85579_01E Weld Certification - Liquid Penetrant Examination LP

8/17/2019 85579_01E Weld Certification - Liquid Penetrant Examination LP

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Course Title: Agricultural Facilities Design and Fabrication

Lesson Title: Liquid Penetrant Examination - Weld Certifcation

TEK Addressed in Lesson: !"#$%" c ! E

http://ritter.tea.state.tx.us/rules/tac/chapter130/index.html

Lesson &b'ecti(es$ T)e student *ill be able to:1 examine the methods of Liquid Penetrant Examination/Inspection;2 examine the adanta!es of LP Examination/Inspection;3 examine the disadanta!es of LP Examination/Inspection;" demonstrate a#ilit$ to perform LP Examination/Inspection of non%

porous material &ith the 'no&led!e necessar$ to accuratel$ report the

results; and() produce a &eld that can pass a LPE test.

Tools and Equi+ment

*elded products for testin!LPE chemicals*ipin! clothsLiquid Penetrant PP+

Ke, Terms .ocabular,

capillar$ actiondeeloperpenetrant d&ell timedeeloper d&ell timed$e penetrant examinationpenetrantsolent

Engage / Interest ,pproach/,nticipator$ -et

on%estructie +estin! #$ usin! the Liquid Penetrant Examination method is ameans of locatin! and determinin! the seerit$ of surface discontinuities in non%

porous material and &eldments #ased upon ca+illar, attraction. apillarit$ orapillar$ ,ction is the action #$ &hich the surface of a liquid( &here it is in contact&ith a solid( is eleated or depressed. +he material( process and procedures used inliquid penetrant testin! are desi!ned to facilitate capillarit$ and to ma'e the resultsof such action isi#le and capa#le of interpretation.

,s a competent &elder( $ou should learn to perform isual examination/inspectionusin! non%destructie methods and accuratel$ report ndin!s.

http://ritter.tea.state.tx.us/rules/tac/chapter130/index.htmlhttp://ritter.tea.state.tx.us/rules/tac/chapter130/index.html


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Ex+lore / Ex+lain / +eachin! Plan and -trate!$ / Presentation of e& aterial

Liquid Penetrant Examination/Inspection is a non%destructie method for ndin!discontinuities that are open to the surface of solid and essentiall$ non%porousmaterials. *ith Liquid Penetrant tests( detecta#le discontinuities such as surface

crac's( porosit$( and throu!h lea's( and lac' of #ond #et&een 4oined metals can#e discoered. Indications of 5a&s can #e found re!ardless of si6e con!uration(internal structures( or chemical composition of the &or' piece #ein! inspected.Liquid Penetrants can seep into arious t$pes of minute openin!s #$ capillar$action. 7ecause of this action( the process is &ell suited for the detection of allt$pes of discontinuities. Liquid Penetrant testin! is successfull$ used on metals suchas aluminum( ma!nesium( #rass( copper( cast iron( car#on steel( lo& allo$ steel(stainless steel( and titanium.

+he limitation for this method is that Liquid Penetrant Examinations can onl$ detectimperfections that are open to the surface. ,lso( surface rou!hness can producefalse indications and porous materials ma$ allo& penetrant d$e to seep into thepores &hich &ill lead to incorrect ealuations of the material.

&01ECT2.E o3 L2452D PE6ET7A6T E8A926AT2&6

Liquid Penetrant is used to ensure the maximum relia#ilit$ of &elds and materialstested #$ proidin! a means of:

a8 9#tainin! a isual ima!e related to a discontinuit$ on the surface of thespecimen tested#8 isclosin! the nature of the discontinuit$ &ithout impairin! the materialc8 -eparatin! accepta#le and unaccepta#le material in accordance &ithspecied standards

56DE7TA6D26 CAP2LLA7; ACT2&6

+he phenomenon of capillar$ action is one of the most important forces in nature. +he rate and extent of the action associated &ith capillarit$ depends upon suchfactors as forces of cohesion and adhesion( surface tension( and iscosit$.apillarit$ can #e o#sered &hen a plastic stra& is inserted into a !lass of &ater.*hen the stra& is inserted( the &ater molecules enter the stra& and #e!in toattract other near#$ molecules( pullin! them up the stra& #$ cohesion. +he &atercontinues to rise until the pull of surface tension is equali6ed. ohesie forcespreent the &ater from fallin! #ac' do&n the stra&. apillar$ action as applied innon%destructie testin! is some&hat more complex( since arious surface conditionshinderin! or assistin! the action are encountered. Liquid penetrants in non%destructie testin! hae lo& tension and hi!h capillarit$.

In Liquid Penetrant testin!( the liquid penetrant is applied to the surface of thespecimen and sucient time is allo&ed for penetration into surface discontinuities.If the discontinuit$ is small or narro&( as in a crac' or pinhole( capillarit$ assists thepenetration. If the discontinuit$ is !ross in nature( the d$e ma$ #e trapped &henpoured oer the specimen.


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Elaborate / ,ctiit$/,pplication/ -tudent En!a!ement /La#orator$

E452P9E6T A6D ELECT2&6 &F PE6ET7A6T ;TE9

+he equipment needed to perform Liquid Penetrant Examinations is simple and lesscostl$ than most other non%destructie methods. +he Liquid Penetrant Examination

method &or's on #oth ma!netic and non%ma!netic materials.

+he desired de!ree of sensitiit$( num#er of articles to #e tested( aaila#ilit$ of&ater( electricit$( compressed air( and aaila#ilit$ of #lac' li!ht( alon! &ith costfactors are usuall$ the driin! factors &hen selectin! a s$stem for conductin! LiquidPenetrant Examinations. +he ma4or penetrant s$stems used are #ro'en do&n intosix s$stems or ariations of s$stems:

Post Emulsia#le luorescent-olent ectie test results.

ommon cleanin! methods used are as follo&s:a8 hemical usin! acid( al'aline( pic'lin!( chemical etchin!#8 echanical methods such as tum#lin!( &et #lastin!( dr$ #lastin!( &ire#rushin!( hi!h pressure &ater( steam cleanin!( and ultrasonic cleanin!c8 ?se of -olents such as apor de!reasin!( &ater &ashin!( solentspra$in!( and solent &ipin!.


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echanical methods must #e used &ith care to ensure that the process used doesnot mas' a 5a& #$ smearin! ad4acent metal. +his is more li'el$ to occur in softmaterial such as copper. -olents inole the use of porta#le equipment to remoecontaminants from the material.

C&6D5CT26 L2452D PE6ET7A6T E8A926AT2&6

?pon completion of pre%cleanin! actiities on the material or &eldment the testin!and inspection ma$ #e conducted. ,s preiousl$ discussed( there are a num#er ofliquid penetrant examination s$stems aaila#le for use. or purposes of thisdiscussion the -olent


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hoose a deeloper color in contrast to penetrant color and #ase metal. ?suall$&hite deeloper is the optimal choice. eeloper should #e li!htl$ spra$ed oer thetest area. eeloper is not to #e #rushed or s&a##ed durin! the applicationprocess to insure that the penetrant is not smeared &hich &ill mas' an$discontinuit$ indicators. , li!ht coatin! of deeloper &ill proide distinct contrast

#et&een the penetrant and deeloper.

eeloper &ell +ime is the &aitin! period to allo& capillar$ action of the penetrantto seep throu!h the deeloper #ac' to the surface &hich allo&s an$ discontinuitiesto #e isi#le for ealuation. ?suall$ e to ten minutes is sucient time for thisaction to occur.

apillar$ action is fundamental for this process to &or'. +he deeloper( &hich actsas a #lotter( dra&s the penetrant from the discontinuit$ and the penetrant appearson the surface of the material as an indicator. +he si6e of the indication( #ecause ofthe di>usion of the penetrant in the deeloper( is usuall$ lar!er than thediscontinuit$.

E(aluation / -ummar$

E.AL5AT2&6< 26TE7P7ETAT2&6< A6D D&C59E6TAT2&6

o liquid penetrant examination is successfull$ completed until an ealuation of theresults is made. Ealuation requires the understandin! of the process and testo#4ecties( as &ell as 'no&led!e of the manufacturin! processes that &ereinoled. +he ultimate success of liquid penetrant testin! depends upon theisi#ilit$ of the discontinuit$. ,ll indications shall #e ealuated in terms of theacceptance standards as !ien in ,-E -ec. =( ,rticle A and client or pro4ectspecications.

+he terms interpretation and ealuation are often confused #$ testin! personnel.,ctuall$( the terms refer to t&o entirel$ di>erent steps in the testin! process. +ointerpret an indication means to decide &hat condition caused it. Ealuation follo&sinterpretation. If a discontinuit$ exists( its e>ect on the usefulness of the materialrequires ealuation( i.e.( the article is either accepted as is( repaired( or scrapped.

+he success and relia#ilit$ of the interpretation and ealuation of liquid penetranttest indications depend upon the thorou!hness of the process.

-ince penetrant can onl$ indicate surface discontinuities( and indication is caused#$ a discontinuit$ in the surface( or #$ penetrant remainin! on the surface fromsome non%releant cause. Proper interpretation( ho&eer( requires familiarit$ &ith

the manufacturin! process( the t$pes of discontinuities li'el$ to occur( and theirappearance. It requires 'no&led!e of ho& di>erent materials fail and &here thefailure is li'el$ to occur.


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P&T E8A926AT2&6

Post%cleanin! after testin! must #e done to preent an$ penetrant( re!ardless ofs$stem used( and deeloper residue remainin! on the surface of the material testedfrom hain! a harmful e>ect once the material piece is placed into serice. ,lltraces of penetrant must #e remoed. +he same method used to pre%clean can #e

used in post%cleanin! remoal of penetrant and deeloper. Especiall$ important if arepair is required to the tested area.

85579_01E Weld Certification - Liquid Penetrant Examination LP

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