THE PRACTICAL REFERENCE GUIDE for WELDING INSPECTION MANAGEMENTTed visual inspection of pressure vessels and pressure piping (1)

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American
Welding
Society
@
The
Practical
Reference
Guide
for
Visual Inspection
of
Pressure
Vessels
and
Pressure Piping
Copyright American Welding Society
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E
THE
PRACTICAL
REFERENCE
GUIDE
for
Visual Inspection
of
Pressure Vessels
and Pressure Piping
WELDING INSPECTION MANAGEMENT-
Ted
V.
Weber
Principal Consultant
Weber
&
Associates
This
publication
is
designed to provide information in regard to the subject matter covered.
It
is made available
with the understanding that the publisher
is

not engaged
in
the rendering of professional advice. Reliance upon
the information contained
in
this
document should not be undertaken without an independent verification of
its application for a particular use. The publisher is not responsible for loss or damage resulting from
use
of
this
publication.
This
document
is
not a consensus standard. Users should refer to the applicable standards for their
particular application.
American
Welding
Society
550
N.W.
LeJeune
Road,
Miami,
Florida
33126
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AUTHOR NOTES
Visual inspection (VT)
is
one
of
the more important inspection methods used to ensure the quality of both
new fabrication, as well as equipment and piping after some period of service. It is used in all industries, and
should be considered as the basic inspection method prior to the selection
of
any other inspection method.
A
phrase that puts
VT
in the proper perspective follows:
“lt
has
been shown repeatedly that
an
efective program
of
visual inspection, conducted

by
properly trained personnel,
will result
in
the discovery
of
the vast majority
of
those defects which would otherwise be discovered later by some more
expensive nondestructive test method.”
Note the emphasis on proper training; without such training, the inspector often only
looks
at things without
actually inspecting them, and critical discontinuities are often overlooked. It is to that end, the training
of
vi-
sual inspectors, that this Guide was prepared. Proper visual inspection requires inspector training
in
many
disciplines and the training should be a continuous, ongoing process. New technologies useful to visual in-
spection are continuing to be developed, and these must be incorporated into the overall inspection efforts to
optimize results.
It was once stated that,
“lnspectors must have been haEfcrazy to have selected inspection as
a
lifetime career!”
While
many of
us
may agree with that statement in part, most would agree that inspection is a very challenging and

catisQing career path,
and
we remain quite proud to be called inspectors.
Ted
V.
Weber
Hendersonville, Tennessee
Photocopy
Rights
Authorization to photocopy items for internal, personal, or educational classroom use only, or the internal,
personal, or educational classroom use only of specific clients,
is
granted by the American Welding Society
(AWS) provided that the appropriate fee
is
paid to the Copyright Clearance Center,
222
Rosewood Drive,
Danvers, MA
01923,
Tel:
978-750-8400;
online: http: //www.copyright.com
O
1999
by the American Welding Society. All rights reserved.
Printed in the United States
of
America.
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TABLE
OF
CONTENTS
Page
No
.
Introduction

1
New Fabrication

3
Base Metals and Filler Metais

4
Welding Procedure Qualification

5
Personnel Qualification

6
Inspection Planning

7
Repairs and Re-inspection

9
Production Welding-New Fabrication

10
Fabrication Codes

12
In-Service Inspection

14
Annex A-Technical and Scientific Organizations

19
Annex -1998
ACME
Boiler
and
Pressure Vessel Code Sections

22
Annex C-Discontinuities

23
Annex &Selected References

28
iii
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Introduction
In
one version of a perfect world of manufacturing,
there are no inspectors. None are needed because
each and every person in the workforce has been
so
thoroughly trained, possesses and applies all the
necessary personal attributes, and is paid a reason-
able salary such that all manufacturing mistakes are
completely eliminated. Think of that perfect sce-
nario: a manufacturing world without mistakes.
Some of today's quality approaches reach for that

ideal goal and have developed precepts that con-
siderably reduce online inspection requirements.
The concept of "continuous improvement" is an
important part of that quest for perfection, and is
found in many quality-concept documents.
One approach to quality is found in the documents,
modified by American organizations, commonly
referred to as IS0 Standards. These often become
the basis for
"IS0
Certification," which many man-
ufacturing sites obtain and market as part of their
quality program. In the
U.S.,
these
IC0
quality pro-
gram standards and guides are published under the
combined authority of ANSI (American National
Standards Institute), IS0 (International Organiza-
tion for Standards), and the ASQ (American Society
for Quality), as "Q" documents. Two of these are
Q9004-1,
Quality Management
and
Quality System
Elements-Guidelines,
and Q9001,
Quality Systems-
Model for Quality Assurance in Design, Development,

Production, installation,
and
Servicing
(see Figure
1).
A thorough understanding of these two quality
documents is very helpful in organizing a Quality
Assurance program for fabrication companies. Ad-
ditional ASQ documents covering fabrication qual-
ity are Q9002,
Quality Systems-Model for Quality
Assurance
in
Production, installation,
and
Servicing,
and Q9003,
Quality Systems-Model
for
Quality As-
surance
in
Final inspection
andTest.
Their cost is min-
imal and can be obtained from the American
Society for Quality,
611
East Wisconsin Avenue,
Milwaukee,

WI
53202.
However, as much
as
these new quality programs
have improved quality in many areas, in our less-
than-ideal, real world, there still remains a need for
skilled inspectors. Most have seen various versions
of the old saying,
"People
do
whaf
you
inspect,
not
what you
expect." While that statement appears to
be quite cynical, many critical manufacturing ef-
forts still follow that credo with great success. In-
spection will continue to be a necessary skill for
AMERICAN NATIONAL STANDARD
AMERICAN
SOUM
FMI
QUAUTY
611
EAST
W6co"
AMNUE
MLWMJKEE.

WISCONCIN
5u202
Figure
1.
ANSVISO/ASQC
Q9001-1994.
decades to come, especially in the fabricating in-
dustries, and visual inspection will certainly con-
tinue on the front line
of
that inspection effort.
In the broad field of Quality Assurance, the control
of welding operations and fabrication of process
equipment encompasses many technical disciplines
including engineering design, materials selection,
welding processes, welding procedures, non-
destructive inspection, and corrosion mechanisms.
Visual inspection plays an important role in all of
these and it requires proper training of personnel to
provide the necessary function of quality control at
each stage of fabrication as well
as
continued in-
spections during the life
of
the component.
Inspector certification programs, such as the AWS
CWI and SCWI certifications, have been developed
to ensure a basic minimum qualification of the
visual inspection personnel (see Figure

2).
Other
organizations such as the American Petroleum
Institute (API), the National Association of Corro-
sion Engineers (NACE), and the American Society
for Nondestructive Testing (ASNT), have developed
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Figure
2.
AWS
QC1-96-Standard for AWS
Certification of Welding Inspectors.
certification programs for general and/or specific
industries. Additionally, several industries and
pri-
vate companies have produced industry-specific or
in-house training programs to train the inspectors
on their particular needs. Nuclear power industries
have such programs, as do the petroleum, petro-
chemical, and aerospace industries.
Visual inspection is learned through experience; al-

most everyone has the inherent capability to see
things, but visual inspection requires a more thor-
ough observance of details that requires consider-
able training, and the learning curve
is
usually very
experience-intensive. One of the first requirements
of a visual inspector in the fabricating realm is to be
able to read and interpret engineering drawings.
Unless the inspector has this first capability, the re-
quirements of the fabrication cannot be properly
determined. Many inspectors learn blueprint read-
ing in school, either in a drafting or engineering
drawing course; others learn on the job. The
method of learning to interpret fabrication draw-
ings is not the important issue. Rather, it
is
the
in-
terpretation itself that must be included as part of
an inspector’s skills.
Slang terms and incorrect terminology often lead to
confusion and errors.
So,
a second requirement is to
know and understand the proper terminology per-
tinent to a given industry. Proper terminology in-
cludes the mechanical aspects of stress, strain,
strength, ductility and many others that aid in de-
scribing the mechanical properties of the materials

used in manufacture. It also includes the necessary
terminology of welding and fabrication processes,
including joint and weld geometry and welding
processes as well as typical discontinuities. Various
base and weld metal discontinuity types have been
defined by AWS and are described in AWS
81.10,
AWS
B1.ll,
AWS A3.0, and in the convenient AWS
publication
The Everyday Pocket
Handbook
for
Visual
Inspection
and
Weld Discontinuities-Causes
and
Rem-
edies
(see Figure 3 and Annex D-Selected Refer-
ences). Excerpts from some of these are found in
Annex C-Discontinuities. Knowledge of corro-
sion terms is also required when completing in-ser-
vice inspections of pressure equipment. Corrosion
terms can also be found in several of the references
noted in Annex D-Selected References.
An important third requirement for the visual in-
spector is a thorough knowledge of the fabrication

codes pertaining to the various industries. The pe-
troleum industry relies on API specifications, the
railroad industry relies on the AAR standards,
and
building construction relies on the AWS structural
codes. Almost every industry has specific codes
that pertain to their particular needs and the inspec-
tor must have access to, and be familiar with, the
applicable codes.
A fourth requirement is precise documentation of
inspection results. Verbal statements regarding in-
spections usually have little value; the inspection
results must be documented such that they can be
referred to months or years later with absolute
un-
derstanding and clarity. With today’s computer
technology, there is little or no excuse not to have
complete, clear, legible, and retrievable documenta-
tion of inspection results readily available as
needed. Today’s technology also includes the excel-
lent digital cameras that permit photographs of the
equipment or condition to be easily inserted into
the records. Video cameras are another method of
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The Everyday
Pocket Handbook
for
Visual Inspection and
Weid Discontinuities-
Causes and Repairs
Compiled
as
a
useful tool for
on-the-job welding personnel
by
the
AWS
Product Development Committee
Figure
3.
The
Everyday Pocket Handbook
for
Visual Inspection and Weld Discontinuities-Causes

and Repairs.
recording inspection results. As one inspector
noted,
”in
today‘s world,
if
it’s not written down, it
hasn’t happened!”
It is certainly recognized that the actual require-
ments for thorough visual inspection may vary
from one industry to another, but all visual inspec-
tion contains the four basic requirements noted
above that must be met to inspect
an
item to the de-
sired and required level. Inspection not only applies
to the original fabrication of the components, but
extends to the in-service inspections as weli. Fitness
for purpose inspections must often continue for the
life of the component, and this usually requires
some form of periodic inspection, performed to
written guidelines, to ensure the continued safe op-
eration of the item. Most are somewhat familiar
with the stringent rules for continued inspection for
aircraft; they receive periodic inspections after
a
set
number of hours of operation. Many pressure ves-
sel codes have similar requirements but usually
have longer time periods between inspections.

It is not the purpose
of
this Guide to repeat in great
detail all the visual inspection procedures found in
these other documents. Rather, practical ap-
proaches to the broad topic of visual inspection will
be covered, both for new fabrication and in-service
inspections. The emphasis will be on piping and
vessels for pressure containment.
New
Fabrication
A
good starting point for any new fabrication
project
is
close communication between the manu-
facturing personnel
and
the design groups.
To
use
a
petrochemical process as an example, the manufac-
turing group knows the task it wants to perform
whether it is to manufacture polyester sheeting ma-
terial, polyethylene pellets for molding machines,
or acids to use as ingredients for other manufactur-
ing processes. The group conveys its desired result
to the design group and after several discussions
and iterations, the final design of the component is

completed. During this design stage, it is very help-
ful
to have input from the welding and metallurgi-
cal engineers as well as the inspectors to assist
in
a
design that first of all can be fabricated, and sec-
ondly, inspected adequately. All too often, designs
are too quickly put together only to find out the
materials selected pose tremendous difficulty in
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welding, or the design makes it impossible to thor-
oughly inspect.
The design of each separate component for a com-

plex process is sometimes done in a rather random
fashion. For example, a vessel is needed to mix the
raw ingredients and is designed by the pressure
vessel group. Then a distillation column is needed
and is designed by the distillation column design-
ers.
A
heat exchanger is needed and is designed by
the heat exchanger designer. When insufficient
communication exists between these various
groups, it can lead to costly redesign, or material
changes, to incorporate exactly what is needed.
Figure
4. A
typical petrochemical complex
showing the complexity and variety
of
pressure
vessels and piping arrangements.
A far better approach is to have good liaison be-
tween the various design sections through a project
manager to ensure compatibility of each compo-
nent, especially regarding the materials of construc-
tion and corrosion issues. The selection of materials
incorporates many different aspects including cost,
availability, strength, weldability, and corrosion re-
sistance. Selection of the correct material may re-
quire fabrication and corrosion testing to ensure
suitability. Visual inspection of these corrosion tests
may be an initial inspection requirement for the

project, and requires
an
understanding and knowl-
edge of the various corrosion tests by the inspector.
Often these are done to ASTM specifications and
the inspector must have ready access to them.
Pressure containment usually requires the use of
welding operations in the manufacturing of the
piping and vessels needed. In the fabrication of
new equipment, the welding operations usually get
considerable attention up front. There are several
reasons for this, but they often include the general
lack of knowledge
of
welding techniques by many
of the engineering staff as well as previous experi-
ences with weld failures. A list of the initial require-
ments for fabrication inspection will usually
include the following:
Base Metals
and
Filler Metals
These should be purchased to specifications listing
all the necessary requirements, with a supporting
Material Test Report requirement on the purchase
order. These necessary requirements usually in-
clude the mechanical properties, chemistry, size,
shape, manufacturing method, surface finish, heat
treatment, and quantity. Base metals are often or-
dered to ASTM, ASME, or API specifications; filler

metals are usually ordered to AWS specifications.
Specific items may require additional data, such as
the protective coatings for corrosion resistance of
steel products or shipping container requirements
for low-hydrogen electrodes, and all the materials
should always be inspected upon receipt to ensure
compliance. Often, for critical applications, check
analyses on the chemistry or mechanical properties
may be made to reflect a higher degree of certainty.
For filler metals, this may require the preparation of
a weld sample to a specification for chemical or me-
chanical testing, with its preparation witnessed by
an inspector.
Once the proper materials have been received and
confirmed, it is imperative that storage
of
these
ma-
terials maintains their proper identification
(ID).
There are many different systems used for main-
taining the
ID
of materials. Coding by different
paint colors can be an acceptable method for mate-
rials control, but consideration should be given to
the effects of sun and weather on the color. Color
changes do occur with exposure to sun, and this
must be recognized. Color changes over time have
led to mistakes in alloy identification. Weather can

also cause deterioration of the materials, and pro-
tection may be needed during storage.
Piping is often ink marked every three or four feet
along its length with its specification, grade, heat
number, etc., which helps maintain its identifica-
tion. Plate is often stamped or paint marked with its
ID
on one corner. Consider what happens if a por-
tion of the plate is used. Often, the corner with the
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Figure 5.
ASME
Section
II,
Part

A,
covering
ferrous material specifications. Section
II,
Part B
of the same code covers nonferrous materials.
Figure
6.
ASME
Section
II,
Part
Cy
covering filler
metals. The
AWS
Filler Metal Specifications
were adopted for use in Part
C.
marking is taken for use and this requires the re-
marking of the “drop” or remainder. Inspectors
should, and often do, play a role in this remarking.
Other items such as forgings, castings, or subassem-
blies may require bar coding, stamping, tagging, or
segregation to maintain their identity.
ways depending on the code requirements in effect
for the project.
In
some codes, test weldments must
be made and tested to qualify a procedure. Other

codes may permit the use of “canned” welding pro-
cedures or the use of mockups. The inspector must
be familiar with the procedure qualifications and
ensure they are met completely and satisfactorily.
Welding Procedu re Qual
if
¡cat
ion
Once the base materials have been received, con-
firmed, and stored properly, the next item requiring
attention for fabrication of pressure containment
equipment
is
the qualification of welding proce-
dures. (This step may be the initial step
in
the
entire
process if the fabricator has little or no experience
with the materials to be used.) A welding process is
selected and a preliminary Welding Procedure
Specification is usually prepared. However, these
procedures can be qualified in several different
Two of the more common procedure qualification
approaches are those found in the AWS standard
B2.1:1998,
and the ASME Boiler and Pressure Vessel
Code, Section
IX
(see Figures

7
and
8).
Either may
be acceptable but
if
an
ASME
Code fabrication is
being produced, Section
IX
is required for proce-
dure qualification.
Too
often, once a welding procedure has been qual-
ified, it disappears into the dark corners of some
office and is never seen again except during formal
audits. While a master list
of
procedures with
current copies should be maintained in an office,
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ü2.1!1998
An
Amorim
Naîiml
Siandard
Specification for
Welding Procedure
and Performance
Figure
7.
ANSVAWS
82.1
:1998 can be used for
welding procedure and personnel qualification.
copies of those welding procedures should also be
placed in binders or protected with plastic covers
and made readily available at the shop floor to the
welding and inspection personnel. This simple step
often eliminates many procedural mistakes during
fabrication.
Personnel Qualification
Once the necessary welding procedures have been
qualified, the next step is to qualify the welders and
welding operators to the applicable code. The in-
spector has a key role to play in this activity; many
codes require the witnessing and documentation of

both the welder performance tests and the mechan-
ical testing of the resulting welded test specimens
by an inspector. Most codes and other standards
cover both the procedure qualification and the
welder performance testing.
0784265
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Figure 8. ASME Section
IX
also covers
qualification of procedures and personnel for
welding.
The inspector should be familiar with the period of
validity
for
the welder to remain qualified; this pe-
riod
is
usually noted in the applicable code. Most
welder qualifications are valid for a six-month pe-
riod, meaning that the qualification is valid as long
as the welder performs the same welding process to
which he or she qualified. If a welder does not per-
form any documented welding with the qualified
welding process in the speciried time period, the
welder is no longer considered qualified. Some
companies adhere strictly to the code qualification
requirements; other retest their welders once a year

regardless
of
the code requirements or continuing
use of the process. There are several software pro-
grams available that aid the tracking of welder
qualifications. Central certification of welders is
another option that allows a company
to
maintain
records
on
qualification. Independent third party
certifications of welders can provide value by in-,
troducing rigorous standardized procedures for
1
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performance testing that eliminates bias and subjec-

tivity in the qualification process.
In addition to welder qualification, attention must
be given to the personnel qualifications of those en-
gaged in nondestructive testing (NDT) which in-
cludes visual inspection. Before specifymg the type
and level of personnel involved in welding inspec-
tion, a decision must be made as to what types of
tests are to be performed. AWS administers a pro-
gram for the certification of welding inspectors
who are engaged in activities that span the welding
fabrication process, including visual inspection, to
assure that the delivered product meets the cus-
tomer’s specification. The AWS Certified Welding
Inspector program has been in existence for over
25
years and
is
recognized for its conhibutions to qual-
ity assurance within the welding industry.
Many welding operations require the application of
inspection methods that do not affect the service-
ability of the finished product. These nondestruc-
tive test methods differ in their scientific principles
and require specially trained and certified individu-
als for each method employed. The most common
NDT methods used today are visual testing (VT),
penetrant testing
(PT),
magnetic particle testing
(MT),

ultrasonic testing (UT), and radiographic test-
ing (RT). Each method has advantages and limita-
tions, and must be specified only after a thorough
understanding of the principles involved and how
they relate to the weldment being examined.
Figure
9.
ASNT SNT TC-1
A,
Recommended
Practice
for
Qüû/i@ing
NDT
Personnel.
The certification of NDT personnel can be em-
ployer-based in accordance with the Recommended
Practice SNT-TC-1 A, published by the American
Society for Nondestructive Testing (ASNT)
(see
Fig-
ure
9),
or can be third-party administered. These
third-party or central certification programs are of-
fered by both AWS and ASNT and provide uniform
personnel testing and portable documentation of
qualifications to the practitioner of specific NDT
methods.
Inspection Planning

At this point, we have qualified the welding proce-
dures, qualified and certified the welders, and qual-
ified and certified the inspectors. Now, the actual
fabrication is about to begin. But before the welding
begins, some thought must be given to the organi-
zation of the inspection efforts. (This step is often
the first action taken on many projects.) On large
projects, just keeping track of the welders and their
qualifications can be difficult, and as mentioned
above, one of several computer programs can often
aid this effort. When hundreds of welds are to be
made each day, identifying and tracking their status
also requires careful planning. Large numbers of
piping welds are often tracked from copies of
the isometric drawings used for fabrication. Shop-
fabricated vessels often maintain control using a
weld map sketch of the vessel in addition to the fab-
rication drawings. Again, computers often can aid
in
this tracking effort.
One of the early considerations for fabrication in-
spection
is
the necessary type and degree of inspec-
tion. Often, the fabrication code will specify the
inspection requirements but these may not be suffi-
cient for the application. While code inspection re-
quirements must be met for compliance, additional
inspection may be required. However, the inspec-
tion philosophy must keep in mind that delaying a

project for three months by requiring too-stringent
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inspection and quality assurance is often just as
costly as having premature failures from poor qual-
ity welds later during the manufacturing operation.
A
balance of quality and economics must always be
an important consideration in developing an in-
spection program. Remember, as one professor of
economics stated,
”General
Motors
is not in business
to
make cars;
they

are
in
business
to
make money.”
These inspection decisions do require a thorough
understanding
of
The criticality of the equipment.
Metallurgy of materials.
Welding processes.
Inspection methods.
Repairs and re-inspection.
If the material leaking has an extremely high eco-
nomic value, product containment becomes a very
high priority. Thus, criticality includes the dollar im-
pact of loss, and its effect on personnel.
If
a leak in a
pressure vessel permits a hazardous material to es-
cape and endanger personnel, subsequent inspec-
tions may include multiple inspection methods, or
the percentage
of
welds inspected is increased,
sometimes to a
100%
level. As expected, safety and
economics play a large role in determining criticality.
One approach used to aid in the criticality or level

of inspection decisions is often referred to as a
‘What If’ analysis. A group of personnel knowl-
edgeable about the overall manufacturing process
and materials considerations meet and review dif-
ferent scenarios using the ’What If’ technique. An
example of this would be the case where the group
asks,
”What
are
the
results
Ifvalve
B
fails?”
The analy-
sis of that scenario then determines the results and
if serious, may lead
to
increased inspection to en-
sure that valve
B
has the required quality.
It
is helpful to examine each of these above items
individually.
C
rit ical ity
A
potable water line designed for
150

psig is not
usually considered a critical item. But consider the
consequences of a weld failure in that piping if it
runs up the side of a 300-foot-high column to cool
the topmost section. If this cooling water supply is
interrupted, a process explosion may occur. In this
case, the degree
of
criticality decision should in-
clude the results of a premature failure. Inspection
of this water line example may warrant including
visual, penetrant, and even radiographic inspection.
Metallurg ¡cal Aspects
The metallurgical aspects should also be consid-
ered, including several general principles:
As
a metal’s strength increases, its weldability
The types of welding discontinuities often vary
Some materials have a greater propensity for
Welding affects a material’s heat treatment
Welding may reduce the material’s corrosion
Not every fabrication project has a metallurgical en-
gineer or metallurgist on staff to review all of the
metallurgical aspects, which makes it imperative
that the inspectors have a basic knowledge of these
fundamentals to aid in planning the inspection pro-
gram. Not being aware of the metallurgical aspects
of welding can lead to production difficulties or
even worse, premature failure of the component.
usually decreases.

between alloys.
cracking or porosity than others.
requirements.
resistance.
Welding
Processes
Figure
10-
Lengthy vertical Piping arrangements
may have a role in determining criticality.
Knowledge
of
the welding processes is also valu-
able because each different welding process brings
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its own advantages and limitations to the fabrica-
tion effort. Some welding processes are more prone

to cracking than others; some have a greater pro-
pensity for porosity; still others should remain in
the shop and not be used in the field under adverse
conditions. Consideration must be given to these
aspects early on, and often, the economics of a par-
ticular process, including productivity and cost
of
filler metal, are the primary drivers.
Inspection Methods
The next item to discuss for organizing the inspec-
tion effort is the selection of the required inspection,
or inspections, from the various methods available.
Just as welding processes have advantages and lim-
itations, inspection methods also have these same
attributes. Some are limited to finding surface dis-
continuities only; others can detect them below the
surface. Some methods require lengthy training
and experience, while other methods may be taught
effectively
in
just a few hours or days. The welding
inspector must have a thorough knowledge of the
more common inspection methods to assist in the
initial selection, and to aid the understanding of
later field inspection results.
Inspection Tip
#
1
PT Chasing for Crack
Removal

When penetrant testing
(Pï)
is used for inspec-
tion, it is often helpful to minimize the amount of
developer applied to the surface to just the bare
minimum required for developing a light, white
background. Applying multiple light coats of de-
veloper to the surface enables detection of very
fine cracking. Another important advantage of
developing to a minimum is that when cracks
are found, a minimum amount of the penetrant
is consumed in the light bleed-out of indications,
leaving an amount of penetrant remaining within
the crack. This remaining penetrant can be avail-
able for subsequent redevelopment steps only,
and does not require completing the entire
PT
procedure for re-inspection. Grinding is often
then used to remove the crack indications, and
the crack can be
chased
in stages for complete
removal.
Crack removal by chasing is done in several
stages; the first being to complete a careful
PT
with a light developer coating. The crack indica-
tion is then ground
a
bit to remove a thin layer of

metal,
1/16-
to l/S-inch depth, depending on the
amount
of
bleed-out. At this point, after light
grinding, a second light developer coat is ap-
plied to the freshly ground surface to determine
if the crack bleeds out again.
If
so,
additional
light grinding is done, followed by a third re-
development of the surface. Typically, the de-
veloper can be applied
2-5
times to obtain suc-
cessive indications, depending on the crack depth
and width and the thickness of the developer
coating. At the point where no indications are
observed on subsequent redevelopment
only,
the
surface is given a complete
IT
once more.
Chasing a crack by subsequent redevelopment
without new penetrant steps saves time and ef-
fort, since the time required for the complete
PT

process is not necessary. When chasing is used,
and no further indications are observed on the
surface after multiple developments, the entire
surface must then be re-cleaned and the entire
IT
process applied once again. If additional indica-
tions are found, the chasing procedure is com-
pleted again using only the application of the
developer in several stages. The alternate ap-
proach of chasing several times followed by a
complete
PT
procedure is repeated until no indi-
cations are observed during a complete
Pï,
indi-
cating complete removal of the defect.
After visual inspection, radiographic testing
(RT)
is
one of the more common methods selected for pres-
sure vessel and piping inspection. Often,
RT
is con-
sidered to be the best or most complete test method
since its capabilities are very good. However, one
serious limitation of RT is its inability to find flat,
planar discontinuities unless they are properly ori-
entated with respect to the incident radiation. The
planar discontinuity must not be oriented normal

or
near normal to the radiation beam if it is to become
visible on the film. This orientation requirement of
the radiation being in line with the edge can se-
verely limit detecting tight incomplete fusion on the
weld joint sidewall, especially for short circuiting
GMAW with its propensity for such problems.
Repairs and Re-inspection
Finally, attention should be given to how rejected
welds are
to
be handled. Will the rejected item be
scrapped, cut out, repaired?
If
weld repairs are to be
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made, will they be complete cutouts or will spot-

repair techniques be used? Care must be taken
to document the repair procedure used, the re-
inspection technique, and the re-inspection results.
Typically, the same inspection method used to find
the defect will be re-applied to the repairs.
Another decision to make is will the welder who
made the defective weld make the repair, or will
repair welders make all repairs? Both approaches
have been used very successfully. Often, in a
production-line approach, the rejects are recycled
through a repair center, leaving the production-line
welders online to maintain production. Repairs
made in the field may often require the original
welder to repair his/her rejects. This last approach
often has the potential for, and inherent advantage
of, being a learning experience for the original
welder. When a welder repairs his/her rejects, they
are usually able to see what condition caused the
reject, and consider how to avoid it in the future.
Production Welding-New
Fabrication
To
this point, we have devoted considerable effort
to
the planning and preparing for the actual fabrica-
tion welding and inspection. These first steps are
very important, and shortcuts should not be taken
in
these early stages. When poor planning and poor
preparation lead to welding defects, it is amazing

how there is always time to weld it correctly the
second time but not the first.
Inspection of production welding is done with a
wide variety of approaches. On one extreme, very
little attention is given to the inspection effort until
the final product is completed, if even then. Weld
quality is left entirely to the welder, yet quite often
this simple approach is adequate. On the opposite
end of that spectrum, very close control of base and
filler metals, joint fitup, tack welding, root-pass
quality, and final weld-out is maintained. Each step
is documented and signed off by an inspector.
Often this tight control is mandated by a code or
specification and is adhered to very closely.
One fact is certain regarding careful visual welding
inspection: a trained and qualified inspection force
is required, and they must be supported whole-
heartedly by management.
If
management consid-
ers the inspection force as a necessary expense
rather than a good investment, quality will often
suffer. The inspection force must also have copies
of, or access to copies of, all applicable and perti-
nent drawings and standards. The inspection su-
pervision should report directly to top management
and have no line responsibilities with respect to
production. This approach has shown itself to be a
successful path to weld quality.
To gain additional insights into visual inspection

programs for field welds, our discussion will now
move to a review of the fabrication of a typical pet-
rochemical process plant using an inspection ap-
proach somewhere between the opposite ends of
the spectrum noted above. As you might expect,
these plants are often built into open structures ex-
posed to the elements and this is an important con-
sideration regarding the inspection requirements.
The plant will often consist of several miles of pro-
cess piping of various diameters and alloys, con-
necting pressure vessel to pressure vessel, and often
placed into pipe bridges above ground level. Pres-
sure vessels are often placed throughout the sev-
eral-story structure and are also fabricated from
different alloys.
Figure
11.
Fabrication of a typical steel
structure for a petrochemical plant is often
multilevel. These structural welds must also be
inspected, often requiring an inspector with
agility as well as experience.
A
decision sometimes made in the above circum-
stances is that every field weld will be visually in-
spected by a welding inspector, and signed off on
the isometric drawing when acceptable. The ques-
tion to be asked in this circumstance is at what
point will the joint or weld be examined? Some feel
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the fitup inspection to be the most important, oth-
ers select the root pass as being the most critical in-
spection point, while still others feel inspecting
only the final weld is adequate. Sometimes, a com-
bination of these is used for weld inspection: the
joint fitup is inspected as well as the root and final
pass. All of these approaches have been used suc-
cessfully for field inspection.
In
addition to a first visual inspection, spot radiog-
raphy can be used as a conventional approach for
obtaining field weld quality. The on-site visual in-
spectors often play an important role in organizing
and documenting the RT inspections. Welds to be
radiographed on a

5%
spot basis are randomly se-
lected by the on-site inspection force using the iso-
metric sketches, and should include at least one
weld from each welder per month. RT results are
also noted on these same isometrics.
A
5% random
RT of field welds is often selected as a suitable
method for checking the welding skills and weld
quality of each welder. For critical services,
100%
of
the welds may be radiographed.
A
statistical re-
view of the required weld percentage to be radio-
graphed shows these
two
percentages to be optimal
for each consideration. If the welders are to be mon-
itored, the
5%
RT approach noted above
is
often
considered adequate.
If
weld quality must be cer-
tain,

100%
RT is usually specified.
In one project, all field welds received visual in-
spections of the fitup, the root pass, and the final
weld, and were signed off after each of the three
visual inspections. This "visual inspection only"
approach was used
in
lieu of the more conventional
spot radiography method and it was very success-
ful. Cost comparisons made between the two ap-
proaches showed a similar cost and similar results
for weld quality.
Inspection Tip
#
2
Identifying Field Welds
When setting
up
an
RT
program for pipe weld
radiography, it is helpful to require the number-
ing system used to delineate the pipe circum-
ference on the film such that the highest number
used to lay out the radiograph is equal to the
nominal pipe diameter being radiographed. For
codes that relate weld length to acceptable dis-
continuity lengths or sizes, this approach is espe-
cially helpful since the radiographic films can be

quickly examined to determine the pipe diame-
ter for the multiple shots. From the pipe diame-
ter, it
is
an easy step to determine weld length.
Typically, the radiographer takes 3 or
4
separate
exposures on pipe; the typical identification sys-
tem used for a 3-shot sequence is A-B,
B-C,
C-A,
and lead letters are placed around the pipe re-
sulting
in
this marking sequence on the film.
A far better approach is to use numbers, starting
at zero and increasing to the nominal pipe diam-
eter as the highest number. The applicable num-
bers are spaced evenly around the pipe diameter
while each pipe segment
is
radiographed. An
8-
inch diameter pipe would be numbered from
O
to
8
and the 3 resulting radiographic films would
show

0-3,
3-6,
and
6-0
respectively, with the
number
8
as the largest number in the last se-
quence (6-7-8-0). To aid field orientation of the
weld, the number
O
is always placed at the 12
o'clock position for horizontal piping with place-
ment of increasing numbers in a clockwise direc-
tion while facing North or East. For vertical
piping, the number
O
is always placed at the
North direction with subsequent numbers in-
creasing in a clockwise direction as if looking
down on the pipe in a plan view. This constant
film orientation during radiography aids
in
field
defect removal by avoiding defect location mix-
ups during field repairs.
To
speed field radiogra-
phy, the various pipe diameters to be tested are
given to the radiographer

in
advance, and mask-
ing tape
is
used on sections with the appropriate
numbers attached to them and with the required
spacing.
Repairs to new fabrication welds are an inherent
part of any fabrication project, and these must be
controlled and tracked as well as the original weld-
ing.
In
some cases, a particular weld may have to be
repaired
two
or more times before it becomes accept-
able, and each repair should be documented and
identified separately to avoid confusion. It may be
helpful to track the weld reject rate for each welder
over time. Such tracking can often lead to sorting out
welders having difficulties that may be solved with
additional training
in
the welding booth. It also can
aid
in
trend analysis for an organization to monitor
their continuous improvement status.
Initially, by using visual inspection and radiogra-
phy on a spot basis as the

two
inspection methods,
the weld reject rate may start at a relatively high
percentage. A îû%-15% rejection rate, and in some
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Figure 12. The diameter
of
pressure piping is
quite variable as shown. The piping in this
photo is covered with thermal insulation.
cases even higher, is not uncommon in the very
early stages of a field project. Until the welders gain
thefeel as to acceptable and unacceptable welds, the
reject rate can be expected to be high. However, as
the welders and inspectors spend time reviewing

the rejected welds, the weld quality improves and
the reject rates often decrease to percentages of
2%-5%. On one field project, the reject rate goal was
to be less than
5%,
which was determined to be
typ-
ical for shop welding using the same inspection ap-
proach. The shop goal became the field-welding
goal, and at project end, the overall reject rate was
less than
4%
for field welds.
Inspection of new fabrication is usually a very
straightforward operation. Decisions are made as to
the extent of inspection required, the trained in-
spectors ensure all inspections are completed, and
records are kept of the efforts. Occasionally, difficult
problems are encountered, but they are not the
usual experience. This is in contrast to the in-service
inspections that are covered a bit later.
Fa
br
kat
ion
Codes
To
this point, we have referred to fabrication codes
in only a general manner. A closer look at some of
the common fabrication codes is a worthwhile ef-

fort and is our next topic for discussion. Some codes
are intended to cover design and fabrication while
others apply to maintaining the equipment integ-
rity after they have been placed in service.
Generally, pressure vessels for petrochemical plants
are designed and fabricated to the ASME Boiler and
Pressure Vessel Code, an international code. Stor-
age tanks for petroleum products are usually de-
signed and fabricated to one of the AH Storage
Tank Codes, API 620 or 650. Petrochemical process
piping is often designed and fabricated to ACME
831.3 which specifically covers pressure piping for
petrochemical and refinery service. Buried process
or petroleum piping
is
often designed and fabri-
cated to API
1104
which covers “Welding of Pipe-
lines and Related Facilities.” Whenever any code is
used, it
is
important to make sure the current
edition of that code is on hand and specified for
use. Most codes are revised on some frequency and
many of the names and addresses found in Annex
A-Technical and Scientific Organizations, can be
helpful for contacting the appropriate code-
producer and determining the current versions.
A

discussion of several commonly used codes follows.
The ACME B&PV Code is published as a new edi-
tion July
l
every three years and revised by ad-
denda which are issued July
1
of each year. In
addition, interpretations to the Code are issued
every six months, as are Code Cases. Code Cases
are special-purpose, limited scope rules that pro-
vide alternative methods
of
construction to those in
the Code. Code Cases are never mandatory, but
may be used if the fabricator wishes to use them.
This
code has eleven sections and these are listed in
Annex B-1998 Boiler and Pressure Vessel Code
Sections.
Pressure vessels may be fabricated to one of three
ACME Code Section VI11 Divisions,
1,
2,
or
3.
Generally, they are fabricated to Division
1,
but
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Division
2
contains alternate rules and does permit
wall thickness reductions along with the require-
ments for increased NDT. Division
3
covers vessel
design pressures above 10,000 psig which are not
covered in the other
two
Divisions. Within a Divi-
sion, decisions regarding service conditions must
be made; for example, low-temperature services re-
quire different considerations such as impact test-
ing requirements for base and filler metals.
Figure

13.
ASME
Boiler
and
Pressure Vessel
CodeSection
VIII,
Division 1. This code is
often used for the design and fabrication of new
unfired pressure vessels. Its rules are very
helpful for in-service equipment examination,
but the
NBIC
is actually the governing document
for maintaining equipment service integrity.
As shown in Annex
B,
the inspector must have ac-
cess to several other Sections such as the four parts,
A,
B,
C, and
D,
of Section
II
for both ferrous and
nonferrous base metals, filler materials, and me-
chanical properties. Section
V
is the NDT section

and Section
IX
refers to ”Welding and Brazing
Qualifications.” Typically, the welding inspector
must have knowledge of each of these sections
since they will all likely apply to vessel welding.
ACME has adopted the AWS filler metal specifica-
tions
in
their entirety for Section
II,
Part C.
The API codes are issued periodically, not on a reg-
ularly scheduled basis, but Interpretations are is-
sued on an annual basis. The API code typically
used for pressure containment of piping is 1104.
Storage tanks are often fabricated to either API 620
or API 650;
620
is used for low-pressure services
(up to 15 psig) and 650 for atmospheric pressure
and open top tanks though it can also be used for
pressure containment construction using special
provisions.
ACME B31.3, Process Piping, is published as a new
edition every three years, and revisions are made
by addenda that are published annually. B31.3 was
specifically written for the petrochemical industry,
and contains several categories
of

services that vary
from routine to severe conditions. Using this code,
the engineer must select the category of service
from several choices as a first step for selecting the
appropriate inspection plan. The piping service cate-
gories are:
Category D Fluid Service-a fluid service that is
nonflammable, nontoxic, not damaging to hu-
mans, with pressures less than 150 psi, and tem-
peratures ranging from -20°F to 366°F.
Category M Fluid Service-a fluid service in
which the potential for personnel exposure is
significant, and exposure to a small quantity of
fluid can produce irreversible harm through con-
tact or breathing.
High-pressure Fluid Service-a fluid service that
exceeds pressures allowed by other ACME codes;
no upper pressure limit is stated.
Normal Fluid Service-a fluid service pertaining
to most piping covered by B31.3 and not subject
to the rules for Categories D, M, or High Pres-
sure, and which are not subject to severe cyclic
conditions. All piping is Normal Fluid Service
unless another category is designated.
In using ACME B31.3, the engineer determines the
actual piping conditions expected in service and
compares them with the above list to select the
appropriate category. Once this is done, the code
denotes actual inspection requirements for the
selected category. The various degrees of inspection

such as
RT
include
loo%,
random, spot, and
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random spot examinations, and these are defined in
In-Service
Inspections
Inspecting piping and equipment that has been in
service for some period of time presents several
unique aspects that must be considered, such as:
.
ACME
B31.3
as follows:
100%-complete examination

of
all of a specified
kind of item in a designated lot.
Random-omplete examination of a percentage
of a specified kind of item in a designated lot.
Spot-a specified partial examination of each of
a specified kind of item in a designated lot;
e.g.,
a
part of the length of shop-fabricated welds in
jacketed pipe.
Random Spot-a specified partial examination
of a percentage of a specified kind of item in a
designated lot.
As
one moves down the list, the amount of in-
spection given
is
decreasing. ACME B31.3 specifies
one of the above inspection categories depending
on
the fluid service category selected previously by
the engineer.
It is also helpful to note the separate definitions
given for Inspection and Examination. Often we
mistakenly use these words interchangeably. B31.3
defines them
as
follows:
Inspection applies to functions performed for the

owner by the owner’s inspector or the inspec-
tor’s delegates. An owner’s inspector conducts
inspections for the owner.
Examination applies to quality control functions
performed by the manufacturer (for components
only), fabricator, or erector.
An
examiner
is
a per-
son who performs quality-control examinations.
Inspection by the owner does not relieve the manu-
facturer, fabricator, or erector of the responsibility
for:
Providing materials, components, and work-
manship in accordance with code requirements
and engineering design.
Performing all required examinations.
Preparing suitable records of examinations and
To summarize this brief section on codes, the weld-
ing inspector must have copies of, or access to, the
applicable codes, read and understand them, and
apply the applicable requirements to the welding
operations.
As
shown above, the various new fabri-
cation codes can differ dramatically on their re-
quirements for welding inspection.
tests for the inspector’s use.
Which code will be used

as
the guideline?
Experience history-type of deterioration ex-
Expected corrosion rate, if any.
Frequency of inspection needed.
Type of inspection required.
Decontamination required for internal inspection.
Plus others aspects.
The three codes often used for in-service inspec-
tions of petrochemical and refinery piping and
equipment are:
National Board Inspection Code (NBIC),
A
Man-
ual
for
Boiler
and
Pressure Vessel Inspectors.
API 510,
Pressure Vessel Inspection Code: Mainfe-
name Inspection, Rafing, Repair, and Alteration.
API
570,
Piping lnspecfion Code: Inspection, Repair,
Alteration, and Rerating
of
ln-Service Piping Systems.
Each of the above has developed Inspector Certifi-
cation programs that are pertinent to the specific

codes. As always, certifications lend credibility to
any inspection program and are encouraged.
Often, for petrochemical plants, annual or biannual
inspections called ‘turnarounds’ or ’shutdowns’ are
scheduled to permit necessary inspections, repairs,
equipment modifications, or other work that cannot
be done while the plant is operating. These events
usually require considerable preplanning to com-
plete the required inspections and repairs in the
shortest time available to minimize production
losses. Work is typically scheduled to continue
around the clock and the inspection work is done in
shifts. This approach requires careful attention to
the communication procedure between successive
shifts to ensure completion of all inspections and
repairs.
A
variety
of
shift arrangements are possible for con-
tinuous work schedules: scheduling three 8-hour
shifts
for the 24-hour day has the advantage of per-
mitting the oncoming shift to overlap briefly with
the off-going shift for communication relay, both
written and verbal. Another approach used is to
pected,
if
any.
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I
Figure
14.
National Board Inspection Code-
A
Manual
for Boiler
and
Pressure Vessel
Inspectors
(NBIC). Many governing agencies
and codes require an Authorized Inspector for
boilers and pressure vessels, usually referring
to one certified as a National Board Inspector
working to the NBIC. The NBIC covers
installations other than those covered by

API
510 unless the jurisdiction rules otherwise.
have
two
10-hour shifts, with a two-hour span be-
tween the shifts to permit radiographic inspection
to occur with minimum personnel available. This
two-shift approach does present more difficulty on
relaying equipment or inspection status since the
verbal link does not occur, but it has been used suc-
cessfully when written communication is done
well.
Typically, in preplanning, if equipment history re-
ports and corrosion data are available, they are
carefully reviewed in an attempt to realistically esti-
mate the following:
Pressure
Vessel Inspection
Code:
Maintenance
Inspection, Rating,
Repair, and Alteration
API
610
EIGKTH
EDTTION,
JUNE
1097
Figure
15.

API 51
O.
Petroleum and
petrochemical process equipment integrity
must conform to 51
O.
Anticipated problems to be found.
Repairs likely to be needed.
Spare parts required.
Time allotment necessary for completing all re-
quired work.
Inspection personnel required.
Inspection equipment and supplies required.
Welding personnel required.
Other issues (asbestos removal, vessel entry
standbys, etc.).
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This approach, if done by experienced personnel,
usually minimizes or eliminates the unexpected
surprises that can cause extended delays in restart-
ing the plant.
A
good preplanning effort is usually
time and effort well spent, often resulting in consid-
erable savings by avoiding extended production
losses.
The inspection personnel used for shutdown work
needs to have considerable background and train-
ing in safety procedures, the particular chemical
or
manufacturing process, equipment inspection, and
repair experience. Often the equipment must be en-
tered to complete a thorough visual inspection and
this requires safe entry procedures and appropriate
standby personnel to ensure the safety of all person-
nel entering the vessels or piping. Knowledge
of
the
manufacturing process, the process chemistry, and
the equipment being inspected generally lead to
completion of the appropriate inspections. Repair
experience is also very helpful since the inspector
is
often the person most familiar with the equipment
internals and the person who not only finds the

ini-
tial equipment deterioration or damage and assists
with the repair procedure, but he/she must also fol-
low up on re-inspecting the field repairs.
Entering and inspecting pressure vessels must be
carefully done to comply with the required safety
procedures as well as to find any existing damage.
Prior to entering a process vessel, the following
steps must be completed as
a
minimum:
A
management-authorized vessel-entry form.
Vessel cleaned and decontaminated.
Vessel blanked out from all piping.
Vessel checked for explosive tendencies and
flammability.
Vessel checked for oxygen content-21%
required.
Lock, tag, and try of agitators or other mechani-
cal devices.
Removal of ail radioactive monitoring equip-
ment if they present a personnel hazard.
Mechanical ventilation of vessel if required by
permit.
A
management-authorized flame permit
if
weld-
ing

is to be done.
Appropriate safety equipment-gloves, hard
hat, goggles, safety shoes, safety harness or
wristlets.
Standby personnel on hand with radio, air horn,
etc.
Appropriate ladders to facilitate entry (scaffold-
ing may be required).
SCBA (Self-contained Breathing Apparatus)
available at vessel entry site.
Once all of the safety considerations have been sat-
isfied, the inspector must check the inspection
equipment to make sure the necessary tools are on
hand. There are several personal items each inspec-
tor should have to aid the visual inspection:
Good flashlight, with fresh batteries, and the ca-
Small scraper, such as a stiff putty knife.
Sharp scribe-a tungsten-pointed one is excel-
lox magnifier-lighted ones are available.
Pencil magnet.
10-12 foot tape.
Six-inch machinist’s scale.
Note pad and pen for notes, sketches.
Small tape recorder for dictation of conditions
A
belt pack to contain the above.
Most of the above items are readily available, but
several of the specialty items can be purchased
from inspection supply firms such as Metallurgical
Supply, Houston, Texas. Additional visual inspec-

tion items such as borescopes, digital or
35mm
cam-
eras, video cameras, and video probes can be very
useful for recording inspection results for future
comparison. Black-and-white camera technology is
often adequate, but color cameras are usually better
for documenting corrosion damage. While this
equipment can be purchased, rental is often the
most economical approach.
The next item to check is the equipment’s identifi-
cation; it must be confirmed by checking its
ID
plate. Some operating functions in a manufacturing
plant are such that more than one identical unit is
available for a particular function. Examples of this
are equipment duplicates that fill the need to take
pability to be focused to a spot.
lent,
or
a stainless-steel dental pick, or both.
(optional but very helpful).
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it in kind, or there may be spare pumps for a partic-
ular location to permit replacement of seals.
A
spare
unit having its own ID is put into place and opera-
tions continue. It is imperative that each unit’s ID
be confirmed before the inspection begins.
Many feel the vessel entry access port should be
the starting point for the vessel inspection; careful
examination prior to entering ensures it is not for-
gotten as you exit the vessel later. (In one case, the
entry nozzle was not inspected, and the existing
corrosion damage that was overlooked caused a
leak and a very expensive and unscheduled shut-
down on startup.) Typically, flange faces, nozzle
necks, and nozzle attachment welds are inspected
for mechanical or corrosion damage as the inspec-
tor makes the initial entry.
Once within the vessel, it is carefully and thor-
oughly inspected for mechanical and corrosion
damage. Vessel inspections may require removal of
internal manways between different levels, or baf-
fling which may obstruct the view of portions of the
vessel. Often, ladders or scaffolding are required to

gain access to all of the interior surfaces. Inspection
of surfaces usually requires accessibility within an
arm’s length; long-distance visual inspection is usu-
ally not adequate since damage may be overlooked.
Some inspectors take the position that if they can-
not touch a surface, they cannot adequately inspect
it.
When damage is found, it should be noted and de-
scribed in some manner to permit accurate report-
age later. The damaged surfaces should also be
marked legibly if further action is required during
the shutdown. For carbon steels, a soapstone
marker is quite good for marking; stainless steels
and other bright alloys may require a paint marker.
When using paint markers, it
is
imperative they do
not contain high sulfur, chlorides, zinc, lead or
other elements whose residue can cause damage to
the metals during subsequent cutting or welding
operations.
After the vessel interior is inspected, the exterior
must also be examined for deterioration.
This
can
be very difficult and costly if the vessel is insulated
as
so
many process vessels are. Damaged insulation
is often the first indication that insulation removal

and inspection may be required.
If
water can find
its way into the insulation via damaged vapor bar-
riers, the resulting moist, hot conditions can cause
severe corrosion of the external surfaces. Radiogra-
phy and ultrasonic testing are often used to inspect
for equipment damage without complete insulation
removal.
When the equipment inspection is complete, all re-
sults should be documented and discussed with the
appropriate management and maintenance person-
nel. Needed repairs are planned and discussed with
the welding or mechanical supervision to ensure
that all damaged areas are well understood as to
their location, extent of damage, and required re-
pairs. Often, the inspector will revisit the equip-
ment location or even reenter the vessel with the
repair personnel to point out exactly what is re-
quired. Once all repairs are completed, they must
be re-inspected.
Piping presents a difficult inspection task because
of several reasons: fluid velocities can create erosion
or corrosion problems on the interior; there may be
so
much of it, it often is not readily accessible at
ground level; it is often insulated, and usually is too
Piping Inspection Code
API
570

SECOND
EDITION. OCTOBER
IC98
Figure
16.
API
570.
This code applies to
maintaining the piping integrity
of
chemical
service piping.
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small to permit personnel entry for internal inspec-
tion. Again, as for pressure vessels, damaged pip-
ing insulation
is
often an indication that further
external inspection is necessary after insulation re-
moval.
RT

and UT are very helpful in determining
the condition of piping, both internally and exter-
nally. When making spot inspections on piping, pri-
mary attention is often given to those areas more
likely to suffer erosion/ corrosion such as locations
of changes in fluid direction at elbows, or areas of
high turbulence, such as branch connections or
valve and pump installations. Experience will often
dictate the trouble spots within a piping system.
Piping suffering from corrosion and wall thinning
may no longer be adequate for containing design
pressures. Sometimes it is possible
to
re-rate the
maximum pressure permitted to a lower value, but
often, piping suffering from wall thinning is
replaced. This same approach can be used for wall
thinning of vessels.
A
design engineer is given the
current condition of the piping or vessel and
through calculations determines the safe working
temperatures and pressures for the damaged
equipment.
Summary
Several aspects of pressure containment equipment
inspection have been reviewed. Distinction was
made between those national codes pertaining to
the design and fabrication of new pressure equip-
ment and those with applicability to maintaining

equipment and piping integrity after the items have
been placed in service. There are numerous techni-
cal references that treat the subject
in
much greater
detail, and the serious inspector
is
encouraged to
seek these out and increase his or her knowledge
and understanding of the entire inspection process.
I
have developed the very strong feeling that in-
spection does not cost money; it saves money. Man-
agement should look at their inspection forces not
as a drain on the economics of their business, but as
one of the more important divisions that protect
them from poor quality often leading to bankrupt-
ing lawsuits.
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Annex A-Technical and Scientific Organizations
Abrasives Engineering Society (AES)

P.O. Box 3157
Butler, PA 16003
(724) 282-6210; fax 282-6210
Aluminum Association (AA)
900 19th Street, N.W.
Suite 300
Washington,
DC
20006
(202) 682-8000; fax 682-8115
America Society for Testing Materials (ASTM)
100 Barr Harbor Drive
W. Conshohocken, PA 19428
(610) 832-9500; fax 832-9555
American Association
of
State Highway
&
Transportation Officials (AASHTO)
444
N. Capital Street, N.W.
Suite 249
Washington,
DC
20001
(202) 6245800; fax 624-5806
American Bureau
of
Shipping (ABS)
Two World Trade Center

106th Floor
New York,
NY
10048
(212) 839-5000; fax 839-5130
American Gas Association (AGA)
1515 Wilson Boulevard
Arlington, VA 22209
(703) 841-8400; fax 841-8406
American Institute of Mining, Metallurgical and
Petroleum Engineers (AIME)
Three ParkAvenue
New York,
NY
10016-5598
(212) 419-7676; fax 371-9622
American Institute of Plant Engineers (AIPE)
8180 Corporate Park Drive
Suite 305
Cincinnati,
OH
45242
(513) 489-2473; fax 247-7422
American Institute
of
Steel Construction (AISC)
One
E.
Wacker Drive
Suite 3100

Chicago, IL 60601-2001
(312) 670-2400; fax 670-6573
I
I
I
l
American Iron and Steel Institute (AISC)
1101
17th Street, N.W.
Washington,
DC
20036-4700
(202) 452-7100; fax 463-6573
American National Standards Institute (ANSI)
11
W.
42nd Street
13th Floor
New York,
NY
10036-8002
(212) 642-4900; fax 398-0023
American Nuclear Society (ANS)
555 N. Kensington Avenue
La Grange, IL 60526
(708) 579-8200; fax 579-8283
American Petroleum Institute (API)
1220
L
Street, N.W.

Washington,
DC
20005-8029
(202) 682-8000; fax 682-8115
Amencan Railway Engineering Association
(AREA)
50
F
Street, N.W.
Suite 7702
Washington,
DC
20001-2183
(202) 639-2190; fax 639-2183
American Society for NondestructiveTesting
(ASNT)
1711
Arlingate Lane
Columbus,
OH
43228-0518
(614) 274-6003; fax 274-6899
American Society
for
Quality (ASQ)
611
E.
Wisconsin Avenue
Milwaukee, WI 53202
(414) 272-8575; fax 272-1734

American Society of Civil Engineers (ASCE)
1801
Alexander Bell Drive
Reston, VA 20191-4400
(703) 295-6000; fax 295-6222
American Society of Mechanical Engineers (ASME)
Three ParkAvenue
New York,
NY
10016-5990
(800) 843-2763; fax (973) 882-1717
American Society of Safety Engineers (ASSE)
1800 East Oakton Street
Des
Plaines,
IL
60018-2187
(708) 692-4121; fax 296-9220
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American Water Works Association (AWWA)
6666 W. Quincy Avenue

Denver,
CO
80235
(303) 794-7711; fax 794-7310
American Welding Society (AWS)
550 N.W. LeJeune Road
Miami, FL 33126
(305) 443-9353; fax 443-7559
ASM International (ASM)
9639 Kinsman Road
Materials Park, OH 44073
(440) 338-5151; fax 338-4634
Association of American Railroads (AAR)
50
F
Street, N.W.
Washington, DC 20001
(202) 639-2100; fax 639-2286
Association of Iron and Steel Engineers (AISE)
Three Gateway Center
Suite 1900
Pittsburgh, PA 15222
(412) 281-6323; fax 471-4858
Canadian Standards Association (CSA)
178 Rexdale Boulevard
Rexdale, Ontario
M9W 1R3 Canada
(416) 747-4000; fax 747-4149
Compressed Gas Association (CGA)
1725 Jefferson Davis Highway

Suite 1004
Arlington,
VA
22202-4102
(703) 412-0900; fax 412-0128
Edison Welding Institute (EWI)
1250 Arthur
E.
Adams Drive
Columbus,
OH
43221
(614) 486-5000; fax 688-5001
Fabricators’ and Manufacturers’ Association
(FMA)
833 Featherstone Road
Rockford,
IL
61107-6302
(815) 399-8700; fax 399-7279
Institute of Electrical and Electronics Engineers
(IEEE)
Three ParkAvenue
New York,
NY
1006
(212) 419-7900; fax 752-4929
Institute of Industrial Engineers (IIE)
25 Technology Park
Norcross, GA 30092

(770) 449-0460; fax 263-8532
International Oxygen Manufacturers’ Association
(IOMA)
P.O.
Box 16248
Cleveland, OH 44116-0248
(216) 228-2166; fax 228-5810
International Titanium Association (ITA)
1871 Folsom Street
Suite 200
Boulder, CO 80302-5714
(303) 443-7515; fax 443-4406
Laser Institute (LI)
12424 Research Parkway
Suite 125
Orlando,
FL
32826
(407) 380-1553; fax 380-5588
Material Handling Industry (MHI)
8720 Red Oak Boulevard
Suite 201
Charlotte, NC 28217-3957
(704) 522-8644; fax 676-1199
National Association of Corrosion Engineers
(NACE)
P.O.
Box 218340
Houston,
TX

77218-8340
(281) 228-6200; fax 228-6300
National Board of Boiler and Pressure Vessel
Inspectors (NBBPVI)
1055 Crupper Avenue
Columbus,
OH
43229
(614) 888-8320; fax 888-0750
National Electrical Manufacturers’ Association
(NEMA)
1300 N. 17th Street
Suite 1847
Rosslyn,
VA
22209
(703) 841-3200; fax 841-5900
National Fire Protection Association (NFPA)
P.O.
Box 9101
One Batterymarch
Park
(617) 770-3000; fax 770-0700
National Institute
of
Standards and Technology
(NIST)
325 Broadway
Boulder, CO 80303-3328
Qu~~cY,

MA
02269-9101
(303) 497-3000
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=
National Society of Professional Engineers (NSPE)
1420
King
Street
1
(703) 684-2800; fax 836-4875
I
Alexandria, VA 22314
National Welding Supply Association (NWSA)
1900 Arch Street
Philadelphia, PA 19103

(215) 564-3484; fax 564-2175
Naval Inventory Point Center
700
Robins
Avenue
Philadelphia, PA 19111
(215) 697-2247; fax 697-5914
Order and Inquiry Desk
U.S.
Government Printing Office
Washington,
DC
20402
(202) 512-1800; fax 512-2250
Resistance Welder Manufacturers’ Association
(RWMA)
1900 Arch Street
Philadelphia, PA 19103
(215) 564-3484; fax 963-9785
Robotics Industries Association (RIA)
900 Victors Way
Ann Arbor, MI 48106
(734) 994-6088; 994-3338
Society of Petroleum Engineers (SPEI
222
Palisades Creek Drive
Richardson,
TX
75083
(972) 952-9393; fax 952-9435

Society of Women Engineers (SWE)
120 Wall Street
New York, NY 10005-3902
(212) 509-9577; fax 509-0224
Steel Tank Institute
(STI)
570 Oakwood Road
Lake Zurich, IL 60047
Uniform Boiler and Pressure Vessel Laws Society
(UBPVLS)
308 N. Evergreen Road
Suite 240
Louisville,
KY
40243-1010
(502) 244-6029; fax 244-6030
(847) 438-8265; 438-9766
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