TRAINING HAND OUT

LIQUID PENETRANT TESTING

General

PT. INSPEKTINDO PRATAMA Jakarta : Gedung Wisma Raharja lt. 4, Jl. TB Simatupang Kav-1, Jakarta Selatan 12560,

phone (021)-78841462,Fax (021)-78841461, workshop : Jl. Ciputat Raya No. 20 E

Pondok Pinang, Jakrta Selatan 12310, Phone (021)-7509518, Fax (021)-7509517,

web : www.inspektindo.co.id, Email :info@inspektindo.co.id

Balikpapan : Jl. Jend. Sudirman Ruko Bandar Balikpapan Blok B-22 Balikpapan 76122 Phone

(0542)-739310, Fax (0542)-739311

Rev. 0, december 2011

Page 0

PT. INSPEKTINDO PRATAMA INSPEKTION, CERTIFICATION & TECHNICAL SERVICES

CONTENTS

page

CHAPTER ONE

Introduction

Basic Principles

The Nature of Discontinuity

Surface Conditioning

History

Commercially Available Liquid Penetrant Materials

Chapter One Review

CHAPTER TWO

Introduction

Surface Preparation

Detergent Cleaning

Vapor Degreasing

Steam Cleaning

Solvent Cleaning

Rust and Scale Remover

Paint Removal

Etching

Ultrasonic Cleaning

Mechanical Cleaning

Stationary Penetrant Test Equipment

Portable Penetrant Test Equipment

Black Light Equipment

5

5

7

8

9

10 11 15 16 16 16 17 17 17 17 18 18 18 18 18 20 21 22

Page 1

Penetrant Material Combinations

Penetrant Testing Materials

Safety Precaution

Chapter Two Review

CHAPTER THREE

Introduction

Cleaning

Penetrant Application

Penetration (Dwell) Time

Penetrant Testing Processes

Leak-through Technique

Filtered Particle Technique

Fixing and Recording Indications

Chapter Three Review

CHAPTER FOUR

Introduction

Post-emulsifiable Penetrant (PE Penetrant)

Lipophilic Method

Hydrophilic Method

Developers Application

Dry Developers

Wet Developers

Guidelines to Choose Developer

Chapter Four Review

23 24 26 29 28 28 28 29 31 33 37 37 38 39 40 40 40 43 44 45 45 46 48 49

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CHAPTER FIVE

Introduction

Inspection

Interpretation and Evaluation of Indications

Typical Indications in Penetrant Inspection

False Indications

Nonrelevant Indications

True Indications

Depth Determination of Penetrant Discontinuities

Post Cleaning

Quality Control of Penetrant Process Variables

Aluminum Test Block

Sensitivity Test

Meniscus Test

Ceramic Block Test

Water Content Test

Viscosity Test

Fluorescent Penetrant Fade Test

Water Washability Test

Developer Test

Portable Equipment

Lighting

Chapter Five Review

50 50 50 50 51 51 52 52 56 56 56 56 57 57 58 58 58 59 59 59 59 60 61

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CHAPTER SIX

Introduction

Categories of Discontinuities

The Origins of Discontinuities

Casting Discontinuities

Processing Discontinuities

Working the Billet

Forging Discontinuities

Service Discontinuities

Chapter Six Review

CHAPTER SEVEN

Introduction

Identification and Comparison of Discontinuities

Training and Certification

Chapter Seven Review

CHAPTER EIGHT

Introduction

Controlling Liquid Penetrant Tests

Standards

Specifications

Written Practice

Sample Specification Penetrant Testing Process

Chapter Eight Review

REFERENCES

62 62 62 63 64 66 66 68 73 75 76 76 76 77 79 80 80 80 80 80 82 83 90 93

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CHAPTER ONE

INTRODUCTION

Liquid penetrant testing is a nondestructive

means of locating surface discontinuities

based on capillarity or capillary action. Capillary

action is responsible for both penetrant entry

and exit from discontinuities.

In the liquid penetrant method, the liquid is

applied to the surface of the specimen and

sufficient time is allowed for penetration of

surface discontinuities. If the discontinuity is

small or narrow as in a crack or pinhole,

capillary assist the penetration.

After sufficient time has passed for the

penetrant to enter the discontinuity, the surface

of the part is cleaned. Capillary action is again

employed to act as blotter to draw penetrant

from the discontinuity.

PENDAHULUAN

Pengujian cairan penetrant merupakan pengujian

tanpa merusak untuk menemukan diskontinuitas

permukaan berdasarkan prinsip kapilaritas.

Kapilaritas bertanggung jawab terhadap masuk

dan keluarnya cairan penetrant dari dan ke dalam

diskontinuitas.

Pada metoda cairan penetrant, cairan diaplikasikan

di atas permukaan spesimen dan diberikan waktu

yang cukup untuk menyusup ke dalam

diskontinuitas. Jika diskontinuitasnya kecil dan

sempit seperti pada retak atau lubang jarum,

kapilaritas membantu penetrasi.

Setelah waktu mencukupi bagi penetrant untuk

memasuki diskontinuitas, permukaan spesimen

kemudian dibersihkan. Gaya kapiler sekali lagi

bekerja sebagai penghisap yang menarik

penetrant keluar dari dalam diskontinuitas.

Page 5

Liquid penetrant inspection is a physical-

chemical process. Application and reaction of

the penetrant (chemical) is dependent upon the

nature of the test article and the discontinuity it

contains (physical).

The ability of penetrant to spread over a solid

surface is referred to as the wetting ability. The

wetting ability and contact angle between solid-

liquid are inversely proportional. The higher the

wetting ability, the smaller the contact angle.

The contact angle determines the wetting

ability.

Pemeriksaan penetrant merupakan proses fisika-

kimia. Aplikasi dan reaksi cairan penetrant (kimia)

tergantung pada sifat artikel yang diuji dan

diskontinuitas yang terdapat padanya (fisika).

Kemampuan penetrant untuk menyebar di atas

pemukaan benda padat disebut kemampu-

basahan (wetting ability). Wetting ability dan sudut

kontak (contact angle) antara benda cair dan

padat adalah berbanding terbalik secara

proporsional. Sudut kontak menentukan wetting

ability.

Penetrating capability of a liquid penetrant is

controlled by:

Surface tension.

Contact angle.

Kemampuan penyusupan

dikendalikan oleh:

Tegangan permukaan.

Sudut kontak.

cairan penetran

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BASIC PRINCIPLES

To insure visibility, the liquid penetrant contains

either a colored dye easily seen in white light,

or a fluorescent dye visible under black

(ultraviolet) light.

A penetrant examination consists of the

following basic steps, regardless of the material

tested:

Step 1: The test object or spot is

thoroughly cleaned and

dried.

Step 2: The penetrant is applied.

Dwell time is allowed to

penetrate discontinuities.

Step 3: The excess surface

penetrant is removed.

Step 4: Developer is applied

Step 5: Indications are evaluated

and accepted or rejected.

Step 6: After the penetrant test, the

test object or spot is

postcleaned.

PRINSIP-PRINSIP DASAR

Agar dapat terlihat, cairan penetrant diberi pewarna

merah yang dapat dilihat dengan cahaya biasa

atau pewarna fluorescent yang dapat dilihat

dengan cahaya ultraviolet.

Pengujian penetrant terdiri dari tahapan-tahapan

berikut tanpa mempertimbangkan material yang

diuji:

Langkah 1: Pembersihan dan pengeringan

benda atau lokasi yang

diperiksa.

Langkah 2: Aplikasi penetrant. Dibiarkan

beberapa lama agar menyusup

ke dalam diskontinuitas.

Langkah 3: Pembersihan penetrant sisa

di permukaan.

Langkah 4: Aplikasi developer

Langkah 5: Evaluasi indikasi, diterima

atau ditolak.

Langkah 6: Pembersihan benda atau lokasi

setelah selesai diuji.

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THE NATURE OF DISCONTINUITY

Discontinuities that are subsurface in one stage

of production could be open to the surface at

another stage, such as after grinding or

machining.

Nonmetallic inclusions and porosity in the ingot

may cause stringers, seams, forging laps, cold

shuts, and the like as the billet or slabs is

processed in the manner shown below.

SIFAT DISCONTINUITAS

Diskontinuitas yang terletak dibawah permukaan

pada satu tahapan produksi dapat terbuka ke

permukaan pada tahapan lainnya seperti akibat

penggerindaan dan permesinan.

Inklusi nonlogam dan porositas dalam ingot dapat

menyebabkan stringers, seams, lipatan tempa,

cold shuts, dan sejenisnya saat billet atau slab

diproses dengan cara seperti di bawah ini.

Page 8

SURFACE CONDITIONING

Anything that could block the penetrant from

entering the discontinuity must be removed.

A list of contaminants that must be removed

would include DIRT, GREASE, RUST,

SCALE, ACIDS, and even WATER. The

cleaning solvent used must be volatile

(readily vaporized) so that it easily

evaporates out of the discontinuity and does

not dilute the penetrant.

Surface preparation by mechanical cleaning

such as wire brushing, abrasive blasting, emery

cloths, and metal scraping are not generally

recommended, but there are times when they

must be used.

When they are used, discontinuities that are

open to the surface may be closed as ilustrated

below.

PENGKONDISIAN PERMUKAAN

Semua kotoran yang menghalangi penetrant untuk

memasuki diskontinuitas harus dibersihkan.

Jenis kotoran yang harus dibersihkan meliputi

DEBU, GEMUK, KARAT, KERAK, ASAM,

bahkan AIR. Solvent yang digunakan untuk

pembersih harus mudah menguap sehingga

cepat keluar dari dalam dikontinuitas dan tidak

mengencerkan penetrant.

Pembersihan permukaan secara mekanis seperti

memakai sikat baja, abrasive blasting, kertas

gosok, dan alat sekrap umumnya tidak

direkomendasikan, namun ada kalanya cara-cara

tersebut harus digunakan.

Apabila digunakan cara-cara di atas, diskontinuitas

yang membuka ke permukaan dapat tertutupi

seperti gambar di bawah ini.

Page 9

HISTORY

Historically, penetrant inspection was called oil

and whiting method. The oil and whiting

method used in the railroad industry, i.e.

locomotive parts, etc. (axles, crank pins and

couplers), in the early 1900s was the first

recognized use of the principles of penetrants

to detect cracks.

The oil and whiting method used dirty or dark-

colored lubricating oil that was thinned with

kerosene followed by the application of a

whiting or chalk coating, which absorbed oil

from the cracks revealing their locations.

By the 1940s, fluorescent or visible dye was

added to the oil used to penetrate test objects.

Following is stages of oil and whiting method.

Experience showed that temperature and soak

time were important.

This started the practice of written instructions

to provide standard, uniform results. The use of

written procedures has evolved, giving the

ability for design engineers and manufacturers

to get the same high standard results from any

properly trained and certified liquid penetrant

testing technician.

SEJARAH PENGUJIAN PENETRANT

Menurut sejarahnya, pemeriksaan penetrant

dulunya disebut metoda minyak dan kapur. Pada

awal tahun 1900an, metoda ini digunakan dalam

industri perkeretaapian untuk memeriksa kompo-

nen lokomotip (batang torsi, batang penggerak,

dan coupler, dll.), yang merupakan awal mula dike-

nalnya prinsip penetrant untuk mendeteksi retak.

Metoda minyak dan kapur memakai minyak lumas

hitam yang diencerkan dengan minyak tanah,

diikuti dengan aplikasi bubuk kapur di atasnya

yang akan menyerap minyak dari dalam retak

sehingga dapat diketahui lokasinya.

Pada tahun 1940an, zat pewarna merah dan

fluorescent dicampurkan ke dalam oli yang

digunakan untuk pemeriksaan.

Berikut adalah tahapan metoda pengujian minyak

dan kapur.

Pengalaman mengajarkan pentingnya mempertim-

bangkan suhu dan waktu celup.

Hal tersebut memicu diterapkannya penggunaan

instruksi tertulis agar hasil pengujian menjadi

standard dan seragam. Pemakaian prosedur

tertulis diharapkan menjadikan pemeriksaan

penetrant akan memberikan hasil dengan standard

tinggi jika dikerjakan oleh teknisi yang terlatih.

Page 10

COMMERCIALLY AVAILABLE LIQUID

PENETRANT MATERIALS

The liquid penetrants used in nondestructive

testing can be categorized by the type of dye

they contain.

1. Visible dye penetrants contain a colored

(usually red) dye.

MATERIAL CAIRAN PENETRANT YANG

TERSEDIA DI PASARAN

Cairan penetrant yang dipakai di dalam NDT dapat

dikagorikan berdasarkan jenis zat pewarna yang

ditambahkan.

1. Visible dye penetrants mengandung zat

pewarna merah.

2. Fluorescent penetrants

fluorescent dye

contain a 2. Fluorescent penetrants mengandung zat

pewarna fluorescent (hijau-kuning).

3. Dual sensitivity penetrants contain a

combination of visible and fluorescent

dyes.

Penetrants can be further categorized by the

processes used to remove the excess

penetrant from the specimen.

1. Water-washable penetrants, are either

self-emulsifying or removable with plain

water.

2. Post-emulsifiable penetrants require a

separate emulsifier to make the penetrant

water washable.

3. Solvent-removable penetrants must be

removed with a solvent which is typical

when using visible dye in pressurized

spray cans.

The basic liquid penetrant classification system

is shown in Table 1.1.

3. Dual sensitivity penetrants, mengandung

kombinasi kedua zat pewarna, visible dan

fluorescent.

Penetrant dikelompokkan lebih lanjut berdasarkan

proses pembersihan sisa penetrant dari permu-

kaan spesimen.

1. Water-washable penetrants, mengandung zat

pengemulsi atau dapat dibilas dengan air.

2. Post-emulsifiable penetrants, memerlukan

pengemulsi terpisah untuk menjadikan

penetrant dapat dibilas dengan air.

3. Solvent removable penerants, harus

dibersihkan dengan solvent khusus jika

menggunakan penetrant visible dalam

kaleng bertekanan.

Sistem klasifikasi cairan penetrant dapat dilihat

dalam Tabel 1.1.

Table 1.1. Basic liquid penetrant classification system.

Page 11

The flowchart below illustrates the processing

Diagram alir berikut memperlihatkan urutan proses

sequence with visible and fluorescent dengan penetran visible dan fluorescent.

penetrants.

Page 12

Dual sensitivity penetrants would follow a

processing sequence similar to that shown

below.

The selection of the best process depends

upon:

1. Sensitivity required.

2. Number of articles to be tested.

3. Surface condition of part being

inspected.

4. Configuration of test specimen.

5. Availability of water, electricity,

compressed air, suitable testing area,

etc.

Dual sensitivity penetrants mengikuti urutan proses

yang diperlihatkan diagram alir di bawah ini. Pemilihan proses terbaik ditentukan oleh:

1. Sensitivitas yang disyaratkan.

2. Jumlah artikel yang diuji.

3. Kondisi permukaan komponen yang

diperiksa.

4. Konfigurasi benda uji.

5. Ketersediaan air, listrik, udara bertekanan,

lokasi pengujian yang sesuai, dll.

Page 13

Penetrant testing is succesfully used on most

any materials, including metallic and

nonmetallic objects.

Metallic materials include aluminum, magne-

sium, titanium, cast iron, stainless steel,

powdered metal products, copper, brass, and

bronze, as well as most other common alloys.

Nonmetallic materials include ceramics, plastic,

molded rubber, composites, and glass.

Penetrant testing is limited by its inability to test

materials with discontinuities that are NOT

OPEN to the surface or having extremely

porous surface.

List below indicates the penetrant systems,

ranging from the most sensitive and expensive

to the least one.

1. Post-emulsified fluorescent.

2. Solvent-removable fluorescent.

3. Water-washable fluorescent.

4. Post-emulsified visible.

5. Solvent-removable visible.

6. Water-washable visible.

Pengujian penetrant secara memuaskan dapat

diplikasikan pada kebanyakan material, termasuk

material logam dan nonlogam.

Material logam termasuk aluminium, magnesium,

titanium, besi cor, stainless steel, produk serbuk

logam, paduan tembaga, kuningan, perunggu,

juga paduan-paduan lainnya.

Material nonlogam termasuk keramik, plastik,

karet, komposit, dan kaca.

Pengujian penetrant tidak dapat diaplikasikan

untuk menemukan diskontinuitas yang TIDAK

MEMBUKA ke permukaan dan permukaan material

yang berpori.

Daftar berikut menunjukkan tingkat sensitivitas

sistem penetrant, dari mulai yang paling senfitif

dan paling mahal.

1. Post-emulsified fluorescent.

2. Solvent-removable fluorescent.

3. Water-washable fluorescent.

4. Post-emulsified visible.

5. Solvent-removable visible.

6. Water-washable visible.

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CHAPTER ONE REVIEW

_______ 1.

_______ 2.

_______ 3.

_______ 4.

_______ 5.

_______ 6.

_______ 7.

_______ 8.

_______ 9.

Nonmetallic inclusions and porosity in the steel ingot are commonly found using liquid penetrant inspection techniques. Type II penetrants, according to our test, are those containing a fluorescent dye. Because of the capillary action of penetrants, this process of inspection works well on parts with very porous surfaces. When doing a liquid penetrant test, the configuration of the specimen has little effect on the effectiveness of the test. Liquid penetrant inspection can be used only on metals such as aluminum and steel. The penetrant inspection method is used only on the finished product. Oil and whiting are the names of the two men who invented the penetrant test method. The first important step in penetrant testing is surface preparation. One of the most common contaminants in the penetrant method is water.

_______ 10. The most common method of surface preparation for penetrant testing is

sandblasting.

_______ 11. Chemical etching Is sometimes used to remove smeared metal from a surface to open discontinuilies.

_______ 12. Some subsurface defects can be tested with the highly sensitive Type II

penetrants.

_______ 13. Blow holes and gas porosity may be detected with the penetrant method.

_______ 14. Solvent cleaning is a common method of surface cleaning parts before penetrant testing.

_______ 15. The one major limitation to penetrant testing is that the part must be

metallic.

_______ 16. Grease and rust would usually be considered a contaminant on the surface of a test piece.

_______ 17. To locate a defect with penetrant testing, the defect must be open to the

surface.

_______ 18. It is considered advantageous for a liquid penetrant material to have low tension and high capillarity.

Page 15

CHAPTER TWO

INTRODUCTION

This chapter discusses the equipment and

material required to perform the various

penetrant test and the required PRE and POST

test cleaning.

SURFACE PREPARATION

As discussed in Chapter 1, there are SIX basic

steps required for a penetrant test. Surface

preparation is entered on the flow diagram

below as step one.

Surface preparation, including proper cleaning

is essential to liquid penetrant testing for TWO

reasons:

1. If the specimen is not physically and

chemically clean and dry, penetrant

testing may be ineffective.

2. If all tracess of penetrant materials are

not removed after the test, they may have

a harmful effect on the specimen after the

test object is placed in service (chlorine

and sulfur may affect some alloys).

Selection of the cleaning process breaks down

to the following basic factors.

Type of contaminant.

Composition of the base material.

Degree of cleanliness required.

Availability of cleaning equipment.

Cost and time factors.

Unless the cleaning methods and chemicals

are known to be compatible with the penetrant,

a final cleaning should be done with the solvent

recommended by the manufacturer.

PENDAHULUAN

Bab ini mendiskusikan peralatan dan bahan yang

diperlukan untuk melakukan pengujian penetrant

serta pembersihan material SEBELUM dan

SESUDAH pengujian.

PENYIAPAN PERMUKAAN

Telah disampaikan dalam Bab 1 bahwa ada ENAM

langkah dasar pengujian penetrant. Penyiapan

permukaan dimasukkan sebagai langkah pertama

dalam diagram alir berikut.

Pembersihan permukaan sangat penting dalam

pengujian cairan penetrant karena DUA alasan:

1. Jika spesimen tidak bersih secara fisika dan

kimia, pengujian penetrant menjadi tidak

efektip.

2. Jika semua bekas material penetrant tidak

dibersihkan setelah pengujian, maka akan

merusak spesimen setelah benda tersebut

terpasang (klorin dan sulfur dapat merusak

beberapa jenis paduan).

Pemilihan proses pembersihan ditentukan oleh

faktor berikut.

Jenis kotoran yang dibersihkan.

Komposisi logam induk.

Tingkat kebersihan yang disyaratkan.

Ketersediaan peralatan pembersih.

Faktor-faktor biaya dan waktu.

Jika kompatibilitas antara metoda pembersihan,

cairan pembersih dan penetrant tidak diketahui,

pembersihan akhir sebaiknya dilakukan dengan

solvent yang direkomendasikan oleh pabrik

penetrant.

Page 16

DETERGENT CLEANING

Immersion tanks and detergent solution may

be used as an effective method for removing

surface soils, particularly when employed as a

hot tank process.

However, since the solutions used may be

either acidic or alkaline in nature, precautions

must be taken to ensure that the selected

detergent is noncorrosive to the article being

cleaned.

When thoroughly rinsed and dried, detergent

cleaning leaves a test surface that is physically

and chemically clean.

VAPOR DEGREASING

Vapor degreasing is effective in the removal of

oil, grease, and similar organic contaminants.

This method does not remove solid contami-

nants such as varnish, paint, scale, or oxide.

However, this method is considered as the

most effective means of precleaning a test

item prior to a penetrant test

Safety and environmental concerns have

virtually eliminated vapor degreasing. The chlo-

rinated solvents employed (methyl chloroform),

if acidic, can be harmful to certain materials

such as nickel, stainless steel, and titanium.

STEAM CLEANING

Steam cleaning is an excellent method of

cleaning large articles, or portions of large

articles that cannot be washed with detergents.

It removes inorganic soils as well as many

organic contaminants, but it may not reach to

the bottom of deep discontinuities. A follow-up

solvent soak is often recommended.

SOLVENT CLEANING

Solvent cleaning may use immersion tank, or

the solvent may be sprayed, brushed, or wiped

on and wiped off. Solvent cleaning is the

process most commonly used for spot

inspections.

Solvent cleaners should only be used to

remove organic contaminants, and are not

recommended for removing rust and scale,

welding flux or spatter. Typical solvents are

kerosene, paint thinner, alcohol, benzol, and

trichloroethylene.

PEMBERSIHAN DENGAN DETERJEN

Tangki perendam dan larutan deterjen dapat

dipakai sebagai metoda yang efektip untuk

membersihkan kotoran permukaan, utamanya jika

memakai proses tangki panas.

Namun demikian mengingat larutan yang dipakai

dapat bersifat asam atau basa, harus diperhatikan

agar deterjen yang dipilih tidak mengakibatkan

korosi terhadap benda yang dibersihkan.

Bila dibilas dengan bersih dan dikeringkan,

pembersih deterjen menghasilkan permukaan

yang bersih secara fisika dan kimia.

PEMBERSIHAN DENGAN UAP SOLVENT

Uap solvent efektif untuk membersihkan minyak,

gemuk, dan kontaminan organik sejenisnya.

Metoda ini tidak menghilangkan kontaminan padat

seperti pernis, cat, kerak, dan oksida.

Namun demikian, metoda ini dianggap sebagai

cara yang paling efektip untuk membersihkan

benda sebelum diuji penetrant.

Masalah keselamatan dan lingkungan telah

melarang penggunaan metoda ini. Chlorinated

solvent yang dipakai (methyl chloroform), jika

bersifat asam dapat merusak material seperti

nickel, stainless steel, dan titanium.

PEMBERSIHAN DENGAN UAP AIR

Pembersihan dengan uap air merupakan cara

yang unggul untuk membersihkan benda beruku-

ran besar yang tidak dapat dicuci dengan deterjen.

Cara ini menghilangkan kotoran organik dan

inorganik, namun tidak dapat mencapai dasar

diskontinuitas yang dalam. Pencelupan ke dalam

solvent setelahnya seringkali direkomendasikan.

PEMBERSIHAN DENGAN SOLVENT

Cara ini dilakukan dengan pencelupan,

penyemprotan, penyikatan, atau pengusapan.

Pembersihan dengan solvent merupakan proses

yang umum digunakan untuk pemeriksaan

setempat.

Solvent pembersih hanya untuk menghilangkan

kotoran organik dan tidak diremomendasikan

untuk menghilangkan karat dan kerak, flux

pengelasan, atau percikan las. Cairan solvent

contohnya minyak tanah, thinner cat, alkohol,

benzol, dan trichloroethylene.

Page 17

RUST AND SURFACE SCALE REMOVER

Rust removers (descaling solutions, either

alkaline or acid), pickling solutions (acid), and

sometimes wire brushing are used to remove

rust and surface scale. Wire brushing is

accomplished with a minimum of pressure to

avoid closing surface discontinuities or filing

them with smeared metal.

PAINT REMOVAL

Dissolving type hot tank paint strippers and

bond release or solvent paint strippers may be

used to remove paint in precleaning.

ETCHING

Etching is normally required on soft metallic

materials (such as aluminum and magnesium),

materials that tend to smear (such as titanium),

and materials which have been mechanically

process-ed by machining, grinding, or similar

procedure. Etching is accomplished with either

an acid or an alkaline solution to open up

grinding burrs and remove metal from surface

discontinuities.

ULTRASONIC CLEANING

Ultrasonic cleaning equipment is useful in the

cleaning of large quantities of small test

objects. Ultrasonic cleaning is often combined

with a solvent or detergent bath to improve

cleaning efficiency and reduce cleaning time.

The method works best with water and deter-

gent cleaning when contaminants to be

removed are inorganic, and with solvents when

contaminants are organic.

MECHANICAL CLEANING

Cleaning processes that are not generally

recommended include abrasive blasting (shot,

sand, grit, or pressure), liquid honing, emery

cloth, wire brushes, and metal scrapers, but

there are times when they must be used.

These processes tend to close discontinuities

by peening or cold working the surface of the

specimen.

PENGHILANG KARAT DAN KERAK PERMUKAAN

Penghilang karat dan kerak (larutan penghilang

kerak, basa atau asam), larutan pickling (asam),

dan kadang kala sikat baja digunakan untuk

menghilangkan karat dan kerak permukaan.

Penyikatan dilakukan dengan tekanan rendah

untuk mencegah penutupan atau pengisian

diskontinuitas permukaan oleh gram.

PENGHILANG CAT

Pengelupas cat dan pelepas ikatan memakai

tangki pelarut panas atau solvent pengelupas cat

dapat dipakai untuk menghilangkan cat saat

pembersihan awal.

ETSA

Etsa biasanya disyaratkan pada material logam

lunak (seperti aluminium dan magnesium), material

yang cenderung teroksidasi (seperti titanium), dan

material yang telah diproses secara mekanis

melalui permesinan, penggerindaan atau sejenis-

nya. Etsa dilakukan dengan larutan asam atau

basa untuk membuka bekas gerinda dan

menghilangkan gram dari permukaan diskonti-

nuitas.

PEMBERSIHAN ULTRASONIK

Peralatan ultrasonik dipakai untuk membersihkan

benda berukuran kecil yang jumlahnya banyak.

Pembersihan ultrasonik seringkali memakai bak

berisi cairan solvent atau deterjen untuk mening-

katkan efisiensi pembersihan dan menghemat

waktu.

Campuran air dan deterjen merupakan yang

terbaik untuk membersihkan kontaminan inorganik,

sementara cairan solvent untuk membersihkan

kontaminan organik.

PEMBERSIHAN SECARA MEKANIS

Proses pembersihan yang umumnya tidak direko-

mendasikan adalah abrasive blasting (pelor, pasir,

atau tekanan), cairan pengasah, ampelas, sikat

baja dan penyekrapan. Namun ada kalanya cara-

cara tersebut harus dilakukan.

Proses ini cenderung menutup diskontinuitas

dengan cara pemukulan atau pengerjaan dingin

pada permukaan spesimen.

Page 18

When mechanical cleaning must be used,

closed discontinuities can be reopened with a

chemical etch that removes a very slight

amount of material from the surface.

Saat pembersihan mekanis harus dilakukan,

diskontinuitas yang menutup dapat dibuka kembali

dengan pengetsaan yang akan menghilangkan

lapisan tipis material dari permukaan.

Table 2.1. Mechanical cleaning processes.

Table 2.2. Chemical cleaning processes.

Page 19

STATIONARY PENETRANT TEST

EQUIPMENT

Stationary equipment is that equipment which

is normally located in one place. The equip-

ment varies in size and is largely dependent

upon the size and type of the test specimen.

Depending on the type and process used, a

stationary system could include the following:

1. Precleaning Station (usually remote from

penetrant test station)

2. Penetrant Station (tank)

3. Drain Station (used with penetrant tank)

4. Emulsifier Station (tank)

5. Rinse Station (tank)

6. Developer Station (tank, dust chamber,

or spray equipment)

7. Dryer Station (usually an oven type)

8. Inspection Station (enclosed booth or

table with lighting facilities)

9. Postcleaning Station (usually remote from penetrant test station)

PERALATAN PENGUJIAN PENETRANT

STASIONER

Peralatan stasioner maksudnya adalah peralatan

yang letaknya menetap di satu lokasi. Peralatan

tersebut ukurannya bervariasi yang bergantung

pada ukuran dan jenis spesimen uji.

Tergantung pada jenis dan proses yang diguna-

kan, sistem stasioner terdiri dari bagian-bagian:

1. Tempat pembersihan awal (jauh dari lokasi

pengujian)

2. Tangki berisi cairan penetrant

3. Tempat pengering (digunakan bareng

dengan tangki penetrant)

4. Tangki berisi cairan pengemulsi

5. Tangki pembilasan

6. Lokasi developer (tangki, dust chamber, atau

peralatan penyemprot)

7. Tempat pengeringan (berupa oven)

8. Tempat pemeriksaan (bilik tertutup atau meja

dengan lampu penerangan)

9. Tempat pembersihan akhir (jauh dari lokasi

pengujian)

Page 20

PORTABLE PENETRANT TEST

EQUIPMENT

Both visible and fluorescent dye penetrants are

available in kits which can be used at a remote

location, or when testing a small portion of a

large article. The liquids are usually supplied in

pressurized (aerosol) spray cans.

A visible dye kit usually consists of:

Solvent cleaner or penetrant remover.

Visible dye penetrant.

Nonaqueous wet developer.

Wiping cloths and brush.

A fluorescent dye kit usually contains the

following:

Solvent cleaner or penetrant remover.

Fluorescent dye penetrant.

Nonaqueous wet developer.

Wiping cloths and brush.

Portable black light and transformer.

Hood to provide darkened area for

viewing indications.

PERALATAN PENGUJIAN PENETRANT

PORTABEL

Baik penetrant visible maupun fluorescent tersedia

dalam bentuk paket yang dapat dipakai memeriksa

di lokasi terbuka, atau saat menguji bagian dari

benda berukuran besar. Keduanya dikemas dalam

bentuk kaleng semprot bertekanan.

Paket penetrant visible terdiri dari:

Kaleng berisi solvent pembersih.

Kaleng berisi penetrant.

Kaleng berisi nonaqueous wet developer.

Kain lap dan kuas.

Paket penetrant fluorescent biasanya terdiri dari:

Kaleng berisi solvent pembersih.

Kaleng berisi penetrant fluorescent.

Kaleng berisi nonaqueous wet developer

Kain lap dan kuas.

Lampu ultraviolet dan trafonya.

Tudung kain hitam untuk melakukan

pemeriksaan.

Page 21

BLACK LIGHT EQUIPMENT

Black light equipment is required in fluorescent

penetrant testing since it supplies light of the

correct wavelengths that fall between visible

and ultraviolet, i.e. 365 nm (3650 angstroms)

to cause fluorescent materials to fluoresce.

For correct test results, the lamp should

produce an intensity of at least 1000 W/cm2

(microwatts per square centi-meter) at the test

surface.

Fluorescent penetrant dyes are usually in the

range of 475 nm to 575 nm, which is in the

visible spectrum of green to yellow.

The deep red-purple filter is designed to pass

only those wavelengths of light that will activate

the fluorescent material. Provided that the filter

is not broken or cracked, there is no danger of

injury to the human eye. It is suggested that the

filter be checked prior to each use.

At least 5 minutes of warm up is required to

reach the required arc temperature when using

mercury arc lamp. Once turned on, the lamp is

usually left on during the entire test or work

period, since switching the lamp on and off

shortens bulb life. If the black light is switched

off, it may take up to 10 minutes for the bulb to

cool sufficiently to reestablish an arc.

LAMPU ULTRAVIOLET

Lampu ultraviolet diperlukan pada pengujian

penetrant fluorescent karena menghasilkan cahaya

dengan panjang gelombang 365 nm (3650

angstroms) yang mengakibatkan material fluores-

cent berpendar.

Agar hasil pengujiannya akurat, lampu tersebut

harus menghasilkan intensitas cahaya minimum

1000 W/cm2 pada permukaan benda yang

diperiksa.

Zat pewarna fluorescent memiliki panjang gelom-

bang antara 475 nm sampai 575 nm, dapat terlihat

dengan spektrum warna hijau sampai kuning.

Filter berwarna merah-keunguan dirancang hanya

untuk dilalui cahaya dengan panjang gelombang

tertentu yang akan mengaktifkan material fluores-

cent. Asalkan filternya tidak pecah atau retak,

lampu ultraviolet tidak membahayakan mata. Disa-

rankan agar filter diperiksa tiap kali akan dipakai.

Minimum 5 menit disyaratkan untuk pemanasan

jika memakai lampu mercury. Setelah dinyalakan,

lampu tersebut sebaiknya dibiarkan menyala

selama pemeriksaan berlangsung karena sering

mematinyalakan lampu akan memperpendek usia

pakai. Jika dimatikan, lampu ultraviolet perlu waktu

10 menit untuk pendinginan yang cukup sebelum

bisa menyala lagi.

Page 22

PENETRANT MATERIAL COMBINATIONS

Penetrant testing materials can be used in a

variety of combinations. Most materials are

available in either pressurized spray cans or in

bulk quantities.

The flow chart below illustrates the different

material combinations. However, care should

always be taken to assure that manufacturers

specifications or company procedures are

closely followed.

Among the combinations, DRY DEVELOPER

KOMBINASI MATERIAL PENETRANT

Material untuk pengujian penetrant dapat dipakai

dalam berbagai kombinasi. Kebanyakan material

tersedia dalam kaleng bertekanan atau cairan

berkuantitas besar.

Diagram alir di bawah ini memperlihatkan kombi-

nasi material penetrant yang berbeda. Namun

demikian perlu diperhatikan agar selalu mengikuti

spesifikasi pabrik pembuat atau prosedur

perusahaan.

Diantara kombinasi tersebut, DEVELOPER KERING

should not be used with VISIBLE DYE sebaiknya tidak dipakai dengan VISIBLE DYE

PENETRANT because of the poor contrast

provided by the thin coating of very fine

powder.

PENETRANT karena kontras yang jelek antara

lapisan tipis serbuk developer dengan cairan

penetrant yang berwarna merah.

The most sensitive developer-penetrant Kombinasi developer-penetrant yang paling

combination: nonaqueous-fluorescent.

The least sensitive developer-penetrant combi-

nation: water suspended-visible.

sensitip: nonaqueous-fluorescent.

Kombinasi developer-penetrant yang paling tidak

sensitip: water suspended-visible.

Page 23

PENETRANT TESTING MATERIALS

Penetrant materials are often restricted to

specific groups. The established groups of

penetrant materials will use the following in a

variety of combinations to obtain the best

results.

1. Water-washable penetrants contain an

emulsifying agent which makes them

easily removable by a water rinse or

wash. This penetrant material can be

obtained with either a visible or

fluorescent dye.

2. Post-emulsifiable penetrants are highly

penetrating, oily visible or fluorescent

penetrants which are not soluble in water.

These penetrants must be treated with an

emulsifier before they can be removed by

a water rinse or wash.

3. Solvent-removable penetrants are oily

penetrants that do not contain an

emulsifying agent and are removable

only by solvents specifically designed for

that purpose.

4. Emulsifier when applied to a penetrant-

coated specimen make the resultant

mixture removable by water rinse or

wash. Emulsifiers have low penetrant

characteristics and do not remove

indications from the specimen surface.

5. Removers (solvent) are designed to be

used in conjunction with specific

penetrants. Typical removers are

available in bulk or pressurizes spray

containers.

6. Dry developers are a fluffy, absorbent

white powder that is used in both

fluorescent and visible dye penetrant

tests. It functions to draw the penetrant

inside discontinuities to the surface thus

making them visible.

7. Wet developers function similarly to dry

developers except that they are a mixture

of a developing powder and water.

8. Nonaqueous wet developers differ from

wet developers in that the developer

powder is mixed with a rapid-drying liquid

solvent.

MATERIAL UNTUK PENGUJIAN PENETRANT

Material penetrant seringkali dibatasi dalam

kelompok-kelompok khusus. Kelompok material

tersebut menggunakan kombinasi di bawah ini

untuk memperoleh hasil terbaik.

1. Water-washable penetrant mengandung

zat pengemulsi yang membuatnya mudah

dibersihkan dengan bilasan air. Material

penetrant ini dapat dibeli dalam bentuk

visible atau fluorescent.

2. Post-emulsifiable penetrant memiliki

kemampuan penetrasi yang bagus, berupa

minyak fluorescent atau visible yang tidak

larut dalam air. Emulsifier harus diaplikasikan

pada permukaan penetrant agar dapat

dibilas dengan air.

3. Solvent-removable penetrant berupa

minyak penetrant yang tidak mengandung

zat pengemulsi, dan hanya bisa dibersihkan

dengan solvent yang khusus digunakan

untuk tujuan tersebut.

4. Zat Pengemulsi jika diaplikasikan pada

lapisan penetrant di permukaan spesimen

menghasilkan campuran yang dapat dibilas

dengan air. Emulsifier memiliki sifat penetrasi

yang buruk sehingga tidak menghilangkan

indikasi dari permukaan benda uji.

5. Remover (solvent) didisain untuk

digunakan bersama dengan jenis penetrant

khusus. Remover tertentu dijual dalam

jumlah besar atau dalam kaleng semprot

bertekanan.

6. Developer kering serbuk penyerap, halus,

berwarna putih yang dipakai bersama

dengan pengujian penetrant visible dan

fluorescent. Fungsinya adalah untuk menarik

penetrant dari dalam diskontinuitas sehingga

tampak di permukaan.

7. Developer basah fungsinya mirip dengan

developer kering, hanya saja merupakan

campuran serbuk developer dengan air.

8. Nonaqueous wet developer berbeda

dengan developer basah, dimana serbuk

developer dicampur dengan cairan solvent

yang mudah menguap.

1.

Liquid oxygen (LOX) compatible materials must be used when articles inspected are subjected to contact with either liquid or gaseous oxygen.

Page 24

9.

Liquid oxygen (LOX) compatible

materials must be used when articles

inspected are subjected to contact with

either liquid or gaseous oxygen. These

materials are specifically designed to be

inert when in the presence of LOX.

During manufacture and testing of the

article, special care is taken not to

contaminate the article with combustible

materials.

By itself, liquid oxygen is nonexplosive,

but whenever it comes in contact with a

combustible material, a spontaneous

explosive situation occur where the

slightest spark could set off a violent

9.

Material yang kompatibel dengan oksigen

cair (LOX) harus digunakan saat benda

yang diperiksa bersinggungan dengan

oksigen cair atau gas oksigen. Material jenis

ini khusus didisain menjadi mulia saat

terkena oksigen cair.

Selama pembuatan dan pengujian artikel,

perhatian khusus harus diberikan untuk tidak

mengotori artikel tersebut dengan material

yang mudah terbakar.

Berdasar sifatnya, oksigen cair tidak mudah

meledak, namun saat terkena kontak dengan

material yang mudah terbakar, ledakan

spontan dapat terjadi akibat adanya percikan

api yang kecil saja.

reaction.

10. Low sulfur and low chlorine When small

quantities of sulfur and chlorine are

ionized and come into contact with

austenitic stainless steels, high nickel

alloys, cobalt alloys and titanium alloys,

corrosion may result.

This corrosiveness is accelerated when

the alloys are used at elevated tempe-

ratures and/or under residual stress

resulting in intergranular corrosion,

hydrogen embrittlement and stress

corrosion.

Sulfur and chlorine are not essential to

penetrant systems but they do exist in

trace amounts in the raw materials.

Nuclear and boiler codes specify from

0.5% to 1% by weight as the maximums.

10. Kadar sulfur dan klorin yang rendah Korosi

akan terjadi apabila sejumlah kecil sulfur dan

klorine terionisasi dan bereaksi dengan

austenitic stainless steel, paduan nickel

kadar tinggi, paduan cobalt, dan paduan

titanium.

Laju korosi akan dipercepat saat paduan

tersebut digunakan pada suhu tinggi

dan/atau terkena tegangan sisa hingga

terjadi korosi batas butir, penggetasan

hidrogen, dan korosi tegangan.

Sulfur dan klorin bukan merupakan unsur

penting dalam sistem penetrant, namun

mereka dalam jumlah kecil terdapat dalam

bahan baku penetrant.

Codes untuk nuklir dan boiler menyebutkan

batas maksimum sebesar 0.5% hingga 1%

berat.

Page 25

SAFETY PRECAUTION

In general, the materials used in penetrant

inspection can be flammable and can cause

skin irritations.

ULTRAVIOLET RADIATION The ultraviolet

spectrum of light rays generated from the

mercury arc lamp can cause sunburn and

may be injurious to the eyes. However, if the

proper filter for fluorescent dye inspection is

used, the harmful rays will be filtered out.

Personnel who use ultraviolet lights to

perform penetrant tests with fluorescent

penetrant that glows in the green-yellow

range should consider wearing yellow

glasses to block ultraviolet light from their

eyes.

FIRE many penetrant materials are

flammable. Occupational Safety and Health

Administration (OSHA) regulations requires

that penetrant materials used in open tanks

have a flashpoint of greater than 93C. The

higher the flashpoint of a material, the less

fire hazard it presents.

SKIN IRRITATION skin irritation can be

avoided by preventing unnecessary contact

and by the use of gloves, aprons, and

protective hand creams.

AIR POLLUTION the developing powders

are considered nontoxic but excessive

inhalation must be avoided. Exhaust fans

should be installed in any confined area

where dry developers or vapors from

penetrants are present.

MASALAH KESELAMATAN KERJA

Pada umumnya material yang dipakai dalam

pemeriksaan penetrant mudah terbakar dan dapat

menyebabkan iritasi kulit.

RADIASI SINAR ULTRAVIOLET spektrum sinar

ultraviolet yang dihasilkan oleh lampu mercury

dapat mengakibatkan kulit terbakar dan melukai

mata. Namun demikian jika filter lampu

digunakan dengan benar, sinar yang merugikan

dapat disaring.

Personil yang menggunakan lampu ultraviolet

untuk melakukan pengujian dengan penetrant

berwarna hijau-kuning sebaiknya memakai kaca

mata pelindung warna kuning untuk

menghalangi masuknya cahaya ultraviolet ke

dalam mata.

KEBAKARAN kebanyakan material penetrant

mudah terbakar. Peraturan OSHA mensyaratkan

bahwa material penetrant yang digunakan

dalam tangki terbuka memiliki titik nyala lebih

dari 93C. Makin tinggi titik nyala suatu material,

makin rendah bahaya kebakaran yang

ditimbulkannya.

IRITASI KULIT iritasi kulit dapat dihindari

dengan mencegah kontak yang tidak perlu dan

dengan pemakaian sarung tangan, baju

pelindung, dan krim pelindung tangan.

POLUSI UDARA serbuk developer tidak

beracun, namun menghirupnya secara

berlebihan harus dihindari. Kipas penghisap

udara sebaiknya dipasang pada daerah tertutup

dimana terdapat serbuk developer atau uap

penetrant.

PENETRANT MATERIAL DISPOSAL - PEMBUANGAN MATERIAL PENETRANT

Penetrant waste should be collected and

treated. This can be very expensive; the best

way to reduce this cost is to control the

amount of penetrant materials used.

Buangan penetrant harus dikumpulkan dan

diolah. Hal ini bisa sangat mahal; cara terbaik

untuk menghemat biaya yaitu dengan mengen-

dalikan jumlah material penetrant yang dipakai.

Page 26

Page 27

Page 28

CHAPTER TWO REVIEW

_______ 1.

_______ 2.

_______ 3.

_______ 4.

_______ 5.

_______ 6.

_______ 7.

_______ 8.

_______ 9.

Wire brushing Is a common and acceptable method of surface cleaning a test part that is to be penetrant inspected. A good exhaust system is recommended when working with cleaning solvents. Vapor degreasing is often used to remove oxidation, rust, and scale before a part is penetrant inspected. Parts that have been painted usually cannot be inspected with penetrants because suitable paint removing techniques have not been developed. Detergent cleaning is acceptable for postcleaning but should never be used for precleaning because it may affect the emulsifier during the penetrant test. Etching is often effective in precleaning a part that has been machined to a specific tolerance by surface grinding. Only visible dye penetrants are available in portable kits because fluorescent dyes will not function in pressurized spray cans. Dry developers are usually only used with visible dye penetrants. Emulsifiers and solvents are both commonly used in penetrant testing as postcleaners.

_______ 10. Wet developers should never be used when they will come into contact with

gaseous or liquid oxygen because of the results caused by oxygen and water mixing.

_______ 11. Emulsifiers must have high penetrating characteristics to emulsify

penetrants that lie in fillets and corners.

_______ 12. The black light used in fluorescent penetrant inspection is not hazardous to the human eyes if the correct filter is in place and not broken or cracked.

_______ 13. Penetrant materials are often placed in groupings that will assure a valid test

with materials that are compatible with each other.

_______ 14. Nonaqueous developer refers to a powder that is applied dry.

_______ 15. Post-emulsifiable penetrants are usually soluble in water after the application of an emulsifier.

_______ 16. Water-washable penetrants are cornmonly used with either a visible or

fluorescent dye.

_______ 17. Flashpoint refers to the lowest temperature at which vapors will ignite when exposed to flame.

Page 29

CHAPTER THREE

INTRODUCTION

This chapter discusses penetrant application.

As discussed in Chapter 2, surface cleaning is

the first step prior to the penetrant application.

CLEANING

The effectiveness of liquid penetrant testing is

based upon the ability of the penetrant to enter

surface discontinuities. All paint, carbon, oil,

varnish, oxide, plating, water, dirt, and similr

coating must be removed before application of

penetrant.

Liquid penetrant placed on the surface of a

specimen does not merely seep into

discontinuities. It is pulled into them by capillary

action. This is the reason one can cover the

under surface of an item with a penetrant and

still have a valid test.

The following are typical cleaning methods

discussed earlier.

1. Detergent cleaning

2. Vapor degreasing

3. Steam cleaning

4. Solvent cleaning

5. Rust and surface scale remover

6. Paint removal

7. Etching

8. Ultrasonic cleaning

9. Mechanical cleaning

PENDAHULUAN

Bab ini mendiskusikan aplikasi penetrant. Seperti

dibahas dalam Bab 2, pembersihan permukaan

adalah tahap pertama sebelum aplikasi penetrant.

PEMBERSIHAN

Efektifitas pengujian cairan penetrant bergantung

pada kemampuan penetrant untuk menyusup ke

dalam cacat permukaan. Semua cat, karbon, oli,

pernis, oksida, lapisan, air, kotoran dan cat

sejenisnya harus dihilangkan sebelum aplikasi

penetrant.

Cairan penetrant di atas permukaan benda uji tidak

semata-mata meresap ke dalam diskontinuitas.

Penetrant tertarik ke dalamnya oleh gaya kapiler.

Inilah mengapa permukaan bagian bawah dari

suatu benda masih dapat diperiksa dengan

penetrant dan memperoleh hasil yang valid. Berikut adalah metoda pembersihan permukaan

seperti didiskusikan sebelumnya:

1. Pembersihan dengan deterjen

2. Pembersihan dengan uap solvent

3. Pembersihan dengan uap air

4. Pembersihan dengan solvent

5. Penghilang karat dan kerak permukaan

6. Penghilang cat

7. Etsa

8. Pembersihan ultrasonik

9. Pembersihan secara mekanis

Page 30

PENETRANT APPLICATION

Since penetrant application is step two in the

process, lets add it to the flow diagram.

Almost any liquid could be considered a

penetrant, but modern penetrants must have:

1. The ability to hold a dye material in

suspension.

2. The ability to spread the dye evenly over

the surface.

3. The ability to carry the dye into any

discontinuity open to the surface.

4. The ability to bring up the dye as it is

coaxed back to the surface.

5. The ability, when desired, to be easily

removed.

There are two types of dye used in modern

penetrants:

1. Visible or color contrast a brightly

colored dye that is highly visible under

normal lighting conditions.

2. Fluorescent or brightness contrast an

almost colorless dye which emits visible

ligh rays when viewed under black light.

A dye with dual sensitivity, or dual-mode, or

dual-response contains a combination of

visible and fluorescent dyes.

The visible color is generally a bright red and

the fluorescent color a bronze-orange or

blue-green.

The combination permits penetrant tests to

be made under visible light and question-

able indications to be resolved under black

light; hence the term dual response.

APLIKASI PENETRANT

Aplikasi penetrant merupakan tahapan kedua

dalam proses pemeriksaan.

Hampir semua cairan dapat dianggap sebagai

penetrant, namun penetrant moderen harus

memiliki:

1. Kemampuan menahan zat pewarna dalam

suspensi.

2. Kemampuan menyebarkan pewarna secara

merata di atas permukaan benda.

3. Kemampuan membawa pewarna ke dalam

diskontinuitas yang terbuka ke permukaan

4. Kemampuan membawa kembali pewarna ke

permukaan.

5. Kemampuan, jika diinginkan, untuk dibersih-

kan dengan mudah.

Ada dua jenis zat pewarna yang digunakan dalam

penetrant moderen:

1. Visible atau color contrast pewarna merah

yang tampak jelas di bawah kondisi

pencahayaan normal.

2. Fluorescent or brightness contrast pewarna

yang akan memancarkan cahaya tampak

apabila dilihat dengan lampu ultraviolet.

Pewarna dengan sensitivitas ganda atau mode

ganda atau respon ganda mengandung kombinasi

pewarna visible dan fluorescent.

Pewarna visible umumnya merah menyala dan

pewarna fluorescent berwarna kuning-perunggu

atau biru-hijau.

Kombinasi ini memungkinkan pengujian

penetrant dilakukan di bawah cahaya biasa dan

indikasi yang meragukan diperiksa di bawah

cahaya ultraviolet.

Page 31

Penetrants, either fluorescent or visible can be

applied by any one of the following means:

1. Spraying usually using a conventional

low pressure spray guns or from

pressurized spray cans.

2. Brushing or swabbing usually applied

with rags, cotton waste, or brushes, when

testing a small, specific area of the

specimen.

3. Dipping or immersion the article is

generally lowered into a tank of

penetrant, then raised and allowed to

drain. This method is impractical when

dealing with large articles, and is wasteful

when only small areas of a large

specimen are to be tested.

4. Flowing or drain-dwell the penetrant is

simply poured over the surface and

allowing it to drain.

The terminology used in penetrant application

is listed in Table 3.1.

Penetrant, baik fluorescent maupun visible dapat

diaplikasikan dengan salah satu dari cara berikut:

1. Penyemprotan biasanya menggunakan alat

penyemprot bertekanan rendah atau dari

kaleng semprot bertekanan.

2. Kuas atau kain bisasanya diaplikasikan

dengan kain lap, kapas, atau kuas, apabila

menguji sebagian kecil/lokasi dari suatu

benda.

3. Pencelupan benda uji dibenamkan ke

dalam tangki penetrant, lalu diangkat dan

ditiriskan. Metoda ini tidak cocok untuk

benda berukuran besar dan merupakan

pemborosan apabila hanya daerah kecil saja

yang diuji.

4. Penuangan penetrant dituangkan di atas

permukaan benda dan setelah itu ditiriskan. Istilah yang digunakan dalam aplikasi penetrant

dapat dilihat dalam Table 3.1.

Table 3.1. Liquid penetrant application terminology.

Page 32

PENETRATION (DWELL) TIME

The period of time during which the penetrant

is permitted to remain on the specimen is a

vital part of the test. This time, known as dwell

time, is directly related to the size and shape of

the discontinuities anticipated since the

dimensions of the discontinuities determine the

rapidity with which penetration occurs.

Tight, crack-like discontinuities may require in

excess of 30 minutes for penetration to an

extent that an adequate indication can be

expected. Gross discontinuities may be

suitably penetrated in 3 to 5 minutes.

The temperature of the specimen and

temperature of the penetrant can affect the

required dwell time.

Warming the specimen accelerates

penetration and shortens dwell time.

However, care should be taken not to

overheat the specimen since too much heat

may cause evaporation of the penetrant

from the discontinuity, and thereby reduce

sensitivity.

Dwell times are based on the assumption

that the penetrant will remain wet on the part

surface. Additional penetrant may be

applied during dwell time.

In each instance, dwell time is determined by

the anticipated discontinuities and the

penetrant manufacturers recommendations.

Typical minimum penetration times are shown

in Table 3.2.

WAKTU PENETRASI (WAKTU DIAM)

Jangka waktu dimana penetrant berada di atas

permukaan benda uji merupakan bagian

terpenting dari pengujian. Jangka waktu ini dikenal

sebagai waktu diam, yang berhubungan langsung

dengan ukuran dan bentuk diskontinuitas yang

dicari mengingat ukuran diskontinuitas menentu-

kan kecepatan terjadinya penetrasi.

Diskontinuitas yang rapat, seperti retakan

memerlukan waktu penetrasi lebih dari 30 menit

untuk terbentuknya indikasi. Diskontinuitas

berukuran besar memerlukan waktu penetrasi

antara 3 sampai 5 menit.

Suhu benda uji dan suhu cairan penetrant dapat

mempengaruhi waktu diam yang disyaratkan.

Menghangatkan benda uji mempercepat

penetrasi dan mempersingkat waktu diam.

Namun demikian perlu diperhatikan agar tidak

berlebihan memanaskan spesimen karena suhu

yang terlalu tinggi menyebabkan penguapan

penetrant dari dalam diskontinuitas, yang

akhirnya akan mengurangi sensitivitas.

Waktu diam didasarkan pada asumsi bahwa

penetrant tetap dalam kondisi basah pada

permukaan benda. Penambahan penetrant

selama waktu diam diperbolehkan.

Pada tiap kasus, waktu diam ditentukan oleh jenis

diskontinuitas yang hendak dicari dan

rekomendasi dari pabrik pembuat penetrant.

Waktu penetrasi minimum untuk kasus tertentu

diperlihatkan dalam Tabel 3.2.

Page 33

Table 3.2. Typical minimum penetration time.

Page 34

PENETRANT TESTING PROCESSES

We previously mentioned the two types of

penetrants: visible and fluorescent. For both

categories, there is a further breakdown.

1. Water-washable (visible or fluorescent).

2. Post-emulsifiable (visible or fluorescent).

3. Solvent-removable (visible or fluorescent).

Water-washable Penetrants (WW Penetrants)

WW penetrants have a built-in emulsifier, or

what-so-called self-emulsifying penetrants.

The penetrant is soluble in water and is easily

removed by a water rinse.

Care must be taken to insure that the spray

volume and force does not wash penetrant out

of the discontinuity. A solid stream of water is

not desirable. A coarse droplet size provides

optimal removal. Water pressure should not

exceed 40 psi.

The recommended temperature range for water

rinse is 10oC - 38oC. Water temperatures above

38oC are not recommended because this may

speed up the evaporation of the penetrant.

At angles of 80-90 degree, the spray droplets

will rebound into oncoming spray, which diverts

the droplets and reduce velocity. Generally, an

angle of 45-75 degree is most effective.

The sketch below represents the steps in a

water-washable penetrant test.

PROSES PENGUJIAN PENETRANT

Telah disebutkan sebelumnya ada dua jenis

penetrant: visible dan fluorescent. Kedua jenis

penetrant tersebut dapat dirinci menjadi:

1. Water-washable (visible atau fluorescent).

2. Post-emulsifiable (visible atau fluorescent).

3. Solvent-removable (visible atau fluorescent).

Water-washable Penetrants (WW Penetrants)

WW penetrant mengandung zat pengemulsi, atau

dinamakan penetrant self-emulsifying. Penetrant

ini larut dalam air dan mudah dibersihkan dengan

bilasan air.

Harus diperhatikan agar volume dan kekuatan

semprot tidak sampai membasuh penetrant dari

dalam diskontinuitas. Aliran air yang pejal tidak

diinginkan. Air dalam bentuk percikan kasar

menghasilkan pembersihan yang optimal. Tekanan

air tidak boleh melebihi 40 psi.

Suhu air pembilas yang direkomendasikan sebesar

10oC - 38oC. Suhu air melebihi 38oC tidak direko-

mendasikan karena dapat mempercepat pengua-

pan penetrant.

Pada sudut 80-90 derajat, titik-titik air akan

memantul kembali dan menabrak titik air yang

datang sehingga mengurangi kecepatan. Sudut

semprot yang paling efektif adalah 45-75 derajat.

Gambar di bawah memperlihatkan langkah-

langkah pengujian water-washable penetrant.

Page 35

Water-washable penetrants are usually

preferred for use on articles with a rough

surface or if they contain threads or keyways.

The built-in emulsifier provides the best

penetrant removal from blind holes and other

hard-to-reach locations, but has the

disadvantage of poor reliability in detecting

wide or shallow discontinuities.

Post-emulsifiable Penetrants (PE Penetrants)

The penetrants employed in the PE process

DO NOT contain an emulsifying agent. The

penetrant is NOT soluble in water.

PE penetrants require a two-step removal

process. Excess penetrant is removed by

applying a separate emulsifier to make the

penetrant water-washable. The emulsifier is

usually applied by dipping/immersion,

spraying, or flowing. The amount of dwell time

in the emulsifier is in the range of one to four

minutes in accordance with manufacturer

recommendations and the type of defects

expected.

The resultant penetrant-emulsifier mixture is

removed by water rinse.

Solvent-removable Penetrants (SR Penetrants)

The solvent removable method employs post-

emulsification-type penetrant. But instead of

using an emulsifier and water wash, excess

penetrant is removed by a solvent.

SR penetrants have the advantage of portability

and can be used outdoors without using heavy

complex equipment.

They are excellent for many maintenance

inspection and for checking portions of larger

structure.

Water-washable penetrant biasanya digunakan

untuk memeriksa benda yang permukaannya kasar

atau benda yang ada ulir atau alurnya.

Emulsifier yang ada di dalamnya mengakibatkan

penetrant mudah dihilangkan dari lubang buntu

dan lokasi yang sulit dijangkau, namun memiliki

kelemahan dalam mendeteksi diskontinuitas yang

lebar dan dangkal. Post-emulsifiable Penetrants (PE Penetrants)

Penetrant yang dipakai pada proses PE tidak

mengandung zat pengemulsi. Penetrant ini tidak

larut dalam air.

PE penetrant memerlukan dua langkah proses

pembersihan. Sisa penetrant dibersihkan dengan

aplikasi emulsifier secara terpisah sehingga

penetrant dapat dibilas dengan air. Emulsifier

biasanya diaplikasikan dengan pencelupan,

penyemprotan, atau penuangan. Lamanya waktu

diam untuk emulsifier adalah satu sampai empat

menit mengacu pada rekomendasi pabrik

pembuat dan jenis cacat yang dicari.

Hasil campuran antara penetrant dan emulsifier

selanjutnya dapat dibilas dengan air.

Solvent-removable Penetrants (SR Penetrants)

Metoda solvent removable menggunakan

penetrant jenis post-emulsification. Solvent

digunakan untuk menghilangkan pentrant sisa

yang ada di permukaan benda.

SR penetrant menguntungkan dari segi portabilitas

dan dapat digunakan di luar tanpa menggunakan

peralatan yang berat dan rumit.

Cara ini sangat memuaskan untuk pemeriksaan

pemeliharaan dan untuk memeriksa bagian dari

suatu struktur yang besar.

Page 36

Penetrant is often applied from a pressurized

spray can which makes the system very

portable.

After the specified dwell time, the excess

penetrant is first removed by wiping with

absorbent towels and then cleaned with towels

dampened with solvent.

Solvent is NEVER applied directly to the

specimen as it might wash out or dilute the

penetrant in the discontinuity.

Table 3.3 lists the preferred processes for

various penetrant test problems.

Penetrant seringkali diaplikasikan dari kaleng

semprot bertekanan yang membuat sistem ini

sangat portabel.

Setelah waktu diam terpenuhi, penetrant sisa pada

mulanya diseka dengan lap penyerap dan

kemudian dibersihkan dengan lap yang dibasahi

dengan solvent.

JANGAN PERNAH menyemprotkan solvent secara

langsung ke permukaan benda karena akan

melenyapkan penetrant dari dalam diskontinuitas.

Tabel 3.3 memperlihatkan macam-macam proses

pengujian penetrant dan kegunaannya.

Table 3.3. Process selection guide.

Page 37

1. Water-washable

2. Post-emulsifiable

3. Solvent-removable

Page 38

LEAK-THROUGH TECHNIQUE

The leak-through technique is well suited for

finding leaks in such articles as tanks, piping,

tubing and hollow castings. There is no

knowledge concerning other quality characte-

ristics of the specimen is obtained.

The sketch below illustrates the liquid penetrant

leak-through test as used on a large plate

section.

FILTERED PARTICLE TECHNIQUE

Filtered particle testing uses small particles

suspended in the penetrant liquid. In most

instances these particles are fluorescent.

The size of the suspended particles varies and

depends upon the porous nature of the

inspection surface.

When testing a porous surface with filtered

particles, all of the liquid penetrant will be

absorbed. There will be no excess requiring

removal. Where a discontinuity (such as a

crack) is present, the increased area created

by a crack (its walls, etc.) will cause more of the

penetrant to be absorbed there than elsewhere.

The crack will filter the penetrant, leaving the

fluorescent particles on the surface. Since more

penetrant will be absorbed there, a greater

buildup of particles will be found at the site of

the crack. This particel buildup provides an

indication of discontinuities open to the

surface.

TEKNIK PEREMBESAN BOCORAN

Teknik perembesan bocoran sangat sesuai untuk

mendeteksi kebocoran pada tangki, pipa, tube,

dan cor-coran berongga. Tidak ada informasi lain

yang diperoleh mengenai karakteristik kualitas

benda.

Gambar di bawah memperlihatkan pengujian

kebocoran dengan penetrant untuk memeriksa

bagian dari suatu pelat.

TEKNIK PARTIKEL TERSARING

Teknik ini menggunakan partikel berukuran kecil

yang tersuspensi dalam cairan penetrant. Partikel

yang dipakai biasanya fluorescent.

Ukuran partikel yang tersuspensi bervariasi,

tergantung pada kondisi pori-pori permukaan

benda yang diperiksa.

Saat menguji permukaan berpori dengan cara ini,

semua cairan penetrant akan diserap. Tidak ada

langkah pembersihan penetrant sisa pada teknik

ini. Pada tempat dimana terdapat diskontinuitas

(seperti retak), penambahan luasan akibat retak

(dinding retak, dll.) akan mengakibatkan penetrant

lebih banyak terserap di daerah tersebut.

Retak akan menyaring penetrant, meninggalkan

jejak partikel fluorescent pada permukaan. Karena

lebih banyak penetrant terserap di sana,

pengumpulan partikel lebih banyak terjadi di

daerah retak. Pengumpulan partikel ini menun-

jukkan adanya diskontinuitas yang membuka ke

permukaan.

Page 39

FIXING AND RECORDING INDICATIONS

Fixing and recording indications can be carried

out by:

1. Photographs digital photography

provide excellent permanent records. In

addition to photographs, video cassette

recorders (VCRs) and closed-circuit

television cameras (CCTVs) are used to

record indications.

2. Special wax and plastic film developers

have been developed to absorb and fix

the penetrant indication to form a

permanent record.

a. Strippable lacquers are sprayed in

several coats over the indication and

when dry can be lifted to provide a

permanent record.

b. Special fixers are sprayed over the

indication and when dry are lifted with

transparent tape.

PEMELIHARAAN DAN PEREKAMAN INDIKASI

Pemeliharaan dan perekaman indikasi dapat

dilakukan dengan:

1. Fotografi foto digital merupakan cara

terbaik untuk merekam indikasi. Disamping

itu video kaset dan kamera CCTV juga dapat

digunakan untuk merekam indikasi.

2. Lilin khusus dan lapisan plastik developers

dikembangkan untuk menyerap dan

mengawetkan indikasi penetrant dan

membentuk rekaman permanen.

a. Lapisan lak disemprotkan beberapa lapis

di atas indikasi, dan setelah kering dapat

dikelupas untuk menghasilkan rekaman

permanen.

b. Fixer khusus disemprotkan di atas indikasi

dan setelah kering diangkat dengan pita

transparan (isolasi).

Page 40

CHAPTER THREE REVIEW

_______ 1.

_______ 2.

_______ 3.

_______ 4.

_______ 5.

_______ 6.

_______ 7.

_______ 8.

_______ 9.

A dual sensitivity penetrant contains a special dye that is visible in white light and will fluoresce without the use of a black light. A part being penetrant inspected must stay immersed in the penetrant tank for the entire specified dwell time. The liquid penetrant leak-through test refers to the ability of a penetrant to spread through the dry developer evenly. Visible dye penetrants are usually considered to be less sensitive than fluorescent penetrants. Water-washable penetrants have a built-in emulsifier that permits good results in penetrant removal from parts suspected of having wide or shallow discontinjuities. Solvent-removable penetrants are available in both visible and fluorescent dye. Excess post-emulsifiable penetrant is commonly removed by spraying the surface of the part with cleaner (solvent) and then wiping with a lint-free towel. Water washable penetrant systems are usually very portable because the materials are commonly used in pressurized spray cans. Warming the specimen to temperatures up to about 20o C tends to accelerate penetration and shortens dwell time.

_______ 10. For the dwell time to be accurate, the surface of the specimen must stay

wet with penetrant for the entire time specified.

_______ 11. The typipal dwell time for most penetrant Inspections is about 20-30 minutes.

_________________________ 12. _________________________

_________________________ 13. _________________________ _________________________

List two (2) of the commonly used methods of applying penetrants to a specimen that is to be inspected. List four (4) of the commonly used methods of precleaning the specimen before penetrant inspection.

_________________________

_______ 14. If you were asked to examine 200 steel bolts, each 3/8 x 3 inches with rolled threads, which penetrant method would you choose?

(a) Post-emulsification (b) Water-washable

_______ 15. The filtered particle method of penetrant inspection used extra fine

fluorescent particles that will not pass through a #120 sieve.

Page 41

CHAPTER FOUR

INTRODUCTION

This chapter discusses emulsification,

penetrant removal, and developer application.

POST EMULSIFIABLE PENETRANT (PE

PENETRANT)

This type of penetrant emulsification is

accomplished by dipping, spraying, or flowing,

but NEVER by brushing. Brushing makes

emulsification more difficult to control, besides

the bristle of the brush may enter the

discontinuity.

PENDAHULUAN

Bab ini mendiskusikan proses emulsifikasi,

pembersihan penetrant, dan aplikasi developer. POST EMULSIFIABLE PENETRANT (PE

PENETRANT)

Emulsifikasi penetrant jenis ini dilakukan dengan

pencelupan, penyemprotan atau penuangan,

namun TIDAK BOLEH diaplikasikan dengan kuas.

Aplikasi dengan kuas menyulitkan pengontrolan

emulsifikasi, disamping bulu-bulu kuas bisa masuk

ke dalam diskontinuitas.

Page 42

The skecth below represents the steps in a

post-emulsifiable penetrant test.

Gambar berikut menunjukkan langkah-langkah

pengujian post-emulsifiable penetrant.

Page 43

The length of time the emulsifier is left to dwell

before commencing the penetrant removal

cycle is determined by the emulsifier used and

the type of discontinuities suspected.

If too short an emulsification time is used, not

all penetrant will be removed, which will cloud

over discontinuities.

If too long a time is used, penetrant within the

discontinuities will also become water soluble

and be washed away with excess penetrant.

The PE penetrant makes the water wash less

critical.

The sketches below compare the effects of

water-washable and post emulsification

penetrants.

Jangka waktu emulsifier dibiarkan di atas

permukaan benda sebelum dilakukan pembersi-

han penetrant ditentukan oleh jenis emulsifier dan

diskontinuitas yang dicari.

Jika waktu emulsifikasi terlalu singkat, tidak semua

penetrant akan tersapu, yang nantinya akan

menghalangi munculnya diskontinuitas.

Jika waktu emulsifikasi terlalu panjang, penetrant di

dalam diskontinuitas akan bereaksi dengan

emulsifier dan akan tersapu oleh air.

PE penetrant membuat pembilasan dengan air

menjadi tidak terlalu kritis.

Gambar di bawah ini membandingkan antara

pemakaian WW dan PE penetrants.

Page 44

There are two types of emulsifiers used in the

removal process LIPOPHILIC (Method B)

and HYDROPHILIC (Method D).

Lipophilic and hydrophilic processes have

completely different mechanisms in converting

the oil based penetrant into a mixture that can

be washed.

LIPOPHILIC METHOD

Lipophilic emulsifier is applied by immersion to

prevent mechanically mixing emulsifier into the

penetrant. In some automatic installations, the

emulsifier is applied as a fog or mist.

The mechanism of lipophilic emulsification is by

DIFFUSION. Molecules of emulsifier enter into

the penetrant layer while at the same time

molecules of penetrant enter the emulsifier

layer. The rate of diffusion increases with

increased concentration and higher

temperatures.

The three properties of lipophilic emulsifiers

that control the washing characteristics are

activity, viscosity and water tolerance.

If a penetrant is highly resistant to water, an

emulsifier with a high activity is needed. High

viscosity emulsifiers diffuse more slowly than

low viscosity emulsifiers. Lipophilic emulsifier

should tolerate 5% water by weight without

gelling, separating or coagulating and still be

capable of passing the penetrant removability

test.

Method B emulsifiers are supplied in the ready-

to-use form and do not require further mixing.

Terdapat dua jenis emulsifier yang digunakan

dalam proses pembersihan LIPOPHILIC (Metoda

B) dan HYDROPHILIC (Metoda D).

Proses lipophylic dan hydrophilic memiliki

mekanisme yang sangat berbeda dalam merubah

penetrant berbahan dasar menjadi campuran yang

bisa dibilas dengan air.

METODA LIPOPHILIC

Emulsifier lipophilic diaplikasikan dengan cara

pencelupan untuk mencegah bercampurnya emul-

sifier dengan penetrant. Pada instalasi otomatis,

emulsifier diaplikasikan secara pengkabutan.

Mekanisme emulsifikasi lipophilic adalah dengan

cara DIFUSI. Molekul emulsifier memasuki lapisan

penetrant, sementara pada saat yang bersamaan

molekul penetrant memasuki lapisan emulsifier.

Laju difusi akan bertambah dengan peningkatan

konsentrasi dan penambahan suhu. Tiga sifat emulsifier lipophilic yang mengontrol

karakteristik pembilasan adalah aktivitas,

kekentalan, dan toleransi terhadap air.

Jika suatu penetrant memiliki ketahanan tinggi

terhadap air, maka diperlukan emulsifier dengan

aktivitas yang tinggi. Emulsifier dengan kekentalan

tinggi berdifusi lebih lambat ketimbang emulsifier

yang encer. Lipophilic emulsifier harus mampu

mentolerir 5% air tanpa mengalami penggumpalan

atau pembekuan dan mampu lulus uji pember-

sihan penetrant.

Emulsifier metoda B dijual dalam bentuk siap pakai

dan tidak memerlukan pencampuran lagi.

Page 45

HYDROPHILIC METHOD

Hydrophilic emulsifier is a water based solution

and is a mixture of chemicals called

surfactants. They are supplied as a concentrate

and are mixed with water either before or

during the removal process. The concentrate is

required to contain a maximum of 5% water.

Hydrophilic emulsifier works based on the

principle to peel the penetrant away or by

dissolving droplets so they do not redeposit on

the surface.

Because post-emulsifiable penetrant is

incompatible with water, prerinsing before

application of emulsifier is recommended.

Prerinsing removes 60-80% of the surface layer

of penetrant, which greatly reduces

contamination of the emulsifier. It also provides

an even layer of surface penetrant.

Hydrophilic emulsifier is applied either by

immersion or spraying.

Immediately following the emulsification, a

fresh water rinse of the entire part is required.

This stops the action of any emulsifier

remaining on the part.

METODA HYDROPHILIC

Emulsifier hydrophilic adalah larutan antara air dan

zat kimia yang disebut surfactant. Dijual di pasaran

dalam bentuk konsentrat dan harus dicampur dulu

dengan air sebelum atau selama proses

pembersihan. Konsentrat disyaratkan mengan-

dung air maksimum sebesar 5%.

Emulsifier hydrophilic bekerja berdasar pada

prinsip pengelupasan lapisan penetrant, atau

dengan melarutkan penetrant sehingga tidak

terdeposit kembali ke permukaan.

Karena post-emulsifiable penetrant tidak

kompatibel dengan air, direkomendasikan untuk

melakukan pembilasan awal sebelum aplikasi

emulsifier. Pembilasan awal menghilangkan 60-

80% lapisan penetrant di permukaan, sehingga

banyak mengurangi terjadinya kontaminasi pada

emulsifier. Pembilasan awal juga menghasilkan

lapisan penetrant permukaan yang rata.

Emulsifier hydrophilic diaplikasikan dengan cara

pencelupan atau penyemprotan.

Segera setelah proses emulsifikasi, disyaratkan

untuk membilas seluruh bagian benda uji dengan

air bersih. Langkah ini akan menghentikan aksi

emulsifikasi yang masih tersisa di permukaan

benda.

Page 46

DEVELOPERS APPLICATION

Some indications may be visible prior to the

application of a developer, but this step will

ensure that ALL discontinuities are visible to the

naked eye.

Developing is accomplished when a highly

absorbent powder is applied to the item being

tested after excess penetrant is removed.

The penetrant is actually drawn out of the

discontinuity by the strong capillary action of

the developer.

As shown above, the image of the discontinuity

in the developer will actually be larger than the

actual size of the discontinuity.

There are two common types of developers in

use today dry and wet. Both use a white

powder and the primary difference is in the

method of application.

DRY DEVELOPERS

Dry developer is supplied as a fine-grained

fluffy white powder.

Methods of application include the use of low

air pressure, such as that from a rubber

squeeze bulb or a spray gun. A soft brush may

sometimes be used; or, since the developer is

a very fine powder, articles may be simply

dipped in the developer, raised, and the

excess powder removed by gently blowing,

shaking, or tapping the article.

APLIKASI DEVELOPER

Beberapa indikasi bisa saja nampak sebelum

developer diaplikasikan, namun langkah ini akan

memastikan bahwa SEMUA diskontinuitas akan

tampak oleh mata telanjang.

Proses developing dilakukan dengan mengapli-

kasikan serbuk berdaya serap tinggi ke permukaan

benda uji setelah sisa penetrant dibersihkan.

Penetrant akan tertarik keluar dari diskontinuitas

akibat gaya kapiler yang kuat dari serbuk

developer. Seperti diperlihatkan dalam gambar di atas, cit