ASTM E 1417 (standard practice for pt) - ASME section v article 6 (doing penetrant and different techniques)

Reporting

• most examinations will require a report of the exam to be completed. These reports will vary in the amount of data to be recorded so make sure you have a copy of the procedure and reporting requirements. • It is important that the location and actual measured sizes are reported when required for future references.

Application of non-aqueous developer

• non-aqueous developers come in spray cans and should be shaken vigorously for a couple of minutes prior to using. • always spray the can away from the part first to verify that the nozzle is operating properly. • hold the can at least 8 inches to 10 inches away from the part and keep the spray moving across the part surface at an even speed to reduce any possibility of heavy coating, pooling or runs.

Evaluation

• once it has been determined whether the indications are false, non-relevant or relevant you must evaluate the indication against the applicable acceptance criteria. • acceptance criteria should be available to the technician for acceptance determination. • do not try to memorize this because if you remember it wrong it could cause for the acceptance of a critical flaw.

Emulsifier time

• once the emulsifier is applied to the surface by dipping or spraying (do not brush on) The time must be watched closely. • then use a course water spray as with normal water washable penetrant. • The requirements for water temperature and pressure will apply for this process as it did with the water washable process.

Penetrant brightness

• penetrant brightness is performed quarterly and should be done in accordance with ASTM standard E-1135. • this test is done by outside labs or the manufacture for many of the users. You can perform it in house.

Materials

• penetrant can be successfully performed on most non - porous material. • Materials such as metals, glass, ceramics, powdered metals and molded rubber can be examined. • metals such as iron, steels, brass, copper, titanium and aluminum can be examined.

Penetrant contamination

• penetrant contamination checks should be performed each day. • The fluid should be checked for particulate floating or building up in the dye, discoloration, milky or a white like appearance to the dye, surface scum or any other changes in appearance. • The dye should be changed in the tank thoroughly clean prior to putting new dye back into the tank.

Safety precautions

• penetrant materials are flammable and should be kept away from any ignition source such as Sparks, cigarettes, lighters, welding torches etc. • if you are going to be using it all day you should wear gloves to prevent skin irritations. • keep the filter on the black light in good repair to prevent harmful radiation waves from getting to you as the operator. • wear safety glasses for the splashing and to filter some of the harmful rays that may escape from the black light.

Penetrant materials

• penetrant materials are often classified by groups. These groups can be used in various combinations depending on the manufactures recommendations. Some specs also limit the combinations permitted to be used together. • water washable penetrant can be used with either visible or fluorescent penetrant and contain an emulsifier in the dye. The excess dye is readily removed with a low pressure course water spray. This technique will have a lower sensitivity than a post emulsified or solvent removable type.

Applying penetrant

• penetrant may be applied by brushing, spraying, dipping, wiping, or pouring the penetrate over the surface. • if the part is dipped it should not be left in the penetrant for the complete dwell time. Some specifications require the part to be removed from the dip for at least half the dwell time. • The penetrant should cover the area completely and remain wet for the full dwell time limit.

Penetrant properties

• penetrant must be able to - hold the dye in suspension - spread the die across the surface evenly and completely - carry the dye into the surface openings - be removed from the surface readily - Bring the dye back to the surface - remember that no one property determines a good penetrant

Recording indications

• pictures are a good way to make a permanent record of the indications. It is a good practice to have some reference in the picture for size comparison. • special tapes and lacquers are available to lift the indication from the part. • Recording the length, width and location by pen or pencil.

Ingot discontinuities

• piping- is caused by the shrinking of the metal (or reduction of the space occupied by the molten metal vs the solidified metal) in the hot top. This is usually controlled so that it does not extend down below the hot top and is then discarded with the hot top. • porosity or gas-this gas (oxygen or nitrogen) that is mixed in with the molten metal when poured and does not escape before solidification. This may be surface or subsurface. • non-metallic inclusions or oxides-this is inclusions that are from oxides forming in the metal and are not removed prior to pouring or from other non-metallic substances such as sand from the mold.

Station identification

• pre-cleaning - this may vary depending on the type of cleaning needed and the type of parts being cleaned. • penetrant • drain station • emulsifier dip tank • drain station • rinse tank • dry station- this will depend on type of developer used. • developer tank- this will depend on the developer used. • inspection booth • post cleaning

Processing discontinuities

• processing discontinuities are those discontinuities that occur due to processes that are used to shape the solidified material and to final finish the part. - examples would be machining tears, heat treat cracks and lack of penetration in a weld. • primary processes are those used to shape the part such as forging, casting, extruding or drawing. • secondary processes are those used to final finish a part such as machining, welding or heat treating.

Relevant indication

• relevant indications are those which are caused by a condition or discontinuity that requires evaluation with respect to the acceptance standards. • Those indications may include cracks, porosity, slag or lamination. • typical standards will define a linear and rounded indication. - an indication can be further evaluated by its persistence. If you wipe over an indication one time with a solvent dampened swab and re-develop it you can determine two things, one if it is a real indication or false indication and two, if it holds a lot of die. (Has a deep well)

• Solvent removable

• removed by dry cloths and solvent dampened cloths. (Method C)

• Water washable

• removed by washing with a course water spray. (Method A)

Cleaner/remover

• solvent cleaners are designed to be used with a particular penetrant type and will be used by dampening a cloth and wiping the surface clean of all penetrant. Never spray the part during the excess penetrant removal step. • cleaner/remover's can be purchased in bulk 55 gallon drums or in spray cans for portable use. • these cleaners are flammable and you should not smoke while using them.

Solvent removable penetrant

• solvent removable penetrants will be removed with a final wiping with a solvent dampened cloth. (Method c) • these dyes are oily and generally cannot be removed by water washing. They are removed by solvents designed for that purpose. • used with a non-aqueous developer this type has good sensitivity.

Poor cleaning techniques

• some cleaning techniques are not recommended but may be used based on the level III and customer approval. • shot and sandblasting are usually prohibited but generally used on sand castings. • grinding and power wire brushing are normally prohibited without an acid etching step prior to performing liquid penetrant.

Surface cleaning techniques

• some cleaning techniques are; - detergent cleaning - vapor degreasing - steam cleaning - solvent cleaning - ultrasonic cleaning - paint strippers - acid and alkaline etching

Stationary penetrant system

• stationary systems are usually set up for higher production rates and will be of the water washable or post emulsification types. • The size of each station and the number of stations will be determined by the size and number of the parts and the type of technique used such as water washable or post emulsified techniques.

Surface Preparation

• surface preparation is one of the most important steps in obtaining a suitable liquid penetrant test. • any contaminant that may block or hinder the penetrant materials to perform their functions must be removed prior to applying the penetrant. • The surface must be smooth enough to allow removal of the die from the surface and not cause extreme "background" indications. • The area to be examined and at least 1 inch additional material should be pre-cleaned prior to the examination.

Categories of discontinuities

• there are three categories of discontinuities. They are inherent, processing and service discontinuities. - processing discontinuities are broke down to two subcategories and they are primary and secondary. • primary processing discontinuities are those in which we are forming the solidified material into a final shape such as forging, drawing or extruding. • secondary processing discontinuities are those in which we are performing finishing type processes such as machining, welding or bending on the product.

Developer types

• there are three types of developers. Dry, aqueous wet and non-aqueous wet. Wet has a couple of subdivisions which are wet soluble and wet suspendible. • The dry developer is a dry powder that is applied after the part surface has had all the excess penetrant removed and dried. • dry developer works best on rough surfaces, sharp fillets, threaded articles and areas with holes. Wet developers tend to leave too much developer in these areas. • dried developers should never be used with visible dyes.

Quenched aluminum block uses

• this block can then be used to compare test results for temperatures outside the normal ranges or for the use of intermixed material families if desired. • this block will not qualify the size of the smallest discontinuity detectable. This test is only a comparison test to prove consistency of detection capabilities with the variables applied.

Surface contaminants

• typical surface contaminants that must be removed are rust, scale, dirt, grease, oil, acids, paints, varnishes, oxides, plating and water. • if the part is not properly pre-cleaned it will prohibit the die from entering any small tight discontinuities open to the surface.

What is the process of pt testing?

• we apply a penetrant fluid to the surface of the part and allow this to enter into any surface openings. We clean off the excess after some given time and develop the part with a whit powder. • the penetrant fluid that remained in the discontinuities will then bleed back to the surface and allow us to see the flaw. • After The penetrant dwell time, the fluid is cleaned from the surface and developer is applied and again capillary action is used to blot the fluid from the flaw onto the surface.

Wet developers

• wet developer shall be checked for florescence by dipping a plate in the developer and viewing it under the black light. The fluid must completely cover the plate and no florescence shall be noted.(form b water soluble, form c water suspendible) • The developer shall also be checked with a Hydro meter (measures specific gravity) for developer concentration and shall meet the manufactures recommendation.

Linear vs. rounded

• what determines what is linear and what is rounded? - linear-any indication in which the long dimension (length) is equal to or greater than three times the short dimension (width). This is not true in all codes or specs. Know what is defined in your codes and procedures. -rounded-anything not meeting the linear description.

Plate

• when a slab is processed to make a plate, it is heated to the proper forming temperature then rolled out to form the right size and thickness plate. • The flaws present in the slab are now flattened out like a very thin pancake called "lamination". • ultrasonic testing is the best method to locate lamination.

Visible light verification

• when performing visible die and at stations where white light is required in fluorescent examination stations the white light shall be verified to be a minimum of 100 foot candles (fc). • The white light in the fluorescent system when black light is being used for evaluation shall be no more than 2 foot candles.

Solvent cleaning of excess penetrant

• when using the solvent removable process, you should use dry clean cloth's to remove as much dye as possible first. You may not even need a solvent dampened cloth for smooth or machined parts. • then slightly damp in the cloth with remover and clean the surface of the remaining traces of the dye. • never spray the part when performing the excess dye removal step. You may wash out discontinuities by the turbulence caused by the spray or cause excessive solvent penetration into the discontinuities thereby removing die from the flaw.