Tip 0492 19

TIP 0402-19
ISSUED – 1993
REVISED – 1999
REVISED – 2005
REVISED – 2012
©2012 TAPPI
The information and data contained in this document were
prepared by a technical committee of the Association. The
committee and the Association assume no liability or responsibility
in connection with the use of such information or data, including
but not limited to any liability under patent, copyright, or trade
secret laws. The user is responsible for determining that this
document is the most recent edition published.
TIP Category: Automatically Periodically Reviewed (Five-year review)
TAPPI
CAUTION:
This Technical Information Paper may require the use, disposal, or both, of chemicals, which may present serious health hazards to humans.
Procedures for the handling of such substances are set forth on Material Safety Data Sheets, which must be developed by all manufacturers
and importers of potentially hazardous chemicals and maintained by all distributors of potentially hazardous chemicals. Prior to the use of this
Technical Information Paper, the user must determine whether any of the chemicals to be used or disposed of are potentially hazardous and, if
so, must follow strictly the procedures specified by both the manufacturer, as well as local, state, and federal authorities for safe use and
disposal of these chemicals.
Guidelines for nondestructive examination of suction
roll shells
Scope
The purpose of this Technical Information Paper is to provide technical guidance for nondestructive examination of
suction roll shells. Although this document is intended primarily for use with shells that have been in service, it is
also applicable to new shells. TAPPI TIP 0402-11 describes liquid dye penetrant examination techniques for new
shells (1). TIP 0402-17 (2) describes procedures for documentation of weld repairs which are sometimes performed
during manufacture of suction rolls.
Timely discovery of cracking, corrosion or other forms of distress is important for avoiding suction roll failures in
service. This TIP discusses various nondestructive examination techniques and provides general guidelines for
examination frequency. In addition, types of indications that are typically found in suction rolls, and procedures for
documenting shell condition are described. This document does not provide guidelines for determining suitability
for service or the remaining useful life of a particular shell.
Safety precautions
Maintenance inspection of suction roll shells may be done at the mill, on or off the paper machine, or at an off-mill
location. In all cases a written safety plan sometimes termed a “job safety breakdown” should be available and be
reviewed by all participating personnel before inspection is performed.
Internal inspection of suction roll shells may be designated as confined space entry, especially for on-machine
inspection where only one head may be removed. All applicable mill or shop safety procedures should be followed.
These may include, but not be limited to:
• lockout for on-machine inspection
• stable support of the roll during all stages of inspection
• provision of adequate ventilation when working with solvents, cleaners, or liquid penetrant inside the shell
• an attendant
• ground fault interrupters for electrical equipment
• personal protective equipment (safety glasses, safety shoes or boots, hearing protection)
• MSDS information for solvents, penetrants and WFMT fluids used.

TIP 0402-19 Guidelines for nondestructive examination of suction roll shells / 2
Overhead hazards may exist if cranes are in use. Compressed air or high-pressure water used to clean suction holes
may eject plugs of fiber from holes with sufficient velocity to cause eye injury. Spills of oil and testing fluids may
pose a slipping hazard.
Suction roll shells - general
Suction roll shells are manufactured from stainless steel or bronze and may be centrifugally cast, rolled-and-welded
from plate, formed from powder and hot isostatically pressed, or forged. Tables 1 and 2 list currently available
suction roll alloys. Table 3 lists alloys that are no longer produced. Suction holes are either twist or gun drilled.
Twist drilled holes may be reamed after drilling. In some cases, holes are countersunk on the shell external surface.
Suction rolls may be used “bare” or with elastomeric or composite covers. The outside surface of a few rolls has
been thermal sprayed with a hard thin tungsten carbide coating to resist wear.
Deterioration of suction roll shells can occur by one or more of the following mechanisms:
• Cracking - stress corrosion, corrosion fatigue, frictional heating
• Corrosion - pitting, crevice, or general
• Erosion (velocity enhanced corrosion) – e.g. hole enlargement in bronze rolls
• Mechanical damage (scoring or impact)
Examination frequency
Frequency of shell examination should depend primarily on the condition of the shell. Thorough cleaning and
careful examination of internal and external surfaces is recommended each time a shell is removed from the machine
and disassembled.
Examination of the shell surfaces for cracking should be performed on a regular basis using an appropriate NDE
technique (see Shell Examination Techniques). The frequency of examination for cracking should be based on
consideration of: 1) previous examination results for the shell; 2) history of previous shells in the same position; 3)
general service record of the shell alloy; and 4) the occurrence of incidents, which may have caused mechanical
damage. A sample report form is found in Appendix A. Appendix B is an example of a properly filled out form
documenting typical problems found in a suction roll shell. It is recommended a maximum service period between
examinations for cracking be established for each shell.
Table 1. Nominal compositions of copper base suction roll shell alloys
Composition(a)
, %Material
designation(s) Cu Sn Pb Zn Al Ni Fe Mn
C83600
1N bronze(b)
84-86 4-6 4-6 4-6
1.0
max.
GC-CuSn5ZnPb
C95810 (mod.)
GC-CuAl9.5Ni(c, d)
81.5-
83.5
9.0-9.5 4.0-4.5 3.0-3.5 0.5-1.0
C90500
GC-CuSn10Zn(c) 86-89 9-11
1.5
max.
1-3
1.0
max.
GC-CuSn10(e)
88-90 9-11
1.0
max.
(a) Composition range, wt%; additional elements may be added or present in minor amounts.
(b) Trade name Sandusky International.
(c) Trade name Kabelmetre Alloys.
(d) Size currently limited to 3,500 mm max. length.
(e) Discontinued.

3 / Guidelines for nondestructive examination of suction roll shells TIP 0402-19
Table 2. Nominal compositions of currently available stainless steel suction roll shell alloys a
Composition, %(a)
Material
C Cr Ni Mo Cu Mn Si
Austenitic
CF3M 0.02 17.7 13.8 2.3 — 1.3 0.8
Martensitic
CA-15, C-169 0.07 12.4 0.6 0.5 — 0.5 0.6
Duplex-Centrifugally Cast
Alloy 86,
Alloy EPV
0.02 26.0 6.8 — 2.0 0.8 0.7
ACX-100(b)
0.02 24.0 5.7 2.4 0.5 0.8 0.8
ACL-105, KRC-
A894
0.02 22.5 4.5 1.5 — 0.6 0.6
KCR-110 0.02 21.0 3.2 0.7 — 0.8 1.0
Duplex-Rolled and Welded
MetShell Pro,
3RE60 SRG(c) 0.02 18.5 5.0 2.8 — 1.5 1.5
2205 SRG
Plus(c) 0.02 22.0 5.2 2.9 — 1.5 0.7
2304 AVS(c)
0.02 22.7 4.7 0.3 — 1.5 0.8
LDX 2101(c)
0.02 21.4 1.5 0.3 0.2 5 0.7
Duplex-Powder Metallurgy
Duplok 22(d)
0.02 22.0 5.3 3.0 - 0.7 0.4
Duplok 27(d)
0.02 26.5 6.5 3.0 — 0.7 0.4
Duplex-Forged
PM-2-2106MC 0.06 21.5 5.0 0.5 1.0 0.5 0.6
(a) Typical composition, wt%; balance of composition is iron; other elements may be added or present in minor amounts.
(b) Contains nitrogen and cobalt.
(c) Contains nitrogen.
(d) Hot isostatic pressed; contains 0.3% nitrogen.
The interval between inspections for an uncracked shell can be based on the rotational speed of the roll and the nip
load. One paper company used the equation below.
Actual running time between inspections
(rounded to next interval year) = 500 / (roll speed, rpm + 0.2 X maximum nip load, pli)
When signs of deterioration are noted on a particular shell, the inspection method and frequency should be adjusted
to accurately trend the rate of deterioration. For additional guidance on examination frequency and a shell’s fitness
for service, the user can consult a machine builder, the shell manufacturer, or a qualified consultant.
Shell preparation
For the most complete examination, the roll should be taken out of the paper machine and the heads and internals
removed. The shell should be washed with water to remove residual fiber and deposits from all surfaces. High-
pressure water can be used to clean the suction holes, provided care is taken not to damage the cover. Chemical
solvents may also be used for cleaning shells; however, before chemical cleaning products are used on a covered
shell, the cover supplier should be consulted regarding any undesirable effects these chemicals may have on the
cover. Caution should be exercised when cleaning covered or bare bronze shells with hot caustic. Laboratory testing
has indicated that 1N bronze and GC-CuSn5ZnPb may exhibit surface roughening and pitting if exposed to caustic
cleaning solutions at elevated temperatures when the caustic solution has a pH value exceeding 12.1.

Table 3. Nominal compositions of discontinued stainless steel suction roll shell alloysa
Composition, %(a)
Material
C Cr Ni Mo Cu Mn Si
Austenitic
CF8M 0.05 17.7 13.8 2.3 — 1.3 0.8
PM-3-1811-
MN
0.015 16.5 13.5 2.1 — 1.6 0.5
Martensitic
DSS-69 0.04 12.4 4.0 0.7 — 0.7 0.6
A-70 0.03 11.9 4.0 1.5 — 0.8 0.5
Duplex–Centrifugally Cast
A-63 0.05 21.8 9.4 2.7 — 0.8 1.3
A-75 0.02 26.0 6.8 — — 0.8 0.5
VK-A170 0.07 23.3 10.7 2.1 — 0.7 1.5
VK-A171 0.07 22.2 8.3 1.2 — 0.8 1.1
VK-A271 0.06 24.6 4.3 0.7 — 0.7 1.3
VK-A378(b)
0.05 20.0 5.0 2.0 3.0 0.7 1.0
KCR-A682(c)
0.06 18.0 5.5 2.3 3.2 0.7 0.7
Forged
PM 4 1300M 0.1 13.0 1.0 2.1 - 0.9 0.7
PM-3-1804M 0.06 17.9 4.0 2.0 — 0.6 0.6
PM-3-1808N 0.08 18.0 9.0 — — 2.0 1.0
PM-2-2205 0.07 26.0 4.0 0.8 — 1.2 1.3
(a) Typical composition, wt%, balance of composition is iron: other elements may be added
or present in minor amounts.
(b) Contains nitrogen and tungsten.
(c) Contains niobium (columbium).
It is imperative that the shell, including the holes, be clean and dry for nondestructive test techniques such as
penetrant and magnetic particle testing. The shell should be moved away from the mist and humidity at the wet end
of the paper machine. Additionally, the shell should be properly supported to prevent unexpected movement during
examination. The shell and/or cover manufacturer’s guidelines for proper shell support should be followed. Rotation
of the shell may facilitate some examination techniques, e.g., penetrant testing and wet fluorescent magnetic particle
testing.
If a shell is examined in position in the paper machine special efforts may be required to provide access to the
external or internal surfaces. Examination of the external surface may require removal of the wire or felt.
Examination of the internal surface requires removal of at least one head and the internals, which in turn necessitates
supplemental, external support of the shell.
If the external surface of a bare shell is to be ground, it should be examined for cracks and its general condition
should be characterized both before and after grinding. Grinding or honing the surface of a shell can smear over fine
remnant cracks; for example, honing may mask cracks caused by frictional overheating by the suction box seal. To
ensure complete crack removal after honing or grinding, inspection should be focused on the areas of the most
severe cracking. Areas with visual indications of smearing or heat burnishing should be lightly polished or sanded in
order to expose masked cracks.
Covered shells
The cover should be examined for blisters, discoloration, streaks, textural variations, cracks, edge disbonding, or
other anomalies. Periodic, thorough examinations of roll covers that remain in service should be performed by an
experienced and qualified inspector.

Before chemical products such as cleaning solvents and penetrants are used on a covered shell, the cover supplier
should be consulted regarding any undesirable effects these chemicals may have on the cover. Some solvents and
solvent residues can damage (soften, harden, crack) certain covers and can weaken the cover bond strength (3).
If the cover is being replaced, the external surface of the shell should be examined after the cover has been
completely removed and the shell has been drill cleaned (drill cleaning is always performed before a new cover is
applied in order to remove residue in the holes and to secure the drill pattern in a CNC program for later drilling
with the new cover in place.)
Inspection personnel qualifications
It is important to use NDT technicians experienced both in performing the techniques selected for suction roll shell
examination and in interpreting the findings. For the techniques in subsections 4, 5, and 8 under “Shell Examination
Techniques,” certification to Level I per ASNT SNT-TC-1A (4) (or equivalent) should be a minimum requirement
for technicians who perform the examination, provided interpretation of the results is done by a technician certified
to at least ASNT Level II. Additionally, prior to any shell examination, the owner should verify that the inspector is
familiar with the inspection technique, the owner’s specifications, and the intricacies of examining suction roll
shells.
The test procedures discussed in subsections 1, 2, 3, 6, 7, and 9 under “Shell Examination Techniques” should be
performed by personnel with applicable certification or demonstrated expertise in such methods. Previous
experience in suction roll testing is desirable.
Shell examination techniques
Written procedures should be used for all shell examination techniques. Commonly used techniques are described
below. Additionally, the shell manufacturer may recommend inspection techniques for the particular shell material.
Visual examination
All accessible surfaces of the shell should be examined for signs of cracking, corrosion, erosion, or mechanical
damage. Figure 1 shows external corrosion of a stainless steel shell. Figure 2 shows thermal cracking on the inside
surface of a stainless steel shell.
Visual examination can be aided by a magnifying glass or low-power microscope. Good lighting is essential for
finding small cracks and for seeing into suction holes. Portable, fluorescent lamps provide diffuse light which
facilitates internal and external examinations. Incandescent lighting at a low angle helps reveal cracks, corrosion
pits, and surface irregularities such as grooving.
Fig. 1. Corrosion damage to a CA-15 martensitic stainless steel shell caused by muriatic acid felt
cleaning.

Video imaging
All accessible surfaces of the shell should be examined for signs of cracking, corrosion, erosion, or mechanical
damage. The shell’s ID and OD (if required) should be inspected using a laptop controlled digital microscope.
Digital micrographs should be taken during the examination using the correct magnification to show the detail
needed for each application (e.g. no magnification for obvious indications and 50-200 times magnification for
minute indications). Figure 3 shows hole-to-hole cracking at 50 times magnification in duplex stainless steel shells.
Figure 4 is an example of thermal fatigue cracking at 50 times magnification that has progressed into hole to hole
fatigue cracking. Figure 5 shows the start of fatigue cracking emanating from porosity in the cast duplex stainless
steel.
If cracking is present the holes that are connected by cracking should be cleaned with sandpaper and the depth
checked with a lighted precision borescope. Locate the bottom of the crack with the borescope, mark its depth with a
stop on the scope’s shaft and measure it using a set of calipers. If the cracking connects several holes the depth
should be measured in several places along its length. Very shallow cracking, less than 1 mm deep, should be noted
as surface depth. If impact damage is present the surrounding area should be checked with the digital microscope
for micro-cracking that could radiate from these areas.
All of the measurements, information and pictures regarding the flawed areas should be noted as per on the video
image report. The angle from the identification stamp on the front end face to the indication should be measured
with the use of an angle meter. Video imaging has been shown to be extremely sensitive, particularly in the softer
bronze shells where metal smearing and corrosion can hide indications from dye penetrant techniques as seen in
Fig. 6.
Fig. 2. Thermal cracking of a duplex stainless steel shell due to frictional heating and quenching

Fig. 3. Hole-to-hole cracking in a duplex stainless steel shell at 50X
Fig. 4. Hole-to-hole fatigue crack with thermal cracking in a duplex stainless steel shell at 50X
Fig. 5. Surface cracking associated with casting porosity in cast duplex stainless steel 50X

Fig. 6. Corrosion and fatigue cracking in bronze shell 50 X
Measurement of hole enlargement in bronze rolls
Bronze shells are susceptible to corrosion and erosion corrosion (Figs. 7 and 8) which can lead to suction hole
enlargement. Black corrosion product on a bronze shell indicates thiosulfate ions or other sulfur species may be
present in the white water.
Hole enlargement weakens a shell; failure occurs when the ligaments between enlarged holes become too thin, Fig.
9. The greatest hole enlargement can be located some distance inside the hole. If the roll has been covered, thinning
will not be apparent on visual examination from the outside surface.
The diameter of suction holes can be measured in order to trend hole enlargement over the life of the shell. Gages
are available for measuring hole diameter - one such gage is shown in Fig. 10. The typical hole enlargement profile
should be determined on several holes across the shell. Hole diameters should be measured at the inside surface, mid
thickness, and outside surface of the shell. Figure 11 shows a typical hole enlargement survey; the roll failed a few
months after the survey.
Hole enlargement can also be measured volumetrically. Duct tape is used to seal off a representative number of
holes and they are filled with water using a pipette. Since the volume of water is known, the average volume of the
holes can be calculated and the percentage hole enlargement determined. This is a rapid technique for measuring
hole sizes at different places along the shell.
Allowable hole enlargement depends on:
• Shell thickness
• Margin of safety used in the shell design
• Shell loads, especially if they exceed the original design values.
A machine builder, roll manufacturer, or qualified consultant can help to determine the allowable hole enlargement
for a particular suction roll. See also reference (5).
NOTE 1: Shell thickness is reduced by external surface grinding and internal wear or honing. Cumulative thinning can be significant for
shells that have been ground many times. Shell thickness reduction should be tracked for shells that are ground.

Fig. 7. Corrosion and erosion on the internal surface of a bronze shell. Comparison of the area outside
the trim left side) with the area inside the wire shows enlarged suction holes in the latter area.
Fig. 8. Corrosion on the external surface of a bronze shell. Visible corrosion on the external surface may
be an indicator of hole enlargement
Fig. 9. Cross section from a failed bronze couch roll. The ligaments between holes thinned to the point of
shell failure.

Fig.10. One example of a hole diameter gage. The gage shown has been modified in order to measure
holes where the diameter at depth is greater than the diameter at the accessible surface. The gauge is
inserted to the depth desired and the knurled end is turned to expand the tips until they contact the inside
surface of the hole. The index mark is noted and the tips are retracted in order to withdraw the gauge.
Once the gage is removed the index mark setting at depth is restored and the tip diameter is measured
using a micrometer.
0.24
0.26
0.28
0.3
0.32
0.34
0.36
0.38
0.4
0 2 4 6 8 10 12 14 16 18 20 22 24
Distance From Front Side (Feet)
HoleDiameter(Inches)
40% enlargement
30% enlargement
outside
midwall
inside
PM1 BRONZE COUCH #1251
JANUARY 2004
Fig. 11.Hole enlargement survey. Hole diameters were measured at the inside and outside surfaces and
mid thickness of a covered roll.

Penetrant testing (PT)
Penetrant testing is recommended for detecting cracks in stainless steel shells. Water-washable, color-contrast (red
dye) penetrant and water washable, fluorescent penetrant are most commonly used. Solvent-removable color-
contrast penetrant can also be used. Figs. 12, 13, 14 and 15 show typical PT crack indications in stainless steel
shells.
Bronze shells can be penetrant tested unless the surface is too rough due to corrosion, especially around the holes.
Appendix E provides more information on liquid penetrant testing of bronze rolls.
The surfaces of the shell and holes must be clean, free of dirt and pulp residue, and completely dry prior to
inspection. Fiber plugs must be removed from the suction holes before penetrant testing or bleed out of penetrant
from the holes will interfere with testing. Compressed air or high pressure water can be used to remove fiber build
ups from the holes. The roll can be dried by placing a clean-burning heater in the open end of the roll while blowing
the water out of the holes from the external surface with dry and oil-free compressed air.
Shell temperature should be above 16°C (60°F); the preferred temperature range to facilitate the capillary action of
penetrant is 27°C to 38°C (80°F to 100°F) or as recommended in the directions for the penetrant.
PT should be performed in accordance with ASTM E 165, “Standard Practice for Liquid Penetrant Inspection
Method” (6) and/or ASTM E 1417 “Practice for Liquid Penetrant Examination” (7). Additional ASTM
specifications (8–13) are available for penetrant testing. Water-washable fluorescent should proceed following the
steps listed in Appendix C.
Low power magnification visual examination can be useful to determine if fine, short, penetrant indications are
cracks.
Fig. 12. Thermal cracking in an ACX-100 cast duplex stainless steel pickup roll revealed by color contrast liquid
penetrant testing.

Fig. 13. Cracking in a cast duplex stainless steel press roll which initiated at a weld repair and grew in
both the axial and circumferential directions.
Fig. 14. PT of a cast duplex stainless steel suction roll shell. There are faint indication at the two grain
boundaries joining holes 9 and 10 and also off the right side of hole b. These may be incipient cracks.
Fig. 15 shows WFMT of the same area.

Fig. 15. WFMT of the same area as Fig. 14. Grain boundaries generate indications. The indications
between holes 9 and 10 and off the right side of hole b could be interpreted as grain boundaries while in
fact they may be incipient cracks based on the PT results in Fig. 14.
Magnetic particle testing (MT)
Wet fluorescent magnetic particle testing (WFMT), using a contour probe (yoke), is recommended for crack testing
in martensitic stainless steel shells (e.g. CA-15). (The shell should be checked with a magnet to confirm it is
magnetic).
Magnetic particle testing should not be used for crack detection in duplex stainless steel shells even though they are
ferromagnetic. Duplex stainless steels have a microstructure with discrete ferrite (magnetic) and austenite (non
magnetic) phases, MT can give false linear indications at the boundaries between the magnetic and non-magnetic
phases, Fig. 15.
Probe spacing of the yoke for MT should not exceed 150 mm (6 in.), unless the magnetic field can be verified
beyond this spacing. Each area should be examined twice, with the yoke for the second examination at 90° to the
first examination position. The examination should be performed in accordance with ASTM E 709, “Standard
Practice for Magnetic Particle Examination” (14) and/or ASTM E1444, “Practice for Magnetic Particle
Examination” (15) and should proceed following the steps listed in Appendix D.
Low power magnification visual examination can be useful to determine if fine, short, magnetic particle indications
are cracks.
In-place (In-situ) metallographic examination
This technique can be used in specific areas of concern identified by one of the above examination techniques. For
example, the mode of cracking (stress corrosion, corrosion fatigue, frictional overheating) and its origin might be
determined.
Small areas of the shell surface are prepared by light grinding, followed by polishing, etching, and examination with
a portable, metallurgical microscope. Some microscopes are equipped with cameras for photographic documentation

of significant findings. Surface replicas may also be taken for optical or electron microscope examination in the
laboratory. In-place metallographic examination techniques for suction rolls have been described by Anliker (16).
Figure 16 shows a one-ligament crack in a VKA-378 cast duplex stainless steel press roll. In-place metallography
was used to determine that the crack originated at a weld repair, Fig. 17. Figure 18 shows thermal crack initiation at
austenite/ferrite grain boundaries in a cast duplex stainless steel shell.
Fig. 16. One ligament crack found in a VKA-378 cast duplex stainless steel suction press roll by penetrant
testing.
Fig. 17. In-place metallographic examination of the cracked ligament shown in Fig. 12. The crack initiated
at a weld repair

Fig. 18. Frictional overheat cracking on the inside surface of a cast duplex stainless steel shell. Arrows
indicate crack initiation at austenite/ferrite grain boundaries.
Figure 19 shows a liquid penetrant indication in a bronze press roll. In-place metallography, Figs. 20 and 21,
revealed the indication occurred at shallow corrosion along microstructural features and was not due to cracking.
Appendix E provides additional information about the interpretation of in-place metallography of bronze rolls.
Fig. 19. Penetrant indication in a 1N bronze press roll

Fig. 20. In-place metallography of the penetrant indication shown in Fig. 16.
Fig. 21. Higher magnification view of the in-place metallography location shown in Fig. 20. The indication
was due to corrosion as outlined in Appendix E.
Borescopic examination
A rigid borescope can be used to examine the suction hole walls for corrosion and cracking. As with the internal
surface of the shell, suction holes show accumulated damage. In other words, since there is no periodic regrinding of

the holes, surface corrosion and cracking of the hole surfaces can continue to occur and propagate. In some cases,
crack depth can be estimated by using a borescope to follow the crack down a suction hole. Various print and video
camera attachments for borescopes are available to document suction hole wall conditions.
Suction holes to be examined should be free of all residual pulp and deposits. Holes can be cleaned by using a
variable speed drill with adhesive-backed sand paper on a suitable diameter twist drill or mandrel.
Eddy current testing (ET)
Eddy current testing, described in 1986 by Hiraishi et al. (17) has not developed into a practical crack testing method
for suction rolls. Testing for cracks with ET should be carefully qualified to ensure its effectiveness.
Acoustic emission testing (AET)
This technique involves modest loading of the roll, usually in four evenly spaced positions around the
circumference, after high frequency sound sensors have been attached at appropriate locations. The sensors detect
acoustic emissions (micro-seismic events) arising at discontinuities like cracks. Computerized analysis of the
acoustic signals allows the location and nature of the emitting source to be defined.
There are no industry standards for AET of suction roll shells. ASTM E 2374 (18) provides guidelines for
verification of acoustic emission system performance. Reference 19 describes AET of suction rolls. The procedures
for AET and the experience base of AET practitioners should be evaluated by mill personnel.
Documentation and trending of examination findings
The objective of a suction roll shell inspection report is to document the condition of the shell in sufficient detail that
comparison with previous and subsequent examinations will permit trending of the rate of any deterioration.
For reporting purposes, indications can generally be grouped into four classifications:
• cracks
• corrosion (e.g. pits, hole enlargement, surface roughness)
• mechanical damage (e.g. grooves, impact marks, gouges)
• manufacturing defects (e.g. porosity, inclusions, shrinkage)
Features and indications revealed by the examination should be plotted to scale and described in detail in a report
similar to the example shown on the following pages. Data sheets should be prepared for both internal and external
surfaces.
Indication locations should be shown in relation to a reference mark, such as the shell serial number often located on
the “front end” of the shell, so they can be reliably found during subsequent examinations. Specific conditions
should be documented photographically (including a scale) and/or by making a pencil “rubbing”. Extra attention
should be given to areas with weld repairs (2). If cracking or corrosion pitting occurs over large areas, the
boundaries of these areas should be indicated on the data sheet. Crack length typically is defined by the number of
holes joined or ligaments crossed.
This TIP does not address the fitness for service of cracked suction rolls. Crack growth rate increases significantly
with crack length (20, 21) and the growth rate of cracks cannot be reliably predicted. A decision to operate a cracked
suction roll shell should be made in consultation with a machine builder, the shell manufacturer, or a qualified
expert.
Keywords
Vacuum rolls, Nondestructive tests, Inspection, Corrosion, Cracks, Stainless steel, Bronze

Additional information
Effective date of issue: September 6, 2012
Working Group:
Paul Glogowski, Chairman, Metso Paper USA
Craig Reid, Acuren Group Inc.
Max Moskal, M&M Engineering Associates, Inc.
Literature cited
1. TAPPI TIP 0402-11 “Liquid Dye Penetrant Testing of New Suction Roll Shells.”
2. TAPPI TIP 0402-17 “Weld Repairs on New Suction Roll Shells.”
3. “Increased chemical, solvent use can intensify press roll cover damage.” Win Pierce, Pulp and Paper, May
1993, pp. 91, 92, 97, 98, 101, 102.
4. ASNT-SNT-TC-1A, Recommended practice for qualification of NDT personnel.
5. “Failure prediction of bronze suction rolls in paper machines.” Max Moskal and Henry Luming, Proceedings of
the 8th
International Symposium on Corrosion in the Pulp and Paper Industry, Stockholm, 1995. pp. 217 – 222.
6. ASTM E 165 “Standard Test Method for Liquid Penetrant Examination.”
7. ASTM E 1417 “Standard Practice for Liquid Penetrant Examination.”
8. ASTM E 1220 “Standard Test Method for Visible Liquid Penetrant Examination Using the Solvent-Removable
Process.”
9. ASTM E 1418 “Standard Test Method for Visible Penetrant Examination Using the Water Washable Process.”
10. ASTM E 1208 ”Standard Test Method for Fluorescent Liquid Penetrant Examination Using the Lipophilic Post-
Emulsification Process.”
11. ASTM E 1209 “Standard Test Method for Fluorescent Liquid Penetrant Examination Using the Water-
Washable Process.”
12. ASTM E 1210 “Standard Test Method for Fluorescent Liquid Penetrant Examination Using the Hydrophilic
Post-Emulsification Process.”
13. ASTM E 1219 “Standard Test Method for Fluorescent Liquid Penetrant Examination Using the Solvent-
Removable Process.”
14. ASTM E 709 “Standard Guide for Magnetic Particle Examination.”
15. ASTM E 1444 “Standard Practice for Magnetic Particle Examination.”
16. “Field and Laboratory Examination of Suction Rolls.” Dennis M. Anliker. Proceedings of the 1984 TAPPI
Engineering Conference, Book 1, TAPPI Press, Atlanta, p.209.
17. “Application of Non-Destructive Inspection by New Eddy Current Testing on Suction Roll Shells.” H. Hiraishi,
T. Kawai, and S. Kitagawa,, Proceedings of the 5th
International Symposium on Corrosion in the Pulp and Paper
Industry, Vancouver, BC, Canada, 1986, p.63.
18. ASTM E 2374 “Standard guide for acoustic emission system performance verification.
19. “Application report: acoustic emission testing of suction rolls” Stanley F. Botten, 2001 TAPPI Engineering
Conference, San Antonio, paper 18-1 in Conference CD, Atlanta, TAPPI.
20. “Corrosion fatigue crack propagation of high strength stainless steels used in suction rolls”. C. Kelley, J.
Vestoala, V. Sailas, and R. Pelloux. Tappi Journal, 58:11 (1975), pp. 80-85.
21. Cracking and inspection of stainless steel suction rolls,” Craig Reid, 2001 TAPPI Engineering Conference, San
Antonio, paper 18-2 in Conference CD, Atlanta, TAPPI.

Appendix A. Sample report form
Instructions: Prepare a drawing of the internal and external surfaces of the suction roll shell as shown in this
example. Plot the location of significant indications using a coordinate system, as shown on the following page.
Detail of specific areas may be documented by photographs or pencil rubbings of these areas. Include manufacturing
information, as shown.
Overall view of shell
Manufacturer: __________________________ Length: ______________________________
Shell serial no. (S/N): ____________________ O.D.: ________________________________
Reference mark (if S/N not used): __________ Thickness: ____________________________
Shell material: __________________________ Time in service: ________________________
Reported by:
Company:
Date:
Page ___ of ___

Appendix B. Sample report form
Internal/External* Surface
Shell S/N: _________________________________________ Reported by: ________________
Examination method:_________________________________ Date: ______________________
Coordinates of indications or areas of indications
Indication Circ. Dist.
From S/N
Axial Dist. From
front end
Description Detailed by: Change
Since Last
Inspection
A entire 200 to 262 in. band of mech.
gouging
photo None
B entire 130 to 220 in. area of minor
pitting
photo None
C 50 to 53 in. 200 in. 3 ½ in. circ. Crack
(12 holes joined)
rubbing extended
1 in.
D 40 in. 40 to 80 in 10 in. axial crack rubbing no
extension
E etc.
View of internal/external* surface of roll rolled out, as observed from inside/outside*. Circumferential measurements
are made in clockwise/counterclockwise* direction from first digit of S/N.
*delete the one that does not apply to this page
Page ___ of ___

Appendix C. Water washable fluorescent penetrant testing
1. Starting on the internal surface, at one end of the shell (the closed end if only one head has been removed), the
first four to six feet of the shell shall be covered with penetrant. Brushing on with a large brush (such as a paint-
brush) is recommended for uniform and complete coverage. After the penetrant has been applied, the entire area
shall be examined under black light to assure total coverage. The penetrant shall dwell for a minimum of thirty
minutes.
2. After the required dwell time, excess penetrant shall be removed with a controlled, coarse water wash. The water
wash shall be started on the outer surface of the shell on the top 180°. This will provide for thorough removal of
excess penetrant from the holes. After this wash has been performed, proceed to the inner surface and complete the
wash. All washed surfaces should be viewed under black light to assure all excess penetrant has been removed.
3. The examination surface shall then be thoroughly dried
4. After thorough drying, a nonaqueous, wet developer shall be applied to the examination surface. The examination
shall begin immediately after the developer has been applied. All areas shall be reinspected after a five to seven
minute development time, looking for minor “bleed outs” caused by very fine or shallow indications.
5. Steps 1 through 4 shall be repeated until the entire surface of the shell has been examined.
6. Examination of the external surface of the shell using the penetrant method should follow the internal inspection
(when applicable). The same precautions regarding dwell time, drying, and developing time shall apply. The shell
will likely need to be rotated to allow 100% examination.
Appendix D. Wet fluorescent magnetic particle testing
Both water- and hydrocarbon-based WFMT solutions exist. Choice of solutions may be based on the wetting ability
of the solutions on the particular shell surface. The yoke should be of either fixed- or moveable-leg style. AC or DC
current may be used. The yoke should have a lifting power of 10 pounds in the AC mode or 40 pounds in the DC
mode at the maximum pole spacing which will be used. Black lights should be routinely checked to assure adequate
light intensity.
1. Position the yoke on the shell surface to be examined and apply the (AC or DC) magnetic current.
2. Spray the fluorescent particles over the area of interest, between the poles of the yoke, while the current remains
on.
3. Then, switch off the magnetizing current and remove the yoke from the shell surface.
4. Evaluate the magnetic particle indications using a black light.
5. Repeat steps 1 through 4 for the same area with the yoke poles oriented 90° from the original position.
Examinations of the shell surface should be conducted with sufficient overlap to assure 100% coverage at the
established test sensitivity, and should include the base material for at least ½ inch beyond either side of the area to
be examined.
Appendix E. Characteristics of 1N bronze
Centrifugally cast 1N bronze is prone to shrinkage porosity, tin segregation, and other imperfections which are
unavoidable due to the solidification characteristics of bronze. Even in the highest quality centrifugal castings, 2%
to 5% shrinkage porosity can be expected especially at the inside surface. There is also linear type porosity
associated with tin segregation that can give crack like penetrant indications as the porosity appears as a broken line.
1N bronze also contains approximately 5% lead by volume which is added for machinability. The lead is insoluble
in copper and appears in the microstructure as black globules. All of the above can show up as indications during
liquid penetrant examination and can be misinterpreted by inspection personnel who are not familiar with the
unusual characteristics of centrifugally cast bronze.
g

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